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authorRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>2015-02-05 23:25:20 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2015-02-06 00:35:29 +0300
commit7ef3ff2fea8bf5e4a21cef47ad87710a3d0fdb52 (patch)
treefae90c5009ed6bf5009cedf9646c0a4edd71304c /fs/nilfs2/nilfs.h
parent81cca6fb1271b91f06b008976ea132bec2f14d86 (diff)
downloadlinux-7ef3ff2fea8bf5e4a21cef47ad87710a3d0fdb52.tar.xz
nilfs2: fix deadlock of segment constructor over I_SYNC flag
Nilfs2 eventually hangs in a stress test with fsstress program. This issue was caused by the following deadlock over I_SYNC flag between nilfs_segctor_thread() and writeback_sb_inodes(): nilfs_segctor_thread() nilfs_segctor_thread_construct() nilfs_segctor_unlock() nilfs_dispose_list() iput() iput_final() evict() inode_wait_for_writeback() * wait for I_SYNC flag writeback_sb_inodes() * set I_SYNC flag on inode->i_state __writeback_single_inode() do_writepages() nilfs_writepages() nilfs_construct_dsync_segment() nilfs_segctor_sync() * wait for completion of segment constructor inode_sync_complete() * clear I_SYNC flag after __writeback_single_inode() completed writeback_sb_inodes() calls do_writepages() for dirty inodes after setting I_SYNC flag on inode->i_state. do_writepages() in turn calls nilfs_writepages(), which can run segment constructor and wait for its completion. On the other hand, segment constructor calls iput(), which can call evict() and wait for the I_SYNC flag on inode_wait_for_writeback(). Since segment constructor doesn't know when I_SYNC will be set, it cannot know whether iput() will block or not unless inode->i_nlink has a non-zero count. We can prevent evict() from being called in iput() by implementing sop->drop_inode(), but it's not preferable to leave inodes with i_nlink == 0 for long periods because it even defers file truncation and inode deallocation. So, this instead resolves the deadlock by calling iput() asynchronously with a workqueue for inodes with i_nlink == 0. Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp> Cc: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/nilfs2/nilfs.h')
-rw-r--r--fs/nilfs2/nilfs.h2
1 files changed, 0 insertions, 2 deletions
diff --git a/fs/nilfs2/nilfs.h b/fs/nilfs2/nilfs.h
index 91093cd74f0d..385704027575 100644
--- a/fs/nilfs2/nilfs.h
+++ b/fs/nilfs2/nilfs.h
@@ -141,7 +141,6 @@ enum {
* @ti_save: Backup of journal_info field of task_struct
* @ti_flags: Flags
* @ti_count: Nest level
- * @ti_garbage: List of inode to be put when releasing semaphore
*/
struct nilfs_transaction_info {
u32 ti_magic;
@@ -150,7 +149,6 @@ struct nilfs_transaction_info {
one of other filesystems has a bug. */
unsigned short ti_flags;
unsigned short ti_count;
- struct list_head ti_garbage;
};
/* ti_magic */