66e01fae4384f6ea140897afbc4f85c3a0500aa1
[linux-2.6.git] / fs / omfs / file.c
1 /*
2  * OMFS (as used by RIO Karma) file operations.
3  * Copyright (C) 2005 Bob Copeland <me@bobcopeland.com>
4  * Released under GPL v2.
5  */
6
7 #include <linux/version.h>
8 #include <linux/module.h>
9 #include <linux/fs.h>
10 #include <linux/buffer_head.h>
11 #include <linux/mpage.h>
12 #include "omfs.h"
13
14 static int omfs_sync_file(struct file *file, struct dentry *dentry,
15                 int datasync)
16 {
17         struct inode *inode = dentry->d_inode;
18         int err;
19
20         err = sync_mapping_buffers(inode->i_mapping);
21         if (!(inode->i_state & I_DIRTY))
22                 return err;
23         if (datasync && !(inode->i_state & I_DIRTY_DATASYNC))
24                 return err;
25         err |= omfs_sync_inode(inode);
26         return err ? -EIO : 0;
27 }
28
29 void omfs_make_empty_table(struct buffer_head *bh, int offset)
30 {
31         struct omfs_extent *oe = (struct omfs_extent *) &bh->b_data[offset];
32
33         oe->e_next = ~0ULL;
34         oe->e_extent_count = cpu_to_be32(1),
35         oe->e_fill = cpu_to_be32(0x22),
36         oe->e_entry.e_cluster = ~0ULL;
37         oe->e_entry.e_blocks = ~0ULL;
38 }
39
40 int omfs_shrink_inode(struct inode *inode)
41 {
42         struct omfs_sb_info *sbi = OMFS_SB(inode->i_sb);
43         struct omfs_extent *oe;
44         struct omfs_extent_entry *entry;
45         struct buffer_head *bh;
46         u64 next, last;
47         u32 extent_count;
48         int ret;
49
50         /* traverse extent table, freeing each entry that is greater
51          * than inode->i_size;
52          */
53         next = inode->i_ino;
54
55         /* only support truncate -> 0 for now */
56         ret = -EIO;
57         if (inode->i_size != 0)
58                 goto out;
59
60         bh = sb_bread(inode->i_sb, clus_to_blk(sbi, next));
61         if (!bh)
62                 goto out;
63
64         oe = (struct omfs_extent *)(&bh->b_data[OMFS_EXTENT_START]);
65
66         for (;;) {
67
68                 if (omfs_is_bad(sbi, (struct omfs_header *) bh->b_data, next)) {
69                         brelse(bh);
70                         goto out;
71                 }
72
73                 extent_count = be32_to_cpu(oe->e_extent_count);
74                 last = next;
75                 next = be64_to_cpu(oe->e_next);
76                 entry = &oe->e_entry;
77
78                 /* ignore last entry as it is the terminator */
79                 for (; extent_count > 1; extent_count--) {
80                         u64 start, count;
81                         start = be64_to_cpu(entry->e_cluster);
82                         count = be64_to_cpu(entry->e_blocks);
83
84                         omfs_clear_range(inode->i_sb, start, (int) count);
85                         entry++;
86                 }
87                 omfs_make_empty_table(bh, (char *) oe - bh->b_data);
88                 mark_buffer_dirty(bh);
89                 brelse(bh);
90
91                 if (last != inode->i_ino)
92                         omfs_clear_range(inode->i_sb, last, sbi->s_mirrors);
93
94                 if (next == ~0)
95                         break;
96
97                 bh = sb_bread(inode->i_sb, clus_to_blk(sbi, next));
98                 if (!bh)
99                         goto out;
100                 oe = (struct omfs_extent *) (&bh->b_data[OMFS_EXTENT_CONT]);
101         }
102         ret = 0;
103 out:
104         return ret;
105 }
106
107 static void omfs_truncate(struct inode *inode)
108 {
109         omfs_shrink_inode(inode);
110         mark_inode_dirty(inode);
111 }
112
113 /*
114  * Add new blocks to the current extent, or create new entries/continuations
115  * as necessary.
