Root/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 */
46enum ocfs2_state_bits {
47    BH_NeedsValidate = BH_JBDPrivateStart,
48};
49
50/* Expand the magic b_state functions */
51BUFFER_FNS(NeedsValidate, needs_validate);
52
53int 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        put_bh(bh);
94        mlog_errno(ret);
95    }
96
97    ocfs2_metadata_cache_io_unlock(ci);
98out:
99    return ret;
100}
101
102int ocfs2_read_blocks_sync(struct ocfs2_super *osb, u64 block,
103               unsigned int nr, struct buffer_head *bhs[])
104{
105    int status = 0;
106    unsigned int i;
107    struct buffer_head *bh;
108
109    trace_ocfs2_read_blocks_sync((unsigned long long)block, nr);
110
111    if (!nr)
112        goto bail;
113
114    for (i = 0 ; i < nr ; i++) {
115        if (bhs[i] == NULL) {
116            bhs[i] = sb_getblk(osb->sb, block++);
117            if (bhs[i] == NULL) {
118                status = -EIO;
119                mlog_errno(status);
120                goto bail;
121            }
122        }
123        bh = bhs[i];
124
125        if (buffer_jbd(bh)) {
126            trace_ocfs2_read_blocks_sync_jbd(
127                    (unsigned long long)bh->b_blocknr);
128            continue;
129        }
130
131        if (buffer_dirty(bh)) {
132            /* This should probably be a BUG, or
133             * at least return an error. */
134            mlog(ML_ERROR,
135                 "trying to sync read a dirty "
136                 "buffer! (blocknr = %llu), skipping\n",
137                 (unsigned long long)bh->b_blocknr);
138            continue;
139        }
140
141        lock_buffer(bh);
142        if (buffer_jbd(bh)) {
143            mlog(ML_ERROR,
144                 "block %llu had the JBD bit set "
145                 "while I was in lock_buffer!",
146                 (unsigned long long)bh->b_blocknr);
147            BUG();
148        }
149
150        clear_buffer_uptodate(bh);
151        get_bh(bh); /* for end_buffer_read_sync() */
152        bh->b_end_io = end_buffer_read_sync;
153        submit_bh(READ, bh);
154    }
155
156    for (i = nr; i > 0; i--) {
157        bh = bhs[i - 1];
158
159        /* No need to wait on the buffer if it's managed by JBD. */
160        if (!buffer_jbd(bh))
161            wait_on_buffer(bh);
162
163        if (!buffer_uptodate(bh)) {
164            /* Status won't be cleared from here on out,
165             * so we can safely record this and loop back
166             * to cleanup the other buffers. */
167            status = -EIO;
168            put_bh(bh);
169            bhs[i - 1] = NULL;
170        }
171    }
172
173bail:
174    return status;
175}
176
177int ocfs2_read_blocks(struct ocfs2_caching_info *ci, u64 block, int nr,
178              struct buffer_head *bhs[], int flags,
179              int (*validate)(struct super_block *sb,
180                      struct buffer_head *bh))
181{
182    int status = 0;
183    int i, ignore_cache = 0;
184    struct buffer_head *bh;
185    struct super_block *sb = ocfs2_metadata_cache_get_super(ci);
186
187    trace_ocfs2_read_blocks_begin(ci, (unsigned long long)block, nr, flags);
188
189    BUG_ON(!ci);
190    BUG_ON((flags & OCFS2_BH_READAHEAD) &&
191           (flags & OCFS2_BH_IGNORE_CACHE));
192
193    if (bhs == NULL) {
194        status = -EINVAL;
195        mlog_errno(status);
196        goto bail;
197    }
198
199    if (nr < 0) {
200        mlog(ML_ERROR, "asked to read %d blocks!\n", nr);
201        status = -EINVAL;
202        mlog_errno(status);
203        goto bail;
204    }
205
206    if (nr == 0) {
207        status = 0;
208        goto bail;
209    }
210
211    ocfs2_metadata_cache_io_lock(ci);
212    for (i = 0 ; i < nr ; i++) {
213        if (bhs[i] == NULL) {
214            bhs[i] = sb_getblk(sb, block++);
215            if (bhs[i] == NULL) {
216                ocfs2_metadata_cache_io_unlock(ci);
217                status = -EIO;
218                mlog_errno(status);
219                goto bail;
220            }
221        }
222        bh = bhs[i];
223        ignore_cache = (flags & OCFS2_BH_IGNORE_CACHE);
224
225        /* There are three read-ahead cases here which we need to
226         * be concerned with. All three assume a buffer has
227         * previously been submitted with OCFS2_BH_READAHEAD
228         * and it hasn't yet completed I/O.
229         *
230         * 1) The current request is sync to disk. This rarely
231         * happens these days, and never when performance
232         * matters - the code can just wait on the buffer
233         * lock and re-submit.
234         *
235         * 2) The current request is cached, but not
236         * readahead. ocfs2_buffer_uptodate() will return
237         * false anyway, so we'll wind up waiting on the
238         * buffer lock to do I/O. We re-check the request
239         * with after getting the lock to avoid a re-submit.
240         *
241         * 3) The current request is readahead (and so must
242         * also be a caching one). We short circuit if the
243         * buffer is locked (under I/O) and if it's in the
244         * uptodate cache. The re-check from #2 catches the
245         * case that the previous read-ahead completes just
246         * before our is-it-in-flight check.
