Merge branch 'for-linus' of git://oss.sgi.com:8090/xfs/xfs-2.6
[linux-3.10.git] / fs / xfs / linux-2.6 / xfs_buf.c
1 /*
2  * Copyright (c) 2000-2006 Silicon Graphics, Inc.
3  * All Rights Reserved.
4  *
5  * This program is free software; you can redistribute it and/or
6  * modify it under the terms of the GNU General Public License as
7  * published by the Free Software Foundation.
8  *
9  * This program is distributed in the hope that it would be useful,
10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
12  * GNU General Public License for more details.
13  *
14  * You should have received a copy of the GNU General Public License
15  * along with this program; if not, write the Free Software Foundation,
16  * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
17  */
18 #include "xfs.h"
19 #include <linux/stddef.h>
20 #include <linux/errno.h>
21 #include <linux/slab.h>
22 #include <linux/pagemap.h>
23 #include <linux/init.h>
24 #include <linux/vmalloc.h>
25 #include <linux/bio.h>
26 #include <linux/sysctl.h>
27 #include <linux/proc_fs.h>
28 #include <linux/workqueue.h>
29 #include <linux/percpu.h>
30 #include <linux/blkdev.h>
31 #include <linux/hash.h>
32 #include <linux/kthread.h>
33 #include <linux/migrate.h>
34 #include <linux/backing-dev.h>
35 #include <linux/freezer.h>
36
37 static kmem_zone_t *xfs_buf_zone;
38 STATIC int xfsbufd(void *);
39 STATIC int xfsbufd_wakeup(int, gfp_t);
40 STATIC void xfs_buf_delwri_queue(xfs_buf_t *, int);
41 static struct shrinker xfs_buf_shake = {
42         .shrink = xfsbufd_wakeup,
43         .seeks = DEFAULT_SEEKS,
44 };
45
46 static struct workqueue_struct *xfslogd_workqueue;
47 struct workqueue_struct *xfsdatad_workqueue;
48
49 #ifdef XFS_BUF_TRACE
50 void
51 xfs_buf_trace(
52         xfs_buf_t       *bp,
53         char            *id,
54         void            *data,
55         void            *ra)
56 {
57         ktrace_enter(xfs_buf_trace_buf,
58                 bp, id,
59                 (void *)(unsigned long)bp->b_flags,
60                 (void *)(unsigned long)bp->b_hold.counter,
61                 (void *)(unsigned long)bp->b_sema.count.counter,
62                 (void *)current,
63                 data, ra,
64                 (void *)(unsigned long)((bp->b_file_offset>>32) & 0xffffffff),
65                 (void *)(unsigned long)(bp->b_file_offset & 0xffffffff),
66                 (void *)(unsigned long)bp->b_buffer_length,
67                 NULL, NULL, NULL, NULL, NULL);
68 }
69 ktrace_t *xfs_buf_trace_buf;
70 #define XFS_BUF_TRACE_SIZE      4096
71 #define XB_TRACE(bp, id, data)  \
72         xfs_buf_trace(bp, id, (void *)data, (void *)__builtin_return_address(0))
73 #else
74 #define XB_TRACE(bp, id, data)  do { } while (0)
75 #endif
76
77 #ifdef XFS_BUF_LOCK_TRACKING
78 # define XB_SET_OWNER(bp)       ((bp)->b_last_holder = current->pid)
79 # define XB_CLEAR_OWNER(bp)     ((bp)->b_last_holder = -1)
80 # define XB_GET_OWNER(bp)       ((bp)->b_last_holder)
81 #else
82 # define XB_SET_OWNER(bp)       do { } while (0)
83 # define XB_CLEAR_OWNER(bp)     do { } while (0)
84 # define XB_GET_OWNER(bp)       do { } while (0)
85 #endif
86
87 #define xb_to_gfp(flags) \
88         ((((flags) & XBF_READ_AHEAD) ? __GFP_NORETRY : \
89           ((flags) & XBF_DONT_BLOCK) ? GFP_NOFS : GFP_KERNEL) | __GFP_NOWARN)
90
91 #define xb_to_km(flags) \
92          (((flags) & XBF_DONT_BLOCK) ? KM_NOFS : KM_SLEEP)
93
94 #define xfs_buf_allocate(flags) \
95         kmem_zone_alloc(xfs_buf_zone, xb_to_km(flags))
96 #define xfs_buf_deallocate(bp) \
97         kmem_zone_free(xfs_buf_zone, (bp));
98
99 /*
100  *      Page Region interfaces.
101  *
102  *      For pages in filesystems where the blocksize is smaller than the
103  *      pagesize, we use the page->private field (long) to hold a bitmap
104  *      of uptodate regions within the page.
105  *
106  *      Each such region is "bytes per page / bits per long" bytes long.
107  *
108  *      NBPPR == number-of-bytes-per-page-region
109  *      BTOPR == bytes-to-page-region (rounded up)
110  *      BTOPRT == bytes-to-page-region-truncated (rounded down)
111  */
112 #if (BITS_PER_LONG == 32)
113 #define PRSHIFT         (PAGE_CACHE_SHIFT - 5)  /* (32 == 1<<5) */
114 #elif (BITS_PER_LONG == 64)
115 #define PRSHIFT         (PAGE_CACHE_SHIFT - 6)  /* (64 == 1<<6) */
116 #else
117 #error BITS_PER_LONG must be 32 or 64
118 #endif
119 #define NBPPR           (PAGE_CACHE_SIZE/BITS_PER_LONG)
120 #define BTOPR(b)        (((unsigned int)(b) + (NBPPR - 1)) >> PRSHIFT)
121 #define BTOPRT(b)       (((unsigned int)(b) >> PRSHIFT))
122
123 STATIC unsigned long
124 page_region_mask(
125         size_t          offset,
126         size_t          length)
127 {
128         unsigned long   mask;
129         int             first, final;
130
131         first = BTOPR(offset);
132         final = BTOPRT(offset + length - 1);
133         first = min(first, final);
134
135         mask = ~0UL;
136         mask <<= BITS_PER_LONG - (final - first);
137         mask >>= BITS_PER_LONG - (final);
138
139         ASSERT(offset + length <= PAGE_CACHE_SIZE);
140         ASSERT((final - first) < BITS_PER_LONG && (final - first) >= 0);
141
142         return mask;
143 }
144
145 STATIC_INLINE void
146 set_page_region(
147         struct page     *page,
148         size_t          offset,
149         size_t          length)
150 {
151         set_page_private(page,
152                 page_private(page) | page_region_mask(offset, length));
153         if (page_private(page) == ~0UL)
154                 SetPageUptodate(page);
155 }
156
157 STATIC_INLINE int
158 test_page_region(
159         struct page     *page,
160         size_t          offset,
161         size_t          length)
162 {
163         unsigned long   mask = page_region_mask(offset, length);
164
165         return (mask && (page_private(page) & mask) == mask);
166 }
167
168 /*
169  *      Mapping of multi-page buffers into contiguous virtual space
170  */
171
172 typedef struct a_list {
173         void            *vm_addr;
174         struct a_list   *next;
175 } a_list_t;
176
177 static a_list_t         *as_free_head;
178 static int              as_list_len;
179 static DEFINE_SPINLOCK(as_lock);
180
181 /*
182  *      Try to batch vunmaps because they are costly.
183  */
184 STATIC void
185 free_address(
186         void            *addr)
187 {
188         a_list_t        *aentry;
189
190 #ifdef CONFIG_XEN
191         /*
192          * Xen needs to be able to make sure it can get an exclusive
193          * RO mapping of pages it wants to turn into a pagetable.  If
194          * a newly allocated page is also still being vmap()ed by xfs,
195          * it will cause pagetable construction to fail.  This is a
196          * quick workaround to always eagerly unmap pages so that Xen
197          * is happy.
198          */
199         vunmap(addr);
200         return;
201 #endif
202
203         aentry = kmalloc(sizeof(a_list_t), GFP_NOWAIT);
204         if (likely(aentry)) {
205                 spin_lock(&as_lock);
206                 aentry->next = as_free_head;
207                 aentry->vm_addr = addr;
208                 as_free_head = aentry;
209                 as_list_len++;
210                 spin_unlock(&as_lock);
211         } else {
212                 vunmap(addr);
213         }
214 }
215
216 STATIC void
217 purge_addresses(void)
218 {
219         a_list_t        *aentry, *old;
220
221         if (as_free_head == NULL)
222                 return;
223
224         spin_lock(&as_lock);
225         aentry = as_free_head;
226         as_free_head = NULL;
227         as_list_len = 0;
228         spin_unlock(&as_lock);
229
230         while ((old = aentry) != NULL) {
231                 vunmap(aentry->vm_addr);
232                 aentry = aentry->next;
233                 kfree(old);
234         }
235 }
236
237 /*
238  *      Internal xfs_buf_t object manipulation
239  */
240
241 STATIC void
242 _xfs_buf_initialize(
243         xfs_buf_t               *bp,
244         xfs_buftarg_t           *target,
245         xfs_off_t               range_base,
246         size_t                  range_length,
247         xfs_buf_flags_t         flags)
248 {
249         /*
250          * We don't want certain flags to appear in b_flags.
