nilfs2: get rid of private page allocator
[linux-2.6.git] / fs / nilfs2 / segment.c
1 /*
2  * segment.c - NILFS segment constructor.
3  *
4  * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
5  *
6  * This program is free software; you can redistribute it and/or modify
7  * it under the terms of the GNU General Public License as published by
8  * the Free Software Foundation; either version 2 of the License, or
9  * (at your option) any later version.
10  *
11  * This program is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14  * GNU General Public License for more details.
15  *
16  * You should have received a copy of the GNU General Public License
17  * along with this program; if not, write to the Free Software
18  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
19  *
20  * Written by Ryusuke Konishi <ryusuke@osrg.net>
21  *
22  */
23
24 #include <linux/pagemap.h>
25 #include <linux/buffer_head.h>
26 #include <linux/writeback.h>
27 #include <linux/bio.h>
28 #include <linux/completion.h>
29 #include <linux/blkdev.h>
30 #include <linux/backing-dev.h>
31 #include <linux/freezer.h>
32 #include <linux/kthread.h>
33 #include <linux/crc32.h>
34 #include <linux/pagevec.h>
35 #include <linux/slab.h>
36 #include "nilfs.h"
37 #include "btnode.h"
38 #include "page.h"
39 #include "segment.h"
40 #include "sufile.h"
41 #include "cpfile.h"
42 #include "ifile.h"
43 #include "segbuf.h"
44
45
46 /*
47  * Segment constructor
48  */
49 #define SC_N_INODEVEC   16   /* Size of locally allocated inode vector */
50
51 #define SC_MAX_SEGDELTA 64   /* Upper limit of the number of segments
52                                 appended in collection retry loop */
53
54 /* Construction mode */
55 enum {
56         SC_LSEG_SR = 1, /* Make a logical segment having a super root */
57         SC_LSEG_DSYNC,  /* Flush data blocks of a given file and make
58                            a logical segment without a super root */
59         SC_FLUSH_FILE,  /* Flush data files, leads to segment writes without
60                            creating a checkpoint */
61         SC_FLUSH_DAT,   /* Flush DAT file. This also creates segments without
62                            a checkpoint */
63 };
64
65 /* Stage numbers of dirty block collection */
66 enum {
67         NILFS_ST_INIT = 0,
68         NILFS_ST_GC,            /* Collecting dirty blocks for GC */
69         NILFS_ST_FILE,
70         NILFS_ST_IFILE,
71         NILFS_ST_CPFILE,
72         NILFS_ST_SUFILE,
73         NILFS_ST_DAT,
74         NILFS_ST_SR,            /* Super root */
75         NILFS_ST_DSYNC,         /* Data sync blocks */
76         NILFS_ST_DONE,
77 };
78
79 /* State flags of collection */
80 #define NILFS_CF_NODE           0x0001  /* Collecting node blocks */
81 #define NILFS_CF_IFILE_STARTED  0x0002  /* IFILE stage has started */
82 #define NILFS_CF_SUFREED        0x0004  /* segment usages has been freed */
83 #define NILFS_CF_HISTORY_MASK   (NILFS_CF_IFILE_STARTED | NILFS_CF_SUFREED)
84
85 /* Operations depending on the construction mode and file type */
86 struct nilfs_sc_operations {
87         int (*collect_data)(struct nilfs_sc_info *, struct buffer_head *,
88                             struct inode *);
89         int (*collect_node)(struct nilfs_sc_info *, struct buffer_head *,
90                             struct inode *);
91         int (*collect_bmap)(struct nilfs_sc_info *, struct buffer_head *,
92                             struct inode *);
93         void (*write_data_binfo)(struct nilfs_sc_info *,
94                                  struct nilfs_segsum_pointer *,
95                                  union nilfs_binfo *);
96         void (*write_node_binfo)(struct nilfs_sc_info *,
97                                  struct nilfs_segsum_pointer *,
98                                  union nilfs_binfo *);
99 };
100
101 /*
102  * Other definitions
103  */
104 static void nilfs_segctor_start_timer(struct nilfs_sc_info *);
105 static void nilfs_segctor_do_flush(struct nilfs_sc_info *, int);
106 static void nilfs_segctor_do_immediate_flush(struct nilfs_sc_info *);
107 static void nilfs_dispose_list(struct the_nilfs *, struct list_head *, int);
108
109 #define nilfs_cnt32_gt(a, b)   \
110         (typecheck(__u32, a) && typecheck(__u32, b) && \
111          ((__s32)(b) - (__s32)(a) < 0))
112 #define nilfs_cnt32_ge(a, b)   \
113         (typecheck(__u32, a) && typecheck(__u32, b) && \
114          ((__s32)(a) - (__s32)(b) >= 0))
115 #define nilfs_cnt32_lt(a, b)  nilfs_cnt32_gt(b, a)
116 #define nilfs_cnt32_le(a, b)  nilfs_cnt32_ge(b, a)
117
118 static int nilfs_prepare_segment_lock(struct nilfs_transaction_info *ti)
119 {
120         struct nilfs_transaction_info *cur_ti = current->journal_info;
121         void *save = NULL;
122
123         if (cur_ti) {
124                 if (cur_ti->ti_magic == NILFS_TI_MAGIC)
125                         return ++cur_ti->ti_count;
126                 else {
127                         /*
128                          * If journal_info field is occupied by other FS,
129                          * it is saved and will be restored on
130                          * nilfs_transaction_commit().
131                          */
132                         printk(KERN_WARNING
133                                "NILFS warning: journal info from a different "
134                                "FS\n");
135                         save = current->journal_info;
136                 }
137         }
138         if (!ti) {
139                 ti = kmem_cache_alloc(nilfs_transaction_cachep, GFP_NOFS);
140                 if (!ti)
141                         return -ENOMEM;
142                 ti->ti_flags = NILFS_TI_DYNAMIC_ALLOC;
143         } else {
144                 ti->ti_flags = 0;
145         }
146         ti->ti_count = 0;
147         ti->ti_save = save;
148         ti->ti_magic = NILFS_TI_MAGIC;
149         current->journal_info = ti;
150         return 0;
151 }
152
153 /**
154  * nilfs_transaction_begin - start indivisible file operations.
155  * @sb: super block
156  * @ti: nilfs_transaction_info
157  * @vacancy_check: flags for vacancy rate checks
158  *
159  * nilfs_transaction_begin() acquires a reader/writer semaphore, called
160  * the segment semaphore, to make a segment construction and write tasks
161  * exclusive.  The function is used with nilfs_transaction_commit() in pairs.
162  * The region enclosed by these two functions can be nested.  To avoid a
163  * deadlock, the semaphore is only acquired or released in the outermost call.
164  *
165  * This function allocates a nilfs_transaction_info struct to keep context
166  * information on it.  It is initialized and hooked onto the current task in
167  * the outermost call.  If a pre-allocated struct is given to @ti, it is used
168  * instead; otherwise a new struct is assigned from a slab.
169  *
170  * When @vacancy_check flag is set, this function will check the amount of
171  * free space, and will wait for the GC to reclaim disk space if low capacity.
172  *
173  * Return Value: On success, 0 is returned. On error, one of the following
174  * negative error code is returned.
175  *
176  * %-ENOMEM - Insufficient memory available.
177  *
178  * %-ENOSPC - No space left on device
179  */
180 int nilfs_transaction_begin(struct super_block *sb,
181                             struct nilfs_transaction_info *ti,
182                             int vacancy_check)
183 {
184         struct the_nilfs *nilfs;
185         int ret = nilfs_prepare_segment_lock(ti);
186
187         if (unlikely(ret < 0))
188                 return ret;
189         if (ret > 0)
190                 return 0;
191
192         vfs_check_frozen(sb, SB_FREEZE_WRITE);
193
194         nilfs = sb->s_fs_info;
195         down_read(&nilfs->ns_segctor_sem);
196         if (vacancy_check && nilfs_near_disk_full(nilfs)) {
197                 up_read(&nilfs->ns_segctor_sem);
198                 ret = -ENOSPC;
199                 goto failed;
200         }
201         return 0;
202
203  failed:
204         ti = current->journal_info;
205         current->journal_info = ti->ti_save;
206         if (ti->ti_flags & NILFS_TI_DYNAMIC_ALLOC)
207                 kmem_cache_free(nilfs_transaction_cachep, ti);
208         return ret;
209 }
210
211 /**
212  * nilfs_transaction_commit - commit indivisible file operations.
213  * @sb: super block
214  *
215  * nilfs_transaction_commit() releases the read semaphore which is
216  * acquired by nilfs_transaction_begin(). This is only performed
217  * in outermost call of this function.  If a commit flag is set,
218  * nilfs_transaction_commit() sets a timer to start the segment
219  * constructor.  If a sync flag is set, it starts construction
220  * directly.
221  */
222 int nilfs_transaction_commit(struct super_block *sb)
223 {
224         struct nilfs_transaction_info *ti = current->journal_info;
225         struct the_nilfs *nilfs = sb->s_fs_info;
226         int err = 0;
227
228         BUG_ON(ti == NULL || ti->ti_magic != NILFS_TI_MAGIC);
229         ti->ti_flags |= NILFS_TI_COMMIT;
230         if (ti->ti_count > 0) {
231                 ti->ti_count--;
232                 return 0;
233         }
234         if (nilfs->ns_writer) {
235                 struct nilfs_sc_info *sci = nilfs->ns_writer;
236
237                 if (ti->ti_flags & NILFS_TI_COMMIT)
238                         nilfs_segctor_start_timer(sci);
239                 if (atomic_read(&nilfs->ns_ndirtyblks) > sci->sc_watermark)
240                         nilfs_segctor_do_flush(sci, 0);
241         }
242         up_read(&nilfs->ns_segctor_sem);
243         current->journal_info = ti->ti_save;
244
245         if (ti->ti_flags & NILFS_TI_SYNC)
246                 err = nilfs_construct_segment(sb);
247         if (ti->ti_flags & NILFS_TI_DYNAMIC_ALLOC)
248                 kmem_cache_free(nilfs_transaction_cachep, ti);
249         return err;
250 }
251
252 void nilfs_transaction_abort(struct super_block *sb)
253 {
254         struct nilfs_transaction_info *ti = current->journal_info;
255         struct the_nilfs *nilfs = sb->s_fs_info;
256
257         BUG_ON(ti == NULL || ti->ti_magic != NILFS_TI_MAGIC);
258         if (ti->ti_count > 0) {
259                 ti->ti_count--;
260                 return;
261         }
262         up_read(&nilfs->ns_segctor_sem);
263
264         current->journal_info = ti->ti_save;
265         if (ti->ti_flags & NILFS_TI_DYNAMIC_ALLOC)
266                 kmem_cache_free(nilfs_transaction_cachep, ti);
267 }
268
269 void nilfs_relax_pressure_in_lock(struct super_block *sb)
270 {
271         struct the_nilfs *nilfs = sb->s_fs_info;
272         struct nilfs_sc_info *sci = nilfs->ns_writer;
273
274         if (!sci || !sci->sc_flush_request)
275                 return;
276
277         set_bit(NILFS_SC_PRIOR_FLUSH, &sci->sc_flags);
278         up_read(&nilfs->ns_segctor_sem);
279
280         down_write(&nilfs->ns_segctor_sem);
281         if (sci->sc_flush_request &&
282             test_bit(NILFS_SC_PRIOR_FLUSH, &sci->sc_flags)) {
283                 struct nilfs_transaction_info *ti = current->journal_info;
284
285                 ti->ti_flags |= NILFS_TI_WRITER;
286                 nilfs_segctor_do_immediate_flush(sci);
287                 ti->ti_flags &= ~NILFS_TI_WRITER;
288         }
289         downgrade_write(&nilfs->ns_segctor_sem);
290 }
291
292 static void nilfs_transaction_lock(struct super_block *sb,
293                                    struct nilfs_transaction_info *ti,
294                                    int gcflag)
295 {
296         struct nilfs_transaction_info *cur_ti = current->journal_info;
297         struct the_nilfs *nilfs = sb->s_fs_info;
298         struct nilfs_sc_info *sci = nilfs->ns_writer;
299
300         WARN_ON(cur_ti);
301         ti->ti_flags = NILFS_TI_WRITER;
302         ti->ti_count = 0;
303         ti->ti_save = cur_ti;
304         ti->ti_magic = NILFS_TI_MAGIC;
305         INIT_LIST_HEAD(&ti->ti_garbage);
306         current->journal_info = ti;
307
308         for (;;) {
309                 down_write(&nilfs->ns_segctor_sem);
310                 if (!test_bit(NILFS_SC_PRIOR_FLUSH, &sci->sc_flags))
311                         break;
312
313                 nilfs_segctor_do_immediate_flush(sci);
314
315                 up_write(&nilfs->ns_segctor_sem);
316                 yield();
317         }
318         if (gcflag)
319                 ti->ti_flags |= NILFS_TI_GC;
320 }
321
322 static void nilfs_transaction_unlock(struct super_block *sb)
323 {
324         struct nilfs_transaction_info *ti = current->journal_info;
