Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6
[linux-2.6] / 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 static u32 omfs_max_extents(struct omfs_sb_info *sbi, int offset)
30 {
31         return (sbi->s_sys_blocksize - offset -
32                 sizeof(struct omfs_extent)) /
33                 sizeof(struct omfs_extent_entry) + 1;
34 }
35
36 void omfs_make_empty_table(struct buffer_head *bh, int offset)
37 {
38         struct omfs_extent *oe = (struct omfs_extent *) &bh->b_data[offset];
39
40         oe->e_next = ~cpu_to_be64(0ULL);
41         oe->e_extent_count = cpu_to_be32(1),
42         oe->e_fill = cpu_to_be32(0x22),
43         oe->e_entry.e_cluster = ~cpu_to_be64(0ULL);
44         oe->e_entry.e_blocks = ~cpu_to_be64(0ULL);
45 }
46
47 int omfs_shrink_inode(struct inode *inode)
48 {
49         struct omfs_sb_info *sbi = OMFS_SB(inode->i_sb);
50         struct omfs_extent *oe;
51         struct omfs_extent_entry *entry;
52         struct buffer_head *bh;
53         u64 next, last;
54         u32 extent_count;
55         u32 max_extents;
56         int ret;
57
58         /* traverse extent table, freeing each entry that is greater
59          * than inode->i_size;
60          */
61         next = inode->i_ino;
62
63         /* only support truncate -> 0 for now */
64         ret = -EIO;
65         if (inode->i_size != 0)
66                 goto out;
67
68         bh = sb_bread(inode->i_sb, clus_to_blk(sbi, next));
69         if (!bh)
70                 goto out;
71
72         oe = (struct omfs_extent *)(&bh->b_data[OMFS_EXTENT_START]);
73         max_extents = omfs_max_extents(sbi, OMFS_EXTENT_START);
74
75         for (;;) {
76
77                 if (omfs_is_bad(sbi, (struct omfs_header *) bh->b_data, next))
78                         goto out_brelse;
79
80                 extent_count = be32_to_cpu(oe->e_extent_count);
81
82                 if (extent_count > max_extents)
83                         goto out_brelse;
84
85                 last = next;
86                 next = be64_to_cpu(oe->e_next);
87                 entry = &oe->e_entry;
88
89                 /* ignore last entry as it is the terminator */
90                 for (; extent_count > 1; extent_count--) {
91                         u64 start, count;
92                         start = be64_to_cpu(entry->e_cluster);
93                         count = be64_to_cpu(entry->e_blocks);
94
95                         omfs_clear_range(inode->i_sb, start, (int) count);
96                         entry++;
97                 }
98                 omfs_make_empty_table(bh, (char *) oe - bh->b_data);
99                 mark_buffer_dirty(bh);
100                 brelse(bh);
101
102                 if (last != inode->i_ino)
103                         omfs_clear_range(inode->i_sb, last, sbi->s_mirrors);
104
105                 if (next == ~0)
106                         break;
107
108                 bh = sb_bread(inode->i_sb, clus_to_blk(sbi, next));
109                 if (!bh)
110                         goto out;
111                 oe = (struct omfs_extent *) (&bh->b_data[OMFS_EXTENT_CONT]);
112                 max_extents = omfs_max_extents(sbi, OMFS_EXTENT_CONT);
113         }
114         ret = 0;
115 out:
116         return ret;
117 out_brelse:
118         brelse(bh);
119         return ret;
120 }
121
122 static void omfs_truncate(struct inode *inode)
123 {
124         omfs_shrink_inode(inode);
125         mark_inode_dirty(inode);
126 }
127
128 /*
129  * Add new blocks to the current extent, or create new entries/continuations
130  * as necessary.
131  */
132 static int omfs_grow_extent(struct inode *inode, struct omfs_extent *oe,
133                         u64 *ret_block)
134 {
135         struct omfs_extent_entry *terminator;
136         struct omfs_extent_entry *entry = &oe->e_entry;
137         struct omfs_sb_info *sbi = OMFS_SB(inode->i_sb);
138         u32 extent_count = be32_to_cpu(oe->e_extent_count);
139         u64 new_block = 0;
140         u32 max_count;
141         int new_count;
142         int ret = 0;
143
144         /* reached the end of the extent table with no blocks mapped.