251          */
252         flags &= ~(XBF_LOCK|XBF_MAPPED|XBF_DONT_BLOCK|XBF_READ_AHEAD);
253
254         memset(bp, 0, sizeof(xfs_buf_t));
255         atomic_set(&bp->b_hold, 1);
256         init_MUTEX_LOCKED(&bp->b_iodonesema);
257         INIT_LIST_HEAD(&bp->b_list);
258         INIT_LIST_HEAD(&bp->b_hash_list);
259         init_MUTEX_LOCKED(&bp->b_sema); /* held, no waiters */
260         XB_SET_OWNER(bp);
261         bp->b_target = target;
262         bp->b_file_offset = range_base;
263         /*
264          * Set buffer_length and count_desired to the same value initially.
265          * I/O routines should use count_desired, which will be the same in
266          * most cases but may be reset (e.g. XFS recovery).
267          */
268         bp->b_buffer_length = bp->b_count_desired = range_length;
269         bp->b_flags = flags;
270         bp->b_bn = XFS_BUF_DADDR_NULL;
271         atomic_set(&bp->b_pin_count, 0);
272         init_waitqueue_head(&bp->b_waiters);
273
274         XFS_STATS_INC(xb_create);
275         XB_TRACE(bp, "initialize", target);
276 }
277
278 /*
279  *      Allocate a page array capable of holding a specified number
280  *      of pages, and point the page buf at it.
281  */
282 STATIC int
283 _xfs_buf_get_pages(
284         xfs_buf_t               *bp,
285         int                     page_count,
286         xfs_buf_flags_t         flags)
287 {
288         /* Make sure that we have a page list */
289         if (bp->b_pages == NULL) {
290                 bp->b_offset = xfs_buf_poff(bp->b_file_offset);
291                 bp->b_page_count = page_count;
292                 if (page_count <= XB_PAGES) {
293                         bp->b_pages = bp->b_page_array;
294                 } else {
295                         bp->b_pages = kmem_alloc(sizeof(struct page *) *
296                                         page_count, xb_to_km(flags));
297                         if (bp->b_pages == NULL)
298                                 return -ENOMEM;
299                 }
300                 memset(bp->b_pages, 0, sizeof(struct page *) * page_count);
301         }
302         return 0;
303 }
304
305 /*
306  *      Frees b_pages if it was allocated.
307  */
308 STATIC void
309 _xfs_buf_free_pages(
310         xfs_buf_t       *bp)
311 {
312         if (bp->b_pages != bp->b_page_array) {
313                 kmem_free(bp->b_pages,
314                           bp->b_page_count * sizeof(struct page *));
315         }
316 }
317
318 /*
319  *      Releases the specified buffer.
320  *
321  *      The modification state of any associated pages is left unchanged.
322  *      The buffer most not be on any hash - use xfs_buf_rele instead for
323  *      hashed and refcounted buffers
324  */
325 void
326 xfs_buf_free(
327         xfs_buf_t               *bp)
328 {
329         XB_TRACE(bp, "free", 0);
330
331         ASSERT(list_empty(&bp->b_hash_list));
332
333         if (bp->b_flags & (_XBF_PAGE_CACHE|_XBF_PAGES)) {
334                 uint            i;
335
336                 if ((bp->b_flags & XBF_MAPPED) && (bp->b_page_count > 1))
337                         free_address(bp->b_addr - bp->b_offset);
338
339                 for (i = 0; i < bp->b_page_count; i++) {
340                         struct page     *page = bp->b_pages[i];
341
342                         if (bp->b_flags & _XBF_PAGE_CACHE)
343                                 ASSERT(!PagePrivate(page));
344                         page_cache_release(page);
345                 }
346                 _xfs_buf_free_pages(bp);
347         }
348
349         xfs_buf_deallocate(bp);
350 }
351
352 /*
353  *      Finds all pages for buffer in question and builds it's page list.
354  */
355 STATIC int
356 _xfs_buf_lookup_pages(
357         xfs_buf_t               *bp,
358         uint                    flags)
359 {
360         struct address_space    *mapping = bp->b_target->bt_mapping;
361         size_t                  blocksize = bp->b_target->bt_bsize;
362         size_t                  size = bp->b_count_desired;
363         size_t                  nbytes, offset;
364         gfp_t                   gfp_mask = xb_to_gfp(flags);
365         unsigned short          page_count, i;
366         pgoff_t                 first;
367         xfs_off_t               end;
368         int                     error;
369
370         end = bp->b_file_offset + bp->b_buffer_length;
371         page_count = xfs_buf_btoc(end) - xfs_buf_btoct(bp->b_file_offset);
372
373         error = _xfs_buf_get_pages(bp, page_count, flags);
374         if (unlikely(error))
375                 return error;
376         bp->b_flags |= _XBF_PAGE_CACHE;
377
378         offset = bp->b_offset;
379         first = bp->b_file_offset >> PAGE_CACHE_SHIFT;
380
381         for (i = 0; i < bp->b_page_count; i++) {
382                 struct page     *page;
383                 uint            retries = 0;
384
385               retry:
386                 page = find_or_create_page(mapping, first + i, gfp_mask);
387                 if (unlikely(page == NULL)) {
388                         if (flags & XBF_READ_AHEAD) {
389                                 bp->b_page_count = i;
390                                 for (i = 0; i < bp->b_page_count; i++)
391                                         unlock_page(bp->b_pages[i]);
392                                 return -ENOMEM;
393                         }
394
395                         /*
396                          * This could deadlock.
397                          *
398                          * But until all the XFS lowlevel code is revamped to
399                          * handle buffer allocation failures we can't do much.
400                          */
401                         if (!(++retries % 100))
402                                 printk(KERN_ERR
403                                         "XFS: possible memory allocation "
404                                         "deadlock in %s (mode:0x%x)\n",
405                                         __FUNCTION__, gfp_mask);
406
407                         XFS_STATS_INC(xb_page_retries);
408                         xfsbufd_wakeup(0, gfp_mask);
409                         congestion_wait(WRITE, HZ/50);
410                         goto retry;
411                 }
412
413                 XFS_STATS_INC(xb_page_found);
414
415                 nbytes = min_t(size_t, size, PAGE_CACHE_SIZE - offset);
416                 size -= nbytes;
417
418                 ASSERT(!PagePrivate(page));
419                 if (!PageUptodate(page)) {
420                         page_count--;
421                         if (blocksize >= PAGE_CACHE_SIZE) {
422                                 if (flags & XBF_READ)
423                                         bp->b_locked = 1;
424                         } else if (!PagePrivate(page)) {
425                                 if (test_page_region(page, offset, nbytes))
426                                         page_count++;
427                         }
428                 }
429
430                 bp->b_pages[i] = page;
431                 offset = 0;
432         }
433
434         if (!bp->b_locked) {
435                 for (i = 0; i < bp->b_page_count; i++)
436                         unlock_page(bp->b_pages[i]);
437         }
438
439         if (page_count == bp->b_page_count)
440                 bp->b_flags |= XBF_DONE;
441
442         XB_TRACE(bp, "lookup_pages", (long)page_count);
443         return error;
444 }
445
446 /*
447  *      Map buffer into kernel address-space if nessecary.
448  */
449 STATIC int
450 _xfs_buf_map_pages(
451         xfs_buf_t               *bp,
452         uint                    flags)
453 {
454         /* A single page buffer is always mappable */
455         if (bp->b_page_count == 1) {
456                 bp->b_addr = page_address(bp->b_pages[0]) + bp->b_offset;
457                 bp->b_flags |= XBF_MAPPED;
458         } else if (flags & XBF_MAPPED) {
459                 if (as_list_len > 64)
460                         purge_addresses();
461                 bp->b_addr = vmap(bp->b_pages, bp->b_page_count,
462                                         VM_MAP, PAGE_KERNEL);
463                 if (unlikely(bp->b_addr == NULL))
464                         return -ENOMEM;
465                 bp->b_addr += bp->b_offset;
466                 bp->b_flags |= XBF_MAPPED;
467         }
468
469         return 0;
470 }
471
472 /*
473  *      Finding and Reading Buffers
474  */
475
476 /*
477  *      Look up, and creates if absent, a lockable buffer for
478  *      a given range of an inode.  The buffer is returned
479  *      locked.  If other overlapping buffers exist, they are
480  *      released before the new buffer is created and locked,
481  *      which may imply that this call will block until those buffers
482  *      are unlocked.  No I/O is implied by this call.
