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[/] [test_project/] [trunk/] [linux_sd_driver/] [fs/] [fs-writeback.c] - Blame information for rev 62

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1 62 marcus.erl
/*
2
 * fs/fs-writeback.c
3
 *
4
 * Copyright (C) 2002, Linus Torvalds.
5
 *
6
 * Contains all the functions related to writing back and waiting
7
 * upon dirty inodes against superblocks, and writing back dirty
8
 * pages against inodes.  ie: data writeback.  Writeout of the
9
 * inode itself is not handled here.
10
 *
11
 * 10Apr2002    akpm@zip.com.au
12
 *              Split out of fs/inode.c
13
 *              Additions for address_space-based writeback
14
 */
15
 
16
#include <linux/kernel.h>
17
#include <linux/module.h>
18
#include <linux/spinlock.h>
19
#include <linux/sched.h>
20
#include <linux/fs.h>
21
#include <linux/mm.h>
22
#include <linux/writeback.h>
23
#include <linux/blkdev.h>
24
#include <linux/backing-dev.h>
25
#include <linux/buffer_head.h>
26
#include "internal.h"
27
 
28
/**
29
 *      __mark_inode_dirty -    internal function
30
 *      @inode: inode to mark
31
 *      @flags: what kind of dirty (i.e. I_DIRTY_SYNC)
32
 *      Mark an inode as dirty. Callers should use mark_inode_dirty or
33
 *      mark_inode_dirty_sync.
34
 *
35
 * Put the inode on the super block's dirty list.
36
 *
37
 * CAREFUL! We mark it dirty unconditionally, but move it onto the
38
 * dirty list only if it is hashed or if it refers to a blockdev.
39
 * If it was not hashed, it will never be added to the dirty list
40
 * even if it is later hashed, as it will have been marked dirty already.
41
 *
42
 * In short, make sure you hash any inodes _before_ you start marking
43
 * them dirty.
44
 *
45
 * This function *must* be atomic for the I_DIRTY_PAGES case -
46
 * set_page_dirty() is called under spinlock in several places.
47
 *
48
 * Note that for blockdevs, inode->dirtied_when represents the dirtying time of
49
 * the block-special inode (/dev/hda1) itself.  And the ->dirtied_when field of
50
 * the kernel-internal blockdev inode represents the dirtying time of the
51
 * blockdev's pages.  This is why for I_DIRTY_PAGES we always use
52
 * page->mapping->host, so the page-dirtying time is recorded in the internal
53
 * blockdev inode.
54
 */
55
void __mark_inode_dirty(struct inode *inode, int flags)
56
{
57
        struct super_block *sb = inode->i_sb;
58
 
59
        /*
60
         * Don't do this for I_DIRTY_PAGES - that doesn't actually
61
         * dirty the inode itself
62
         */
63
        if (flags & (I_DIRTY_SYNC | I_DIRTY_DATASYNC)) {
64
                if (sb->s_op->dirty_inode)
65
                        sb->s_op->dirty_inode(inode);
66
        }
67
 
68
        /*
69
         * make sure that changes are seen by all cpus before we test i_state
70
         * -- mikulas
71
         */
72
        smp_mb();
73
 
74
        /* avoid the locking if we can */
75
        if ((inode->i_state & flags) == flags)
76
                return;
77
 
78
        if (unlikely(block_dump)) {
79
                struct dentry *dentry = NULL;
80
                const char *name = "?";
81
 
82
                if (!list_empty(&inode->i_dentry)) {
83
                        dentry = list_entry(inode->i_dentry.next,
84
                                            struct dentry, d_alias);
85
                        if (dentry && dentry->d_name.name)
86
                                name = (const char *) dentry->d_name.name;
87
                }
88
 
89
                if (inode->i_ino || strcmp(inode->i_sb->s_id, "bdev"))
90
                        printk(KERN_DEBUG
91
                               "%s(%d): dirtied inode %lu (%s) on %s\n",
92
                               current->comm, task_pid_nr(current), inode->i_ino,
93
                               name, inode->i_sb->s_id);
94
        }
95
 
