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 #include <linux/bio.h>
30
31 #include <cluster/masklog.h>
32
33 #include "ocfs2.h"
34
35 #include "alloc.h"
36 #include "inode.h"
37 #include "journal.h"
38 #include "uptodate.h"
39 #include "buffer_head_io.h"
40 #include "ocfs2_trace.h"
41
42 /*
43 * Bits on bh->b_state used by ocfs2.
44 *
45 * These MUST be after the JBD2 bits. Hence, we use BH_JBDPrivateStart.
46 */
47 enum ocfs2_state_bits {
48 BH_NeedsValidate = BH_JBDPrivateStart,
49 };
50
51 /* Expand the magic b_state functions */
52 BUFFER_FNS(NeedsValidate, needs_validate);
53
ocfs2_write_block(struct ocfs2_super * osb,struct buffer_head * bh,struct ocfs2_caching_info * ci)54 int ocfs2_write_block(struct ocfs2_super *osb, struct buffer_head *bh,
55 struct ocfs2_caching_info *ci)
56 {
57 int ret = 0;
58
59 trace_ocfs2_write_block((unsigned long long)bh->b_blocknr, ci);
60
61 BUG_ON(bh->b_blocknr < OCFS2_SUPER_BLOCK_BLKNO);
62 BUG_ON(buffer_jbd(bh));
63
64 /* No need to check for a soft readonly file system here. non
65 * journalled writes are only ever done on system files which
66 * can get modified during recovery even if read-only. */
67 if (ocfs2_is_hard_readonly(osb)) {
68 ret = -EROFS;
69 mlog_errno(ret);
70 goto out;
71 }
72
73 ocfs2_metadata_cache_io_lock(ci);
74
75 lock_buffer(bh);
76 set_buffer_uptodate(bh);
77
78 /* remove from dirty list before I/O. */
79 clear_buffer_dirty(bh);
80
81 get_bh(bh); /* for end_buffer_write_sync() */
82 bh->b_end_io = end_buffer_write_sync;
83 submit_bh(REQ_OP_WRITE, 0, bh);
84
85 wait_on_buffer(bh);
86
87 if (buffer_uptodate(bh)) {
88 ocfs2_set_buffer_uptodate(ci, bh);
89 } else {
90 /* We don't need to remove the clustered uptodate
91 * information for this bh as it's not marked locally
92 * uptodate. */
93 ret = -EIO;
94 mlog_errno(ret);
95 }
96
97 ocfs2_metadata_cache_io_unlock(ci);
98 out:
99 return ret;
100 }
101
102 /* Caller must provide a bhs[] with all NULL or non-NULL entries, so it
103 * will be easier to handle read failure.
104 */
ocfs2_read_blocks_sync(struct ocfs2_super * osb,u64 block,unsigned int nr,struct buffer_head * bhs[])105 int ocfs2_read_blocks_sync(struct ocfs2_super *osb, u64 block,
106 unsigned int nr, struct buffer_head *bhs[])
107 {
108 int status = 0;
109 unsigned int i;
110 struct buffer_head *bh;
111 int new_bh = 0;
112
113 trace_ocfs2_read_blocks_sync((unsigned long long)block, nr);
114
115 if (!nr)
116 goto bail;
117
118 /* Don't put buffer head and re-assign it to NULL if it is allocated
119 * outside since the caller can't be aware of this alternation!