325         struct the_nilfs *nilfs = sb->s_fs_info;
326
327         BUG_ON(ti == NULL || ti->ti_magic != NILFS_TI_MAGIC);
328         BUG_ON(ti->ti_count > 0);
329
330         up_write(&nilfs->ns_segctor_sem);
331         current->journal_info = ti->ti_save;
332         if (!list_empty(&ti->ti_garbage))
333                 nilfs_dispose_list(nilfs, &ti->ti_garbage, 0);
334 }
335
336 static void *nilfs_segctor_map_segsum_entry(struct nilfs_sc_info *sci,
337                                             struct nilfs_segsum_pointer *ssp,
338                                             unsigned bytes)
339 {
340         struct nilfs_segment_buffer *segbuf = sci->sc_curseg;
341         unsigned blocksize = sci->sc_super->s_blocksize;
342         void *p;
343
344         if (unlikely(ssp->offset + bytes > blocksize)) {
345                 ssp->offset = 0;
346                 BUG_ON(NILFS_SEGBUF_BH_IS_LAST(ssp->bh,
347                                                &segbuf->sb_segsum_buffers));
348                 ssp->bh = NILFS_SEGBUF_NEXT_BH(ssp->bh);
349         }
350         p = ssp->bh->b_data + ssp->offset;
351         ssp->offset += bytes;
352         return p;
353 }
354
355 /**
356  * nilfs_segctor_reset_segment_buffer - reset the current segment buffer
357  * @sci: nilfs_sc_info
358  */
359 static int nilfs_segctor_reset_segment_buffer(struct nilfs_sc_info *sci)
360 {
361         struct nilfs_segment_buffer *segbuf = sci->sc_curseg;
362         struct buffer_head *sumbh;
363         unsigned sumbytes;
364         unsigned flags = 0;
365         int err;
366
367         if (nilfs_doing_gc())
368                 flags = NILFS_SS_GC;
369         err = nilfs_segbuf_reset(segbuf, flags, sci->sc_seg_ctime, sci->sc_cno);
370         if (unlikely(err))
371                 return err;
372
373         sumbh = NILFS_SEGBUF_FIRST_BH(&segbuf->sb_segsum_buffers);
374         sumbytes = segbuf->sb_sum.sumbytes;
375         sci->sc_finfo_ptr.bh = sumbh;  sci->sc_finfo_ptr.offset = sumbytes;
376         sci->sc_binfo_ptr.bh = sumbh;  sci->sc_binfo_ptr.offset = sumbytes;
377         sci->sc_blk_cnt = sci->sc_datablk_cnt = 0;
378         return 0;
379 }
380
381 static int nilfs_segctor_feed_segment(struct nilfs_sc_info *sci)
382 {
383         sci->sc_nblk_this_inc += sci->sc_curseg->sb_sum.nblocks;
384         if (NILFS_SEGBUF_IS_LAST(sci->sc_curseg, &sci->sc_segbufs))
385                 return -E2BIG; /* The current segment is filled up
386                                   (internal code) */
387         sci->sc_curseg = NILFS_NEXT_SEGBUF(sci->sc_curseg);
388         return nilfs_segctor_reset_segment_buffer(sci);
389 }
390
391 static int nilfs_segctor_add_super_root(struct nilfs_sc_info *sci)
392 {
393         struct nilfs_segment_buffer *segbuf = sci->sc_curseg;
394         int err;
395
396         if (segbuf->sb_sum.nblocks >= segbuf->sb_rest_blocks) {
397                 err = nilfs_segctor_feed_segment(sci);
398                 if (err)
399                         return err;
400                 segbuf = sci->sc_curseg;
401         }
402         err = nilfs_segbuf_extend_payload(segbuf, &segbuf->sb_super_root);
403         if (likely(!err))
404                 segbuf->sb_sum.flags |= NILFS_SS_SR;
405         return err;
406 }
407
408 /*
409  * Functions for making segment summary and payloads
410  */
411 static int nilfs_segctor_segsum_block_required(
412         struct nilfs_sc_info *sci, const struct nilfs_segsum_pointer *ssp,
413         unsigned binfo_size)
414 {
415         unsigned blocksize = sci->sc_super->s_blocksize;
416         /* Size of finfo and binfo is enough small against blocksize */
417
418         return ssp->offset + binfo_size +
419                 (!sci->sc_blk_cnt ? sizeof(struct nilfs_finfo) : 0) >
420                 blocksize;
421 }
422
423 static void nilfs_segctor_begin_finfo(struct nilfs_sc_info *sci,
424                                       struct inode *inode)
425 {
426         sci->sc_curseg->sb_sum.nfinfo++;
427         sci->sc_binfo_ptr = sci->sc_finfo_ptr;
428         nilfs_segctor_map_segsum_entry(
429                 sci, &sci->sc_binfo_ptr, sizeof(struct nilfs_finfo));
430
431         if (NILFS_I(inode)->i_root &&
432             !test_bit(NILFS_SC_HAVE_DELTA, &sci->sc_flags))
433                 set_bit(NILFS_SC_HAVE_DELTA, &sci->sc_flags);
434         /* skip finfo */
435 }
436
437 static void nilfs_segctor_end_finfo(struct nilfs_sc_info *sci,
438                                     struct inode *inode)
439 {
440         struct nilfs_finfo *finfo;
441         struct nilfs_inode_info *ii;
442         struct nilfs_segment_buffer *segbuf;
443         __u64 cno;
444
445         if (sci->sc_blk_cnt == 0)
446                 return;
447
448         ii = NILFS_I(inode);
449
450         if (test_bit(NILFS_I_GCINODE, &ii->i_state))
451                 cno = ii->i_cno;
452         else if (NILFS_ROOT_METADATA_FILE(inode->i_ino))
453                 cno = 0;
454         else
455                 cno = sci->sc_cno;
456
457         finfo = nilfs_segctor_map_segsum_entry(sci, &sci->sc_finfo_ptr,
458                                                  sizeof(*finfo));
459         finfo->fi_ino = cpu_to_le64(inode->i_ino);
460         finfo->fi_nblocks = cpu_to_le32(sci->sc_blk_cnt);
461         finfo->fi_ndatablk = cpu_to_le32(sci->sc_datablk_cnt);
462         finfo->fi_cno = cpu_to_le64(cno);
463
464         segbuf = sci->sc_curseg;
465         segbuf->sb_sum.sumbytes = sci->sc_binfo_ptr.offset +
466                 sci->sc_super->s_blocksize * (segbuf->sb_sum.nsumblk - 1);
467         sci->sc_finfo_ptr = sci->sc_binfo_ptr;
468         sci->sc_blk_cnt = sci->sc_datablk_cnt = 0;
469 }
470
471 static int nilfs_segctor_add_file_block(struct nilfs_sc_info *sci,
472                                         struct buffer_head *bh,
473                                         struct inode *inode,
474                                         unsigned binfo_size)
475 {
476         struct nilfs_segment_buffer *segbuf;
477         int required, err = 0;
478
479  retry:
480         segbuf = sci->sc_curseg;
481         required = nilfs_segctor_segsum_block_required(
482                 sci, &sci->sc_binfo_ptr, binfo_size);
483         if (segbuf->sb_sum.nblocks + required + 1 > segbuf->sb_rest_blocks) {
484                 nilfs_segctor_end_finfo(sci, inode);
485                 err = nilfs_segctor_feed_segment(sci);
486                 if (err)
487                         return err;
488                 goto retry;
489         }
490         if (unlikely(required)) {
491                 err = nilfs_segbuf_extend_segsum(segbuf);
492                 if (unlikely(err))
493                         goto failed;
494         }
495         if (sci->sc_blk_cnt == 0)
496                 nilfs_segctor_begin_finfo(sci, inode);
497
498         nilfs_segctor_map_segsum_entry(sci, &sci->sc_binfo_ptr, binfo_size);
499         /* Substitution to vblocknr is delayed until update_blocknr() */
500         nilfs_segbuf_add_file_buffer(segbuf, bh);
501         sci->sc_blk_cnt++;
502  failed:
503         return err;
504 }
505
506 /*
507  * Callback functions that enumerate, mark, and collect dirty blocks
508  */
509 static int nilfs_collect_file_data(struct nilfs_sc_info *sci,
510                                    struct buffer_head *bh, struct inode *inode)
511 {
512         int err;
513
514         err = nilfs_bmap_propagate(NILFS_I(inode)->i_bmap, bh);
515         if (err < 0)
516                 return err;
517
518         err = nilfs_segctor_add_file_block(sci, bh, inode,
519                                            sizeof(struct nilfs_binfo_v));
520         if (!err)
521                 sci->sc_datablk_cnt++;
522         return err;
523 }
524
525 static int nilfs_collect_file_node(struct nilfs_sc_info *sci,
526                                    struct buffer_head *bh,
527                                    struct inode *inode)
528 {
529         return nilfs_bmap_propagate(NILFS_I(inode)->i_bmap, bh);
530 }
531
532 static int nilfs_collect_file_bmap(struct nilfs_sc_info *sci,
533                                    struct buffer_head *bh,
534                                    struct inode *inode)
535 {
536         WARN_ON(!buffer_dirty(bh));
537         return nilfs_segctor_add_file_block(sci, bh, inode, sizeof(__le64));
538 }
539
540 static void nilfs_write_file_data_binfo(struct nilfs_sc_info *sci,
541                                         struct nilfs_segsum_pointer *ssp,
542                                         union nilfs_binfo *binfo)
543 {
544         struct nilfs_binfo_v *binfo_v = nilfs_segctor_map_segsum_entry(
545                 sci, ssp, sizeof(*binfo_v));
546         *binfo_v = binfo->bi_v;
547 }
548
549 static void nilfs_write_file_node_binfo(struct nilfs_sc_info *sci,
550                                         struct nilfs_segsum_pointer *ssp,
551                                         union nilfs_binfo *binfo)
552 {
553         __le64 *vblocknr = nilfs_segctor_map_segsum_entry(
554                 sci, ssp, sizeof(*vblocknr));
555         *vblocknr = binfo->bi_v.bi_vblocknr;
556 }
557
558 static struct nilfs_sc_operations nilfs_sc_file_ops = {
559         .collect_data = nilfs_collect_file_data,
560         .collect_node = nilfs_collect_file_node,
561         .collect_bmap = nilfs_collect_file_bmap,
562         .write_data_binfo = nilfs_write_file_data_binfo,
563         .write_node_binfo = nilfs_write_file_node_binfo,
564 };
565
566 static int nilfs_collect_dat_data(struct nilfs_sc_info *sci,
567                                   struct buffer_head *bh, struct inode *inode)
568 {
569         int err;
570
571         err = nilfs_bmap_propagate(NILFS_I(inode)->i_bmap, bh);
572         if (err < 0)
573                 return err;
574
575         err = nilfs_segctor_add_file_block(sci, bh, inode, sizeof(__le64));
576         if (!err)
577                 sci->sc_datablk_cnt++;
578         return err;
579 }
580
581 static int nilfs_collect_dat_bmap(struct nilfs_sc_info *sci,
582                                   struct buffer_head *bh, struct inode *inode)
583 {
584         WARN_ON(!buffer_dirty(bh));
585         return nilfs_segctor_add_file_block(sci, bh, inode,
586                                             sizeof(struct nilfs_binfo_dat));
587 }
588
589 static void nilfs_write_dat_data_binfo(struct nilfs_sc_info *sci,
590                                        struct nilfs_segsum_pointer *ssp,
591                                        union nilfs_binfo *binfo)
592 {
593         __le64 *blkoff = nilfs_segctor_map_segsum_entry(sci, ssp,
594                                                           sizeof(*blkoff));
595         *blkoff = binfo->bi_dat.bi_blkoff;
596 }
597
598 static void nilfs_write_dat_node_binfo(struct nilfs_sc_info *sci,
599                                        struct nilfs_segsum_pointer *ssp,
600                                        union nilfs_binfo *binfo)
601 {
602         struct nilfs_binfo_dat *binfo_dat =
603                 nilfs_segctor_map_segsum_entry(sci, ssp, sizeof(*binfo_dat));
604         *binfo_dat = binfo->bi_dat;
605 }
606
607 static struct nilfs_sc_operations nilfs_sc_dat_ops = {
608         .collect_data = nilfs_collect_dat_data,
609         .collect_node = nilfs_collect_file_node,
610         .collect_bmap = nilfs_collect_dat_bmap,
611         .write_data_binfo = nilfs_write_dat_data_binfo,
612         .write_node_binfo = nilfs_write_dat_node_binfo,
613 };
614
615 static struct nilfs_sc_operations nilfs_sc_dsync_ops = {
616         .collect_data = nilfs_collect_file_data,
617         .collect_node = NULL,
618         .collect_bmap = NULL,
619         .write_data_binfo = nilfs_write_file_data_binfo,
620         .write_node_binfo = NULL,
621 };
622
623 static size_t nilfs_lookup_dirty_data_buffers(struct inode *inode,
624                                               struct list_head *listp,
625                                               size_t nlimit,
626                                               loff_t start, loff_t end)
627 {
628         struct address_space *mapping = inode->i_mapping;
629         struct pagevec pvec;
630         pgoff_t index = 0, last = ULONG_MAX;
631         size_t ndirties = 0;
632         int i;
633
634         if (unlikely(start != 0 || end != LLONG_MAX)) {
635                 /*
636                  * A valid range is given for sync-ing data pages. The
637                  * range is rounded to per-page; extra dirty buffers
638                  * may be included if blocksize < pagesize.
