Merge tag 'staging-3.15-rc8' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh...
[sfrench/cifs-2.6.git] / fs / ocfs2 / buffer_head_io.c
1 /* -*- mode: c; c-basic-offset: 8; -*-
2  * vim: noexpandtab sw=8 ts=8 sts=0:
3  *
4  * io.c
5  *
6  * Buffer cache handling
7  *
8  * Copyright (C) 2002, 2004 Oracle.  All rights reserved.
9  *
10  * This program is free software; you can redistribute it and/or
11  * modify it under the terms of the GNU General Public
12  * License as published by the Free Software Foundation; either
13  * version 2 of the License, or (at your option) any later version.
14  *
15  * This program is distributed in the hope that it will be useful,
16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
18  * General Public License for more details.
19  *
20  * You should have received a copy of the GNU General Public
21  * License along with this program; if not, write to the
22  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
23  * Boston, MA 021110-1307, USA.
24  */
25
26 #include <linux/fs.h>
27 #include <linux/types.h>
28 #include <linux/highmem.h>
29
30 #include <cluster/masklog.h>
31
32 #include "ocfs2.h"
33
34 #include "alloc.h"
35 #include "inode.h"
36 #include "journal.h"
37 #include "uptodate.h"
38 #include "buffer_head_io.h"
39 #include "ocfs2_trace.h"
40
41 /*
42  * Bits on bh->b_state used by ocfs2.
43  *
44  * These MUST be after the JBD2 bits.  Hence, we use BH_JBDPrivateStart.
45  */
46 enum ocfs2_state_bits {
47         BH_NeedsValidate = BH_JBDPrivateStart,
48 };
49
50 /* Expand the magic b_state functions */
51 BUFFER_FNS(NeedsValidate, needs_validate);
52
53 int ocfs2_write_block(struct ocfs2_super *osb, struct buffer_head *bh,
54                       struct ocfs2_caching_info *ci)
55 {
56         int ret = 0;
57
58         trace_ocfs2_write_block((unsigned long long)bh->b_blocknr, ci);
59
60         BUG_ON(bh->b_blocknr < OCFS2_SUPER_BLOCK_BLKNO);
61         BUG_ON(buffer_jbd(bh));
62
63         /* No need to check for a soft readonly file system here. non
64          * journalled writes are only ever done on system files which
65          * can get modified during recovery even if read-only. */
66         if (ocfs2_is_hard_readonly(osb)) {
67                 ret = -EROFS;
68                 mlog_errno(ret);
69                 goto out;
70         }
71
72         ocfs2_metadata_cache_io_lock(ci);
73
74         lock_buffer(bh);
75         set_buffer_uptodate(bh);
76
77         /* remove from dirty list before I/O. */
78         clear_buffer_dirty(bh);
79
80         get_bh(bh); /* for end_buffer_write_sync() */
81         bh->b_end_io = end_buffer_write_sync;
82         submit_bh(WRITE, bh);
83
84         wait_on_buffer(bh);
85
86         if (buffer_uptodate(bh)) {
87                 ocfs2_set_buffer_uptodate(ci, bh);
88         } else {
89                 /* We don't need to remove the clustered uptodate
90                  * information for this bh as it's not marked locally
91                  * uptodate. */
92                 ret = -EIO;
93                 mlog_errno(ret);
94         }
95
96         ocfs2_metadata_cache_io_unlock(ci);
97 out:
98         return ret;
99 }
100
101 int ocfs2_read_blocks_sync(struct ocfs2_super *osb, u64 block,
102                            unsigned int nr, struct buffer_head *bhs[])
103 {
104         int status = 0;
105         unsigned int i;
106         struct buffer_head *bh;
107
108         trace_ocfs2_read_blocks_sync((unsigned long long)block, nr);
109
110         if (!nr)
111                 goto bail;
112
113         for (i = 0 ; i < nr ; i++) {
114                 if (bhs[i] == NULL) {
115                         bhs[i] = sb_getblk(osb->sb, block++);
116                         if (bhs[i] == NULL) {
117                                 status = -ENOMEM;
118                                 mlog_errno(status);
119                                 goto bail;
120                         }
121                 }
122                 bh = bhs[i];
123
124                 if (buffer_jbd(bh)) {
125                         trace_ocfs2_read_blocks_sync_jbd(
126                                         (unsigned long long)bh->b_blocknr);
127                         continue;
128                 }
129
130                 if (buffer_dirty(bh)) {
131                         /* This should probably be a BUG, or
132                          * at least return an error. */
133                         mlog(ML_ERROR,
134                              "trying to sync read a dirty "
135                              "buffer! (blocknr = %llu), skipping\n",