145          * there are three possibilities for adding: grow last extent,
146          * add a new extent to the current extent table, and add a
147          * continuation inode.  in last two cases need an allocator for
148          * sbi->s_cluster_size
149          */
150
151         /* TODO: handle holes */
152
153         /* should always have a terminator */
154         if (extent_count < 1)
155                 return -EIO;
156
157         /* trivially grow current extent, if next block is not taken */
158         terminator = entry + extent_count - 1;
159         if (extent_count > 1) {
160                 entry = terminator-1;
161                 new_block = be64_to_cpu(entry->e_cluster) +
162                         be64_to_cpu(entry->e_blocks);
163
164                 if (omfs_allocate_block(inode->i_sb, new_block)) {
165                         entry->e_blocks =
166                                 cpu_to_be64(be64_to_cpu(entry->e_blocks) + 1);
167                         terminator->e_blocks = ~(cpu_to_be64(
168                                 be64_to_cpu(~terminator->e_blocks) + 1));
169                         goto out;
170                 }
171         }
172         max_count = omfs_max_extents(sbi, OMFS_EXTENT_START);
173
174         /* TODO: add a continuation block here */
175         if (be32_to_cpu(oe->e_extent_count) > max_count-1)
176                 return -EIO;
177
178         /* try to allocate a new cluster */
179         ret = omfs_allocate_range(inode->i_sb, 1, sbi->s_clustersize,
180                 &new_block, &new_count);
181         if (ret)
182                 goto out_fail;
183
184         /* copy terminator down an entry */
185         entry = terminator;
186         terminator++;
187         memcpy(terminator, entry, sizeof(struct omfs_extent_entry));
188
189         entry->e_cluster = cpu_to_be64(new_block);
190         entry->e_blocks = cpu_to_be64((u64) new_count);
191
192         terminator->e_blocks = ~(cpu_to_be64(
193                 be64_to_cpu(~terminator->e_blocks) + (u64) new_count));
194
195         /* write in new entry */
196         oe->e_extent_count = cpu_to_be32(1 + be32_to_cpu(oe->e_extent_count));
197
198 out:
199         *ret_block = new_block;
200 out_fail:
201         return ret;
202 }
203
204 /*
205  * Scans across the directory table for a given file block number.
206  * If block not found, return 0.
207  */
208 static sector_t find_block(struct inode *inode, struct omfs_extent_entry *ent,
209                         sector_t block, int count, int *left)
210 {
211         /* count > 1 because of terminator */
212         sector_t searched = 0;
213         for (; count > 1; count--) {
214                 int numblocks = clus_to_blk(OMFS_SB(inode->i_sb),
215                         be64_to_cpu(ent->e_blocks));
216
217                 if (block >= searched  &&
218                     block < searched + numblocks) {
219                         /*
220                          * found it at cluster + (block - searched)
221                          * numblocks - (block - searched) is remainder
222                          */
223                         *left = numblocks - (block - searched);
224                         return clus_to_blk(OMFS_SB(inode->i_sb),
225                                 be64_to_cpu(ent->e_cluster)) +
226                                 block - searched;
227                 }
228                 searched += numblocks;
229                 ent++;
230         }
231         return 0;
232 }
233
234 static int omfs_get_block(struct inode *inode, sector_t block,
235                           struct buffer_head *bh_result, int create)
236 {
237         struct buffer_head *bh;
238         sector_t next, offset;
239         int ret;
240         u64 new_block;
241         u32 max_extents;
242         int extent_count;
243         struct omfs_extent *oe;
244         struct omfs_extent_entry *entry;
245         struct omfs_sb_info *sbi = OMFS_SB(inode->i_sb);
246         int max_blocks = bh_result->b_size >> inode->i_blkbits;
247         int remain;
248
249         ret = -EIO;
250         bh = sb_bread(inode->i_sb, clus_to_blk(sbi, inode->i_ino));
251         if (!bh)