96
        spin_lock(&inode_lock);
97
        if ((inode->i_state & flags) != flags) {
98
                const int was_dirty = inode->i_state & I_DIRTY;
99
 
100
                inode->i_state |= flags;
101
 
102
                /*
103
                 * If the inode is being synced, just update its dirty state.
104
                 * The unlocker will place the inode on the appropriate
105
                 * superblock list, based upon its state.
106
                 */
107
                if (inode->i_state & I_SYNC)
108
                        goto out;
109
 
110
                /*
111
                 * Only add valid (hashed) inodes to the superblock's
112
                 * dirty list.  Add blockdev inodes as well.
113
                 */
114
                if (!S_ISBLK(inode->i_mode)) {
115
                        if (hlist_unhashed(&inode->i_hash))
116
                                goto out;
117
                }
118
                if (inode->i_state & (I_FREEING|I_CLEAR))
119
                        goto out;
120
 
121
                /*
122
                 * If the inode was already on s_dirty/s_io/s_more_io, don't
123
                 * reposition it (that would break s_dirty time-ordering).
124
                 */
125
                if (!was_dirty) {
126
                        inode->dirtied_when = jiffies;
127
                        list_move(&inode->i_list, &sb->s_dirty);
128
                }
129
        }
130
out:
131
        spin_unlock(&inode_lock);
132
}
133
 
134
EXPORT_SYMBOL(__mark_inode_dirty);
135
 
136
static int write_inode(struct inode *inode, int sync)
137
{
138
        if (inode->i_sb->s_op->write_inode && !is_bad_inode(inode))
139
                return inode->i_sb->s_op->write_inode(inode, sync);
140
        return 0;
141
}
142
 
143
/*
144
 * Redirty an inode: set its when-it-was dirtied timestamp and move it to the
145
 * furthest end of its superblock's dirty-inode list.
146
 *
147
 * Before stamping the inode's ->dirtied_when, we check to see whether it is
148
 * already the most-recently-dirtied inode on the s_dirty list.  If that is
149
 * the case then the inode must have been redirtied while it was being written
150
 * out and we don't reset its dirtied_when.
151
 */
152
static void redirty_tail(struct inode *inode)
153
{
154
        struct super_block *sb = inode->i_sb;
155
 
156
        if (!list_empty(&sb->s_dirty)) {
157
                struct inode *tail_inode;
158
 
159
                tail_inode = list_entry(sb->s_dirty.next, struct inode, i_list);
160
                if (!time_after_eq(inode->dirtied_when,
161
                                tail_inode->dirtied_when))
162
                        inode->dirtied_when = jiffies;
163
        }
164
        list_move(&inode->i_list, &sb->s_dirty);
165
}
166
 
167
/*
168
 * requeue inode for re-scanning after sb->s_io list is exhausted.
169
 */
170
static void requeue_io(struct inode *inode)
171
{
172
        list_move(&inode->i_list, &inode->i_sb->s_more_io);
173
}
174
 
175
static void inode_sync_complete(struct inode *inode)
176
{
177
        /*
178
         * Prevent speculative execution through spin_unlock(&inode_lock);
179
         */
180
        smp_mb();
181
        wake_up_bit(&inode->i_state, __I_SYNC);
182
}
183
 
184
/*
185
 * Move expired dirty inodes from @delaying_queue to @dispatch_queue.
186
 */
187
static void move_expired_inodes(struct list_head *delaying_queue,
188
                               struct list_head *dispatch_queue,
189
                                unsigned long *older_than_this)
190
{
191
        while (!list_empty(delaying_queue)) {
192
                struct inode *inode = list_entry(delaying_queue->prev,
193
                                                struct inode, i_list);
194
                if (older_than_this &&
195
                        time_after(inode->dirtied_when, *older_than_this))
196
                        break;
197
                list_move(&inode->i_list, dispatch_queue);
198
        }
199
}
200
 