136                              (unsigned long long)bh->b_blocknr);
137                         continue;
138                 }
139
140                 lock_buffer(bh);
141                 if (buffer_jbd(bh)) {
142                         mlog(ML_ERROR,
143                              "block %llu had the JBD bit set "
144                              "while I was in lock_buffer!",
145                              (unsigned long long)bh->b_blocknr);
146                         BUG();
147                 }
148
149                 clear_buffer_uptodate(bh);
150                 get_bh(bh); /* for end_buffer_read_sync() */
151                 bh->b_end_io = end_buffer_read_sync;
152                 submit_bh(READ, bh);
153         }
154
155         for (i = nr; i > 0; i--) {
156                 bh = bhs[i - 1];
157
158                 /* No need to wait on the buffer if it's managed by JBD. */
159                 if (!buffer_jbd(bh))
160                         wait_on_buffer(bh);
161
162                 if (!buffer_uptodate(bh)) {
163                         /* Status won't be cleared from here on out,
164                          * so we can safely record this and loop back
165                          * to cleanup the other buffers. */
166                         status = -EIO;
167                         put_bh(bh);
168                         bhs[i - 1] = NULL;
169                 }
170         }
171
172 bail:
173         return status;
174 }
175
176 int ocfs2_read_blocks(struct ocfs2_caching_info *ci, u64 block, int nr,
177                       struct buffer_head *bhs[], int flags,
178                       int (*validate)(struct super_block *sb,
179                                       struct buffer_head *bh))
180 {
181         int status = 0;
182         int i, ignore_cache = 0;
183         struct buffer_head *bh;
184         struct super_block *sb = ocfs2_metadata_cache_get_super(ci);
185
186         trace_ocfs2_read_blocks_begin(ci, (unsigned long long)block, nr, flags);
187
188         BUG_ON(!ci);
189         BUG_ON((flags & OCFS2_BH_READAHEAD) &&
190                (flags & OCFS2_BH_IGNORE_CACHE));
191
192         if (bhs == NULL) {
193                 status = -EINVAL;
194                 mlog_errno(status);
195                 goto bail;
196         }
197
198         if (nr < 0) {
199                 mlog(ML_ERROR, "asked to read %d blocks!\n", nr);
200                 status = -EINVAL;
201                 mlog_errno(status);
202                 goto bail;
203         }
204
205         if (nr == 0) {
206                 status = 0;
207                 goto bail;
208         }
209
210         ocfs2_metadata_cache_io_lock(ci);
211         for (i = 0 ; i < nr ; i++) {
212                 if (bhs[i] == NULL) {
213                         bhs[i] = sb_getblk(sb, block++);
214                         if (bhs[i] == NULL) {
215                                 ocfs2_metadata_cache_io_unlock(ci);
216                                 status = -ENOMEM;
217                                 mlog_errno(status);
218                                 goto bail;
219                         }
220                 }
221                 bh = bhs[i];
222                 ignore_cache = (flags & OCFS2_BH_IGNORE_CACHE);
223
224                 /* There are three read-ahead cases here which we need to
225                  * be concerned with. All three assume a buffer has
226                  * previously been submitted with OCFS2_BH_READAHEAD
227                  * and it hasn't yet completed I/O.
228                  *
229                  * 1) The current request is sync to disk. This rarely
230                  *    happens these days, and never when performance
231                  *    matters - the code can just wait on the buffer
232                  *    lock and re-submit.
233                  *
234                  * 2) The current request is cached, but not
235                  *    readahead. ocfs2_buffer_uptodate() will return
236                  *    false anyway, so we'll wind up waiting on the
237                  *    buffer lock to do I/O. We re-check the request
238                  *    with after getting the lock to avoid a re-submit.
239                  *
240                  * 3) The current request is readahead (and so must
241                  *    also be a caching one). We short circuit if the
242                  *    buffer is locked (under I/O) and if it's in the
243                  *    uptodate cache. The re-check from #2 catches the
244                  *    case that the previous read-ahead completes just
245                  *    before our is-it-in-flight check.
