diff options
authorWu Fengguang <fengguang.wu@intel.com>2009-06-16 15:33:17 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2009-06-16 19:47:45 -0700
commit84a892456046921a40646114deed65e2df93a1bc (patch)
parent81236810226f71bd9ff77321c8e8276dae7efc61 (diff)
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>
1 files changed, 3 insertions, 3 deletions
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 40308e98c6a..caf049146ca 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)
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,
- if (inode->i_state & I_NEW) {
+ if (inode->i_state & (I_NEW | I_WILL_FREE)) {
@@ -523,7 +523,7 @@ void generic_sync_sb_inodes(struct super_block *sb,
if (current_is_pdflush() && !writeback_acquire(bdi))
- BUG_ON(inode->i_state & I_FREEING);
+ BUG_ON(inode->i_state & (I_FREEING | I_CLEAR));
pages_skipped = wbc->pages_skipped;
__writeback_single_inode(inode, wbc);