201
/*
202
 * Queue all expired dirty inodes for io, eldest first.
203
 */
204
static void queue_io(struct super_block *sb,
205
                                unsigned long *older_than_this)
206
{
207
        list_splice_init(&sb->s_more_io, sb->s_io.prev);
208
        move_expired_inodes(&sb->s_dirty, &sb->s_io, older_than_this);
209
}
210
 
211
int sb_has_dirty_inodes(struct super_block *sb)
212
{
213
        return !list_empty(&sb->s_dirty) ||
214
               !list_empty(&sb->s_io) ||
215
               !list_empty(&sb->s_more_io);
216
}
217
EXPORT_SYMBOL(sb_has_dirty_inodes);
218
 
219
/*
220
 * Write a single inode's dirty pages and inode data out to disk.
221
 * If `wait' is set, wait on the writeout.
222
 *
223
 * The whole writeout design is quite complex and fragile.  We want to avoid
224
 * starvation of particular inodes when others are being redirtied, prevent
225
 * livelocks, etc.
226
 *
227
 * Called under inode_lock.
228
 */
229
static int
230
__sync_single_inode(struct inode *inode, struct writeback_control *wbc)
231
{
232
        unsigned dirty;
233
        struct address_space *mapping = inode->i_mapping;
234
        int wait = wbc->sync_mode == WB_SYNC_ALL;
235
        int ret;
236
 
237
        BUG_ON(inode->i_state & I_SYNC);
238
 
239
        /* Set I_SYNC, reset I_DIRTY */
240
        dirty = inode->i_state & I_DIRTY;
241
        inode->i_state |= I_SYNC;
242
        inode->i_state &= ~I_DIRTY;
243
 
244
        spin_unlock(&inode_lock);
245
 
246
        ret = do_writepages(mapping, wbc);
247
 
248
        /* Don't write the inode if only I_DIRTY_PAGES was set */
249
        if (dirty & (I_DIRTY_SYNC | I_DIRTY_DATASYNC)) {
250
                int err = write_inode(inode, wait);
251
                if (ret == 0)
252
                        ret = err;
253
        }
254
 
255
        if (wait) {
256
                int err = filemap_fdatawait(mapping);
257
                if (ret == 0)
258
                        ret = err;
259
        }
260
 
261
        spin_lock(&inode_lock);
262
        inode->i_state &= ~I_SYNC;
263
        if (!(inode->i_state & I_FREEING)) {
264
                if (!(inode->i_state & I_DIRTY) &&
265
                    mapping_tagged(mapping, PAGECACHE_TAG_DIRTY)) {
266
                        /*
267
                         * We didn't write back all the pages.  nfs_writepages()
268
                         * sometimes bales out without doing anything. Redirty
269
                         * the inode; Move it from s_io onto s_more_io/s_dirty.
270
                         */
271
                        /*
272
                         * akpm: if the caller was the kupdate function we put
273
                         * this inode at the head of s_dirty so it gets first
274
                         * consideration.  Otherwise, move it to the tail, for
275
                         * the reasons described there.  I'm not really sure
276
                         * how much sense this makes.  Presumably I had a good
277
                         * reasons for doing it this way, and I'd rather not
278
                         * muck with it at present.
279
                         */
280
                        if (wbc->for_kupdate) {
281
                                /*
282
                                 * For the kupdate function we move the inode
283
                                 * to s_more_io so it will get more writeout as
284
                                 * soon as the queue becomes uncongested.
285
                                 */
286
                                inode->i_state |= I_DIRTY_PAGES;
287
                                requeue_io(inode);
288
                        } else {
289
                                /*
290
                                 * Otherwise fully redirty the inode so that
291
                                 * other inodes on this superblock will get some
292
                                 * writeout.  Otherwise heavy writing to one
293
                                 * file would indefinitely suspend writeout of
294
                                 * all the other files.
295
                                 */
296
                                inode->i_state |= I_DIRTY_PAGES;
297
                                redirty_tail(inode);
298
                        }
299
                } else if (inode->i_state & I_DIRTY) {
300
                        /*
301
                         * Someone redirtied the inode while were writing back
302
                         * the pages.
303
                         */
304
                        redirty_tail(inode);
305
                } else if (atomic_read(&inode->i_count)) {
306
                        /*
307
                         * The inode is clean, inuse
308
                         */
309
                        list_move(&inode->i_list, &inode_in_use);
310
                } else {
311
                        /*
312
                         * The inode is clean, unused
313
                         */
314
                        list_move(&inode->i_list, &inode_unused);
315
                }
316
        }
317
        inode_sync_complete(inode);
318
        return ret;
319
}
320
 