483  */
484 xfs_buf_t *
485 _xfs_buf_find(
486         xfs_buftarg_t           *btp,   /* block device target          */
487         xfs_off_t               ioff,   /* starting offset of range     */
488         size_t                  isize,  /* length of range              */
489         xfs_buf_flags_t         flags,
490         xfs_buf_t               *new_bp)
491 {
492         xfs_off_t               range_base;
493         size_t                  range_length;
494         xfs_bufhash_t           *hash;
495         xfs_buf_t               *bp, *n;
496
497         range_base = (ioff << BBSHIFT);
498         range_length = (isize << BBSHIFT);
499
500         /* Check for IOs smaller than the sector size / not sector aligned */
501         ASSERT(!(range_length < (1 << btp->bt_sshift)));
502         ASSERT(!(range_base & (xfs_off_t)btp->bt_smask));
503
504         hash = &btp->bt_hash[hash_long((unsigned long)ioff, btp->bt_hashshift)];
505
506         spin_lock(&hash->bh_lock);
507
508         list_for_each_entry_safe(bp, n, &hash->bh_list, b_hash_list) {
509                 ASSERT(btp == bp->b_target);
510                 if (bp->b_file_offset == range_base &&
511                     bp->b_buffer_length == range_length) {
512                         /*
513                          * If we look at something, bring it to the
514                          * front of the list for next time.
515                          */
516                         atomic_inc(&bp->b_hold);
517                         list_move(&bp->b_hash_list, &hash->bh_list);
518                         goto found;
519                 }
520         }
521
522         /* No match found */
523         if (new_bp) {
524                 _xfs_buf_initialize(new_bp, btp, range_base,
525                                 range_length, flags);
526                 new_bp->b_hash = hash;
527                 list_add(&new_bp->b_hash_list, &hash->bh_list);
528         } else {
529                 XFS_STATS_INC(xb_miss_locked);
530         }
531
532         spin_unlock(&hash->bh_lock);
533         return new_bp;
534
535 found:
536         spin_unlock(&hash->bh_lock);
537
538         /* Attempt to get the semaphore without sleeping,
539          * if this does not work then we need to drop the
540          * spinlock and do a hard attempt on the semaphore.
541          */
542         if (down_trylock(&bp->b_sema)) {
543                 if (!(flags & XBF_TRYLOCK)) {
544                         /* wait for buffer ownership */
545                         XB_TRACE(bp, "get_lock", 0);
546                         xfs_buf_lock(bp);
547                         XFS_STATS_INC(xb_get_locked_waited);
548                 } else {
549                         /* We asked for a trylock and failed, no need
550                          * to look at file offset and length here, we
551                          * know that this buffer at least overlaps our
552                          * buffer and is locked, therefore our buffer
553                          * either does not exist, or is this buffer.
554                          */
555                         xfs_buf_rele(bp);
556                         XFS_STATS_INC(xb_busy_locked);
557                         return NULL;
558                 }
559         } else {
560                 /* trylock worked */
561                 XB_SET_OWNER(bp);
562         }
563
564         if (bp->b_flags & XBF_STALE) {
565                 ASSERT((bp->b_flags & _XBF_DELWRI_Q) == 0);
566                 bp->b_flags &= XBF_MAPPED;
567         }
568         XB_TRACE(bp, "got_lock", 0);
569         XFS_STATS_INC(xb_get_locked);
570         return bp;
571 }
572
573 /*
574  *      Assembles a buffer covering the specified range.
575  *      Storage in memory for all portions of the buffer will be allocated,
576  *      although backing storage may not be.
577  */
578 xfs_buf_t *
579 xfs_buf_get_flags(
580         xfs_buftarg_t           *target,/* target for buffer            */
581         xfs_off_t               ioff,   /* starting offset of range     */
582         size_t                  isize,  /* length of range              */
583         xfs_buf_flags_t         flags)
584 {
585         xfs_buf_t               *bp, *new_bp;
586         int                     error = 0, i;
587
588         new_bp = xfs_buf_allocate(flags);
589         if (unlikely(!new_bp))
590                 return NULL;
591
592         bp = _xfs_buf_find(target, ioff, isize, flags, new_bp);
593         if (bp == new_bp) {
594                 error = _xfs_buf_lookup_pages(bp, flags);
595                 if (error)
596                         goto no_buffer;
597         } else {
598                 xfs_buf_deallocate(new_bp);
599                 if (unlikely(bp == NULL))
600                         return NULL;
601         }
602
603         for (i = 0; i < bp->b_page_count; i++)
604                 mark_page_accessed(bp->b_pages[i]);
605
606         if (!(bp->b_flags & XBF_MAPPED)) {
607                 error = _xfs_buf_map_pages(bp, flags);
608                 if (unlikely(error)) {
609                         printk(KERN_WARNING "%s: failed to map pages\n",
610                                         __FUNCTION__);
611                         goto no_buffer;
612                 }
613         }
614
615         XFS_STATS_INC(xb_get);
616
617         /*
618          * Always fill in the block number now, the mapped cases can do
619          * their own overlay of this later.
620          */
621         bp->b_bn = ioff;
622         bp->b_count_desired = bp->b_buffer_length;
623
624         XB_TRACE(bp, "get", (unsigned long)flags);
625         return bp;
626
627  no_buffer:
628         if (flags & (XBF_LOCK | XBF_TRYLOCK))
629                 xfs_buf_unlock(bp);
630         xfs_buf_rele(bp);
631         return NULL;
632 }
633
634 xfs_buf_t *
635 xfs_buf_read_flags(
636         xfs_buftarg_t           *target,
637         xfs_off_t               ioff,
638         size_t                  isize,
639         xfs_buf_flags_t         flags)
640 {
641         xfs_buf_t               *bp;
642
643         flags |= XBF_READ;
644
645         bp = xfs_buf_get_flags(target, ioff, isize, flags);
646         if (bp) {
647                 if (!XFS_BUF_ISDONE(bp)) {
648                         XB_TRACE(bp, "read", (unsigned long)flags);
649                         XFS_STATS_INC(xb_get_read);
650                         xfs_buf_iostart(bp, flags);
651                 } else if (flags & XBF_ASYNC) {
652                         XB_TRACE(bp, "read_async", (unsigned long)flags);
653                         /*
654                          * Read ahead call which is already satisfied,
655                          * drop the buffer
656                          */
657                         goto no_buffer;
658                 } else {
659                         XB_TRACE(bp, "read_done", (unsigned long)flags);
660                         /* We do not want read in the flags */
661                         bp->b_flags &= ~XBF_READ;
662                 }
663         }
664
665         return bp;
666
667  no_buffer:
668         if (flags & (XBF_LOCK | XBF_TRYLOCK))
669                 xfs_buf_unlock(bp);
670         xfs_buf_rele(bp);
671         return NULL;
672 }
673
674 /*
675  *      If we are not low on memory then do the readahead in a deadlock
676  *      safe manner.