639                  */
640                 index = start >> PAGE_SHIFT;
641                 last = end >> PAGE_SHIFT;
642         }
643         pagevec_init(&pvec, 0);
644  repeat:
645         if (unlikely(index > last) ||
646             !pagevec_lookup_tag(&pvec, mapping, &index, PAGECACHE_TAG_DIRTY,
647                                 min_t(pgoff_t, last - index,
648                                       PAGEVEC_SIZE - 1) + 1))
649                 return ndirties;
650
651         for (i = 0; i < pagevec_count(&pvec); i++) {
652                 struct buffer_head *bh, *head;
653                 struct page *page = pvec.pages[i];
654
655                 if (unlikely(page->index > last))
656                         break;
657
658                 if (mapping->host) {
659                         lock_page(page);
660                         if (!page_has_buffers(page))
661                                 create_empty_buffers(page,
662                                                      1 << inode->i_blkbits, 0);
663                         unlock_page(page);
664                 }
665
666                 bh = head = page_buffers(page);
667                 do {
668                         if (!buffer_dirty(bh))
669                                 continue;
670                         get_bh(bh);
671                         list_add_tail(&bh->b_assoc_buffers, listp);
672                         ndirties++;
673                         if (unlikely(ndirties >= nlimit)) {
674                                 pagevec_release(&pvec);
675                                 cond_resched();
676                                 return ndirties;
677                         }
678                 } while (bh = bh->b_this_page, bh != head);
679         }
680         pagevec_release(&pvec);
681         cond_resched();
682         goto repeat;
683 }
684
685 static void nilfs_lookup_dirty_node_buffers(struct inode *inode,
686                                             struct list_head *listp)
687 {
688         struct nilfs_inode_info *ii = NILFS_I(inode);
689         struct address_space *mapping = &ii->i_btnode_cache;
690         struct pagevec pvec;
691         struct buffer_head *bh, *head;
692         unsigned int i;
693         pgoff_t index = 0;
694
695         pagevec_init(&pvec, 0);
696
697         while (pagevec_lookup_tag(&pvec, mapping, &index, PAGECACHE_TAG_DIRTY,
698                                   PAGEVEC_SIZE)) {
699                 for (i = 0; i < pagevec_count(&pvec); i++) {
700                         bh = head = page_buffers(pvec.pages[i]);
701                         do {
702                                 if (buffer_dirty(bh)) {
703                                         get_bh(bh);
704                                         list_add_tail(&bh->b_assoc_buffers,
705                                                       listp);
706                                 }
707                                 bh = bh->b_this_page;
708                         } while (bh != head);
709                 }
710                 pagevec_release(&pvec);
711                 cond_resched();
712         }
713 }
714
715 static void nilfs_dispose_list(struct the_nilfs *nilfs,
716                                struct list_head *head, int force)
717 {
718         struct nilfs_inode_info *ii, *n;
719         struct nilfs_inode_info *ivec[SC_N_INODEVEC], **pii;
720         unsigned nv = 0;
721
722         while (!list_empty(head)) {
723                 spin_lock(&nilfs->ns_inode_lock);
724                 list_for_each_entry_safe(ii, n, head, i_dirty) {
725                         list_del_init(&ii->i_dirty);
726                         if (force) {
727                                 if (unlikely(ii->i_bh)) {
728                                         brelse(ii->i_bh);
729                                         ii->i_bh = NULL;
730                                 }
731                         } else if (test_bit(NILFS_I_DIRTY, &ii->i_state)) {
732                                 set_bit(NILFS_I_QUEUED, &ii->i_state);
733                                 list_add_tail(&ii->i_dirty,
734                                               &nilfs->ns_dirty_files);
735                                 continue;
736                         }
737                         ivec[nv++] = ii;
738                         if (nv == SC_N_INODEVEC)
739                                 break;
740                 }
741                 spin_unlock(&nilfs->ns_inode_lock);
742
743                 for (pii = ivec; nv > 0; pii++, nv--)
744                         iput(&(*pii)->vfs_inode);
745         }
746 }
747
748 static int nilfs_test_metadata_dirty(struct the_nilfs *nilfs,
749                                      struct nilfs_root *root)
750 {
751         int ret = 0;
752
753         if (nilfs_mdt_fetch_dirty(root->ifile))
754                 ret++;
755         if (nilfs_mdt_fetch_dirty(nilfs->ns_cpfile))
756                 ret++;
757         if (nilfs_mdt_fetch_dirty(nilfs->ns_sufile))
758                 ret++;
759         if ((ret || nilfs_doing_gc()) && nilfs_mdt_fetch_dirty(nilfs->ns_dat))
760                 ret++;
761         return ret;
762 }
763
764 static int nilfs_segctor_clean(struct nilfs_sc_info *sci)
765 {
766         return list_empty(&sci->sc_dirty_files) &&
767                 !test_bit(NILFS_SC_DIRTY, &sci->sc_flags) &&
768                 sci->sc_nfreesegs == 0 &&
769                 (!nilfs_doing_gc() || list_empty(&sci->sc_gc_inodes));
770 }
771
772 static int nilfs_segctor_confirm(struct nilfs_sc_info *sci)
773 {
774         struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
775         int ret = 0;
776
777         if (nilfs_test_metadata_dirty(nilfs, sci->sc_root))
778                 set_bit(NILFS_SC_DIRTY, &sci->sc_flags);
779
780         spin_lock(&nilfs->ns_inode_lock);
781         if (list_empty(&nilfs->ns_dirty_files) && nilfs_segctor_clean(sci))
782                 ret++;
783
784         spin_unlock(&nilfs->ns_inode_lock);
785         return ret;
786 }
787
788 static void nilfs_segctor_clear_metadata_dirty(struct nilfs_sc_info *sci)
789 {
790         struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
791
792         nilfs_mdt_clear_dirty(sci->sc_root->ifile);
793         nilfs_mdt_clear_dirty(nilfs->ns_cpfile);
794         nilfs_mdt_clear_dirty(nilfs->ns_sufile);
795         nilfs_mdt_clear_dirty(nilfs->ns_dat);
796 }
797
798 static int nilfs_segctor_create_checkpoint(struct nilfs_sc_info *sci)
799 {
800         struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
801         struct buffer_head *bh_cp;
802         struct nilfs_checkpoint *raw_cp;
803         int err;
804
805         /* XXX: this interface will be changed */
806         err = nilfs_cpfile_get_checkpoint(nilfs->ns_cpfile, nilfs->ns_cno, 1,
807                                           &raw_cp, &bh_cp);
808         if (likely(!err)) {
809                 /* The following code is duplicated with cpfile.  But, it is
810                    needed to collect the checkpoint even if it was not newly
811                    created */
812                 nilfs_mdt_mark_buffer_dirty(bh_cp);
813                 nilfs_mdt_mark_dirty(nilfs->ns_cpfile);
814                 nilfs_cpfile_put_checkpoint(
815                         nilfs->ns_cpfile, nilfs->ns_cno, bh_cp);
816         } else
817                 WARN_ON(err == -EINVAL || err == -ENOENT);
818
819         return err;
820 }
821
822 static int nilfs_segctor_fill_in_checkpoint(struct nilfs_sc_info *sci)
823 {
824         struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
825         struct buffer_head *bh_cp;
826         struct nilfs_checkpoint *raw_cp;
827         int err;
828
829         err = nilfs_cpfile_get_checkpoint(nilfs->ns_cpfile, nilfs->ns_cno, 0,
830                                           &raw_cp, &bh_cp);
831         if (unlikely(err)) {
832                 WARN_ON(err == -EINVAL || err == -ENOENT);
833                 goto failed_ibh;
834         }
835         raw_cp->cp_snapshot_list.ssl_next = 0;
836         raw_cp->cp_snapshot_list.ssl_prev = 0;
837         raw_cp->cp_inodes_count =
838                 cpu_to_le64(atomic_read(&sci->sc_root->inodes_count));
839         raw_cp->cp_blocks_count =
840                 cpu_to_le64(atomic_read(&sci->sc_root->blocks_count));
841         raw_cp->cp_nblk_inc =
842                 cpu_to_le64(sci->sc_nblk_inc + sci->sc_nblk_this_inc);
843         raw_cp->cp_create = cpu_to_le64(sci->sc_seg_ctime);
844         raw_cp->cp_cno = cpu_to_le64(nilfs->ns_cno);
845
846         if (test_bit(NILFS_SC_HAVE_DELTA, &sci->sc_flags))
847                 nilfs_checkpoint_clear_minor(raw_cp);
848         else
849                 nilfs_checkpoint_set_minor(raw_cp);
850
851         nilfs_write_inode_common(sci->sc_root->ifile,
852                                  &raw_cp->cp_ifile_inode, 1);
853         nilfs_cpfile_put_checkpoint(nilfs->ns_cpfile, nilfs->ns_cno, bh_cp);
854         return 0;
855
856  failed_ibh:
857         return err;
858 }
859
860 static void nilfs_fill_in_file_bmap(struct inode *ifile,
861                                     struct nilfs_inode_info *ii)
862
863 {
864         struct buffer_head *ibh;
865         struct nilfs_inode *raw_inode;
866
867         if (test_bit(NILFS_I_BMAP, &ii->i_state)) {
868                 ibh = ii->i_bh;
869                 BUG_ON(!ibh);
870                 raw_inode = nilfs_ifile_map_inode(ifile, ii->vfs_inode.i_ino,
871                                                   ibh);
872                 nilfs_bmap_write(ii->i_bmap, raw_inode);
873                 nilfs_ifile_unmap_inode(ifile, ii->vfs_inode.i_ino, ibh);
874         }
875 }
876
877 static void nilfs_segctor_fill_in_file_bmap(struct nilfs_sc_info *sci)
878 {
879         struct nilfs_inode_info *ii;
880
881         list_for_each_entry(ii, &sci->sc_dirty_files, i_dirty) {
882                 nilfs_fill_in_file_bmap(sci->sc_root->ifile, ii);
883                 set_bit(NILFS_I_COLLECTED, &ii->i_state);
884         }
885 }
886
887 static void nilfs_segctor_fill_in_super_root(struct nilfs_sc_info *sci,
888                                              struct the_nilfs *nilfs)
889 {
890         struct buffer_head *bh_sr;
891         struct nilfs_super_root *raw_sr;
892         unsigned isz = nilfs->ns_inode_size;
893
894         bh_sr = NILFS_LAST_SEGBUF(&sci->sc_segbufs)->sb_super_root;
895         raw_sr = (struct nilfs_super_root *)bh_sr->b_data;
896
897         raw_sr->sr_bytes = cpu_to_le16(NILFS_SR_BYTES);
898         raw_sr->sr_nongc_ctime
899                 = cpu_to_le64(nilfs_doing_gc() ?
900                               nilfs->ns_nongc_ctime : sci->sc_seg_ctime);
901         raw_sr->sr_flags = 0;
902
903         nilfs_write_inode_common(nilfs->ns_dat, (void *)raw_sr +
904                                  NILFS_SR_DAT_OFFSET(isz), 1);
905         nilfs_write_inode_common(nilfs->ns_cpfile, (void *)raw_sr +
906                                  NILFS_SR_CPFILE_OFFSET(isz), 1);
907         nilfs_write_inode_common(nilfs->ns_sufile, (void *)raw_sr +
908                                  NILFS_SR_SUFILE_OFFSET(isz), 1);
909 }
910
911 static void nilfs_redirty_inodes(struct list_head *head)
912 {
913         struct nilfs_inode_info *ii;
914
915         list_for_each_entry(ii, head, i_dirty) {
916                 if (test_bit(NILFS_I_COLLECTED, &ii->i_state))
917                         clear_bit(NILFS_I_COLLECTED, &ii->i_state);
918         }
919 }
920
921 static void nilfs_drop_collected_inodes(struct list_head *head)
922 {
923         struct nilfs_inode_info *ii;
924
925         list_for_each_entry(ii, head, i_dirty) {
926                 if (!test_and_clear_bit(NILFS_I_COLLECTED, &ii->i_state))
927                         continue;
928
929                 clear_bit(NILFS_I_INODE_DIRTY, &ii->i_state);
930                 set_bit(NILFS_I_UPDATED, &ii->i_state);
931         }
932 }
933
934 static int nilfs_segctor_apply_buffers(struct nilfs_sc_info *sci,
935                                        struct inode *inode,
936                                        struct list_head *listp,
937                                        int (*collect)(struct nilfs_sc_info *,
938                                                       struct buffer_head *,
939                                                       struct inode *))
940 {
941         struct buffer_head *bh, *n;
942         int err = 0;
943
944         if (collect) {
945                 list_for_each_entry_safe(bh, n, listp, b_assoc_buffers) {
946                         list_del_init(&bh->b_assoc_buffers);
947                         err = collect(sci, bh, inode);
948                         brelse(bh);
949                         if (unlikely(err))
950                                 goto dispose_buffers;
951                 }
952                 return 0;
953         }
954
955  dispose_buffers:
956         while (!list_empty(listp)) {
957                 bh = list_entry(listp->next, struct buffer_head,
958                                 b_assoc_buffers);
959                 list_del_init(&bh->b_assoc_buffers);
960                 brelse(bh);
961         }
962         return err;
963 }
964
965 static size_t nilfs_segctor_buffer_rest(struct nilfs_sc_info *sci)
966 {
967         /* Remaining number of blocks within segment buffer */
968         return sci->sc_segbuf_nblocks -
969                 (sci->sc_nblk_this_inc + sci->sc_curseg->sb_sum.nblocks);
970 }
971
972 static int nilfs_segctor_scan_file(struct nilfs_sc_info *sci,
973                                    struct inode *inode,
974                                    struct nilfs_sc_operations *sc_ops)
975 {
976         LIST_HEAD(data_buffers);
977         LIST_HEAD(node_buffers);