321
/*
322
 * Write out an inode's dirty pages.  Called under inode_lock.  Either the
323
 * caller has ref on the inode (either via __iget or via syscall against an fd)
324
 * or the inode has I_WILL_FREE set (via generic_forget_inode)
325
 */
326
static int
327
__writeback_single_inode(struct inode *inode, struct writeback_control *wbc)
328
{
329
        wait_queue_head_t *wqh;
330
 
331
        if (!atomic_read(&inode->i_count))
332
                WARN_ON(!(inode->i_state & (I_WILL_FREE|I_FREEING)));
333
        else
334
                WARN_ON(inode->i_state & I_WILL_FREE);
335
 
336
        if ((wbc->sync_mode != WB_SYNC_ALL) && (inode->i_state & I_SYNC)) {
337
                struct address_space *mapping = inode->i_mapping;
338
                int ret;
339
 
340
                /*
341
                 * We're skipping this inode because it's locked, and we're not
342
                 * doing writeback-for-data-integrity.  Move it to s_more_io so
343
                 * that writeback can proceed with the other inodes on s_io.
344
                 * We'll have another go at writing back this inode when we
345
                 * completed a full scan of s_io.
346
                 */
347
                requeue_io(inode);
348
 
349
                /*
350
                 * Even if we don't actually write the inode itself here,
351
                 * we can at least start some of the data writeout..
352
                 */
353
                spin_unlock(&inode_lock);
354
                ret = do_writepages(mapping, wbc);
355
                spin_lock(&inode_lock);
356
                return ret;
357
        }
358
 
359
        /*
360
         * It's a data-integrity sync.  We must wait.
361
         */
362
        if (inode->i_state & I_SYNC) {
363
                DEFINE_WAIT_BIT(wq, &inode->i_state, __I_SYNC);
364
 
365
                wqh = bit_waitqueue(&inode->i_state, __I_SYNC);
366
                do {
367
                        spin_unlock(&inode_lock);
368
                        __wait_on_bit(wqh, &wq, inode_wait,
369
                                                        TASK_UNINTERRUPTIBLE);
370
                        spin_lock(&inode_lock);
371
                } while (inode->i_state & I_SYNC);
372
        }
373
        return __sync_single_inode(inode, wbc);
374
}
375
 
376
/*
377
 * Write out a superblock's list of dirty inodes.  A wait will be performed
378
 * upon no inodes, all inodes or the final one, depending upon sync_mode.
379
 *
380
 * If older_than_this is non-NULL, then only write out inodes which
381
 * had their first dirtying at a time earlier than *older_than_this.
382
 *
383
 * If we're a pdlfush thread, then implement pdflush collision avoidance
384
 * against the entire list.
385
 *
386
 * WB_SYNC_HOLD is a hack for sys_sync(): reattach the inode to sb->s_dirty so
387
 * that it can be located for waiting on in __writeback_single_inode().
388
 *
389
 * Called under inode_lock.
390
 *
391
 * If `bdi' is non-zero then we're being asked to writeback a specific queue.
392
 * This function assumes that the blockdev superblock's inodes are backed by
393
 * a variety of queues, so all inodes are searched.  For other superblocks,
394
 * assume that all inodes are backed by the same queue.
395
 *
396
 * FIXME: this linear search could get expensive with many fileystems.  But
397
 * how to fix?  We need to go from an address_space to all inodes which share
398
 * a queue with that address_space.  (Easy: have a global "dirty superblocks"
399
 * list).
400
 *
401
 * The inodes to be written are parked on sb->s_io.  They are moved back onto
402
 * sb->s_dirty as they are selected for writing.  This way, none can be missed
403
 * on the writer throttling path, and we get decent balancing between many
404
 * throttled threads: we don't want them all piling up on inode_sync_wait.
405
 */
406
static void
407
sync_sb_inodes(struct super_block *sb, struct writeback_control *wbc)
408
{
409
        const unsigned long start = jiffies;    /* livelock avoidance */
410
 
