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| author | Wu Fengguang <fengguang.wu@intel.com> | 2009-06-17 02:33:17 +0400 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-06-17 06:47:45 +0400 |
| commit | 84a892456046921a40646114deed65e2df93a1bc (patch) | |
| tree | 2639b6031e55988b8780960c023618c381d61c55 /fs/fs-writeback.c | |
| parent | 81236810226f71bd9ff77321c8e8276dae7efc61 (diff) | |
| download | linux-84a892456046921a40646114deed65e2df93a1bc.tar.xz | |
writeback: skip new or to-be-freed inodes
1) I_FREEING tests should be coupled with I_CLEAR
The two I_FREEING tests are racy because clear_inode() can set i_state to
I_CLEAR between the clear of I_SYNC and the test of I_FREEING.
2) skip I_WILL_FREE inodes in generic_sync_sb_inodes() to avoid possible
races with generic_forget_inode()
generic_forget_inode() sets I_WILL_FREE call writeback on its own, so
generic_sync_sb_inodes() shall not try to step in and create possible races:
generic_forget_inode
inode->i_state |= I_WILL_FREE;
spin_unlock(&inode_lock);
generic_sync_sb_inodes()
spin_lock(&inode_lock);
__iget(inode);
__writeback_single_inode
// see non zero i_count
may WARN here ==> WARN_ON(inode->i_state & I_WILL_FREE);
spin_unlock(&inode_lock);
may call generic_forget_inode again ==> iput(inode);
The above race and warning didn't turn up because writeback_inodes() holds
the s_umount lock, so generic_forget_inode() finds MS_ACTIVE and returns
early. But we are not sure the UBIFS calls and future callers will
guarantee that. So skip I_WILL_FREE inodes for the sake of safety.
Cc: Eric Sandeen <sandeen@sandeen.net>
Acked-by: Jeff Layton <jlayton@redhat.com>
Cc: Masayoshi MIZUMA <m.mizuma@jp.fujitsu.com>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Cc: Artem Bityutskiy <dedekind1@gmail.com>
Cc: Christoph Hellwig <hch@infradead.org>
Acked-by: Jan Kara <jack@suse.cz>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/fs-writeback.c')
| -rw-r--r-- | fs/fs-writeback.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c index 40308e98c6a4..caf049146ca2 100644 --- a/fs/fs-writeback.c +++ b/fs/fs-writeback.c @@ -321,7 +321,7 @@ __sync_single_inode(struct inode *inode, struct writeback_control *wbc) spin_lock(&inode_lock); inode->i_state &= ~I_SYNC; - if (!(inode->i_state & I_FREEING)) { + if (!(inode->i_state & (I_FREEING | I_CLEAR))) { if (!(inode->i_state & I_DIRTY) && mapping_tagged(mapping, PAGECACHE_TAG_DIRTY)) { /* @@ -492,7 +492,7 @@ void generic_sync_sb_inodes(struct super_block *sb, break; } - if (inode->i_state & I_NEW) { + if (inode->i_state & (I_NEW | I_WILL_FREE)) { requeue_io(inode); continue; } @@ -523,7 +523,7 @@ void generic_sync_sb_inodes(struct super_block *sb, if (current_is_pdflush() && !writeback_acquire(bdi)) break; - BUG_ON(inode->i_state & I_FREEING); + BUG_ON(inode->i_state & (I_FREEING | I_CLEAR)); __iget(inode); pages_skipped = wbc->pages_skipped; __writeback_single_inode(inode, wbc); |