120 */
121 new_bh = (bhs[0] == NULL);
122
123 for (i = 0 ; i < nr ; i++) {
124 if (bhs[i] == NULL) {
125 bhs[i] = sb_getblk(osb->sb, block++);
126 if (bhs[i] == NULL) {
127 status = -ENOMEM;
128 mlog_errno(status);
129 break;
130 }
131 }
132 bh = bhs[i];
133
134 if (buffer_jbd(bh)) {
135 trace_ocfs2_read_blocks_sync_jbd(
136 (unsigned long long)bh->b_blocknr);
137 continue;
138 }
139
140 if (buffer_dirty(bh)) {
141 /* This should probably be a BUG, or
142 * at least return an error. */
143 mlog(ML_ERROR,
144 "trying to sync read a dirty "
145 "buffer! (blocknr = %llu), skipping\n",
146 (unsigned long long)bh->b_blocknr);
147 continue;
148 }
149
150 lock_buffer(bh);
151 if (buffer_jbd(bh)) {
152 #ifdef CATCH_BH_JBD_RACES
153 mlog(ML_ERROR,
154 "block %llu had the JBD bit set "
155 "while I was in lock_buffer!",
156 (unsigned long long)bh->b_blocknr);
157 BUG();
158 #else
159 unlock_buffer(bh);
160 continue;
161 #endif
162 }
163
164 get_bh(bh); /* for end_buffer_read_sync() */
165 bh->b_end_io = end_buffer_read_sync;
166 submit_bh(REQ_OP_READ, 0, bh);
167 }
168
169 read_failure:
170 for (i = nr; i > 0; i--) {
171 bh = bhs[i - 1];
172
173 if (unlikely(status)) {
174 if (new_bh && bh) {
175 /* If middle bh fails, let previous bh
176 * finish its read and then put it to
177 * aovoid bh leak
178 */
179 if (!buffer_jbd(bh))
180 wait_on_buffer(bh);
181 put_bh(bh);
182 bhs[i - 1] = NULL;
183 } else if (bh && buffer_uptodate(bh)) {
184 clear_buffer_uptodate(bh);
185 }
186 continue;
187 }
188
189 /* No need to wait on the buffer if it's managed by JBD. */
190 if (!buffer_jbd(bh))
191 wait_on_buffer(bh);
192
193 if (!buffer_uptodate(bh)) {
194 /* Status won't be cleared from here on out,
195 * so we can safely record this and loop back
196 * to cleanup the other buffers. */
197 status = -EIO;
198 goto read_failure;
199 }
200 }
201
202 bail:
203 return status;
204 }
205
206 /* Caller must provide a bhs[] with all NULL or non-NULL entries, so it
207 * will be easier to handle read failure.
208 */
ocfs2_read_blocks(struct ocfs2_caching_info * ci,u64 block,int nr,struct buffer_head * bhs[],int flags,int (* validate)(struct super_block * sb,struct buffer_head * bh))209 int ocfs2_read_blocks(struct ocfs2_caching_info *ci, u64 block, int nr,
210 struct buffer_head *bhs[], int flags,
211 int (*validate)(struct super_block *sb,
212 struct buffer_head *bh))
213 {
214 int status = 0;
215 int i, ignore_cache = 0;
216 struct buffer_head *bh;
217 struct super_block *sb = ocfs2_metadata_cache_get_super(ci);
218 int new_bh = 0;
219
220 trace_ocfs2_read_blocks_begin(ci, (unsigned long long)block, nr, flags);
221
222 BUG_ON(!ci);
223 BUG_ON((flags & OCFS2_BH_READAHEAD) &&
224 (flags & OCFS2_BH_IGNORE_CACHE));
225
226 if (bhs == NULL) {
227 status = -EINVAL;
228 mlog_errno(status);
229 goto bail;
230 }
231
232 if (nr < 0) {
233 mlog(ML_ERROR, "asked to read %d blocks!\n", nr);
234 status = -EINVAL;
235 mlog_errno(status);
236 goto bail;
237 }
238
239 if (nr == 0) {
240 status = 0;
241 goto bail;
242 }
243
244 /* Don't put buffer head and re-assign it to NULL if it is allocated
245 * outside since the caller can't be aware of this alternation!