246                  */
247
248                 if (!ignore_cache && !ocfs2_buffer_uptodate(ci, bh)) {
249                         trace_ocfs2_read_blocks_from_disk(
250                              (unsigned long long)bh->b_blocknr,
251                              (unsigned long long)ocfs2_metadata_cache_owner(ci));
252                         /* We're using ignore_cache here to say
253                          * "go to disk" */
254                         ignore_cache = 1;
255                 }
256
257                 trace_ocfs2_read_blocks_bh((unsigned long long)bh->b_blocknr,
258                         ignore_cache, buffer_jbd(bh), buffer_dirty(bh));
259
260                 if (buffer_jbd(bh)) {
261                         continue;
262                 }
263
264                 if (ignore_cache) {
265                         if (buffer_dirty(bh)) {
266                                 /* This should probably be a BUG, or
267                                  * at least return an error. */
268                                 continue;
269                         }
270
271                         /* A read-ahead request was made - if the
272                          * buffer is already under read-ahead from a
273                          * previously submitted request than we are
274                          * done here. */
275                         if ((flags & OCFS2_BH_READAHEAD)
276                             && ocfs2_buffer_read_ahead(ci, bh))
277                                 continue;
278
279                         lock_buffer(bh);
280                         if (buffer_jbd(bh)) {
281 #ifdef CATCH_BH_JBD_RACES
282                                 mlog(ML_ERROR, "block %llu had the JBD bit set "
283                                                "while I was in lock_buffer!",
284                                      (unsigned long long)bh->b_blocknr);
285                                 BUG();
286 #else
287                                 unlock_buffer(bh);
288                                 continue;
289 #endif
290                         }
291
292                         /* Re-check ocfs2_buffer_uptodate() as a
293                          * previously read-ahead buffer may have
294                          * completed I/O while we were waiting for the
295                          * buffer lock. */
296                         if (!(flags & OCFS2_BH_IGNORE_CACHE)
297                             && !(flags & OCFS2_BH_READAHEAD)
298                             && ocfs2_buffer_uptodate(ci, bh)) {
299                                 unlock_buffer(bh);
300                                 continue;
301                         }
302
303                         clear_buffer_uptodate(bh);
304                         get_bh(bh); /* for end_buffer_read_sync() */
305                         if (validate)
306                                 set_buffer_needs_validate(bh);
307                         bh->b_end_io = end_buffer_read_sync;
308                         submit_bh(READ, bh);
309                         continue;
310                 }
311         }
312
313         status = 0;
314
315         for (i = (nr - 1); i >= 0; i--) {
316                 bh = bhs[i];
317
318                 if (!(flags & OCFS2_BH_READAHEAD)) {
319                         /* We know this can't have changed as we hold the
320                          * owner sem. Avoid doing any work on the bh if the
321                          * journal has it. */
322                         if (!buffer_jbd(bh))
323                                 wait_on_buffer(bh);
324
325                         if (!buffer_uptodate(bh)) {
326                                 /* Status won't be cleared from here on out,
327                                  * so we can safely record this and loop back
328                                  * to cleanup the other buffers. Don't need to
329                                  * remove the clustered uptodate information
330                                  * for this bh as it's not marked locally
331                                  * uptodate. */
332                                 status = -EIO;
333                                 put_bh(bh);
334                                 bhs[i] = NULL;
335                                 continue;
336                         }
337
338                         if (buffer_needs_validate(bh)) {
339                                 /* We never set NeedsValidate if the
340                                  * buffer was held by the journal, so
341                                  * that better not have changed */
342                                 BUG_ON(buffer_jbd(bh));
343                                 clear_buffer_needs_validate(bh);
344                                 status = validate(sb, bh);
345                                 if (status) {
346                                         put_bh(bh);
347                                         bhs[i] = NULL;
348                                         continue;
349                                 }
350                         }
351                 }
352
353                 /* Always set the buffer in the cache, even if it was
354                  * a forced read, or read-ahead which hasn't yet
355                  * completed. */
356                 ocfs2_set_buffer_uptodate(ci, bh);
357         }
358         ocfs2_metadata_cache_io_unlock(ci);
359
360         trace_ocfs2_read_blocks_end((unsigned long long)block, nr,
361                                     flags, ignore_cache);
362
363 bail:
364
365         return status;
366 }
367
368 /* Check whether the blkno is the super block or one of the backups. */
369 static void ocfs2_check_super_or_backup(struct super_block *sb,
370                                         sector_t blkno)
371 {
372         int i;
373         u64 backup_blkno;
374
375         if (blkno == OCFS2_SUPER_BLOCK_BLKNO)
376                 return;
377
378         for (i = 0; i < OCFS2_MAX_BACKUP_SUPERBLOCKS; i++) {
379                 backup_blkno = ocfs2_backup_super_blkno(sb, i);
380                 if (backup_blkno == blkno)
381                         return;
382         }
383
384         BUG();
385 }
386
387 /*
388  * Write super block and backups doesn't need to collaborate with journal,
389  * so we don't need to lock ip_io_mutex and ci doesn't need to bea passed
390  * into this function.
391  */
392 int ocfs2_write_super_or_backup(struct ocfs2_super *osb,
393                                 struct buffer_head *bh)
394 {
395         int ret = 0;
396         struct ocfs2_dinode *di = (struct ocfs2_dinode *)bh->b_data;
397
398         BUG_ON(buffer_jbd(bh));
399         ocfs2_check_super_or_backup(osb->sb, bh->b_blocknr);
400
401         if (ocfs2_is_hard_readonly(osb) || ocfs2_is_soft_readonly(osb)) {
402                 ret = -EROFS;
403                 mlog_errno(ret);
404                 goto out;
405         }
406
407         lock_buffer(bh);
408         set_buffer_uptodate(bh);
409
410         /* remove from dirty list before I/O. */
411         clear_buffer_dirty(bh);
412
413         get_bh(bh); /* for end_buffer_write_sync() */
414         bh->b_end_io = end_buffer_write_sync;
415         ocfs2_compute_meta_ecc(osb->sb, bh->b_data, &di->i_check);
416         submit_bh(WRITE, bh);
417
418         wait_on_buffer(bh);
419
420         if (!buffer_uptodate(bh)) {
421                 ret = -EIO;
422                 mlog_errno(ret);
423         }
424
425 out:
426         return ret;
427 }