116  */
117 static int omfs_grow_extent(struct inode *inode, struct omfs_extent *oe,
118                         u64 *ret_block)
119 {
120         struct omfs_extent_entry *terminator;
121         struct omfs_extent_entry *entry = &oe->e_entry;
122         struct omfs_sb_info *sbi = OMFS_SB(inode->i_sb);
123         u32 extent_count = be32_to_cpu(oe->e_extent_count);
124         u64 new_block = 0;
125         u32 max_count;
126         int new_count;
127         int ret = 0;
128
129         /* reached the end of the extent table with no blocks mapped.
130          * there are three possibilities for adding: grow last extent,
131          * add a new extent to the current extent table, and add a
132          * continuation inode.  in last two cases need an allocator for
133          * sbi->s_cluster_size
134          */
135
136         /* TODO: handle holes */
137
138         /* should always have a terminator */
139         if (extent_count < 1)
140                 return -EIO;
141
142         /* trivially grow current extent, if next block is not taken */
143         terminator = entry + extent_count - 1;
144         if (extent_count > 1) {
145                 entry = terminator-1;
146                 new_block = be64_to_cpu(entry->e_cluster) +
147                         be64_to_cpu(entry->e_blocks);
148
149                 if (omfs_allocate_block(inode->i_sb, new_block)) {
150                         entry->e_blocks =
151                                 cpu_to_be64(be64_to_cpu(entry->e_blocks) + 1);
152                         terminator->e_blocks = ~(cpu_to_be64(
153                                 be64_to_cpu(~terminator->e_blocks) + 1));
154                         goto out;
155                 }
156         }
157         max_count = (sbi->s_sys_blocksize - OMFS_EXTENT_START -
158                 sizeof(struct omfs_extent)) /
159                 sizeof(struct omfs_extent_entry) + 1;
160
161         /* TODO: add a continuation block here */
162         if (be32_to_cpu(oe->e_extent_count) > max_count-1)
163                 return -EIO;
164
165         /* try to allocate a new cluster */
166         ret = omfs_allocate_range(inode->i_sb, 1, sbi->s_clustersize,
167                 &new_block, &new_count);
168         if (ret)
169                 goto out_fail;
170
171         /* copy terminator down an entry */
172         entry = terminator;
173         terminator++;
174         memcpy(terminator, entry, sizeof(struct omfs_extent_entry));
175
176         entry->e_cluster = cpu_to_be64(new_block);
177         entry->e_blocks = cpu_to_be64((u64) new_count);
178
179         terminator->e_blocks = ~(cpu_to_be64(
180                 be64_to_cpu(~terminator->e_blocks) + (u64) new_count));
181
182         /* write in new entry */
183         oe->e_extent_count = cpu_to_be32(1 + be32_to_cpu(oe->e_extent_count));
184
185 out:
186         *ret_block = new_block;
187 out_fail:
188         return ret;
189 }
190
191 /*
192  * Scans across the directory table for a given file block number.
193  * If block not found, return 0.