978         int err;
979
980         if (!(sci->sc_stage.flags & NILFS_CF_NODE)) {
981                 size_t n, rest = nilfs_segctor_buffer_rest(sci);
982
983                 n = nilfs_lookup_dirty_data_buffers(
984                         inode, &data_buffers, rest + 1, 0, LLONG_MAX);
985                 if (n > rest) {
986                         err = nilfs_segctor_apply_buffers(
987                                 sci, inode, &data_buffers,
988                                 sc_ops->collect_data);
989                         BUG_ON(!err); /* always receive -E2BIG or true error */
990                         goto break_or_fail;
991                 }
992         }
993         nilfs_lookup_dirty_node_buffers(inode, &node_buffers);
994
995         if (!(sci->sc_stage.flags & NILFS_CF_NODE)) {
996                 err = nilfs_segctor_apply_buffers(
997                         sci, inode, &data_buffers, sc_ops->collect_data);
998                 if (unlikely(err)) {
999                         /* dispose node list */
1000                         nilfs_segctor_apply_buffers(
1001                                 sci, inode, &node_buffers, NULL);
1002                         goto break_or_fail;
1003                 }
1004                 sci->sc_stage.flags |= NILFS_CF_NODE;
1005         }
1006         /* Collect node */
1007         err = nilfs_segctor_apply_buffers(
1008                 sci, inode, &node_buffers, sc_ops->collect_node);
1009         if (unlikely(err))
1010                 goto break_or_fail;
1011
1012         nilfs_bmap_lookup_dirty_buffers(NILFS_I(inode)->i_bmap, &node_buffers);
1013         err = nilfs_segctor_apply_buffers(
1014                 sci, inode, &node_buffers, sc_ops->collect_bmap);
1015         if (unlikely(err))
1016                 goto break_or_fail;
1017
1018         nilfs_segctor_end_finfo(sci, inode);
1019         sci->sc_stage.flags &= ~NILFS_CF_NODE;
1020
1021  break_or_fail:
1022         return err;
1023 }
1024
1025 static int nilfs_segctor_scan_file_dsync(struct nilfs_sc_info *sci,
1026                                          struct inode *inode)
1027 {
1028         LIST_HEAD(data_buffers);
1029         size_t n, rest = nilfs_segctor_buffer_rest(sci);
1030         int err;
1031
1032         n = nilfs_lookup_dirty_data_buffers(inode, &data_buffers, rest + 1,
1033                                             sci->sc_dsync_start,
1034                                             sci->sc_dsync_end);
1035
1036         err = nilfs_segctor_apply_buffers(sci, inode, &data_buffers,
1037                                           nilfs_collect_file_data);
1038         if (!err) {
1039                 nilfs_segctor_end_finfo(sci, inode);
1040                 BUG_ON(n > rest);
1041                 /* always receive -E2BIG or true error if n > rest */
1042         }
1043         return err;
1044 }
1045
1046 static int nilfs_segctor_collect_blocks(struct nilfs_sc_info *sci, int mode)
1047 {
1048         struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
1049         struct list_head *head;
1050         struct nilfs_inode_info *ii;
1051         size_t ndone;
1052         int err = 0;
1053
1054         switch (sci->sc_stage.scnt) {
1055         case NILFS_ST_INIT:
1056                 /* Pre-processes */
1057                 sci->sc_stage.flags = 0;
1058
1059                 if (!test_bit(NILFS_SC_UNCLOSED, &sci->sc_flags)) {
1060                         sci->sc_nblk_inc = 0;
1061                         sci->sc_curseg->sb_sum.flags = NILFS_SS_LOGBGN;
1062                         if (mode == SC_LSEG_DSYNC) {
1063                                 sci->sc_stage.scnt = NILFS_ST_DSYNC;
1064                                 goto dsync_mode;
1065                         }
1066                 }
1067
1068                 sci->sc_stage.dirty_file_ptr = NULL;
1069                 sci->sc_stage.gc_inode_ptr = NULL;
1070                 if (mode == SC_FLUSH_DAT) {
1071                         sci->sc_stage.scnt = NILFS_ST_DAT;
1072                         goto dat_stage;
1073                 }
1074                 sci->sc_stage.scnt++;  /* Fall through */
1075         case NILFS_ST_GC:
1076                 if (nilfs_doing_gc()) {
1077                         head = &sci->sc_gc_inodes;
1078                         ii = list_prepare_entry(sci->sc_stage.gc_inode_ptr,
1079                                                 head, i_dirty);
1080                         list_for_each_entry_continue(ii, head, i_dirty) {
1081                                 err = nilfs_segctor_scan_file(
1082                                         sci, &ii->vfs_inode,
1083                                         &nilfs_sc_file_ops);
1084                                 if (unlikely(err)) {
1085                                         sci->sc_stage.gc_inode_ptr = list_entry(
1086                                                 ii->i_dirty.prev,
1087                                                 struct nilfs_inode_info,
1088                                                 i_dirty);
1089                                         goto break_or_fail;
1090                                 }
1091                                 set_bit(NILFS_I_COLLECTED, &ii->i_state);
1092                         }
1093                         sci->sc_stage.gc_inode_ptr = NULL;
1094                 }
1095                 sci->sc_stage.scnt++;  /* Fall through */
1096         case NILFS_ST_FILE:
1097                 head = &sci->sc_dirty_files;
1098                 ii = list_prepare_entry(sci->sc_stage.dirty_file_ptr, head,
1099                                         i_dirty);
1100                 list_for_each_entry_continue(ii, head, i_dirty) {
1101                         clear_bit(NILFS_I_DIRTY, &ii->i_state);
1102
1103                         err = nilfs_segctor_scan_file(sci, &ii->vfs_inode,
1104                                                       &nilfs_sc_file_ops);
1105                         if (unlikely(err)) {
1106                                 sci->sc_stage.dirty_file_ptr =
1107                                         list_entry(ii->i_dirty.prev,
1108                                                    struct nilfs_inode_info,
1109                                                    i_dirty);
1110                                 goto break_or_fail;
1111                         }
1112                         /* sci->sc_stage.dirty_file_ptr = NILFS_I(inode); */
1113                         /* XXX: required ? */
1114                 }
1115                 sci->sc_stage.dirty_file_ptr = NULL;
1116                 if (mode == SC_FLUSH_FILE) {
1117                         sci->sc_stage.scnt = NILFS_ST_DONE;
1118                         return 0;
1119                 }
1120                 sci->sc_stage.scnt++;
1121                 sci->sc_stage.flags |= NILFS_CF_IFILE_STARTED;
1122                 /* Fall through */
1123         case NILFS_ST_IFILE:
1124                 err = nilfs_segctor_scan_file(sci, sci->sc_root->ifile,
1125                                               &nilfs_sc_file_ops);
1126                 if (unlikely(err))
1127                         break;
1128                 sci->sc_stage.scnt++;
1129                 /* Creating a checkpoint */
1130                 err = nilfs_segctor_create_checkpoint(sci);
1131                 if (unlikely(err))
1132                         break;
1133                 /* Fall through */
1134         case NILFS_ST_CPFILE:
1135                 err = nilfs_segctor_scan_file(sci, nilfs->ns_cpfile,
1136                                               &nilfs_sc_file_ops);
1137                 if (unlikely(err))
1138                         break;
1139                 sci->sc_stage.scnt++;  /* Fall through */
1140         case NILFS_ST_SUFILE:
1141                 err = nilfs_sufile_freev(nilfs->ns_sufile, sci->sc_freesegs,
1142                                          sci->sc_nfreesegs, &ndone);
1143                 if (unlikely(err)) {
1144                         nilfs_sufile_cancel_freev(nilfs->ns_sufile,
1145                                                   sci->sc_freesegs, ndone,
1146                                                   NULL);
1147                         break;
1148                 }
1149                 sci->sc_stage.flags |= NILFS_CF_SUFREED;
1150
1151                 err = nilfs_segctor_scan_file(sci, nilfs->ns_sufile,
1152                                               &nilfs_sc_file_ops);
1153                 if (unlikely(err))
1154                         break;
1155                 sci->sc_stage.scnt++;  /* Fall through */
1156         case NILFS_ST_DAT:
1157  dat_stage:
1158                 err = nilfs_segctor_scan_file(sci, nilfs->ns_dat,
1159                                               &nilfs_sc_dat_ops);
1160                 if (unlikely(err))
1161                         break;
1162                 if (mode == SC_FLUSH_DAT) {
1163                         sci->sc_stage.scnt = NILFS_ST_DONE;
1164                         return 0;
1165                 }
1166                 sci->sc_stage.scnt++;  /* Fall through */
1167         case NILFS_ST_SR:
1168                 if (mode == SC_LSEG_SR) {
1169                         /* Appending a super root */
1170                         err = nilfs_segctor_add_super_root(sci);
1171                         if (unlikely(err))
1172                                 break;
1173                 }
1174                 /* End of a logical segment */
1175                 sci->sc_curseg->sb_sum.flags |= NILFS_SS_LOGEND;
1176                 sci->sc_stage.scnt = NILFS_ST_DONE;
1177                 return 0;
1178         case NILFS_ST_DSYNC:
1179  dsync_mode:
1180                 sci->sc_curseg->sb_sum.flags |= NILFS_SS_SYNDT;
1181                 ii = sci->sc_dsync_inode;
1182                 if (!test_bit(NILFS_I_BUSY, &ii->i_state))
1183                         break;
1184
1185                 err = nilfs_segctor_scan_file_dsync(sci, &ii->vfs_inode);
1186                 if (unlikely(err))
1187                         break;
1188                 sci->sc_curseg->sb_sum.flags |= NILFS_SS_LOGEND;
1189                 sci->sc_stage.scnt = NILFS_ST_DONE;
1190                 return 0;
1191         case NILFS_ST_DONE:
1192                 return 0;
1193         default:
1194                 BUG();
1195         }
1196
1197  break_or_fail:
1198         return err;
1199 }
1200
1201 /**
1202  * nilfs_segctor_begin_construction - setup segment buffer to make a new log
1203  * @sci: nilfs_sc_info
1204  * @nilfs: nilfs object
1205  */
1206 static int nilfs_segctor_begin_construction(struct nilfs_sc_info *sci,
1207                                             struct the_nilfs *nilfs)
1208 {
1209         struct nilfs_segment_buffer *segbuf, *prev;
1210         __u64 nextnum;
1211         int err, alloc = 0;
1212
1213         segbuf = nilfs_segbuf_new(sci->sc_super);
1214         if (unlikely(!segbuf))
1215                 return -ENOMEM;
1216
1217         if (list_empty(&sci->sc_write_logs)) {
1218                 nilfs_segbuf_map(segbuf, nilfs->ns_segnum,
1219                                  nilfs->ns_pseg_offset, nilfs);
1220                 if (segbuf->sb_rest_blocks < NILFS_PSEG_MIN_BLOCKS) {
1221                         nilfs_shift_to_next_segment(nilfs);
1222                         nilfs_segbuf_map(segbuf, nilfs->ns_segnum, 0, nilfs);
1223                 }
1224
1225                 segbuf->sb_sum.seg_seq = nilfs->ns_seg_seq;
1226                 nextnum = nilfs->ns_nextnum;
1227
1228                 if (nilfs->ns_segnum == nilfs->ns_nextnum)
1229                         /* Start from the head of a new full segment */
1230                         alloc++;
1231         } else {
1232                 /* Continue logs */
1233                 prev = NILFS_LAST_SEGBUF(&sci->sc_write_logs);
1234                 nilfs_segbuf_map_cont(segbuf, prev);
1235                 segbuf->sb_sum.seg_seq = prev->sb_sum.seg_seq;
1236                 nextnum = prev->sb_nextnum;
1237
1238                 if (segbuf->sb_rest_blocks < NILFS_PSEG_MIN_BLOCKS) {
1239                         nilfs_segbuf_map(segbuf, prev->sb_nextnum, 0, nilfs);
1240                         segbuf->sb_sum.seg_seq++;
1241                         alloc++;
1242                 }
1243         }
1244
1245         err = nilfs_sufile_mark_dirty(nilfs->ns_sufile, segbuf->sb_segnum);
1246         if (err)
1247                 goto failed;
1248
1249         if (alloc) {
1250                 err = nilfs_sufile_alloc(nilfs->ns_sufile, &nextnum);
1251                 if (err)
1252                         goto failed;
1253         }
1254         nilfs_segbuf_set_next_segnum(segbuf, nextnum, nilfs);
1255
1256         BUG_ON(!list_empty(&sci->sc_segbufs));
1257         list_add_tail(&segbuf->sb_list, &sci->sc_segbufs);
1258         sci->sc_segbuf_nblocks = segbuf->sb_rest_blocks;
1259         return 0;
1260
1261  failed:
1262         nilfs_segbuf_free(segbuf);
1263         return err;
1264 }
1265
1266 static int nilfs_segctor_extend_segments(struct nilfs_sc_info *sci,
1267                                          struct the_nilfs *nilfs, int nadd)
1268 {
1269         struct nilfs_segment_buffer *segbuf, *prev;
1270         struct inode *sufile = nilfs->ns_sufile;
1271         __u64 nextnextnum;
1272         LIST_HEAD(list);
1273         int err, ret, i;
1274
1275         prev = NILFS_LAST_SEGBUF(&sci->sc_segbufs);
1276         /*
1277          * Since the segment specified with nextnum might be allocated during
1278          * the previous construction, the buffer including its segusage may
1279          * not be dirty.  The following call ensures that the buffer is dirty
1280          * and will pin the buffer on memory until the sufile is written.