677  */
678 void
679 xfs_buf_readahead(
680         xfs_buftarg_t           *target,
681         xfs_off_t               ioff,
682         size_t                  isize,
683         xfs_buf_flags_t         flags)
684 {
685         struct backing_dev_info *bdi;
686
687         bdi = target->bt_mapping->backing_dev_info;
688         if (bdi_read_congested(bdi))
689                 return;
690
691         flags |= (XBF_TRYLOCK|XBF_ASYNC|XBF_READ_AHEAD);
692         xfs_buf_read_flags(target, ioff, isize, flags);
693 }
694
695 xfs_buf_t *
696 xfs_buf_get_empty(
697         size_t                  len,
698         xfs_buftarg_t           *target)
699 {
700         xfs_buf_t               *bp;
701
702         bp = xfs_buf_allocate(0);
703         if (bp)
704                 _xfs_buf_initialize(bp, target, 0, len, 0);
705         return bp;
706 }
707
708 static inline struct page *
709 mem_to_page(
710         void                    *addr)
711 {
712         if (((unsigned long)addr < VMALLOC_START) ||
713             ((unsigned long)addr >= VMALLOC_END)) {
714                 return virt_to_page(addr);
715         } else {
716                 return vmalloc_to_page(addr);
717         }
718 }
719
720 int
721 xfs_buf_associate_memory(
722         xfs_buf_t               *bp,
723         void                    *mem,
724         size_t                  len)
725 {
726         int                     rval;
727         int                     i = 0;
728         size_t                  ptr;
729         size_t                  end, end_cur;
730         off_t                   offset;
731         int                     page_count;
732
733         page_count = PAGE_CACHE_ALIGN(len) >> PAGE_CACHE_SHIFT;
734         offset = (off_t) mem - ((off_t)mem & PAGE_CACHE_MASK);
735         if (offset && (len > PAGE_CACHE_SIZE))
736                 page_count++;
737
738         /* Free any previous set of page pointers */
739         if (bp->b_pages)
740                 _xfs_buf_free_pages(bp);
741
742         bp->b_pages = NULL;
743         bp->b_addr = mem;
744
745         rval = _xfs_buf_get_pages(bp, page_count, 0);
746         if (rval)
747                 return rval;
748
749         bp->b_offset = offset;
750         ptr = (size_t) mem & PAGE_CACHE_MASK;
751         end = PAGE_CACHE_ALIGN((size_t) mem + len);
752         end_cur = end;
753         /* set up first page */
754         bp->b_pages[0] = mem_to_page(mem);
755
756         ptr += PAGE_CACHE_SIZE;
757         bp->b_page_count = ++i;
758         while (ptr < end) {
759                 bp->b_pages[i] = mem_to_page((void *)ptr);
760                 bp->b_page_count = ++i;
761                 ptr += PAGE_CACHE_SIZE;
762         }
763         bp->b_locked = 0;
764
765         bp->b_count_desired = bp->b_buffer_length = len;
766         bp->b_flags |= XBF_MAPPED;
767
768         return 0;
769 }
770
771 xfs_buf_t *
772 xfs_buf_get_noaddr(
773         size_t                  len,
774         xfs_buftarg_t           *target)
775 {
776         unsigned long           page_count = PAGE_ALIGN(len) >> PAGE_SHIFT;
777         int                     error, i;
778         xfs_buf_t               *bp;
779
780         bp = xfs_buf_allocate(0);
781         if (unlikely(bp == NULL))
782                 goto fail;
783         _xfs_buf_initialize(bp, target, 0, len, 0);
784
785         error = _xfs_buf_get_pages(bp, page_count, 0);
786         if (error)
787                 goto fail_free_buf;
788
789         for (i = 0; i < page_count; i++) {
790                 bp->b_pages[i] = alloc_page(GFP_KERNEL);
791                 if (!bp->b_pages[i])
792                         goto fail_free_mem;
793         }
794         bp->b_flags |= _XBF_PAGES;
795
796         error = _xfs_buf_map_pages(bp, XBF_MAPPED);
797         if (unlikely(error)) {
798                 printk(KERN_WARNING "%s: failed to map pages\n",
799                                 __FUNCTION__);
800                 goto fail_free_mem;
801         }
802
803         xfs_buf_unlock(bp);
804
805         XB_TRACE(bp, "no_daddr", len);
806         return bp;
807
808  fail_free_mem:
809         while (--i >= 0)
810                 __free_page(bp->b_pages[i]);
811         _xfs_buf_free_pages(bp);
812  fail_free_buf:
813         xfs_buf_deallocate(bp);
814  fail:
815         return NULL;
816 }
817
818 /*
819  *      Increment reference count on buffer, to hold the buffer concurrently
820  *      with another thread which may release (free) the buffer asynchronously.
821  *      Must hold the buffer already to call this function.
822  */
823 void
824 xfs_buf_hold(
825         xfs_buf_t               *bp)
826 {
827         atomic_inc(&bp->b_hold);
828         XB_TRACE(bp, "hold", 0);
829 }
830
831 /*
832  *      Releases a hold on the specified buffer.  If the
833  *      the hold count is 1, calls xfs_buf_free.
834  */
835 void
836 xfs_buf_rele(
837         xfs_buf_t               *bp)
838 {
839         xfs_bufhash_t           *hash = bp->b_hash;
840
841         XB_TRACE(bp, "rele", bp->b_relse);
842
843         if (unlikely(!hash)) {
844                 ASSERT(!bp->b_relse);
845                 if (atomic_dec_and_test(&bp->b_hold))
846                         xfs_buf_free(bp);
847                 return;
848         }
849
850         if (atomic_dec_and_lock(&bp->b_hold, &hash->bh_lock)) {
851                 if (bp->b_relse) {
852                         atomic_inc(&bp->b_hold);
853                         spin_unlock(&hash->bh_lock);
854                         (*(bp->b_relse)) (bp);
855                 } else if (bp->b_flags & XBF_FS_MANAGED) {
856                         spin_unlock(&hash->bh_lock);
857                 } else {
858                         ASSERT(!(bp->b_flags & (XBF_DELWRI|_XBF_DELWRI_Q)));
859                         list_del_init(&bp->b_hash_list);
860                         spin_unlock(&hash->bh_lock);
861                         xfs_buf_free(bp);
862                 }
863         } else {
864                 /*
865                  * Catch reference count leaks
866                  */
867                 ASSERT(atomic_read(&bp->b_hold) >= 0);
868         }
869 }
870
871
872 /*
873  *      Mutual exclusion on buffers.  Locking model:
874  *
875  *      Buffers associated with inodes for which buffer locking
876  *      is not enabled are not protected by semaphores, and are
877  *      assumed to be exclusively owned by the caller.  There is a
878  *      spinlock in the buffer, used by the caller when concurrent
879  *      access is possible.
880  */
881
882 /*
883  *      Locks a buffer object, if it is not already locked.
884  *      Note that this in no way locks the underlying pages, so it is only
885  *      useful for synchronizing concurrent use of buffer objects, not for
886  *      synchronizing independent access to the underlying pages.
887  */
888 int
889 xfs_buf_cond_lock(
890         xfs_buf_t               *bp)
891 {
892         int                     locked;
893
894         locked = down_trylock(&bp->b_sema) == 0;
895         if (locked) {
896                 XB_SET_OWNER(bp);
897         }
898         XB_TRACE(bp, "cond_lock", (long)locked);
899         return locked ? 0 : -EBUSY;
900 }
901
902 #if defined(DEBUG) || defined(XFS_BLI_TRACE)
903 int
904 xfs_buf_lock_value(
905         xfs_buf_t               *bp)
906 {
907         return atomic_read(&bp->b_sema.count);
908 }
909 #endif
910
911 /*
912  *      Locks a buffer object.
913  *      Note that this in no way locks the underlying pages, so it is only
914  *      useful for synchronizing concurrent use of buffer objects, not for
915  *      synchronizing independent access to the underlying pages.
916  */
917 void
918 xfs_buf_lock(
919         xfs_buf_t               *bp)
920 {
921         XB_TRACE(bp, "lock", 0);
922         if (atomic_read(&bp->b_io_remaining))
923                 blk_run_address_space(bp->b_target->bt_mapping);
924         down(&bp->b_sema);
925         XB_SET_OWNER(bp);
926         XB_TRACE(bp, "locked", 0);
927 }
928
929 /*
930  *      Releases the lock on the buffer object.
931  *      If the buffer is marked delwri but is not queued, do so before we
932  *      unlock the buffer as we need to set flags correctly.  We also need to
933  *      take a reference for the delwri queue because the unlocker is going to
934  *      drop their's and they don't know we just queued it.
935  */
936 void
937 xfs_buf_unlock(
938         xfs_buf_t               *bp)
939 {
940         if ((bp->b_flags & (XBF_DELWRI|_XBF_DELWRI_Q)) == XBF_DELWRI) {
941                 atomic_inc(&bp->b_hold);
942                 bp->b_flags |= XBF_ASYNC;
943                 xfs_buf_delwri_queue(bp, 0);
944         }
945
946         XB_CLEAR_OWNER(bp);
947         up(&bp->b_sema);
948         XB_TRACE(bp, "unlock", 0);
949 }
950
951
952 /*
953  *      Pinning Buffer Storage in Memory
954  *      Ensure that no attempt to force a buffer to disk will succeed.