246 */
247 new_bh = (bhs[0] == NULL);
248
249 ocfs2_metadata_cache_io_lock(ci);
250 for (i = 0 ; i < nr ; i++) {
251 if (bhs[i] == NULL) {
252 bhs[i] = sb_getblk(sb, block++);
253 if (bhs[i] == NULL) {
254 ocfs2_metadata_cache_io_unlock(ci);
255 status = -ENOMEM;
256 mlog_errno(status);
257 /* Don't forget to put previous bh! */
258 break;
259 }
260 }
261 bh = bhs[i];
262 ignore_cache = (flags & OCFS2_BH_IGNORE_CACHE);
263
264 /* There are three read-ahead cases here which we need to
265 * be concerned with. All three assume a buffer has
266 * previously been submitted with OCFS2_BH_READAHEAD
267 * and it hasn't yet completed I/O.
268 *
269 * 1) The current request is sync to disk. This rarely
270 * happens these days, and never when performance
271 * matters - the code can just wait on the buffer
272 * lock and re-submit.
273 *
274 * 2) The current request is cached, but not
275 * readahead. ocfs2_buffer_uptodate() will return
276 * false anyway, so we'll wind up waiting on the
277 * buffer lock to do I/O. We re-check the request
278 * with after getting the lock to avoid a re-submit.
279 *
280 * 3) The current request is readahead (and so must
281 * also be a caching one). We short circuit if the
282 * buffer is locked (under I/O) and if it's in the
283 * uptodate cache. The re-check from #2 catches the
284 * case that the previous read-ahead completes just
285 * before our is-it-in-flight check.
286 */
287
288 if (!ignore_cache && !ocfs2_buffer_uptodate(ci, bh)) {
289 trace_ocfs2_read_blocks_from_disk(
290 (unsigned long long)bh->b_blocknr,
291 (unsigned long long)ocfs2_metadata_cache_owner(ci));
292 /* We're using ignore_cache here to say
293 * "go to disk" */
294 ignore_cache = 1;
295 }
296
297 trace_ocfs2_read_blocks_bh((unsigned long long)bh->b_blocknr,
298 ignore_cache, buffer_jbd(bh), buffer_dirty(bh));
299
300 if (buffer_jbd(bh)) {
301 continue;
302 }
303
304 if (ignore_cache) {
305 if (buffer_dirty(bh)) {
306 /* This should probably be a BUG, or
307 * at least return an error. */
308 continue;
309 }
310
311 /* A read-ahead request was made - if the
312 * buffer is already under read-ahead from a
313 * previously submitted request than we are
314 * done here. */
315 if ((flags & OCFS2_BH_READAHEAD)
316 && ocfs2_buffer_read_ahead(ci, bh))
317 continue;
318
319 lock_buffer(bh);
320 if (buffer_jbd(bh)) {
321 #ifdef CATCH_BH_JBD_RACES
322 mlog(ML_ERROR, "block %llu had the JBD bit set "
323 "while I was in lock_buffer!",
324 (unsigned long long)bh->b_blocknr);
325 BUG();
326 #else
327 unlock_buffer(bh);
328 continue;
329 #endif
330 }
331
332 /* Re-check ocfs2_buffer_uptodate() as a
333 * previously read-ahead buffer may have
334 * completed I/O while we were waiting for the
335 * buffer lock. */
336 if (!(flags & OCFS2_BH_IGNORE_CACHE)
337 && !(flags & OCFS2_BH_READAHEAD)
338 && ocfs2_buffer_uptodate(ci, bh)) {
339 unlock_buffer(bh);
340 continue;
341 }
342
343 get_bh(bh); /* for end_buffer_read_sync() */
344 if (validate)
345 set_buffer_needs_validate(bh);
346 bh->b_end_io = end_buffer_read_sync;
347 submit_bh(REQ_OP_READ, 0, bh);
348 continue;
349 }
350 }
351
352 read_failure:
353 for (i = (nr - 1); i >= 0; i--) {
354 bh = bhs[i];
355
356 if (!(flags & OCFS2_BH_READAHEAD)) {
357 if (unlikely(status)) {