194  */
195 static sector_t find_block(struct inode *inode, struct omfs_extent_entry *ent,
196                         sector_t block, int count, int *left)
197 {
198         /* count > 1 because of terminator */
199         sector_t searched = 0;
200         for (; count > 1; count--) {
201                 int numblocks = clus_to_blk(OMFS_SB(inode->i_sb),
202                         be64_to_cpu(ent->e_blocks));
203
204                 if (block >= searched  &&
205                     block < searched + numblocks) {
206                         /*
207                          * found it at cluster + (block - searched)
208                          * numblocks - (block - searched) is remainder
209                          */
210                         *left = numblocks - (block - searched);
211                         return clus_to_blk(OMFS_SB(inode->i_sb),
212                                 be64_to_cpu(ent->e_cluster)) +
213                                 block - searched;
214                 }
215                 searched += numblocks;
216                 ent++;
217         }
218         return 0;
219 }
220
221 static int omfs_get_block(struct inode *inode, sector_t block,
222                           struct buffer_head *bh_result, int create)
223 {
224         struct buffer_head *bh;
225         sector_t next, offset;
226         int ret;
227         u64 new_block;
228         int extent_count;
229         struct omfs_extent *oe;
230         struct omfs_extent_entry *entry;
231         struct omfs_sb_info *sbi = OMFS_SB(inode->i_sb);
232         int max_blocks = bh_result->b_size >> inode->i_blkbits;
233         int remain;
234
235         ret = -EIO;
236         bh = sb_bread(inode->i_sb, clus_to_blk(sbi, inode->i_ino));
237         if (!bh)
238                 goto out;
239
240         oe = (struct omfs_extent *)(&bh->b_data[OMFS_EXTENT_START]);
241         next = inode->i_ino;
242
243         for (;;) {
244
245                 if (omfs_is_bad(sbi, (struct omfs_header *) bh->b_data, next))
246                         goto out_brelse;
247
248                 extent_count = be32_to_cpu(oe->e_extent_count);
249                 next = be64_to_cpu(oe->e_next);
250                 entry = &oe->e_entry;
251
252                 offset = find_block(inode, entry, block, extent_count, &remain);
253                 if (offset > 0) {
254                         ret = 0;
255                         map_bh(bh_result, inode->i_sb, offset);
256                         if (remain > max_blocks)
257                                 remain = max_blocks;
258                         bh_result->b_size = (remain << inode->i_blkbits);
259                         goto out_brelse;
260                 }
261                 if (next == ~0)
262                         break;
263
264                 brelse(bh);
265                 bh = sb_bread(inode->i_sb, clus_to_blk(sbi, next));
266                 if (!bh)
267                         goto out;
268                 oe = (struct omfs_extent *) (&bh->b_data[OMFS_EXTENT_CONT]);
269         }
270         if (create) {
271                 ret = omfs_grow_extent(inode, oe, &new_block);
272                 if (ret == 0) {
273                         mark_buffer_dirty(bh);
274                         mark_inode_dirty(inode);
275                         map_bh(bh_result, inode->i_sb,
276                                         clus_to_blk(sbi, new_block));
277                 }
278         }
279 out_brelse:
280         brelse(bh);
281 out:
282         return ret;
283 }
284
285 static int omfs_readpage(struct file *file, struct page *page)
286 {
287         return block_read_full_page(page, omfs_get_block);
288 }
289
290 static int omfs_readpages(struct file *file, struct address_space *mapping,
291                 struct list_head *pages, unsigned nr_pages)
292 {
293         return mpage_readpages(mapping, pages, nr_pages, omfs_get_block);
294 }
295
296 static int omfs_writepage(struct page *page, struct writeback_control *wbc)
297 {
298         return block_write_full_page(page, omfs_get_block, wbc);
299 }
300
301 static int
302 omfs_writepages(struct address_space *mapping, struct writeback_control *wbc)
303 {
304         return mpage_writepages(mapping, wbc, omfs_get_block);
305 }
306
307 static int omfs_write_begin(struct file *file, struct address_space *mapping,
308                         loff_t pos, unsigned len, unsigned flags,
309                         struct page **pagep, void **fsdata)
310 {
311         *pagep = NULL;
312         return block_write_begin(file, mapping, pos, len, flags,
313                                 pagep, fsdata, omfs_get_block);
314 }
315
316 static sector_t omfs_bmap(struct address_space *mapping, sector_t block)
317 {
318         return generic_block_bmap(mapping, block, omfs_get_block);
319 }
320
321 struct file_operations omfs_file_operations = {
322         .llseek = generic_file_llseek,
323         .read = do_sync_read,
324         .write = do_sync_write,
325         .aio_read = generic_file_aio_read,
326         .aio_write = generic_file_aio_write,
327         .mmap = generic_file_mmap,
328         .fsync = omfs_sync_file,
329         .splice_read = generic_file_splice_read,
330 };
331
332 struct inode_operations omfs_file_inops = {
333         .truncate = omfs_truncate
334 };
335
336 struct address_space_operations omfs_aops = {
337         .readpage = omfs_readpage,
338         .readpages = omfs_readpages,
339         .writepage = omfs_writepage,
340         .writepages = omfs_writepages,
341         .sync_page = block_sync_page,
342         .write_begin = omfs_write_begin,
343         .write_end = generic_write_end,
344         .bmap = omfs_bmap,
345 };
346