955  */
956 void
957 xfs_buf_pin(
958         xfs_buf_t               *bp)
959 {
960         atomic_inc(&bp->b_pin_count);
961         XB_TRACE(bp, "pin", (long)bp->b_pin_count.counter);
962 }
963
964 void
965 xfs_buf_unpin(
966         xfs_buf_t               *bp)
967 {
968         if (atomic_dec_and_test(&bp->b_pin_count))
969                 wake_up_all(&bp->b_waiters);
970         XB_TRACE(bp, "unpin", (long)bp->b_pin_count.counter);
971 }
972
973 int
974 xfs_buf_ispin(
975         xfs_buf_t               *bp)
976 {
977         return atomic_read(&bp->b_pin_count);
978 }
979
980 STATIC void
981 xfs_buf_wait_unpin(
982         xfs_buf_t               *bp)
983 {
984         DECLARE_WAITQUEUE       (wait, current);
985
986         if (atomic_read(&bp->b_pin_count) == 0)
987                 return;
988
989         add_wait_queue(&bp->b_waiters, &wait);
990         for (;;) {
991                 set_current_state(TASK_UNINTERRUPTIBLE);
992                 if (atomic_read(&bp->b_pin_count) == 0)
993                         break;
994                 if (atomic_read(&bp->b_io_remaining))
995                         blk_run_address_space(bp->b_target->bt_mapping);
996                 schedule();
997         }
998         remove_wait_queue(&bp->b_waiters, &wait);
999         set_current_state(TASK_RUNNING);
1000 }
1001
1002 /*
1003  *      Buffer Utility Routines
1004  */
1005
1006 STATIC void
1007 xfs_buf_iodone_work(
1008         struct work_struct      *work)
1009 {
1010         xfs_buf_t               *bp =
1011                 container_of(work, xfs_buf_t, b_iodone_work);
1012
1013         /*
1014          * We can get an EOPNOTSUPP to ordered writes.  Here we clear the
1015          * ordered flag and reissue them.  Because we can't tell the higher
1016          * layers directly that they should not issue ordered I/O anymore, they
1017          * need to check if the ordered flag was cleared during I/O completion.
1018          */
1019         if ((bp->b_error == EOPNOTSUPP) &&
1020             (bp->b_flags & (XBF_ORDERED|XBF_ASYNC)) == (XBF_ORDERED|XBF_ASYNC)) {
1021                 XB_TRACE(bp, "ordered_retry", bp->b_iodone);
1022                 bp->b_flags &= ~XBF_ORDERED;
1023                 xfs_buf_iorequest(bp);
1024         } else if (bp->b_iodone)
1025                 (*(bp->b_iodone))(bp);
1026         else if (bp->b_flags & XBF_ASYNC)
1027                 xfs_buf_relse(bp);
1028 }
1029
1030 void
1031 xfs_buf_ioend(
1032         xfs_buf_t               *bp,
1033         int                     schedule)
1034 {
1035         bp->b_flags &= ~(XBF_READ | XBF_WRITE);
1036         if (bp->b_error == 0)
1037                 bp->b_flags |= XBF_DONE;
1038
1039         XB_TRACE(bp, "iodone", bp->b_iodone);
1040
1041         if ((bp->b_iodone) || (bp->b_flags & XBF_ASYNC)) {
1042                 if (schedule) {
1043                         INIT_WORK(&bp->b_iodone_work, xfs_buf_iodone_work);
1044                         queue_work(xfslogd_workqueue, &bp->b_iodone_work);
1045                 } else {
1046                         xfs_buf_iodone_work(&bp->b_iodone_work);
1047                 }
1048         } else {
1049                 up(&bp->b_iodonesema);
1050         }
1051 }
1052
1053 void
1054 xfs_buf_ioerror(
1055         xfs_buf_t               *bp,
1056         int                     error)
1057 {
1058         ASSERT(error >= 0 && error <= 0xffff);
1059         bp->b_error = (unsigned short)error;
1060         XB_TRACE(bp, "ioerror", (unsigned long)error);
1061 }
1062
1063 /*
1064  *      Initiate I/O on a buffer, based on the flags supplied.
1065  *      The b_iodone routine in the buffer supplied will only be called
1066  *      when all of the subsidiary I/O requests, if any, have been completed.
1067  */
1068 int
1069 xfs_buf_iostart(
1070         xfs_buf_t               *bp,
1071         xfs_buf_flags_t         flags)
1072 {
1073         int                     status = 0;
1074
1075         XB_TRACE(bp, "iostart", (unsigned long)flags);
1076
1077         if (flags & XBF_DELWRI) {
1078                 bp->b_flags &= ~(XBF_READ | XBF_WRITE | XBF_ASYNC);
1079                 bp->b_flags |= flags & (XBF_DELWRI | XBF_ASYNC);
1080                 xfs_buf_delwri_queue(bp, 1);
1081                 return status;
1082         }
1083
1084         bp->b_flags &= ~(XBF_READ | XBF_WRITE | XBF_ASYNC | XBF_DELWRI | \
1085                         XBF_READ_AHEAD | _XBF_RUN_QUEUES);
1086         bp->b_flags |= flags & (XBF_READ | XBF_WRITE | XBF_ASYNC | \
1087                         XBF_READ_AHEAD | _XBF_RUN_QUEUES);
1088
1089         BUG_ON(bp->b_bn == XFS_BUF_DADDR_NULL);
1090
1091         /* For writes allow an alternate strategy routine to precede
1092          * the actual I/O request (which may not be issued at all in
1093          * a shutdown situation, for example).
1094          */
1095         status = (flags & XBF_WRITE) ?
1096                 xfs_buf_iostrategy(bp) : xfs_buf_iorequest(bp);
1097
1098         /* Wait for I/O if we are not an async request.
1099          * Note: async I/O request completion will release the buffer,
1100          * and that can already be done by this point.  So using the
1101          * buffer pointer from here on, after async I/O, is invalid.
1102          */
1103         if (!status && !(flags & XBF_ASYNC))
1104                 status = xfs_buf_iowait(bp);
1105
1106         return status;
1107 }
1108
1109 STATIC_INLINE int
1110 _xfs_buf_iolocked(
1111         xfs_buf_t               *bp)
1112 {
1113         ASSERT(bp->b_flags & (XBF_READ | XBF_WRITE));
1114         if (bp->b_flags & XBF_READ)
1115                 return bp->b_locked;
1116         return 0;
1117 }
1118
1119 STATIC_INLINE void
1120 _xfs_buf_ioend(
1121         xfs_buf_t               *bp,
1122         int                     schedule)
1123 {
1124         if (atomic_dec_and_test(&bp->b_io_remaining) == 1) {
1125                 bp->b_locked = 0;
1126                 xfs_buf_ioend(bp, schedule);
1127         }
1128 }
1129
1130 STATIC void
1131 xfs_buf_bio_end_io(
1132         struct bio              *bio,
1133         int                     error)
1134 {
1135         xfs_buf_t               *bp = (xfs_buf_t *)bio->bi_private;
1136         unsigned int            blocksize = bp->b_target->bt_bsize;
1137         struct bio_vec          *bvec = bio->bi_io_vec + bio->bi_vcnt - 1;
1138
1139         if (!test_bit(BIO_UPTODATE, &bio->bi_flags))
1140                 bp->b_error = EIO;
1141
1142         do {
1143                 struct page     *page = bvec->bv_page;
1144
1145                 ASSERT(!PagePrivate(page));
1146                 if (unlikely(bp->b_error)) {
1147                         if (bp->b_flags & XBF_READ)
1148                                 ClearPageUptodate(page);
1149                 } else if (blocksize >= PAGE_CACHE_SIZE) {
1150                         SetPageUptodate(page);
1151                 } else if (!PagePrivate(page) &&
1152                                 (bp->b_flags & _XBF_PAGE_CACHE)) {
1153                         set_page_region(page, bvec->bv_offset, bvec->bv_len);
1154                 }
1155
1156                 if (--bvec >= bio->bi_io_vec)
1157                         prefetchw(&bvec->bv_page->flags);
1158
1159                 if (_xfs_buf_iolocked(bp)) {
1160                         unlock_page(page);
1161                 }
1162         } while (bvec >= bio->bi_io_vec);
1163
1164         _xfs_buf_ioend(bp, 1);
1165         bio_put(bio);
1166 }
1167
1168 STATIC void
1169 _xfs_buf_ioapply(
1170         xfs_buf_t               *bp)
1171 {
1172         int                     i, rw, map_i, total_nr_pages, nr_pages;
1173         struct bio              *bio;
1174         int                     offset = bp->b_offset;
1175         int                     size = bp->b_count_desired;
1176         sector_t                sector = bp->b_bn;
1177         unsigned int            blocksize = bp->b_target->bt_bsize;
1178         int                     locking = _xfs_buf_iolocked(bp);
1179
1180         total_nr_pages = bp->b_page_count;
1181         map_i = 0;
1182
1183         if (bp->b_flags & XBF_ORDERED) {
1184                 ASSERT(!(bp->b_flags & XBF_READ));
1185                 rw = WRITE_BARRIER;
1186         } else if (bp->b_flags & _XBF_RUN_QUEUES) {
1187                 ASSERT(!(bp->b_flags & XBF_READ_AHEAD));
1188                 bp->b_flags &= ~_XBF_RUN_QUEUES;
1189                 rw = (bp->b_flags & XBF_WRITE) ? WRITE_SYNC : READ_SYNC;
1190         } else {
1191                 rw = (bp->b_flags & XBF_WRITE) ? WRITE :
1192                      (bp->b_flags & XBF_READ_AHEAD) ? READA : READ;
1193         }
1194
1195         /* Special code path for reading a sub page size buffer in --
1196          * we populate up the whole page, and hence the other metadata
1197          * in the same page.  This optimization is only valid when the
1198          * filesystem block size is not smaller than the page size.