411
        if (!wbc->for_kupdate || list_empty(&sb->s_io))
412
                queue_io(sb, wbc->older_than_this);
413
 
414
        while (!list_empty(&sb->s_io)) {
415
                struct inode *inode = list_entry(sb->s_io.prev,
416
                                                struct inode, i_list);
417
                struct address_space *mapping = inode->i_mapping;
418
                struct backing_dev_info *bdi = mapping->backing_dev_info;
419
                long pages_skipped;
420
 
421
                if (!bdi_cap_writeback_dirty(bdi)) {
422
                        redirty_tail(inode);
423
                        if (sb_is_blkdev_sb(sb)) {
424
                                /*
425
                                 * Dirty memory-backed blockdev: the ramdisk
426
                                 * driver does this.  Skip just this inode
427
                                 */
428
                                continue;
429
                        }
430
                        /*
431
                         * Dirty memory-backed inode against a filesystem other
432
                         * than the kernel-internal bdev filesystem.  Skip the
433
                         * entire superblock.
434
                         */
435
                        break;
436
                }
437
 
438
                if (wbc->nonblocking && bdi_write_congested(bdi)) {
439
                        wbc->encountered_congestion = 1;
440
                        if (!sb_is_blkdev_sb(sb))
441
                                break;          /* Skip a congested fs */
442
                        requeue_io(inode);
443
                        continue;               /* Skip a congested blockdev */
444
                }
445
 
446
                if (wbc->bdi && bdi != wbc->bdi) {
447
                        if (!sb_is_blkdev_sb(sb))
448
                                break;          /* fs has the wrong queue */
449
                        requeue_io(inode);
450
                        continue;               /* blockdev has wrong queue */
451
                }
452
 
453
                /* Was this inode dirtied after sync_sb_inodes was called? */
454
                if (time_after(inode->dirtied_when, start))
455
                        break;
456
 
457
                /* Is another pdflush already flushing this queue? */
458
                if (current_is_pdflush() && !writeback_acquire(bdi))
459
                        break;
460
 
461
                BUG_ON(inode->i_state & I_FREEING);
462
                __iget(inode);
463
                pages_skipped = wbc->pages_skipped;
464
                __writeback_single_inode(inode, wbc);
465
                if (wbc->sync_mode == WB_SYNC_HOLD) {
466
                        inode->dirtied_when = jiffies;
467
                        list_move(&inode->i_list, &sb->s_dirty);
468
                }
469
                if (current_is_pdflush())
470
                        writeback_release(bdi);
471
                if (wbc->pages_skipped != pages_skipped) {
472
                        /*
473
                         * writeback is not making progress due to locked
474
                         * buffers.  Skip this inode for now.
475
                         */
476
                        redirty_tail(inode);
477
                }
478
                spin_unlock(&inode_lock);
479
                iput(inode);
480
                cond_resched();
481
                spin_lock(&inode_lock);
482
                if (wbc->nr_to_write <= 0)
483
                        break;
484
        }
485
        return;         /* Leave any unwritten inodes on s_io */
486
}
487
 