1281          */
1282         err = nilfs_sufile_mark_dirty(sufile, prev->sb_nextnum);
1283         if (unlikely(err))
1284                 return err;
1285
1286         for (i = 0; i < nadd; i++) {
1287                 /* extend segment info */
1288                 err = -ENOMEM;
1289                 segbuf = nilfs_segbuf_new(sci->sc_super);
1290                 if (unlikely(!segbuf))
1291                         goto failed;
1292
1293                 /* map this buffer to region of segment on-disk */
1294                 nilfs_segbuf_map(segbuf, prev->sb_nextnum, 0, nilfs);
1295                 sci->sc_segbuf_nblocks += segbuf->sb_rest_blocks;
1296
1297                 /* allocate the next next full segment */
1298                 err = nilfs_sufile_alloc(sufile, &nextnextnum);
1299                 if (unlikely(err))
1300                         goto failed_segbuf;
1301
1302                 segbuf->sb_sum.seg_seq = prev->sb_sum.seg_seq + 1;
1303                 nilfs_segbuf_set_next_segnum(segbuf, nextnextnum, nilfs);
1304
1305                 list_add_tail(&segbuf->sb_list, &list);
1306                 prev = segbuf;
1307         }
1308         list_splice_tail(&list, &sci->sc_segbufs);
1309         return 0;
1310
1311  failed_segbuf:
1312         nilfs_segbuf_free(segbuf);
1313  failed:
1314         list_for_each_entry(segbuf, &list, sb_list) {
1315                 ret = nilfs_sufile_free(sufile, segbuf->sb_nextnum);
1316                 WARN_ON(ret); /* never fails */
1317         }
1318         nilfs_destroy_logs(&list);
1319         return err;
1320 }
1321
1322 static void nilfs_free_incomplete_logs(struct list_head *logs,
1323                                        struct the_nilfs *nilfs)
1324 {
1325         struct nilfs_segment_buffer *segbuf, *prev;
1326         struct inode *sufile = nilfs->ns_sufile;
1327         int ret;
1328
1329         segbuf = NILFS_FIRST_SEGBUF(logs);
1330         if (nilfs->ns_nextnum != segbuf->sb_nextnum) {
1331                 ret = nilfs_sufile_free(sufile, segbuf->sb_nextnum);
1332                 WARN_ON(ret); /* never fails */
1333         }
1334         if (atomic_read(&segbuf->sb_err)) {
1335                 /* Case 1: The first segment failed */
1336                 if (segbuf->sb_pseg_start != segbuf->sb_fseg_start)
1337                         /* Case 1a:  Partial segment appended into an existing
1338                            segment */
1339                         nilfs_terminate_segment(nilfs, segbuf->sb_fseg_start,
1340                                                 segbuf->sb_fseg_end);
1341                 else /* Case 1b:  New full segment */
1342                         set_nilfs_discontinued(nilfs);
1343         }
1344
1345         prev = segbuf;
1346         list_for_each_entry_continue(segbuf, logs, sb_list) {
1347                 if (prev->sb_nextnum != segbuf->sb_nextnum) {
1348                         ret = nilfs_sufile_free(sufile, segbuf->sb_nextnum);
1349                         WARN_ON(ret); /* never fails */
1350                 }
1351                 if (atomic_read(&segbuf->sb_err) &&
1352                     segbuf->sb_segnum != nilfs->ns_nextnum)
1353                         /* Case 2: extended segment (!= next) failed */
1354                         nilfs_sufile_set_error(sufile, segbuf->sb_segnum);
1355                 prev = segbuf;
1356         }
1357 }
1358
1359 static void nilfs_segctor_update_segusage(struct nilfs_sc_info *sci,
1360                                           struct inode *sufile)
1361 {
1362         struct nilfs_segment_buffer *segbuf;
1363         unsigned long live_blocks;
1364         int ret;
1365
1366         list_for_each_entry(segbuf, &sci->sc_segbufs, sb_list) {
1367                 live_blocks = segbuf->sb_sum.nblocks +
1368                         (segbuf->sb_pseg_start - segbuf->sb_fseg_start);
1369                 ret = nilfs_sufile_set_segment_usage(sufile, segbuf->sb_segnum,
1370                                                      live_blocks,
1371                                                      sci->sc_seg_ctime);
1372                 WARN_ON(ret); /* always succeed because the segusage is dirty */
1373         }
1374 }
1375
1376 static void nilfs_cancel_segusage(struct list_head *logs, struct inode *sufile)
1377 {
1378         struct nilfs_segment_buffer *segbuf;
1379         int ret;
1380
1381         segbuf = NILFS_FIRST_SEGBUF(logs);
1382         ret = nilfs_sufile_set_segment_usage(sufile, segbuf->sb_segnum,
1383                                              segbuf->sb_pseg_start -
1384                                              segbuf->sb_fseg_start, 0);
1385         WARN_ON(ret); /* always succeed because the segusage is dirty */
1386
1387         list_for_each_entry_continue(segbuf, logs, sb_list) {
1388                 ret = nilfs_sufile_set_segment_usage(sufile, segbuf->sb_segnum,
1389                                                      0, 0);
1390                 WARN_ON(ret); /* always succeed */
1391         }
1392 }
1393
1394 static void nilfs_segctor_truncate_segments(struct nilfs_sc_info *sci,
1395                                             struct nilfs_segment_buffer *last,
1396                                             struct inode *sufile)
1397 {
1398         struct nilfs_segment_buffer *segbuf = last;
1399         int ret;
1400
1401         list_for_each_entry_continue(segbuf, &sci->sc_segbufs, sb_list) {
1402                 sci->sc_segbuf_nblocks -= segbuf->sb_rest_blocks;
1403                 ret = nilfs_sufile_free(sufile, segbuf->sb_nextnum);
1404                 WARN_ON(ret);
1405         }
1406         nilfs_truncate_logs(&sci->sc_segbufs, last);
1407 }
1408
1409
1410 static int nilfs_segctor_collect(struct nilfs_sc_info *sci,
1411                                  struct the_nilfs *nilfs, int mode)
1412 {
1413         struct nilfs_cstage prev_stage = sci->sc_stage;
1414         int err, nadd = 1;
1415
1416         /* Collection retry loop */
1417         for (;;) {
1418                 sci->sc_nblk_this_inc = 0;
1419                 sci->sc_curseg = NILFS_FIRST_SEGBUF(&sci->sc_segbufs);
1420
1421                 err = nilfs_segctor_reset_segment_buffer(sci);
1422                 if (unlikely(err))
1423                         goto failed;
1424
1425                 err = nilfs_segctor_collect_blocks(sci, mode);
1426                 sci->sc_nblk_this_inc += sci->sc_curseg->sb_sum.nblocks;
1427                 if (!err)
1428                         break;
1429
1430                 if (unlikely(err != -E2BIG))
1431                         goto failed;
1432
1433                 /* The current segment is filled up */
1434                 if (mode != SC_LSEG_SR || sci->sc_stage.scnt < NILFS_ST_CPFILE)
1435                         break;
1436
1437                 nilfs_clear_logs(&sci->sc_segbufs);
1438
1439                 err = nilfs_segctor_extend_segments(sci, nilfs, nadd);
1440                 if (unlikely(err))
1441                         return err;
1442
1443                 if (sci->sc_stage.flags & NILFS_CF_SUFREED) {
1444                         err = nilfs_sufile_cancel_freev(nilfs->ns_sufile,
1445                                                         sci->sc_freesegs,
1446                                                         sci->sc_nfreesegs,
1447                                                         NULL);
1448                         WARN_ON(err); /* do not happen */
1449                 }
1450                 nadd = min_t(int, nadd << 1, SC_MAX_SEGDELTA);
1451                 sci->sc_stage = prev_stage;
1452         }
1453         nilfs_segctor_truncate_segments(sci, sci->sc_curseg, nilfs->ns_sufile);
1454         return 0;
1455
1456  failed:
1457         return err;
1458 }
1459
1460 static void nilfs_list_replace_buffer(struct buffer_head *old_bh,
1461                                       struct buffer_head *new_bh)
1462 {
1463         BUG_ON(!list_empty(&new_bh->b_assoc_buffers));
1464
1465         list_replace_init(&old_bh->b_assoc_buffers, &new_bh->b_assoc_buffers);
1466         /* The caller must release old_bh */
1467 }
1468
1469 static int
1470 nilfs_segctor_update_payload_blocknr(struct nilfs_sc_info *sci,
1471                                      struct nilfs_segment_buffer *segbuf,
1472                                      int mode)
1473 {
1474         struct inode *inode = NULL;
1475         sector_t blocknr;
1476         unsigned long nfinfo = segbuf->sb_sum.nfinfo;
1477         unsigned long nblocks = 0, ndatablk = 0;
1478         struct nilfs_sc_operations *sc_op = NULL;
1479         struct nilfs_segsum_pointer ssp;
1480         struct nilfs_finfo *finfo = NULL;
1481         union nilfs_binfo binfo;
1482         struct buffer_head *bh, *bh_org;
1483         ino_t ino = 0;
1484         int err = 0;
1485
1486         if (!nfinfo)
1487                 goto out;
1488
1489         blocknr = segbuf->sb_pseg_start + segbuf->sb_sum.nsumblk;
1490         ssp.bh = NILFS_SEGBUF_FIRST_BH(&segbuf->sb_segsum_buffers);
1491         ssp.offset = sizeof(struct nilfs_segment_summary);
1492
1493         list_for_each_entry(bh, &segbuf->sb_payload_buffers, b_assoc_buffers) {
1494                 if (bh == segbuf->sb_super_root)
1495                         break;
1496                 if (!finfo) {
1497                         finfo = nilfs_segctor_map_segsum_entry(
1498                                 sci, &ssp, sizeof(*finfo));
1499                         ino = le64_to_cpu(finfo->fi_ino);
1500                         nblocks = le32_to_cpu(finfo->fi_nblocks);
1501                         ndatablk = le32_to_cpu(finfo->fi_ndatablk);
1502
1503                         if (buffer_nilfs_node(bh))
1504                                 inode = NILFS_BTNC_I(bh->b_page->mapping);
1505                         else
1506                                 inode = NILFS_AS_I(bh->b_page->mapping);
1507
1508                         if (mode == SC_LSEG_DSYNC)
1509                                 sc_op = &nilfs_sc_dsync_ops;
1510                         else if (ino == NILFS_DAT_INO)
1511                                 sc_op = &nilfs_sc_dat_ops;
1512                         else /* file blocks */
1513                                 sc_op = &nilfs_sc_file_ops;
1514                 }
1515                 bh_org = bh;
1516                 get_bh(bh_org);
1517                 err = nilfs_bmap_assign(NILFS_I(inode)->i_bmap, &bh, blocknr,
1518                                         &binfo);
1519                 if (bh != bh_org)
1520                         nilfs_list_replace_buffer(bh_org, bh);
1521                 brelse(bh_org);
1522                 if (unlikely(err))
1523                         goto failed_bmap;
1524
1525                 if (ndatablk > 0)
1526                         sc_op->write_data_binfo(sci, &ssp, &binfo);
1527                 else
1528                         sc_op->write_node_binfo(sci, &ssp, &binfo);
1529
1530                 blocknr++;
1531                 if (--nblocks == 0) {
1532                         finfo = NULL;
1533                         if (--nfinfo == 0)
1534                                 break;
1535                 } else if (ndatablk > 0)
1536                         ndatablk--;
1537         }
1538  out:
1539         return 0;
1540
1541  failed_bmap:
1542         return err;
1543 }
1544
1545 static int nilfs_segctor_assign(struct nilfs_sc_info *sci, int mode)
1546 {
1547         struct nilfs_segment_buffer *segbuf;
1548         int err;
1549
1550         list_for_each_entry(segbuf, &sci->sc_segbufs, sb_list) {
1551                 err = nilfs_segctor_update_payload_blocknr(sci, segbuf, mode);
1552                 if (unlikely(err))
1553                         return err;
1554                 nilfs_segbuf_fill_in_segsum(segbuf);
1555         }
1556         return 0;
1557 }
1558
1559 static void nilfs_begin_page_io(struct page *page)
1560 {
1561         if (!page || PageWriteback(page))
1562                 /* For split b-tree node pages, this function may be called
1563                    twice.  We ignore the 2nd or later calls by this check. */
1564                 return;
1565
1566         lock_page(page);
1567         clear_page_dirty_for_io(page);
1568         set_page_writeback(page);
1569         unlock_page(page);
1570 }
1571
1572 static void nilfs_segctor_prepare_write(struct nilfs_sc_info *sci)
1573 {
1574         struct nilfs_segment_buffer *segbuf;
1575         struct page *bd_page = NULL, *fs_page = NULL;
1576
1577         list_for_each_entry(segbuf, &sci->sc_segbufs, sb_list) {
1578                 struct buffer_head *bh;
1579
1580                 list_for_each_entry(bh, &segbuf->sb_segsum_buffers,
1581                                     b_assoc_buffers) {
1582                         if (bh->b_page != bd_page) {
1583                                 if (bd_page) {
1584                                         lock_page(bd_page);
1585                                         clear_page_dirty_for_io(bd_page);
1586                                         set_page_writeback(bd_page);
1587                                         unlock_page(bd_page);
1588                                 }
1589                                 bd_page = bh->b_page;
1590                         }
1591                 }
1592
1593                 list_for_each_entry(bh, &segbuf->sb_payload_buffers,
1594                                     b_assoc_buffers) {
1595                         if (bh == segbuf->sb_super_root) {
1596                                 if (bh->b_page != bd_page) {
1597                                         lock_page(bd_page);
1598                                         clear_page_dirty_for_io(bd_page);
1599                                         set_page_writeback(bd_page);
1600                                         unlock_page(bd_page);
1601                                         bd_page = bh->b_page;
1602                                 }
1603                                 break;
1604                         }
1605                         if (bh->b_page != fs_page) {
1606                                 nilfs_begin_page_io(fs_page);
1607                                 fs_page = bh->b_page;
1608                         }
1609                 }
1610         }
1611         if (bd_page) {
1612                 lock_page(bd_page);
1613                 clear_page_dirty_for_io(bd_page);
1614                 set_page_writeback(bd_page);
1615                 unlock_page(bd_page);
1616         }
1617         nilfs_begin_page_io(fs_page);
1618 }
1619
1620 static int nilfs_segctor_write(struct nilfs_sc_info *sci,
1621                                struct the_nilfs *nilfs)
1622 {
1623         int ret;
1624
1625         ret = nilfs_write_logs(&sci->sc_segbufs, nilfs);
1626         list_splice_tail_init(&sci->sc_segbufs, &sci->sc_write_logs);
1627         return ret;
1628 }
1629
1630 static void nilfs_end_page_io(struct page *page, int err)
1631 {
1632         if (!page)
1633                 return;
1634
1635         if (buffer_nilfs_node(page_buffers(page)) && !PageWriteback(page)) {
1636                 /*
1637                  * For b-tree node pages, this function may be called twice
1638                  * or more because they might be split in a segment.
1639                  */
1640                 if (PageDirty(page)) {
1641                         /*
1642                          * For pages holding split b-tree node buffers, dirty
1643                          * flag on the buffers may be cleared discretely.
1644                          * In that case, the page is once redirtied for
1645                          * remaining buffers, and it must be cancelled if
1646                          * all the buffers get cleaned later.