358 /* Clear the buffers on error including those
359 * ever succeeded in reading
360 */
361 if (new_bh && bh) {
362 /* If middle bh fails, let previous bh
363 * finish its read and then put it to
364 * aovoid bh leak
365 */
366 if (!buffer_jbd(bh))
367 wait_on_buffer(bh);
368 put_bh(bh);
369 bhs[i] = NULL;
370 } else if (bh && buffer_uptodate(bh)) {
371 clear_buffer_uptodate(bh);
372 }
373 continue;
374 }
375 /* We know this can't have changed as we hold the
376 * owner sem. Avoid doing any work on the bh if the
377 * journal has it. */
378 if (!buffer_jbd(bh))
379 wait_on_buffer(bh);
380
381 if (!buffer_uptodate(bh)) {
382 /* Status won't be cleared from here on out,
383 * so we can safely record this and loop back
384 * to cleanup the other buffers. Don't need to
385 * remove the clustered uptodate information
386 * for this bh as it's not marked locally
387 * uptodate. */
388 status = -EIO;
389 clear_buffer_needs_validate(bh);
390 goto read_failure;
391 }
392
393 if (buffer_needs_validate(bh)) {
394 /* We never set NeedsValidate if the
395 * buffer was held by the journal, so
396 * that better not have changed */
397 BUG_ON(buffer_jbd(bh));
398 clear_buffer_needs_validate(bh);
399 status = validate(sb, bh);
400 if (status)
401 goto read_failure;
402 }
403 }
404
405 /* Always set the buffer in the cache, even if it was
406 * a forced read, or read-ahead which hasn't yet
407 * completed. */
408 ocfs2_set_buffer_uptodate(ci, bh);
409 }
410 ocfs2_metadata_cache_io_unlock(ci);
411
412 trace_ocfs2_read_blocks_end((unsigned long long)block, nr,
413 flags, ignore_cache);
414
415 bail:
416
417 return status;
418 }
419
420 /* Check whether the blkno is the super block or one of the backups. */
ocfs2_check_super_or_backup(struct super_block * sb,sector_t blkno)421 static void ocfs2_check_super_or_backup(struct super_block *sb,
422 sector_t blkno)
423 {
424 int i;
425 u64 backup_blkno;
426
427 if (blkno == OCFS2_SUPER_BLOCK_BLKNO)
428 return;
429
430 for (i = 0; i < OCFS2_MAX_BACKUP_SUPERBLOCKS; i++) {
431 backup_blkno = ocfs2_backup_super_blkno(sb, i);
432 if (backup_blkno == blkno)
433 return;
434 }
435
436 BUG();
437 }
438
439 /*
440 * Write super block and backups doesn't need to collaborate with journal,
441 * so we don't need to lock ip_io_mutex and ci doesn't need to bea passed
442 * into this function.
443 */
ocfs2_write_super_or_backup(struct ocfs2_super * osb,struct buffer_head * bh)444 int ocfs2_write_super_or_backup(struct ocfs2_super *osb,
445 struct buffer_head *bh)
446 {
447 int ret = 0;
448 struct ocfs2_dinode *di = (struct ocfs2_dinode *)bh->b_data;
449
450 BUG_ON(buffer_jbd(bh));
451 ocfs2_check_super_or_backup(osb->sb, bh->b_blocknr);
452
453 if (ocfs2_is_hard_readonly(osb) || ocfs2_is_soft_readonly(osb)) {
454 ret = -EROFS;
455 mlog_errno(ret);
456 goto out;
457 }
458
459 lock_buffer(bh);
460 set_buffer_uptodate(bh);
461
462 /* remove from dirty list before I/O. */
463 clear_buffer_dirty(bh);
464
465 get_bh(bh); /* for end_buffer_write_sync() */
466 bh->b_end_io = end_buffer_write_sync;
467 ocfs2_compute_meta_ecc(osb->sb, bh->b_data, &di->i_check);
468 submit_bh(REQ_OP_WRITE, 0, bh);
469
470 wait_on_buffer(bh);
471
472 if (!buffer_uptodate(bh)) {
473 ret = -EIO;
474 mlog_errno(ret);
475 }
476
477 out:
478 return ret;
479 }
480