1199          */
1200         if ((bp->b_buffer_length < PAGE_CACHE_SIZE) &&
1201             (bp->b_flags & XBF_READ) && locking &&
1202             (blocksize >= PAGE_CACHE_SIZE)) {
1203                 bio = bio_alloc(GFP_NOIO, 1);
1204
1205                 bio->bi_bdev = bp->b_target->bt_bdev;
1206                 bio->bi_sector = sector - (offset >> BBSHIFT);
1207                 bio->bi_end_io = xfs_buf_bio_end_io;
1208                 bio->bi_private = bp;
1209
1210                 bio_add_page(bio, bp->b_pages[0], PAGE_CACHE_SIZE, 0);
1211                 size = 0;
1212
1213                 atomic_inc(&bp->b_io_remaining);
1214
1215                 goto submit_io;
1216         }
1217
1218         /* Lock down the pages which we need to for the request */
1219         if (locking && (bp->b_flags & XBF_WRITE) && (bp->b_locked == 0)) {
1220                 for (i = 0; size; i++) {
1221                         int             nbytes = PAGE_CACHE_SIZE - offset;
1222                         struct page     *page = bp->b_pages[i];
1223
1224                         if (nbytes > size)
1225                                 nbytes = size;
1226
1227                         lock_page(page);
1228
1229                         size -= nbytes;
1230                         offset = 0;
1231                 }
1232                 offset = bp->b_offset;
1233                 size = bp->b_count_desired;
1234         }
1235
1236 next_chunk:
1237         atomic_inc(&bp->b_io_remaining);
1238         nr_pages = BIO_MAX_SECTORS >> (PAGE_SHIFT - BBSHIFT);
1239         if (nr_pages > total_nr_pages)
1240                 nr_pages = total_nr_pages;
1241
1242         bio = bio_alloc(GFP_NOIO, nr_pages);
1243         bio->bi_bdev = bp->b_target->bt_bdev;
1244         bio->bi_sector = sector;
1245         bio->bi_end_io = xfs_buf_bio_end_io;
1246         bio->bi_private = bp;
1247
1248         for (; size && nr_pages; nr_pages--, map_i++) {
1249                 int     rbytes, nbytes = PAGE_CACHE_SIZE - offset;
1250
1251                 if (nbytes > size)
1252                         nbytes = size;
1253
1254                 rbytes = bio_add_page(bio, bp->b_pages[map_i], nbytes, offset);
1255                 if (rbytes < nbytes)
1256                         break;
1257
1258                 offset = 0;
1259                 sector += nbytes >> BBSHIFT;
1260                 size -= nbytes;
1261                 total_nr_pages--;
1262         }
1263
1264 submit_io:
1265         if (likely(bio->bi_size)) {
1266                 submit_bio(rw, bio);
1267                 if (size)
1268                         goto next_chunk;
1269         } else {
1270                 bio_put(bio);
1271                 xfs_buf_ioerror(bp, EIO);
1272         }
1273 }
1274
1275 int
1276 xfs_buf_iorequest(
1277         xfs_buf_t               *bp)
1278 {
1279         XB_TRACE(bp, "iorequest", 0);
1280
1281         if (bp->b_flags & XBF_DELWRI) {
1282                 xfs_buf_delwri_queue(bp, 1);
1283                 return 0;
1284         }
1285
1286         if (bp->b_flags & XBF_WRITE) {
1287                 xfs_buf_wait_unpin(bp);
1288         }
1289
1290         xfs_buf_hold(bp);
1291
1292         /* Set the count to 1 initially, this will stop an I/O
1293          * completion callout which happens before we have started
1294          * all the I/O from calling xfs_buf_ioend too early.
1295          */
1296         atomic_set(&bp->b_io_remaining, 1);
1297         _xfs_buf_ioapply(bp);
1298         _xfs_buf_ioend(bp, 0);
1299
1300         xfs_buf_rele(bp);
1301         return 0;
1302 }
1303
1304 /*
1305  *      Waits for I/O to complete on the buffer supplied.
1306  *      It returns immediately if no I/O is pending.
1307  *      It returns the I/O error code, if any, or 0 if there was no error.
1308  */
1309 int
1310 xfs_buf_iowait(
1311         xfs_buf_t               *bp)
1312 {
1313         XB_TRACE(bp, "iowait", 0);
1314         if (atomic_read(&bp->b_io_remaining))
1315                 blk_run_address_space(bp->b_target->bt_mapping);
1316         down(&bp->b_iodonesema);
1317         XB_TRACE(bp, "iowaited", (long)bp->b_error);
1318         return bp->b_error;
1319 }
1320
1321 xfs_caddr_t
1322 xfs_buf_offset(
1323         xfs_buf_t               *bp,
1324         size_t                  offset)
1325 {
1326         struct page             *page;
1327
1328         if (bp->b_flags & XBF_MAPPED)
1329                 return XFS_BUF_PTR(bp) + offset;
1330
1331         offset += bp->b_offset;
1332         page = bp->b_pages[offset >> PAGE_CACHE_SHIFT];
1333         return (xfs_caddr_t)page_address(page) + (offset & (PAGE_CACHE_SIZE-1));
1334 }
1335
1336 /*
1337  *      Move data into or out of a buffer.
1338  */
1339 void
1340 xfs_buf_iomove(
1341         xfs_buf_t               *bp,    /* buffer to process            */
1342         size_t                  boff,   /* starting buffer offset       */
1343         size_t                  bsize,  /* length to copy               */
1344         caddr_t                 data,   /* data address                 */
1345         xfs_buf_rw_t            mode)   /* read/write/zero flag         */
1346 {
1347         size_t                  bend, cpoff, csize;
1348         struct page             *page;
1349
1350         bend = boff + bsize;
1351         while (boff < bend) {
1352                 page = bp->b_pages[xfs_buf_btoct(boff + bp->b_offset)];
1353                 cpoff = xfs_buf_poff(boff + bp->b_offset);
1354                 csize = min_t(size_t,
1355                               PAGE_CACHE_SIZE-cpoff, bp->b_count_desired-boff);
1356
1357                 ASSERT(((csize + cpoff) <= PAGE_CACHE_SIZE));
1358
1359                 switch (mode) {
1360                 case XBRW_ZERO:
1361                         memset(page_address(page) + cpoff, 0, csize);
1362                         break;
1363                 case XBRW_READ:
1364                         memcpy(data, page_address(page) + cpoff, csize);
1365                         break;
1366                 case XBRW_WRITE:
1367                         memcpy(page_address(page) + cpoff, data, csize);
1368                 }
1369
1370                 boff += csize;
1371                 data += csize;
1372         }
1373 }
1374
1375 /*
1376  *      Handling of buffer targets (buftargs).
1377  */
1378
1379 /*
1380  *      Wait for any bufs with callbacks that have been submitted but
1381  *      have not yet returned... walk the hash list for the target.
1382  */
1383 void
1384 xfs_wait_buftarg(
1385         xfs_buftarg_t   *btp)
1386 {
1387         xfs_buf_t       *bp, *n;
1388         xfs_bufhash_t   *hash;
1389         uint            i;
1390
1391         for (i = 0; i < (1 << btp->bt_hashshift); i++) {
1392                 hash = &btp->bt_hash[i];
1393 again:
1394                 spin_lock(&hash->bh_lock);
1395                 list_for_each_entry_safe(bp, n, &hash->bh_list, b_hash_list) {
1396                         ASSERT(btp == bp->b_target);
1397                         if (!(bp->b_flags & XBF_FS_MANAGED)) {
1398                                 spin_unlock(&hash->bh_lock);
1399                                 /*
1400                                  * Catch superblock reference count leaks
1401                                  * immediately
1402                                  */
1403                                 BUG_ON(bp->b_bn == 0);
1404                                 delay(100);
1405                                 goto again;
1406                         }
1407                 }
1408                 spin_unlock(&hash->bh_lock);
1409         }
1410 }
1411
1412 /*
1413  *      Allocate buffer hash table for a given target.
1414  *      For devices containing metadata (i.e. not the log/realtime devices)
1415  *      we need to allocate a much larger hash table.