1647                          */
1648                         lock_page(page);
1649                         if (nilfs_page_buffers_clean(page))
1650                                 __nilfs_clear_page_dirty(page);
1651                         unlock_page(page);
1652                 }
1653                 return;
1654         }
1655
1656         if (!err) {
1657                 if (!nilfs_page_buffers_clean(page))
1658                         __set_page_dirty_nobuffers(page);
1659                 ClearPageError(page);
1660         } else {
1661                 __set_page_dirty_nobuffers(page);
1662                 SetPageError(page);
1663         }
1664
1665         end_page_writeback(page);
1666 }
1667
1668 static void nilfs_abort_logs(struct list_head *logs, int err)
1669 {
1670         struct nilfs_segment_buffer *segbuf;
1671         struct page *bd_page = NULL, *fs_page = NULL;
1672         struct buffer_head *bh;
1673
1674         if (list_empty(logs))
1675                 return;
1676
1677         list_for_each_entry(segbuf, logs, sb_list) {
1678                 list_for_each_entry(bh, &segbuf->sb_segsum_buffers,
1679                                     b_assoc_buffers) {
1680                         if (bh->b_page != bd_page) {
1681                                 if (bd_page)
1682                                         end_page_writeback(bd_page);
1683                                 bd_page = bh->b_page;
1684                         }
1685                 }
1686
1687                 list_for_each_entry(bh, &segbuf->sb_payload_buffers,
1688                                     b_assoc_buffers) {
1689                         if (bh == segbuf->sb_super_root) {
1690                                 if (bh->b_page != bd_page) {
1691                                         end_page_writeback(bd_page);
1692                                         bd_page = bh->b_page;
1693                                 }
1694                                 break;
1695                         }
1696                         if (bh->b_page != fs_page) {
1697                                 nilfs_end_page_io(fs_page, err);
1698                                 fs_page = bh->b_page;
1699                         }
1700                 }
1701         }
1702         if (bd_page)
1703                 end_page_writeback(bd_page);
1704
1705         nilfs_end_page_io(fs_page, err);
1706 }
1707
1708 static void nilfs_segctor_abort_construction(struct nilfs_sc_info *sci,
1709                                              struct the_nilfs *nilfs, int err)
1710 {
1711         LIST_HEAD(logs);
1712         int ret;
1713
1714         list_splice_tail_init(&sci->sc_write_logs, &logs);
1715         ret = nilfs_wait_on_logs(&logs);
1716         nilfs_abort_logs(&logs, ret ? : err);
1717
1718         list_splice_tail_init(&sci->sc_segbufs, &logs);
1719         nilfs_cancel_segusage(&logs, nilfs->ns_sufile);
1720         nilfs_free_incomplete_logs(&logs, nilfs);
1721
1722         if (sci->sc_stage.flags & NILFS_CF_SUFREED) {
1723                 ret = nilfs_sufile_cancel_freev(nilfs->ns_sufile,
1724                                                 sci->sc_freesegs,
1725                                                 sci->sc_nfreesegs,
1726                                                 NULL);
1727                 WARN_ON(ret); /* do not happen */
1728         }
1729
1730         nilfs_destroy_logs(&logs);
1731 }
1732
1733 static void nilfs_set_next_segment(struct the_nilfs *nilfs,
1734                                    struct nilfs_segment_buffer *segbuf)
1735 {
1736         nilfs->ns_segnum = segbuf->sb_segnum;
1737         nilfs->ns_nextnum = segbuf->sb_nextnum;
1738         nilfs->ns_pseg_offset = segbuf->sb_pseg_start - segbuf->sb_fseg_start
1739                 + segbuf->sb_sum.nblocks;
1740         nilfs->ns_seg_seq = segbuf->sb_sum.seg_seq;
1741         nilfs->ns_ctime = segbuf->sb_sum.ctime;
1742 }
1743
1744 static void nilfs_segctor_complete_write(struct nilfs_sc_info *sci)
1745 {
1746         struct nilfs_segment_buffer *segbuf;
1747         struct page *bd_page = NULL, *fs_page = NULL;
1748         struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
1749         int update_sr = false;
1750
1751         list_for_each_entry(segbuf, &sci->sc_write_logs, sb_list) {
1752                 struct buffer_head *bh;
1753
1754                 list_for_each_entry(bh, &segbuf->sb_segsum_buffers,
1755                                     b_assoc_buffers) {
1756                         set_buffer_uptodate(bh);
1757                         clear_buffer_dirty(bh);
1758                         if (bh->b_page != bd_page) {
1759                                 if (bd_page)
1760                                         end_page_writeback(bd_page);
1761                                 bd_page = bh->b_page;
1762                         }
1763                 }
1764                 /*
1765                  * We assume that the buffers which belong to the same page
1766                  * continue over the buffer list.
1767                  * Under this assumption, the last BHs of pages is
1768                  * identifiable by the discontinuity of bh->b_page
1769                  * (page != fs_page).
1770                  *
1771                  * For B-tree node blocks, however, this assumption is not
1772                  * guaranteed.  The cleanup code of B-tree node pages needs
1773                  * special care.
1774                  */
1775                 list_for_each_entry(bh, &segbuf->sb_payload_buffers,
1776                                     b_assoc_buffers) {
1777                         set_buffer_uptodate(bh);
1778                         clear_buffer_dirty(bh);
1779                         clear_buffer_delay(bh);
1780                         clear_buffer_nilfs_volatile(bh);
1781                         clear_buffer_nilfs_redirected(bh);
1782                         if (bh == segbuf->sb_super_root) {
1783                                 if (bh->b_page != bd_page) {
1784                                         end_page_writeback(bd_page);
1785                                         bd_page = bh->b_page;
1786                                 }
1787                                 update_sr = true;
1788                                 break;
1789                         }
1790                         if (bh->b_page != fs_page) {
1791                                 nilfs_end_page_io(fs_page, 0);
1792                                 fs_page = bh->b_page;
1793                         }
1794                 }
1795
1796                 if (!nilfs_segbuf_simplex(segbuf)) {
1797                         if (segbuf->sb_sum.flags & NILFS_SS_LOGBGN) {
1798                                 set_bit(NILFS_SC_UNCLOSED, &sci->sc_flags);
1799                                 sci->sc_lseg_stime = jiffies;
1800                         }
1801                         if (segbuf->sb_sum.flags & NILFS_SS_LOGEND)
1802                                 clear_bit(NILFS_SC_UNCLOSED, &sci->sc_flags);
1803                 }
1804         }
1805         /*
1806          * Since pages may continue over multiple segment buffers,
1807          * end of the last page must be checked outside of the loop.
1808          */
1809         if (bd_page)
1810                 end_page_writeback(bd_page);
1811
1812         nilfs_end_page_io(fs_page, 0);
1813
1814         nilfs_drop_collected_inodes(&sci->sc_dirty_files);
1815
1816         if (nilfs_doing_gc())
1817                 nilfs_drop_collected_inodes(&sci->sc_gc_inodes);
1818         else
1819                 nilfs->ns_nongc_ctime = sci->sc_seg_ctime;
1820
1821         sci->sc_nblk_inc += sci->sc_nblk_this_inc;
1822
1823         segbuf = NILFS_LAST_SEGBUF(&sci->sc_write_logs);
1824         nilfs_set_next_segment(nilfs, segbuf);
1825
1826         if (update_sr) {
1827                 nilfs_set_last_segment(nilfs, segbuf->sb_pseg_start,
1828                                        segbuf->sb_sum.seg_seq, nilfs->ns_cno++);
1829
1830                 clear_bit(NILFS_SC_HAVE_DELTA, &sci->sc_flags);
1831                 clear_bit(NILFS_SC_DIRTY, &sci->sc_flags);
1832                 set_bit(NILFS_SC_SUPER_ROOT, &sci->sc_flags);
1833                 nilfs_segctor_clear_metadata_dirty(sci);
1834         } else
1835                 clear_bit(NILFS_SC_SUPER_ROOT, &sci->sc_flags);
1836 }
1837
1838 static int nilfs_segctor_wait(struct nilfs_sc_info *sci)
1839 {
1840         int ret;
1841
1842         ret = nilfs_wait_on_logs(&sci->sc_write_logs);
1843         if (!ret) {
1844                 nilfs_segctor_complete_write(sci);
1845                 nilfs_destroy_logs(&sci->sc_write_logs);
1846         }
1847         return ret;
1848 }
1849
1850 static int nilfs_segctor_collect_dirty_files(struct nilfs_sc_info *sci,
1851                                              struct the_nilfs *nilfs)
1852 {
1853         struct nilfs_inode_info *ii, *n;
1854         struct inode *ifile = sci->sc_root->ifile;
1855
1856         spin_lock(&nilfs->ns_inode_lock);
1857  retry:
1858         list_for_each_entry_safe(ii, n, &nilfs->ns_dirty_files, i_dirty) {
1859                 if (!ii->i_bh) {
1860                         struct buffer_head *ibh;
1861                         int err;
1862
1863                         spin_unlock(&nilfs->ns_inode_lock);
1864                         err = nilfs_ifile_get_inode_block(
1865                                 ifile, ii->vfs_inode.i_ino, &ibh);
1866                         if (unlikely(err)) {
1867                                 nilfs_warning(sci->sc_super, __func__,
1868                                               "failed to get inode block.\n");
1869                                 return err;
1870                         }
1871                         nilfs_mdt_mark_buffer_dirty(ibh);
1872                         nilfs_mdt_mark_dirty(ifile);
1873                         spin_lock(&nilfs->ns_inode_lock);
1874                         if (likely(!ii->i_bh))
1875                                 ii->i_bh = ibh;
1876                         else
1877                                 brelse(ibh);
1878                         goto retry;
1879                 }
1880
1881                 clear_bit(NILFS_I_QUEUED, &ii->i_state);
1882                 set_bit(NILFS_I_BUSY, &ii->i_state);
1883                 list_move_tail(&ii->i_dirty, &sci->sc_dirty_files);
1884         }
1885         spin_unlock(&nilfs->ns_inode_lock);
1886
1887         return 0;
1888 }
1889
1890 static void nilfs_segctor_drop_written_files(struct nilfs_sc_info *sci,
1891                                              struct the_nilfs *nilfs)
1892 {
1893         struct nilfs_transaction_info *ti = current->journal_info;
1894         struct nilfs_inode_info *ii, *n;
1895
1896         spin_lock(&nilfs->ns_inode_lock);
1897         list_for_each_entry_safe(ii, n, &sci->sc_dirty_files, i_dirty) {
1898                 if (!test_and_clear_bit(NILFS_I_UPDATED, &ii->i_state) ||
1899                     test_bit(NILFS_I_DIRTY, &ii->i_state))
1900                         continue;
1901
1902                 clear_bit(NILFS_I_BUSY, &ii->i_state);
1903                 brelse(ii->i_bh);
1904                 ii->i_bh = NULL;
1905                 list_move_tail(&ii->i_dirty, &ti->ti_garbage);
1906         }
1907         spin_unlock(&nilfs->ns_inode_lock);
1908 }
1909
1910 /*
1911  * Main procedure of segment constructor
1912  */
1913 static int nilfs_segctor_do_construct(struct nilfs_sc_info *sci, int mode)
1914 {
1915         struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
1916         int err;
1917
1918         sci->sc_stage.scnt = NILFS_ST_INIT;
1919         sci->sc_cno = nilfs->ns_cno;
1920
1921         err = nilfs_segctor_collect_dirty_files(sci, nilfs);
1922         if (unlikely(err))
1923                 goto out;
1924
1925         if (nilfs_test_metadata_dirty(nilfs, sci->sc_root))
1926                 set_bit(NILFS_SC_DIRTY, &sci->sc_flags);
1927
1928         if (nilfs_segctor_clean(sci))
1929                 goto out;
1930
1931         do {
1932                 sci->sc_stage.flags &= ~NILFS_CF_HISTORY_MASK;
1933
1934                 err = nilfs_segctor_begin_construction(sci, nilfs);
1935                 if (unlikely(err))
1936                         goto out;
1937
1938                 /* Update time stamp */
1939                 sci->sc_seg_ctime = get_seconds();
1940
1941                 err = nilfs_segctor_collect(sci, nilfs, mode);
1942                 if (unlikely(err))
1943                         goto failed;
1944
1945                 /* Avoid empty segment */
1946                 if (sci->sc_stage.scnt == NILFS_ST_DONE &&
1947                     nilfs_segbuf_empty(sci->sc_curseg)) {
1948                         nilfs_segctor_abort_construction(sci, nilfs, 1);
1949                         goto out;
1950                 }
1951
1952                 err = nilfs_segctor_assign(sci, mode);
1953                 if (unlikely(err))
1954                         goto failed;
1955
1956                 if (sci->sc_stage.flags & NILFS_CF_IFILE_STARTED)
1957                         nilfs_segctor_fill_in_file_bmap(sci);
1958
1959                 if (mode == SC_LSEG_SR &&
1960                     sci->sc_stage.scnt >= NILFS_ST_CPFILE) {
1961                         err = nilfs_segctor_fill_in_checkpoint(sci);
1962                         if (unlikely(err))
1963                                 goto failed_to_write;
1964
1965                         nilfs_segctor_fill_in_super_root(sci, nilfs);
1966                 }
1967                 nilfs_segctor_update_segusage(sci, nilfs->ns_sufile);
1968
1969                 /* Write partial segments */
1970                 nilfs_segctor_prepare_write(sci);
1971
1972                 nilfs_add_checksums_on_logs(&sci->sc_segbufs,
1973                                             nilfs->ns_crc_seed);
1974
1975                 err = nilfs_segctor_write(sci, nilfs);
1976                 if (unlikely(err))
1977                         goto failed_to_write;
1978
1979                 if (sci->sc_stage.scnt == NILFS_ST_DONE ||
1980                     nilfs->ns_blocksize_bits != PAGE_CACHE_SHIFT) {
1981                         /*
1982                          * At this point, we avoid double buffering
1983                          * for blocksize < pagesize because page dirty
1984                          * flag is turned off during write and dirty
1985                          * buffers are not properly collected for
1986                          * pages crossing over segments.
1987                          */
1988                         err = nilfs_segctor_wait(sci);
1989                         if (err)
1990                                 goto failed_to_write;
1991                 }
1992         } while (sci->sc_stage.scnt != NILFS_ST_DONE);
1993
1994  out:
1995         nilfs_segctor_drop_written_files(sci, nilfs);
1996         return err;
1997
1998  failed_to_write:
1999         if (sci->sc_stage.flags & NILFS_CF_IFILE_STARTED)
2000                 nilfs_redirty_inodes(&sci->sc_dirty_files);
2001
2002  failed:
2003         if (nilfs_doing_gc())
2004                 nilfs_redirty_inodes(&sci->sc_gc_inodes);
2005         nilfs_segctor_abort_construction(sci, nilfs, err);
2006         goto out;
2007 }
2008
2009 /**
2010  * nilfs_segctor_start_timer - set timer of background write
2011  * @sci: nilfs_sc_info
2012  *
2013  * If the timer has already been set, it ignores the new request.
2014  * This function MUST be called within a section locking the segment
2015  * semaphore.