252                 goto out;
253
254         oe = (struct omfs_extent *)(&bh->b_data[OMFS_EXTENT_START]);
255         max_extents = omfs_max_extents(sbi, OMFS_EXTENT_START);
256         next = inode->i_ino;
257
258         for (;;) {
259
260                 if (omfs_is_bad(sbi, (struct omfs_header *) bh->b_data, next))
261                         goto out_brelse;
262
263                 extent_count = be32_to_cpu(oe->e_extent_count);
264                 next = be64_to_cpu(oe->e_next);
265                 entry = &oe->e_entry;
266
267                 if (extent_count > max_extents)
268                         goto out_brelse;
269
270                 offset = find_block(inode, entry, block, extent_count, &remain);
271                 if (offset > 0) {
272                         ret = 0;
273                         map_bh(bh_result, inode->i_sb, offset);
274                         if (remain > max_blocks)
275                                 remain = max_blocks;
276                         bh_result->b_size = (remain << inode->i_blkbits);
277                         goto out_brelse;
278                 }
279                 if (next == ~0)
280                         break;
281
282                 brelse(bh);
283                 bh = sb_bread(inode->i_sb, clus_to_blk(sbi, next));
284                 if (!bh)
285                         goto out;
286                 oe = (struct omfs_extent *) (&bh->b_data[OMFS_EXTENT_CONT]);
287                 max_extents = omfs_max_extents(sbi, OMFS_EXTENT_CONT);
288         }
289         if (create) {
290                 ret = omfs_grow_extent(inode, oe, &new_block);
291                 if (ret == 0) {
292                         mark_buffer_dirty(bh);
293                         mark_inode_dirty(inode);
294                         map_bh(bh_result, inode->i_sb,
295                                         clus_to_blk(sbi, new_block));
296                 }
297         }
298 out_brelse:
299         brelse(bh);
300 out:
301         return ret;
302 }
303
304 static int omfs_readpage(struct file *file, struct page *page)
305 {
306         return block_read_full_page(page, omfs_get_block);
307 }
308
309 static int omfs_readpages(struct file *file, struct address_space *mapping,
310                 struct list_head *pages, unsigned nr_pages)
311 {
312         return mpage_readpages(mapping, pages, nr_pages, omfs_get_block);
313 }
314
315 static int omfs_writepage(struct page *page, struct writeback_control *wbc)
316 {
317         return block_write_full_page(page, omfs_get_block, wbc);
318 }
319
320 static int
321 omfs_writepages(struct address_space *mapping, struct writeback_control *wbc)
322 {
323         return mpage_writepages(mapping, wbc, omfs_get_block);
324 }
325
326 static int omfs_write_begin(struct file *file, struct address_space *mapping,
327                         loff_t pos, unsigned len, unsigned flags,
328                         struct page **pagep, void **fsdata)
329 {
330         *pagep = NULL;
331         return block_write_begin(file, mapping, pos, len, flags,
332                                 pagep, fsdata, omfs_get_block);
333 }
334
335 static sector_t omfs_bmap(struct address_space *mapping, sector_t block)
336 {
337         return generic_block_bmap(mapping, block, omfs_get_block);
338 }
339
340 struct file_operations omfs_file_operations = {
341         .llseek = generic_file_llseek,
342         .read = do_sync_read,
343         .write = do_sync_write,
344         .aio_read = generic_file_aio_read,
345         .aio_write = generic_file_aio_write,
346         .mmap = generic_file_mmap,
347         .fsync = omfs_sync_file,
348         .splice_read = generic_file_splice_read,
349 };
350
351 struct inode_operations omfs_file_inops = {
352         .truncate = omfs_truncate
353 };
354
355 struct address_space_operations omfs_aops = {
356         .readpage = omfs_readpage,
357         .readpages = omfs_readpages,
358         .writepage = omfs_writepage,
359         .writepages = omfs_writepages,
360         .sync_page = block_sync_page,
361         .write_begin = omfs_write_begin,
362         .write_end = generic_write_end,
363         .bmap = omfs_bmap,
364 };
365