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authorDave Chinner <dchinner@redhat.com>2011-07-08 00:14:41 -0400
committerAl Viro <viro@zeniv.linux.org.uk>2011-07-20 01:44:38 -0400
commit12ad3ab66103e6582ca69c0c9de18b13487eaaef (patch)
tree52d1ecd11d48faa7e6f8d6600c8e76807b0985a5 /fs/fs-writeback.c
parent09cc9fc7a7c3d872065426d7fb0f0ad6d3eb90fc (diff)
superblock: move pin_sb_for_writeback() to fs/super.c
The per-sb shrinker has the same requirement as the writeback threads of ensuring that the superblock is usable and pinned for the time it takes to run the work. Both need to take a passive reference to the sb, take a read lock on the s_umount lock and then only continue if an unmount is not in progress. pin_sb_for_writeback() does this exactly, so move it to fs/super.c and rename it to grab_super_passive() and exporting it via fs/internal.h for all the VFS code to be able to use. Signed-off-by: Dave Chinner <dchinner@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs/fs-writeback.c')
-rw-r--r--fs/fs-writeback.c28
1 files changed, 1 insertions, 27 deletions
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 0f015a0468de..b8c507ca42f7 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -461,32 +461,6 @@ writeback_single_inode(struct inode *inode, struct writeback_control *wbc)
461} 461}
462 462
463/* 463/*
464 * For background writeback the caller does not have the sb pinned
465 * before calling writeback. So make sure that we do pin it, so it doesn't
466 * go away while we are writing inodes from it.
467 */
468static bool pin_sb_for_writeback(struct super_block *sb)
469{
470 spin_lock(&sb_lock);
471 if (list_empty(&sb->s_instances)) {
472 spin_unlock(&sb_lock);
473 return false;
474 }
475
476 sb->s_count++;
477 spin_unlock(&sb_lock);
478
479 if (down_read_trylock(&sb->s_umount)) {
480 if (sb->s_root)
481 return true;
482 up_read(&sb->s_umount);
483 }
484
485 put_super(sb);
486 return false;
487}
488
489/*
490 * Write a portion of b_io inodes which belong to @sb. 464 * Write a portion of b_io inodes which belong to @sb.
491 * 465 *
492 * If @only_this_sb is true, then find and write all such 466 * If @only_this_sb is true, then find and write all such
@@ -585,7 +559,7 @@ void writeback_inodes_wb(struct bdi_writeback *wb,
585 struct inode *inode = wb_inode(wb->b_io.prev); 559 struct inode *inode = wb_inode(wb->b_io.prev);
586 struct super_block *sb = inode->i_sb; 560 struct super_block *sb = inode->i_sb;
587 561
588 if (!pin_sb_for_writeback(sb)) { 562 if (!grab_super_passive(sb)) {
589 requeue_io(inode); 563 requeue_io(inode);
590 continue; 564 continue;
591 } 565 }