488
/*
489
 * Start writeback of dirty pagecache data against all unlocked inodes.
490
 *
491
 * Note:
492
 * We don't need to grab a reference to superblock here. If it has non-empty
493
 * ->s_dirty it's hadn't been killed yet and kill_super() won't proceed
494
 * past sync_inodes_sb() until the ->s_dirty/s_io/s_more_io lists are all
495
 * empty. Since __sync_single_inode() regains inode_lock before it finally moves
496
 * inode from superblock lists we are OK.
497
 *
498
 * If `older_than_this' is non-zero then only flush inodes which have a
499
 * flushtime older than *older_than_this.
500
 *
501
 * If `bdi' is non-zero then we will scan the first inode against each
502
 * superblock until we find the matching ones.  One group will be the dirty
503
 * inodes against a filesystem.  Then when we hit the dummy blockdev superblock,
504
 * sync_sb_inodes will seekout the blockdev which matches `bdi'.  Maybe not
505
 * super-efficient but we're about to do a ton of I/O...
506
 */
507
void
508
writeback_inodes(struct writeback_control *wbc)
509
{
510
        struct super_block *sb;
511
 
512
        might_sleep();
513
        spin_lock(&sb_lock);
514
restart:
515
        sb = sb_entry(super_blocks.prev);
516
        for (; sb != sb_entry(&super_blocks); sb = sb_entry(sb->s_list.prev)) {
517
                if (sb_has_dirty_inodes(sb)) {
518
                        /* we're making our own get_super here */
519
                        sb->s_count++;
520
                        spin_unlock(&sb_lock);
521
                        /*
522
                         * If we can't get the readlock, there's no sense in
523
                         * waiting around, most of the time the FS is going to
524
                         * be unmounted by the time it is released.
525
                         */
526
                        if (down_read_trylock(&sb->s_umount)) {
527
                                if (sb->s_root) {
528
                                        spin_lock(&inode_lock);
529
                                        sync_sb_inodes(sb, wbc);
530
                                        spin_unlock(&inode_lock);
531
                                }
532
                                up_read(&sb->s_umount);
533
                        }
534
                        spin_lock(&sb_lock);
535
                        if (__put_super_and_need_restart(sb))
536
                                goto restart;
537
                }
538
                if (wbc->nr_to_write <= 0)
539
                        break;
540
        }
541
        spin_unlock(&sb_lock);
542
}
543
 
544
/*
545
 * writeback and wait upon the filesystem's dirty inodes.  The caller will
546
 * do this in two passes - one to write, and one to wait.  WB_SYNC_HOLD is
547
 * used to park the written inodes on sb->s_dirty for the wait pass.
548
 *
549
 * A finite limit is set on the number of pages which will be written.
550
 * To prevent infinite livelock of sys_sync().
551
 *
552
 * We add in the number of potentially dirty inodes, because each inode write
553
 * can dirty pagecache in the underlying blockdev.
554
 */
555
void sync_inodes_sb(struct super_block *sb, int wait)
556
{
557
        struct writeback_control wbc = {
558
                .sync_mode      = wait ? WB_SYNC_ALL : WB_SYNC_HOLD,
559
                .range_start    = 0,
560
                .range_end      = LLONG_MAX,
561
        };
562
        unsigned long nr_dirty = global_page_state(NR_FILE_DIRTY);
563
        unsigned long nr_unstable = global_page_state(NR_UNSTABLE_NFS);
564
 
565
        wbc.nr_to_write = nr_dirty + nr_unstable +
566
                        (inodes_stat.nr_inodes - inodes_stat.nr_unused) +
567
                        nr_dirty + nr_unstable;
568
        wbc.nr_to_write += wbc.nr_to_write / 2;         /* Bit more for luck */
569
        spin_lock(&inode_lock);
570
        sync_sb_inodes(sb, &wbc);
571
        spin_unlock(&inode_lock);
572
}
573
 