2016  */
2017 static void nilfs_segctor_start_timer(struct nilfs_sc_info *sci)
2018 {
2019         spin_lock(&sci->sc_state_lock);
2020         if (!(sci->sc_state & NILFS_SEGCTOR_COMMIT)) {
2021                 sci->sc_timer.expires = jiffies + sci->sc_interval;
2022                 add_timer(&sci->sc_timer);
2023                 sci->sc_state |= NILFS_SEGCTOR_COMMIT;
2024         }
2025         spin_unlock(&sci->sc_state_lock);
2026 }
2027
2028 static void nilfs_segctor_do_flush(struct nilfs_sc_info *sci, int bn)
2029 {
2030         spin_lock(&sci->sc_state_lock);
2031         if (!(sci->sc_flush_request & (1 << bn))) {
2032                 unsigned long prev_req = sci->sc_flush_request;
2033
2034                 sci->sc_flush_request |= (1 << bn);
2035                 if (!prev_req)
2036                         wake_up(&sci->sc_wait_daemon);
2037         }
2038         spin_unlock(&sci->sc_state_lock);
2039 }
2040
2041 /**
2042  * nilfs_flush_segment - trigger a segment construction for resource control
2043  * @sb: super block
2044  * @ino: inode number of the file to be flushed out.
2045  */
2046 void nilfs_flush_segment(struct super_block *sb, ino_t ino)
2047 {
2048         struct the_nilfs *nilfs = sb->s_fs_info;
2049         struct nilfs_sc_info *sci = nilfs->ns_writer;
2050
2051         if (!sci || nilfs_doing_construction())
2052                 return;
2053         nilfs_segctor_do_flush(sci, NILFS_MDT_INODE(sb, ino) ? ino : 0);
2054                                         /* assign bit 0 to data files */
2055 }
2056
2057 struct nilfs_segctor_wait_request {
2058         wait_queue_t    wq;
2059         __u32           seq;
2060         int             err;
2061         atomic_t        done;
2062 };
2063
2064 static int nilfs_segctor_sync(struct nilfs_sc_info *sci)
2065 {
2066         struct nilfs_segctor_wait_request wait_req;
2067         int err = 0;
2068
2069         spin_lock(&sci->sc_state_lock);
2070         init_wait(&wait_req.wq);
2071         wait_req.err = 0;
2072         atomic_set(&wait_req.done, 0);
2073         wait_req.seq = ++sci->sc_seq_request;
2074         spin_unlock(&sci->sc_state_lock);
2075
2076         init_waitqueue_entry(&wait_req.wq, current);
2077         add_wait_queue(&sci->sc_wait_request, &wait_req.wq);
2078         set_current_state(TASK_INTERRUPTIBLE);
2079         wake_up(&sci->sc_wait_daemon);
2080
2081         for (;;) {
2082                 if (atomic_read(&wait_req.done)) {
2083                         err = wait_req.err;
2084                         break;
2085                 }
2086                 if (!signal_pending(current)) {
2087                         schedule();
2088                         continue;
2089                 }
2090                 err = -ERESTARTSYS;
2091                 break;
2092         }
2093         finish_wait(&sci->sc_wait_request, &wait_req.wq);
2094         return err;
2095 }
2096
2097 static void nilfs_segctor_wakeup(struct nilfs_sc_info *sci, int err)
2098 {
2099         struct nilfs_segctor_wait_request *wrq, *n;
2100         unsigned long flags;
2101
2102         spin_lock_irqsave(&sci->sc_wait_request.lock, flags);
2103         list_for_each_entry_safe(wrq, n, &sci->sc_wait_request.task_list,
2104                                  wq.task_list) {
2105                 if (!atomic_read(&wrq->done) &&
2106                     nilfs_cnt32_ge(sci->sc_seq_done, wrq->seq)) {
2107                         wrq->err = err;
2108                         atomic_set(&wrq->done, 1);
2109                 }
2110                 if (atomic_read(&wrq->done)) {
2111                         wrq->wq.func(&wrq->wq,
2112                                      TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE,
2113                                      0, NULL);
2114                 }
2115         }
2116         spin_unlock_irqrestore(&sci->sc_wait_request.lock, flags);
2117 }
2118
2119 /**
2120  * nilfs_construct_segment - construct a logical segment
2121  * @sb: super block
2122  *
2123  * Return Value: On success, 0 is retured. On errors, one of the following
2124  * negative error code is returned.
2125  *
2126  * %-EROFS - Read only filesystem.
2127  *
2128  * %-EIO - I/O error
2129  *
2130  * %-ENOSPC - No space left on device (only in a panic state).
2131  *
2132  * %-ERESTARTSYS - Interrupted.
2133  *
2134  * %-ENOMEM - Insufficient memory available.
2135  */
2136 int nilfs_construct_segment(struct super_block *sb)
2137 {
2138         struct the_nilfs *nilfs = sb->s_fs_info;
2139         struct nilfs_sc_info *sci = nilfs->ns_writer;
2140         struct nilfs_transaction_info *ti;
2141         int err;
2142
2143         if (!sci)
2144                 return -EROFS;
2145
2146         /* A call inside transactions causes a deadlock. */
2147         BUG_ON((ti = current->journal_info) && ti->ti_magic == NILFS_TI_MAGIC);
2148
2149         err = nilfs_segctor_sync(sci);
2150         return err;
2151 }
2152
2153 /**
2154  * nilfs_construct_dsync_segment - construct a data-only logical segment
2155  * @sb: super block
2156  * @inode: inode whose data blocks should be written out
2157  * @start: start byte offset
2158  * @end: end byte offset (inclusive)
2159  *
2160  * Return Value: On success, 0 is retured. On errors, one of the following
2161  * negative error code is returned.
2162  *
2163  * %-EROFS - Read only filesystem.
2164  *
2165  * %-EIO - I/O error
2166  *
2167  * %-ENOSPC - No space left on device (only in a panic state).
2168  *
2169  * %-ERESTARTSYS - Interrupted.
2170  *
2171  * %-ENOMEM - Insufficient memory available.
2172  */
2173 int nilfs_construct_dsync_segment(struct super_block *sb, struct inode *inode,
2174                                   loff_t start, loff_t end)
2175 {
2176         struct the_nilfs *nilfs = sb->s_fs_info;
2177         struct nilfs_sc_info *sci = nilfs->ns_writer;
2178         struct nilfs_inode_info *ii;
2179         struct nilfs_transaction_info ti;
2180         int err = 0;
2181
2182         if (!sci)
2183                 return -EROFS;
2184
2185         nilfs_transaction_lock(sb, &ti, 0);
2186
2187         ii = NILFS_I(inode);
2188         if (test_bit(NILFS_I_INODE_DIRTY, &ii->i_state) ||
2189             nilfs_test_opt(nilfs, STRICT_ORDER) ||
2190             test_bit(NILFS_SC_UNCLOSED, &sci->sc_flags) ||
2191             nilfs_discontinued(nilfs)) {
2192                 nilfs_transaction_unlock(sb);
2193                 err = nilfs_segctor_sync(sci);
2194                 return err;
2195         }
2196
2197         spin_lock(&nilfs->ns_inode_lock);
2198         if (!test_bit(NILFS_I_QUEUED, &ii->i_state) &&
2199             !test_bit(NILFS_I_BUSY, &ii->i_state)) {
2200                 spin_unlock(&nilfs->ns_inode_lock);
2201                 nilfs_transaction_unlock(sb);
2202                 return 0;
2203         }
2204         spin_unlock(&nilfs->ns_inode_lock);
2205         sci->sc_dsync_inode = ii;
2206         sci->sc_dsync_start = start;
2207         sci->sc_dsync_end = end;
2208
2209         err = nilfs_segctor_do_construct(sci, SC_LSEG_DSYNC);
2210
2211         nilfs_transaction_unlock(sb);
2212         return err;
2213 }
2214
2215 #define FLUSH_FILE_BIT  (0x1) /* data file only */
2216 #define FLUSH_DAT_BIT   (1 << NILFS_DAT_INO) /* DAT only */
2217
2218 /**
2219  * nilfs_segctor_accept - record accepted sequence count of log-write requests
2220  * @sci: segment constructor object
2221  */
2222 static void nilfs_segctor_accept(struct nilfs_sc_info *sci)
2223 {
2224         spin_lock(&sci->sc_state_lock);
2225         sci->sc_seq_accepted = sci->sc_seq_request;
2226         spin_unlock(&sci->sc_state_lock);
2227         del_timer_sync(&sci->sc_timer);
2228 }
2229
2230 /**
2231  * nilfs_segctor_notify - notify the result of request to caller threads
2232  * @sci: segment constructor object
2233  * @mode: mode of log forming
2234  * @err: error code to be notified
2235  */
2236 static void nilfs_segctor_notify(struct nilfs_sc_info *sci, int mode, int err)
2237 {
2238         /* Clear requests (even when the construction failed) */
2239         spin_lock(&sci->sc_state_lock);
2240
2241         if (mode == SC_LSEG_SR) {
2242                 sci->sc_state &= ~NILFS_SEGCTOR_COMMIT;
2243                 sci->sc_seq_done = sci->sc_seq_accepted;
2244                 nilfs_segctor_wakeup(sci, err);
2245                 sci->sc_flush_request = 0;
2246         } else {
2247                 if (mode == SC_FLUSH_FILE)
2248                         sci->sc_flush_request &= ~FLUSH_FILE_BIT;
2249                 else if (mode == SC_FLUSH_DAT)
2250                         sci->sc_flush_request &= ~FLUSH_DAT_BIT;
2251
2252                 /* re-enable timer if checkpoint creation was not done */
2253                 if ((sci->sc_state & NILFS_SEGCTOR_COMMIT) &&
2254                     time_before(jiffies, sci->sc_timer.expires))
2255                         add_timer(&sci->sc_timer);
2256         }
2257         spin_unlock(&sci->sc_state_lock);
2258 }
2259
2260 /**
2261  * nilfs_segctor_construct - form logs and write them to disk
2262  * @sci: segment constructor object
2263  * @mode: mode of log forming
2264  */
2265 static int nilfs_segctor_construct(struct nilfs_sc_info *sci, int mode)
2266 {
2267         struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
2268         struct nilfs_super_block **sbp;
2269         int err = 0;
2270
2271         nilfs_segctor_accept(sci);
2272
2273         if (nilfs_discontinued(nilfs))
2274                 mode = SC_LSEG_SR;
2275         if (!nilfs_segctor_confirm(sci))
2276                 err = nilfs_segctor_do_construct(sci, mode);
2277
2278         if (likely(!err)) {
2279                 if (mode != SC_FLUSH_DAT)
2280                         atomic_set(&nilfs->ns_ndirtyblks, 0);
2281                 if (test_bit(NILFS_SC_SUPER_ROOT, &sci->sc_flags) &&
2282                     nilfs_discontinued(nilfs)) {
2283                         down_write(&nilfs->ns_sem);
2284                         err = -EIO;
2285                         sbp = nilfs_prepare_super(sci->sc_super,
2286                                                   nilfs_sb_will_flip(nilfs));
2287                         if (likely(sbp)) {
2288                                 nilfs_set_log_cursor(sbp[0], nilfs);
2289                                 err = nilfs_commit_super(sci->sc_super,
2290                                                          NILFS_SB_COMMIT);
2291                         }
2292                         up_write(&nilfs->ns_sem);
2293                 }
2294         }
2295
2296         nilfs_segctor_notify(sci, mode, err);
2297         return err;
2298 }
2299
2300 static void nilfs_construction_timeout(unsigned long data)
2301 {
2302         struct task_struct *p = (struct task_struct *)data;
2303         wake_up_process(p);
2304 }
2305
2306 static void
2307 nilfs_remove_written_gcinodes(struct the_nilfs *nilfs, struct list_head *head)
2308 {
2309         struct nilfs_inode_info *ii, *n;
2310
2311         list_for_each_entry_safe(ii, n, head, i_dirty) {
2312                 if (!test_bit(NILFS_I_UPDATED, &ii->i_state))
2313                         continue;
2314                 list_del_init(&ii->i_dirty);
2315                 iput(&ii->vfs_inode);
2316         }
2317 }
2318
2319 int nilfs_clean_segments(struct super_block *sb, struct nilfs_argv *argv,
2320                          void **kbufs)
2321 {
2322         struct the_nilfs *nilfs = sb->s_fs_info;
2323         struct nilfs_sc_info *sci = nilfs->ns_writer;
2324         struct nilfs_transaction_info ti;
2325         int err;
2326
2327         if (unlikely(!sci))
2328                 return -EROFS;
2329
2330         nilfs_transaction_lock(sb, &ti, 1);
2331
2332         err = nilfs_mdt_save_to_shadow_map(nilfs->ns_dat);
2333         if (unlikely(err))
2334                 goto out_unlock;
2335
2336         err = nilfs_ioctl_prepare_clean_segments(nilfs, argv, kbufs);
2337         if (unlikely(err)) {
2338                 nilfs_mdt_restore_from_shadow_map(nilfs->ns_dat);
2339                 goto out_unlock;
2340         }
2341
2342         sci->sc_freesegs = kbufs[4];
2343         sci->sc_nfreesegs = argv[4].v_nmembs;
2344         list_splice_tail_init(&nilfs->ns_gc_inodes, &sci->sc_gc_inodes);
2345
2346         for (;;) {
2347                 err = nilfs_segctor_construct(sci, SC_LSEG_SR);
2348                 nilfs_remove_written_gcinodes(nilfs, &sci->sc_gc_inodes);
2349
2350                 if (likely(!err))
2351                         break;
2352
2353                 nilfs_warning(sb, __func__,
2354                               "segment construction failed. (err=%d)", err);
2355                 set_current_state(TASK_INTERRUPTIBLE);
2356                 schedule_timeout(sci->sc_interval);
2357         }
2358         if (nilfs_test_opt(nilfs, DISCARD)) {
2359                 int ret = nilfs_discard_segments(nilfs, sci->sc_freesegs,
2360                                                  sci->sc_nfreesegs);
2361                 if (ret) {
2362                         printk(KERN_WARNING
2363                                "NILFS warning: error %d on discard request, "
2364                                "turning discards off for the device\n", ret);
2365                         nilfs_clear_opt(nilfs, DISCARD);
2366                 }
2367         }
2368
2369  out_unlock:
2370         sci->sc_freesegs = NULL;
2371         sci->sc_nfreesegs = 0;
2372         nilfs_mdt_clear_shadow_map(nilfs->ns_dat);
2373         nilfs_transaction_unlock(sb);
2374         return err;
2375 }
2376
2377 static void nilfs_segctor_thread_construct(struct nilfs_sc_info *sci, int mode)
2378 {
2379         struct nilfs_transaction_info ti;
2380
2381         nilfs_transaction_lock(sci->sc_super, &ti, 0);
2382         nilfs_segctor_construct(sci, mode);
2383
2384         /*
2385          * Unclosed segment should be retried.  We do this using sc_timer.