247         */
248
249        if (!ignore_cache && !ocfs2_buffer_uptodate(ci, bh)) {
250            trace_ocfs2_read_blocks_from_disk(
251                 (unsigned long long)bh->b_blocknr,
252                 (unsigned long long)ocfs2_metadata_cache_owner(ci));
253            /* We're using ignore_cache here to say
254             * "go to disk" */
255            ignore_cache = 1;
256        }
257
258        trace_ocfs2_read_blocks_bh((unsigned long long)bh->b_blocknr,
259            ignore_cache, buffer_jbd(bh), buffer_dirty(bh));
260
261        if (buffer_jbd(bh)) {
262            continue;
263        }
264
265        if (ignore_cache) {
266            if (buffer_dirty(bh)) {
267                /* This should probably be a BUG, or
268                 * at least return an error. */
269                continue;
270            }
271
272            /* A read-ahead request was made - if the
273             * buffer is already under read-ahead from a
274             * previously submitted request than we are
275             * done here. */
276            if ((flags & OCFS2_BH_READAHEAD)
277                && ocfs2_buffer_read_ahead(ci, bh))
278                continue;
279
280            lock_buffer(bh);
281            if (buffer_jbd(bh)) {
282#ifdef CATCH_BH_JBD_RACES
283                mlog(ML_ERROR, "block %llu had the JBD bit set "
284                           "while I was in lock_buffer!",
285                     (unsigned long long)bh->b_blocknr);
286                BUG();
287#else
288                unlock_buffer(bh);
289                continue;
290#endif
291            }
292
293            /* Re-check ocfs2_buffer_uptodate() as a
294             * previously read-ahead buffer may have
295             * completed I/O while we were waiting for the
296             * buffer lock. */
297            if (!(flags & OCFS2_BH_IGNORE_CACHE)
298                && !(flags & OCFS2_BH_READAHEAD)
299                && ocfs2_buffer_uptodate(ci, bh)) {
300                unlock_buffer(bh);
301                continue;
302            }
303
304            clear_buffer_uptodate(bh);
305            get_bh(bh); /* for end_buffer_read_sync() */
306            if (validate)
307                set_buffer_needs_validate(bh);
308            bh->b_end_io = end_buffer_read_sync;
309            submit_bh(READ, bh);
310            continue;
311        }
312    }
313
314    status = 0;
315
316    for (i = (nr - 1); i >= 0; i--) {
317        bh = bhs[i];
318
319        if (!(flags & OCFS2_BH_READAHEAD)) {
320            /* We know this can't have changed as we hold the
321             * owner sem. Avoid doing any work on the bh if the
322             * journal has it. */
323            if (!buffer_jbd(bh))
324                wait_on_buffer(bh);
325
326            if (!buffer_uptodate(bh)) {
327                /* Status won't be cleared from here on out,
328                 * so we can safely record this and loop back
329                 * to cleanup the other buffers. Don't need to
330                 * remove the clustered uptodate information
331                 * for this bh as it's not marked locally
332                 * uptodate. */
333                status = -EIO;
334                put_bh(bh);
335                bhs[i] = NULL;
336                continue;
337            }
338
339            if (buffer_needs_validate(bh)) {
340                /* We never set NeedsValidate if the
341                 * buffer was held by the journal, so
342                 * that better not have changed */
343                BUG_ON(buffer_jbd(bh));
344                clear_buffer_needs_validate(bh);
345                status = validate(sb, bh);
346                if (status) {
347                    put_bh(bh);
348                    bhs[i] = NULL;
349                    continue;
350                }
351            }
352        }
353
354        /* Always set the buffer in the cache, even if it was
355         * a forced read, or read-ahead which hasn't yet
356         * completed. */
357        ocfs2_set_buffer_uptodate(ci, bh);
358    }
359    ocfs2_metadata_cache_io_unlock(ci);
360
361    trace_ocfs2_read_blocks_end((unsigned long long)block, nr,
362                    flags, ignore_cache);
363
364bail:
365
366    return status;
367}
368
369/* Check whether the blkno is the super block or one of the backups. */
370static void ocfs2_check_super_or_backup(struct super_block *sb,
371                    sector_t blkno)
372{
373    int i;
374    u64 backup_blkno;
375
376    if (blkno == OCFS2_SUPER_BLOCK_BLKNO)
377        return;
378
379    for (i = 0; i < OCFS2_MAX_BACKUP_SUPERBLOCKS; i++) {
380        backup_blkno = ocfs2_backup_super_blkno(sb, i);
381        if (backup_blkno == blkno)
382            return;
383    }
384
385    BUG();
386}
387
388/*
389 * Write super block and backups doesn't need to collaborate with journal,
390 * so we don't need to lock ip_io_mutex and ci doesn't need to bea passed
391 * into this function.
392 */
393int ocfs2_write_super_or_backup(struct ocfs2_super *osb,
394                struct buffer_head *bh)
395{
396    int ret = 0;
397    struct ocfs2_dinode *di = (struct ocfs2_dinode *)bh->b_data;
398
399    BUG_ON(buffer_jbd(bh));
400    ocfs2_check_super_or_backup(osb->sb, bh->b_blocknr);
401
402    if (ocfs2_is_hard_readonly(osb) || ocfs2_is_soft_readonly(osb)) {
403        ret = -EROFS;
404        mlog_errno(ret);
405        goto out;
406    }
407
408    lock_buffer(bh);
409    set_buffer_uptodate(bh);
410
411    /* remove from dirty list before I/O. */
412    clear_buffer_dirty(bh);
413
414    get_bh(bh); /* for end_buffer_write_sync() */
415    bh->b_end_io = end_buffer_write_sync;
416    ocfs2_compute_meta_ecc(osb->sb, bh->b_data, &di->i_check);
417    submit_bh(WRITE, bh);
418
419    wait_on_buffer(bh);
420
421    if (!buffer_uptodate(bh)) {
422        ret = -EIO;
423        put_bh(bh);
424        mlog_errno(ret);
425    }
426
427out:
428    return ret;
429}
430

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