574
/*
575
 * Rather lame livelock avoidance.
576
 */
577
static void set_sb_syncing(int val)
578
{
579
        struct super_block *sb;
580
        spin_lock(&sb_lock);
581
        sb = sb_entry(super_blocks.prev);
582
        for (; sb != sb_entry(&super_blocks); sb = sb_entry(sb->s_list.prev)) {
583
                sb->s_syncing = val;
584
        }
585
        spin_unlock(&sb_lock);
586
}
587
 
588
/**
589
 * sync_inodes - writes all inodes to disk
590
 * @wait: wait for completion
591
 *
592
 * sync_inodes() goes through each super block's dirty inode list, writes the
593
 * inodes out, waits on the writeout and puts the inodes back on the normal
594
 * list.
595
 *
596
 * This is for sys_sync().  fsync_dev() uses the same algorithm.  The subtle
597
 * part of the sync functions is that the blockdev "superblock" is processed
598
 * last.  This is because the write_inode() function of a typical fs will
599
 * perform no I/O, but will mark buffers in the blockdev mapping as dirty.
600
 * What we want to do is to perform all that dirtying first, and then write
601
 * back all those inode blocks via the blockdev mapping in one sweep.  So the
602
 * additional (somewhat redundant) sync_blockdev() calls here are to make
603
 * sure that really happens.  Because if we call sync_inodes_sb(wait=1) with
604
 * outstanding dirty inodes, the writeback goes block-at-a-time within the
605
 * filesystem's write_inode().  This is extremely slow.
606
 */
607
static void __sync_inodes(int wait)
608
{
609
        struct super_block *sb;
610
 
611
        spin_lock(&sb_lock);
612
restart:
613
        list_for_each_entry(sb, &super_blocks, s_list) {
614
                if (sb->s_syncing)
615
                        continue;
616
                sb->s_syncing = 1;
617
                sb->s_count++;
618
                spin_unlock(&sb_lock);
619
                down_read(&sb->s_umount);
620
                if (sb->s_root) {
621
                        sync_inodes_sb(sb, wait);
622
                        sync_blockdev(sb->s_bdev);
623
                }
624
                up_read(&sb->s_umount);
625
                spin_lock(&sb_lock);
626
                if (__put_super_and_need_restart(sb))
627
                        goto restart;
628
        }
629
        spin_unlock(&sb_lock);
630
}
631
 
632
void sync_inodes(int wait)
633
{
634
        set_sb_syncing(0);
635
        __sync_inodes(0);
636
 
637
        if (wait) {
638
                set_sb_syncing(0);
639
                __sync_inodes(1);
640
        }
641
}
642
 
643
/**
644
 * write_inode_now      -       write an inode to disk
645
 * @inode: inode to write to disk
646
 * @sync: whether the write should be synchronous or not
647
 *
648
 * This function commits an inode to disk immediately if it is dirty. This is
649
 * primarily needed by knfsd.
650
 *
651
 * The caller must either have a ref on the inode or must have set I_WILL_FREE.
652
 */
653
int write_inode_now(struct inode *inode, int sync)
654
{
655
        int ret;
656
        struct writeback_control wbc = {
657
                .nr_to_write = LONG_MAX,
658
                .sync_mode = WB_SYNC_ALL,
659
                .range_start = 0,
660
                .range_end = LLONG_MAX,
661
        };
662
 
663
        if (!mapping_cap_writeback_dirty(inode->i_mapping))
664
                wbc.nr_to_write = 0;
665
 
666
        might_sleep();
667
        spin_lock(&inode_lock);
668
        ret = __writeback_single_inode(inode, &wbc);
669
        spin_unlock(&inode_lock);
670
        if (sync)
671
                inode_sync_wait(inode);
672
        return ret;
673
}
674
EXPORT_SYMBOL(write_inode_now);
675
 
676
/**
677
 * sync_inode - write an inode and its pages to disk.
678
 * @inode: the inode to sync
679
 * @wbc: controls the writeback mode
680
 *
681
 * sync_inode() will write an inode and its pages to disk.  It will also
682
 * correctly update the inode on its superblock's dirty inode lists and will
683
 * update inode->i_state.
684
 *
685
 * The caller must have a ref on the inode.
686
 */
687
int sync_inode(struct inode *inode, struct writeback_control *wbc)
688
{
689
        int ret;
690
 