2386          * Timeout of sc_timer will invoke complete construction which leads
2387          * to close the current logical segment.
2388          */
2389         if (test_bit(NILFS_SC_UNCLOSED, &sci->sc_flags))
2390                 nilfs_segctor_start_timer(sci);
2391
2392         nilfs_transaction_unlock(sci->sc_super);
2393 }
2394
2395 static void nilfs_segctor_do_immediate_flush(struct nilfs_sc_info *sci)
2396 {
2397         int mode = 0;
2398         int err;
2399
2400         spin_lock(&sci->sc_state_lock);
2401         mode = (sci->sc_flush_request & FLUSH_DAT_BIT) ?
2402                 SC_FLUSH_DAT : SC_FLUSH_FILE;
2403         spin_unlock(&sci->sc_state_lock);
2404
2405         if (mode) {
2406                 err = nilfs_segctor_do_construct(sci, mode);
2407
2408                 spin_lock(&sci->sc_state_lock);
2409                 sci->sc_flush_request &= (mode == SC_FLUSH_FILE) ?
2410                         ~FLUSH_FILE_BIT : ~FLUSH_DAT_BIT;
2411                 spin_unlock(&sci->sc_state_lock);
2412         }
2413         clear_bit(NILFS_SC_PRIOR_FLUSH, &sci->sc_flags);
2414 }
2415
2416 static int nilfs_segctor_flush_mode(struct nilfs_sc_info *sci)
2417 {
2418         if (!test_bit(NILFS_SC_UNCLOSED, &sci->sc_flags) ||
2419             time_before(jiffies, sci->sc_lseg_stime + sci->sc_mjcp_freq)) {
2420                 if (!(sci->sc_flush_request & ~FLUSH_FILE_BIT))
2421                         return SC_FLUSH_FILE;
2422                 else if (!(sci->sc_flush_request & ~FLUSH_DAT_BIT))
2423                         return SC_FLUSH_DAT;
2424         }
2425         return SC_LSEG_SR;
2426 }
2427
2428 /**
2429  * nilfs_segctor_thread - main loop of the segment constructor thread.
2430  * @arg: pointer to a struct nilfs_sc_info.
2431  *
2432  * nilfs_segctor_thread() initializes a timer and serves as a daemon
2433  * to execute segment constructions.
2434  */
2435 static int nilfs_segctor_thread(void *arg)
2436 {
2437         struct nilfs_sc_info *sci = (struct nilfs_sc_info *)arg;
2438         struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
2439         int timeout = 0;
2440
2441         sci->sc_timer.data = (unsigned long)current;
2442         sci->sc_timer.function = nilfs_construction_timeout;
2443
2444         /* start sync. */
2445         sci->sc_task = current;
2446         wake_up(&sci->sc_wait_task); /* for nilfs_segctor_start_thread() */
2447         printk(KERN_INFO
2448                "segctord starting. Construction interval = %lu seconds, "
2449                "CP frequency < %lu seconds\n",
2450                sci->sc_interval / HZ, sci->sc_mjcp_freq / HZ);
2451
2452         spin_lock(&sci->sc_state_lock);
2453  loop:
2454         for (;;) {
2455                 int mode;
2456
2457                 if (sci->sc_state & NILFS_SEGCTOR_QUIT)
2458                         goto end_thread;
2459
2460                 if (timeout || sci->sc_seq_request != sci->sc_seq_done)
2461                         mode = SC_LSEG_SR;
2462                 else if (!sci->sc_flush_request)
2463                         break;
2464                 else
2465                         mode = nilfs_segctor_flush_mode(sci);
2466
2467                 spin_unlock(&sci->sc_state_lock);
2468                 nilfs_segctor_thread_construct(sci, mode);
2469                 spin_lock(&sci->sc_state_lock);
2470                 timeout = 0;
2471         }
2472
2473
2474         if (freezing(current)) {
2475                 spin_unlock(&sci->sc_state_lock);
2476                 refrigerator();
2477                 spin_lock(&sci->sc_state_lock);
2478         } else {
2479                 DEFINE_WAIT(wait);
2480                 int should_sleep = 1;
2481
2482                 prepare_to_wait(&sci->sc_wait_daemon, &wait,
2483                                 TASK_INTERRUPTIBLE);
2484
2485                 if (sci->sc_seq_request != sci->sc_seq_done)
2486                         should_sleep = 0;
2487                 else if (sci->sc_flush_request)
2488                         should_sleep = 0;
2489                 else if (sci->sc_state & NILFS_SEGCTOR_COMMIT)
2490                         should_sleep = time_before(jiffies,
2491                                         sci->sc_timer.expires);
2492
2493                 if (should_sleep) {
2494                         spin_unlock(&sci->sc_state_lock);
2495                         schedule();
2496                         spin_lock(&sci->sc_state_lock);
2497                 }
2498                 finish_wait(&sci->sc_wait_daemon, &wait);
2499                 timeout = ((sci->sc_state & NILFS_SEGCTOR_COMMIT) &&
2500                            time_after_eq(jiffies, sci->sc_timer.expires));
2501
2502                 if (nilfs_sb_dirty(nilfs) && nilfs_sb_need_update(nilfs))
2503                         set_nilfs_discontinued(nilfs);
2504         }
2505         goto loop;
2506
2507  end_thread:
2508         spin_unlock(&sci->sc_state_lock);
2509
2510         /* end sync. */
2511         sci->sc_task = NULL;
2512         wake_up(&sci->sc_wait_task); /* for nilfs_segctor_kill_thread() */
2513         return 0;
2514 }
2515
2516 static int nilfs_segctor_start_thread(struct nilfs_sc_info *sci)
2517 {
2518         struct task_struct *t;
2519
2520         t = kthread_run(nilfs_segctor_thread, sci, "segctord");
2521         if (IS_ERR(t)) {
2522                 int err = PTR_ERR(t);
2523
2524                 printk(KERN_ERR "NILFS: error %d creating segctord thread\n",
2525                        err);
2526                 return err;
2527         }
2528         wait_event(sci->sc_wait_task, sci->sc_task != NULL);
2529         return 0;
2530 }
2531
2532 static void nilfs_segctor_kill_thread(struct nilfs_sc_info *sci)
2533         __acquires(&sci->sc_state_lock)
2534         __releases(&sci->sc_state_lock)
2535 {
2536         sci->sc_state |= NILFS_SEGCTOR_QUIT;
2537
2538         while (sci->sc_task) {
2539                 wake_up(&sci->sc_wait_daemon);
2540                 spin_unlock(&sci->sc_state_lock);
2541                 wait_event(sci->sc_wait_task, sci->sc_task == NULL);
2542                 spin_lock(&sci->sc_state_lock);
2543         }
2544 }
2545
2546 /*
2547  * Setup & clean-up functions
2548  */
2549 static struct nilfs_sc_info *nilfs_segctor_new(struct super_block *sb,
2550                                                struct nilfs_root *root)
2551 {
2552         struct the_nilfs *nilfs = sb->s_fs_info;
2553         struct nilfs_sc_info *sci;
2554
2555         sci = kzalloc(sizeof(*sci), GFP_KERNEL);
2556         if (!sci)
2557                 return NULL;
2558
2559         sci->sc_super = sb;
2560
2561         nilfs_get_root(root);
2562         sci->sc_root = root;
2563
2564         init_waitqueue_head(&sci->sc_wait_request);
2565         init_waitqueue_head(&sci->sc_wait_daemon);
2566         init_waitqueue_head(&sci->sc_wait_task);
2567         spin_lock_init(&sci->sc_state_lock);
2568         INIT_LIST_HEAD(&sci->sc_dirty_files);
2569         INIT_LIST_HEAD(&sci->sc_segbufs);
2570         INIT_LIST_HEAD(&sci->sc_write_logs);
2571         INIT_LIST_HEAD(&sci->sc_gc_inodes);
2572         init_timer(&sci->sc_timer);
2573
2574         sci->sc_interval = HZ * NILFS_SC_DEFAULT_TIMEOUT;
2575         sci->sc_mjcp_freq = HZ * NILFS_SC_DEFAULT_SR_FREQ;
2576         sci->sc_watermark = NILFS_SC_DEFAULT_WATERMARK;
2577
2578         if (nilfs->ns_interval)
2579                 sci->sc_interval = nilfs->ns_interval;
2580         if (nilfs->ns_watermark)
2581                 sci->sc_watermark = nilfs->ns_watermark;
2582         return sci;
2583 }
2584
2585 static void nilfs_segctor_write_out(struct nilfs_sc_info *sci)
2586 {
2587         int ret, retrycount = NILFS_SC_CLEANUP_RETRY;
2588
2589         /* The segctord thread was stopped and its timer was removed.
2590            But some tasks remain. */
2591         do {
2592                 struct nilfs_transaction_info ti;
2593
2594                 nilfs_transaction_lock(sci->sc_super, &ti, 0);
2595                 ret = nilfs_segctor_construct(sci, SC_LSEG_SR);
2596                 nilfs_transaction_unlock(sci->sc_super);
2597
2598         } while (ret && retrycount-- > 0);
2599 }
2600
2601 /**
2602  * nilfs_segctor_destroy - destroy the segment constructor.
2603  * @sci: nilfs_sc_info
2604  *
2605  * nilfs_segctor_destroy() kills the segctord thread and frees
2606  * the nilfs_sc_info struct.
2607  * Caller must hold the segment semaphore.
2608  */
2609 static void nilfs_segctor_destroy(struct nilfs_sc_info *sci)
2610 {
2611         struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
2612         int flag;
2613
2614         up_write(&nilfs->ns_segctor_sem);
2615
2616         spin_lock(&sci->sc_state_lock);
2617         nilfs_segctor_kill_thread(sci);
2618         flag = ((sci->sc_state & NILFS_SEGCTOR_COMMIT) || sci->sc_flush_request
2619                 || sci->sc_seq_request != sci->sc_seq_done);
2620         spin_unlock(&sci->sc_state_lock);
2621
2622         if (flag || !nilfs_segctor_confirm(sci))
2623                 nilfs_segctor_write_out(sci);
2624
2625         if (!list_empty(&sci->sc_dirty_files)) {
2626                 nilfs_warning(sci->sc_super, __func__,
2627                               "dirty file(s) after the final construction\n");
2628                 nilfs_dispose_list(nilfs, &sci->sc_dirty_files, 1);
2629         }
2630
2631         WARN_ON(!list_empty(&sci->sc_segbufs));
2632         WARN_ON(!list_empty(&sci->sc_write_logs));
2633
2634         nilfs_put_root(sci->sc_root);
2635
2636         down_write(&nilfs->ns_segctor_sem);
2637
2638         del_timer_sync(&sci->sc_timer);
2639         kfree(sci);
2640 }
2641
2642 /**
2643  * nilfs_attach_log_writer - attach log writer
2644  * @sb: super block instance
2645  * @root: root object of the current filesystem tree
2646  *
2647  * This allocates a log writer object, initializes it, and starts the
2648  * log writer.
2649  *
2650  * Return Value: On success, 0 is returned. On error, one of the following
2651  * negative error code is returned.
2652  *
2653  * %-ENOMEM - Insufficient memory available.
2654  */
2655 int nilfs_attach_log_writer(struct super_block *sb, struct nilfs_root *root)
2656 {
2657         struct the_nilfs *nilfs = sb->s_fs_info;
2658         int err;
2659
2660         if (nilfs->ns_writer) {
2661                 /*
2662                  * This happens if the filesystem was remounted
2663                  * read/write after nilfs_error degenerated it into a
2664                  * read-only mount.
2665                  */
2666                 nilfs_detach_log_writer(sb);
2667         }
2668
2669         nilfs->ns_writer = nilfs_segctor_new(sb, root);
2670         if (!nilfs->ns_writer)
2671                 return -ENOMEM;
2672
2673         err = nilfs_segctor_start_thread(nilfs->ns_writer);
2674         if (err) {
2675                 kfree(nilfs->ns_writer);
2676                 nilfs->ns_writer = NULL;
2677         }
2678         return err;
2679 }
2680
2681 /**
2682  * nilfs_detach_log_writer - destroy log writer
2683  * @sb: super block instance
2684  *
2685  * This kills log writer daemon, frees the log writer object, and
2686  * destroys list of dirty files.
2687  */
2688 void nilfs_detach_log_writer(struct super_block *sb)
2689 {
2690         struct the_nilfs *nilfs = sb->s_fs_info;
2691         LIST_HEAD(garbage_list);
2692
2693         down_write(&nilfs->ns_segctor_sem);
2694         if (nilfs->ns_writer) {
2695                 nilfs_segctor_destroy(nilfs->ns_writer);
2696                 nilfs->ns_writer = NULL;
2697         }
2698
2699         /* Force to free the list of dirty files */
2700         spin_lock(&nilfs->ns_inode_lock);
2701         if (!list_empty(&nilfs->ns_dirty_files)) {
2702                 list_splice_init(&nilfs->ns_dirty_files, &garbage_list);
2703                 nilfs_warning(sb, __func__,
2704                               "Hit dirty file after stopped log writer\n");
2705         }
2706         spin_unlock(&nilfs->ns_inode_lock);
2707         up_write(&nilfs->ns_segctor_sem);
2708
2709         nilfs_dispose_list(nilfs, &garbage_list, 1);
2710 }