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
ocfs2_write_block(struct ocfs2_super * osb,struct buffer_head * bh,struct ocfs2_caching_info * ci)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
ocfs2_read_blocks_sync(struct ocfs2_super * osb,u64 block,unsigned int nr,struct buffer_head * bhs[])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
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))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. */
ocfs2_check_super_or_backup(struct super_block * sb,sector_t blkno)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 */
ocfs2_write_super_or_backup(struct ocfs2_super * osb,struct buffer_head * bh)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 }
428