1416  */
1417 STATIC void
1418 xfs_alloc_bufhash(
1419         xfs_buftarg_t           *btp,
1420         int                     external)
1421 {
1422         unsigned int            i;
1423
1424         btp->bt_hashshift = external ? 3 : 8;   /* 8 or 256 buckets */
1425         btp->bt_hashmask = (1 << btp->bt_hashshift) - 1;
1426         btp->bt_hash = kmem_zalloc((1 << btp->bt_hashshift) *
1427                                         sizeof(xfs_bufhash_t), KM_SLEEP | KM_LARGE);
1428         for (i = 0; i < (1 << btp->bt_hashshift); i++) {
1429                 spin_lock_init(&btp->bt_hash[i].bh_lock);
1430                 INIT_LIST_HEAD(&btp->bt_hash[i].bh_list);
1431         }
1432 }
1433
1434 STATIC void
1435 xfs_free_bufhash(
1436         xfs_buftarg_t           *btp)
1437 {
1438         kmem_free(btp->bt_hash, (1<<btp->bt_hashshift) * sizeof(xfs_bufhash_t));
1439         btp->bt_hash = NULL;
1440 }
1441
1442 /*
1443  *      buftarg list for delwrite queue processing
1444  */
1445 static LIST_HEAD(xfs_buftarg_list);
1446 static DEFINE_SPINLOCK(xfs_buftarg_lock);
1447
1448 STATIC void
1449 xfs_register_buftarg(
1450         xfs_buftarg_t           *btp)
1451 {
1452         spin_lock(&xfs_buftarg_lock);
1453         list_add(&btp->bt_list, &xfs_buftarg_list);
1454         spin_unlock(&xfs_buftarg_lock);
1455 }
1456
1457 STATIC void
1458 xfs_unregister_buftarg(
1459         xfs_buftarg_t           *btp)
1460 {
1461         spin_lock(&xfs_buftarg_lock);
1462         list_del(&btp->bt_list);
1463         spin_unlock(&xfs_buftarg_lock);
1464 }
1465
1466 void
1467 xfs_free_buftarg(
1468         xfs_buftarg_t           *btp,
1469         int                     external)
1470 {
1471         xfs_flush_buftarg(btp, 1);
1472         xfs_blkdev_issue_flush(btp);
1473         if (external)
1474                 xfs_blkdev_put(btp->bt_bdev);
1475         xfs_free_bufhash(btp);
1476         iput(btp->bt_mapping->host);
1477
1478         /* Unregister the buftarg first so that we don't get a
1479          * wakeup finding a non-existent task
1480          */
1481         xfs_unregister_buftarg(btp);
1482         kthread_stop(btp->bt_task);
1483
1484         kmem_free(btp, sizeof(*btp));
1485 }
1486
1487 STATIC int
1488 xfs_setsize_buftarg_flags(
1489         xfs_buftarg_t           *btp,
1490         unsigned int            blocksize,
1491         unsigned int            sectorsize,
1492         int                     verbose)
1493 {
1494         btp->bt_bsize = blocksize;
1495         btp->bt_sshift = ffs(sectorsize) - 1;
1496         btp->bt_smask = sectorsize - 1;
1497
1498         if (set_blocksize(btp->bt_bdev, sectorsize)) {
1499                 printk(KERN_WARNING
1500                         "XFS: Cannot set_blocksize to %u on device %s\n",
1501                         sectorsize, XFS_BUFTARG_NAME(btp));
1502                 return EINVAL;
1503         }
1504
1505         if (verbose &&
1506             (PAGE_CACHE_SIZE / BITS_PER_LONG) > sectorsize) {
1507                 printk(KERN_WARNING
1508                         "XFS: %u byte sectors in use on device %s.  "
1509                         "This is suboptimal; %u or greater is ideal.\n",
1510                         sectorsize, XFS_BUFTARG_NAME(btp),
1511                         (unsigned int)PAGE_CACHE_SIZE / BITS_PER_LONG);
1512         }
1513
1514         return 0;
1515 }
1516
1517 /*
1518  *      When allocating the initial buffer target we have not yet
1519  *      read in the superblock, so don't know what sized sectors
1520  *      are being used is at this early stage.  Play safe.
1521  */
1522 STATIC int
1523 xfs_setsize_buftarg_early(
1524         xfs_buftarg_t           *btp,
1525         struct block_device     *bdev)
1526 {
1527         return xfs_setsize_buftarg_flags(btp,
1528                         PAGE_CACHE_SIZE, bdev_hardsect_size(bdev), 0);
1529 }
1530
1531 int
1532 xfs_setsize_buftarg(
1533         xfs_buftarg_t           *btp,
1534         unsigned int            blocksize,
1535         unsigned int            sectorsize)
1536 {
1537         return xfs_setsize_buftarg_flags(btp, blocksize, sectorsize, 1);
1538 }
1539
1540 STATIC int
1541 xfs_mapping_buftarg(
1542         xfs_buftarg_t           *btp,
1543         struct block_device     *bdev)
1544 {
1545         struct backing_dev_info *bdi;
1546         struct inode            *inode;
1547         struct address_space    *mapping;
1548         static const struct address_space_operations mapping_aops = {
1549                 .sync_page = block_sync_page,
1550                 .migratepage = fail_migrate_page,
1551         };
1552
1553         inode = new_inode(bdev->bd_inode->i_sb);
1554         if (!inode) {
1555                 printk(KERN_WARNING
1556                         "XFS: Cannot allocate mapping inode for device %s\n",
1557                         XFS_BUFTARG_NAME(btp));
1558                 return ENOMEM;
1559         }
1560         inode->i_mode = S_IFBLK;
1561         inode->i_bdev = bdev;
1562         inode->i_rdev = bdev->bd_dev;
1563         bdi = blk_get_backing_dev_info(bdev);
1564         if (!bdi)
1565                 bdi = &default_backing_dev_info;
1566         mapping = &inode->i_data;
1567         mapping->a_ops = &mapping_aops;
1568         mapping->backing_dev_info = bdi;
1569         mapping_set_gfp_mask(mapping, GFP_NOFS);
1570         btp->bt_mapping = mapping;
1571         return 0;
1572 }
1573
1574 STATIC int
1575 xfs_alloc_delwrite_queue(
1576         xfs_buftarg_t           *btp)
1577 {
1578         int     error = 0;
1579
1580         INIT_LIST_HEAD(&btp->bt_list);
1581         INIT_LIST_HEAD(&btp->bt_delwrite_queue);
1582         spinlock_init(&btp->bt_delwrite_lock, "delwri_lock");
1583         btp->bt_flags = 0;
1584         btp->bt_task = kthread_run(xfsbufd, btp, "xfsbufd");
1585         if (IS_ERR(btp->bt_task)) {
1586                 error = PTR_ERR(btp->bt_task);
1587                 goto out_error;
1588         }
1589         xfs_register_buftarg(btp);
1590 out_error:
1591         return error;
1592 }
1593
1594 xfs_buftarg_t *
1595 xfs_alloc_buftarg(
1596         struct block_device     *bdev,
1597         int                     external)
1598 {
1599         xfs_buftarg_t           *btp;
1600
1601         btp = kmem_zalloc(sizeof(*btp), KM_SLEEP);
1602
1603         btp->bt_dev =  bdev->bd_dev;
1604         btp->bt_bdev = bdev;
1605         if (xfs_setsize_buftarg_early(btp, bdev))
1606                 goto error;
1607         if (xfs_mapping_buftarg(btp, bdev))
1608                 goto error;
1609         if (xfs_alloc_delwrite_queue(btp))
1610                 goto error;
1611         xfs_alloc_bufhash(btp, external);
1612         return btp;
1613
1614 error:
1615         kmem_free(btp, sizeof(*btp));
1616         return NULL;
1617 }
1618
1619
1620 /*
1621  *      Delayed write buffer handling
1622  */
1623 STATIC void
1624 xfs_buf_delwri_queue(
1625         xfs_buf_t               *bp,
1626         int                     unlock)
1627 {
1628         struct list_head        *dwq = &bp->b_target->bt_delwrite_queue;
1629         spinlock_t              *dwlk = &bp->b_target->bt_delwrite_lock;
1630
1631         XB_TRACE(bp, "delwri_q", (long)unlock);
1632         ASSERT((bp->b_flags&(XBF_DELWRI|XBF_ASYNC)) == (XBF_DELWRI|XBF_ASYNC));
1633
1634         spin_lock(dwlk);
1635         /* If already in the queue, dequeue and place at tail */
1636         if (!list_empty(&bp->b_list)) {
1637                 ASSERT(bp->b_flags & _XBF_DELWRI_Q);
1638                 if (unlock)
1639                         atomic_dec(&bp->b_hold);
1640                 list_del(&bp->b_list);
1641         }
1642
1643         bp->b_flags |= _XBF_DELWRI_Q;
1644         list_add_tail(&bp->b_list, dwq);
1645         bp->b_queuetime = jiffies;
1646         spin_unlock(dwlk);
1647
1648         if (unlock)
1649                 xfs_buf_unlock(bp);
1650 }
1651
1652 void
1653 xfs_buf_delwri_dequeue(
1654         xfs_buf_t               *bp)
1655 {
1656         spinlock_t              *dwlk = &bp->b_target->bt_delwrite_lock;
1657         int                     dequeued = 0;
1658
1659         spin_lock(dwlk);
1660         if ((bp->b_flags & XBF_DELWRI) && !list_empty(&bp->b_list)) {
1661                 ASSERT(bp->b_flags & _XBF_DELWRI_Q);
1662                 list_del_init(&bp->b_list);
1663                 dequeued = 1;
1664         }
1665         bp->b_flags &= ~(XBF_DELWRI|_XBF_DELWRI_Q);
1666         spin_unlock(dwlk);
1667
1668         if (dequeued)
1669                 xfs_buf_rele(bp);
1670
1671         XB_TRACE(bp, "delwri_dq", (long)dequeued);
1672 }
1673
1674 STATIC void
1675 xfs_buf_runall_queues(
1676         struct workqueue_struct *queue)
1677 {
1678         flush_workqueue(queue);
1679 }
1680
1681 STATIC int
1682 xfsbufd_wakeup(
1683         int                     priority,
1684         gfp_t                   mask)
1685 {
1686         xfs_buftarg_t           *btp;
1687
1688         spin_lock(&xfs_buftarg_lock);
1689         list_for_each_entry(btp, &xfs_buftarg_list, bt_list) {
1690                 if (test_bit(XBT_FORCE_SLEEP, &btp->bt_flags))
1691                         continue;
1692                 set_bit(XBT_FORCE_FLUSH, &btp->bt_flags);
1693                 wake_up_process(btp->bt_task);
1694         }
1695         spin_unlock(&xfs_buftarg_lock);
1696         return 0;
1697 }
1698
1699 /*
1700  * Move as many buffers as specified to the supplied list
1701  * idicating if we skipped any buffers to prevent deadlocks.