691
        spin_lock(&inode_lock);
692
        ret = __writeback_single_inode(inode, wbc);
693
        spin_unlock(&inode_lock);
694
        return ret;
695
}
696
EXPORT_SYMBOL(sync_inode);
697
 
698
/**
699
 * generic_osync_inode - flush all dirty data for a given inode to disk
700
 * @inode: inode to write
701
 * @mapping: the address_space that should be flushed
702
 * @what:  what to write and wait upon
703
 *
704
 * This can be called by file_write functions for files which have the
705
 * O_SYNC flag set, to flush dirty writes to disk.
706
 *
707
 * @what is a bitmask, specifying which part of the inode's data should be
708
 * written and waited upon.
709
 *
710
 *    OSYNC_DATA:     i_mapping's dirty data
711
 *    OSYNC_METADATA: the buffers at i_mapping->private_list
712
 *    OSYNC_INODE:    the inode itself
713
 */
714
 
715
int generic_osync_inode(struct inode *inode, struct address_space *mapping, int what)
716
{
717
        int err = 0;
718
        int need_write_inode_now = 0;
719
        int err2;
720
 
721
        if (what & OSYNC_DATA)
722
                err = filemap_fdatawrite(mapping);
723
        if (what & (OSYNC_METADATA|OSYNC_DATA)) {
724
                err2 = sync_mapping_buffers(mapping);
725
                if (!err)
726
                        err = err2;
727
        }
728
        if (what & OSYNC_DATA) {
729
                err2 = filemap_fdatawait(mapping);
730
                if (!err)
731
                        err = err2;
732
        }
733
 
734
        spin_lock(&inode_lock);
735
        if ((inode->i_state & I_DIRTY) &&
736
            ((what & OSYNC_INODE) || (inode->i_state & I_DIRTY_DATASYNC)))
737
                need_write_inode_now = 1;
738
        spin_unlock(&inode_lock);
739
 
740
        if (need_write_inode_now) {
741
                err2 = write_inode_now(inode, 1);
742
                if (!err)
743
                        err = err2;
744
        }
745
        else
746
                inode_sync_wait(inode);
747
 
748
        return err;
749
}
750
 
751
EXPORT_SYMBOL(generic_osync_inode);
752
 
753
/**
754
 * writeback_acquire: attempt to get exclusive writeback access to a device
755
 * @bdi: the device's backing_dev_info structure
756
 *
757
 * It is a waste of resources to have more than one pdflush thread blocked on
758
 * a single request queue.  Exclusion at the request_queue level is obtained
759
 * via a flag in the request_queue's backing_dev_info.state.
760
 *
761
 * Non-request_queue-backed address_spaces will share default_backing_dev_info,
762
 * unless they implement their own.  Which is somewhat inefficient, as this
763
 * may prevent concurrent writeback against multiple devices.
764
 */
765
int writeback_acquire(struct backing_dev_info *bdi)
766
{
767
        return !test_and_set_bit(BDI_pdflush, &bdi->state);
768
}
769
 
770
/**
771
 * writeback_in_progress: determine whether there is writeback in progress
772
 * @bdi: the device's backing_dev_info structure.
773
 *
774
 * Determine whether there is writeback in progress against a backing device.
775
 */
776
int writeback_in_progress(struct backing_dev_info *bdi)
777
{
778
        return test_bit(BDI_pdflush, &bdi->state);
779
}
780
 
781
/**
782
 * writeback_release: relinquish exclusive writeback access against a device.
783
 * @bdi: the device's backing_dev_info structure
784
 */
785
void writeback_release(struct backing_dev_info *bdi)
786
{
787
        BUG_ON(!writeback_in_progress(bdi));
788
        clear_bit(BDI_pdflush, &bdi->state);
789
}

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