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Linux/fs/ocfs2/buffer_head_io.c

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  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 }
428 

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