1702  */
1703 STATIC int
1704 xfs_buf_delwri_split(
1705         xfs_buftarg_t   *target,
1706         struct list_head *list,
1707         unsigned long   age)
1708 {
1709         xfs_buf_t       *bp, *n;
1710         struct list_head *dwq = &target->bt_delwrite_queue;
1711         spinlock_t      *dwlk = &target->bt_delwrite_lock;
1712         int             skipped = 0;
1713         int             force;
1714
1715         force = test_and_clear_bit(XBT_FORCE_FLUSH, &target->bt_flags);
1716         INIT_LIST_HEAD(list);
1717         spin_lock(dwlk);
1718         list_for_each_entry_safe(bp, n, dwq, b_list) {
1719                 XB_TRACE(bp, "walkq1", (long)xfs_buf_ispin(bp));
1720                 ASSERT(bp->b_flags & XBF_DELWRI);
1721
1722                 if (!xfs_buf_ispin(bp) && !xfs_buf_cond_lock(bp)) {
1723                         if (!force &&
1724                             time_before(jiffies, bp->b_queuetime + age)) {
1725                                 xfs_buf_unlock(bp);
1726                                 break;
1727                         }
1728
1729                         bp->b_flags &= ~(XBF_DELWRI|_XBF_DELWRI_Q|
1730                                          _XBF_RUN_QUEUES);
1731                         bp->b_flags |= XBF_WRITE;
1732                         list_move_tail(&bp->b_list, list);
1733                 } else
1734                         skipped++;
1735         }
1736         spin_unlock(dwlk);
1737
1738         return skipped;
1739
1740 }
1741
1742 STATIC int
1743 xfsbufd(
1744         void            *data)
1745 {
1746         struct list_head tmp;
1747         xfs_buftarg_t   *target = (xfs_buftarg_t *)data;
1748         int             count;
1749         xfs_buf_t       *bp;
1750
1751         current->flags |= PF_MEMALLOC;
1752
1753         do {
1754                 if (unlikely(freezing(current))) {
1755                         set_bit(XBT_FORCE_SLEEP, &target->bt_flags);
1756                         refrigerator();
1757                 } else {
1758                         clear_bit(XBT_FORCE_SLEEP, &target->bt_flags);
1759                 }
1760
1761                 schedule_timeout_interruptible(
1762                         xfs_buf_timer_centisecs * msecs_to_jiffies(10));
1763
1764                 xfs_buf_delwri_split(target, &tmp,
1765                                 xfs_buf_age_centisecs * msecs_to_jiffies(10));
1766
1767                 count = 0;
1768                 while (!list_empty(&tmp)) {
1769                         bp = list_entry(tmp.next, xfs_buf_t, b_list);
1770                         ASSERT(target == bp->b_target);
1771
1772                         list_del_init(&bp->b_list);
1773                         xfs_buf_iostrategy(bp);
1774                         count++;
1775                 }
1776
1777                 if (as_list_len > 0)
1778                         purge_addresses();
1779                 if (count)
1780                         blk_run_address_space(target->bt_mapping);
1781
1782         } while (!kthread_should_stop());
1783
1784         return 0;
1785 }
1786
1787 /*
1788  *      Go through all incore buffers, and release buffers if they belong to
1789  *      the given device. This is used in filesystem error handling to
1790  *      preserve the consistency of its metadata.
1791  */
1792 int
1793 xfs_flush_buftarg(
1794         xfs_buftarg_t   *target,
1795         int             wait)
1796 {
1797         struct list_head tmp;
1798         xfs_buf_t       *bp, *n;
1799         int             pincount = 0;
1800
1801         xfs_buf_runall_queues(xfsdatad_workqueue);
1802         xfs_buf_runall_queues(xfslogd_workqueue);
1803
1804         set_bit(XBT_FORCE_FLUSH, &target->bt_flags);
1805         pincount = xfs_buf_delwri_split(target, &tmp, 0);
1806
1807         /*
1808          * Dropped the delayed write list lock, now walk the temporary list
1809          */
1810         list_for_each_entry_safe(bp, n, &tmp, b_list) {
1811                 ASSERT(target == bp->b_target);
1812                 if (wait)
1813                         bp->b_flags &= ~XBF_ASYNC;
1814                 else
1815                         list_del_init(&bp->b_list);
1816
1817                 xfs_buf_iostrategy(bp);
1818         }
1819
1820         if (wait)
1821                 blk_run_address_space(target->bt_mapping);
1822
1823         /*
1824          * Remaining list items must be flushed before returning
1825          */
1826         while (!list_empty(&tmp)) {
1827                 bp = list_entry(tmp.next, xfs_buf_t, b_list);
1828
1829                 list_del_init(&bp->b_list);
1830                 xfs_iowait(bp);
1831                 xfs_buf_relse(bp);
1832         }
1833
1834         return pincount;
1835 }
1836
1837 int __init
1838 xfs_buf_init(void)
1839 {
1840 #ifdef XFS_BUF_TRACE
1841         xfs_buf_trace_buf = ktrace_alloc(XFS_BUF_TRACE_SIZE, KM_SLEEP);
1842 #endif
1843
1844         xfs_buf_zone = kmem_zone_init_flags(sizeof(xfs_buf_t), "xfs_buf",
1845                                                 KM_ZONE_HWALIGN, NULL);
1846         if (!xfs_buf_zone)
1847                 goto out_free_trace_buf;
1848
1849         xfslogd_workqueue = create_workqueue("xfslogd");
1850         if (!xfslogd_workqueue)
1851                 goto out_free_buf_zone;
1852
1853         xfsdatad_workqueue = create_workqueue("xfsdatad");
1854         if (!xfsdatad_workqueue)
1855                 goto out_destroy_xfslogd_workqueue;
1856
1857         register_shrinker(&xfs_buf_shake);
1858         return 0;
1859
1860  out_destroy_xfslogd_workqueue:
1861         destroy_workqueue(xfslogd_workqueue);
1862  out_free_buf_zone:
1863         kmem_zone_destroy(xfs_buf_zone);
1864  out_free_trace_buf:
1865 #ifdef XFS_BUF_TRACE
1866         ktrace_free(xfs_buf_trace_buf);
1867 #endif
1868         return -ENOMEM;
1869 }
1870
1871 void
1872 xfs_buf_terminate(void)
1873 {
1874         unregister_shrinker(&xfs_buf_shake);
1875         destroy_workqueue(xfsdatad_workqueue);
1876         destroy_workqueue(xfslogd_workqueue);
1877         kmem_zone_destroy(xfs_buf_zone);
1878 #ifdef XFS_BUF_TRACE
1879         ktrace_free(xfs_buf_trace_buf);
1880 #endif
1881 }
1882
1883 #ifdef CONFIG_KDB_MODULES
1884 struct list_head *
1885 xfs_get_buftarg_list(void)
1886 {
1887         return &xfs_buftarg_list;
1888 }
1889 #endif