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| author | Tao Ma <boyu.mt@taobao.com> | 2011-10-30 18:26:08 -0400 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2011-10-30 18:26:08 -0400 |
| commit | d73d5046a72467d4510825b99e2269e09ad80e15 (patch) | |
| tree | 4ac8b5729e1aeffe8348557a7f77da1791c268cc | |
| parent | 6d6a435190bdf2e04c9465cde5bdc3ac68cf11a4 (diff) | |
| download | linux-d73d5046a72467d4510825b99e2269e09ad80e15.tar.gz linux-d73d5046a72467d4510825b99e2269e09ad80e15.tar.bz2 linux-d73d5046a72467d4510825b99e2269e09ad80e15.zip | |
ext4: Use correct locking for ext4_end_io_nolock()
We must hold i_completed_io_lock when manipulating anything on the
i_completed_io_list linked list. This includes io->lock, which we
were checking in ext4_end_io_nolock().
So move this check to ext4_end_io_work(). This also has the bonus of
avoiding extra work if it is already done without needing to take the
mutex.
Signed-off-by: Tao Ma <boyu.mt@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
| -rw-r--r-- | fs/ext4/fsync.c | 3 | ||||
| -rw-r--r-- | fs/ext4/page-io.c | 14 |
2 files changed, 11 insertions, 6 deletions
diff --git a/fs/ext4/fsync.c b/fs/ext4/fsync.c index c942924a0645..851ac5b3cec9 100644 --- a/fs/ext4/fsync.c +++ b/fs/ext4/fsync.c @@ -83,9 +83,6 @@ int ext4_flush_completed_IO(struct inode *inode) int ret = 0; int ret2 = 0; - if (list_empty(&ei->i_completed_io_list)) - return ret; - dump_completed_IO(inode); spin_lock_irqsave(&ei->i_completed_io_lock, flags); while (!list_empty(&ei->i_completed_io_list)){ diff --git a/fs/ext4/page-io.c b/fs/ext4/page-io.c index 92f38ee13f8a..aed40966f342 100644 --- a/fs/ext4/page-io.c +++ b/fs/ext4/page-io.c @@ -87,6 +87,9 @@ void ext4_free_io_end(ext4_io_end_t *io) /* * check a range of space and convert unwritten extents to written. + * + * Called with inode->i_mutex; we depend on this when we manipulate + * io->flag, since we could otherwise race with ext4_flush_completed_IO() */ int ext4_end_io_nolock(ext4_io_end_t *io) { @@ -100,9 +103,6 @@ int ext4_end_io_nolock(ext4_io_end_t *io) "list->prev 0x%p\n", io, inode->i_ino, io->list.next, io->list.prev); - if (list_empty(&io->list)) - return ret; - if (!(io->flag & EXT4_IO_END_UNWRITTEN)) return ret; @@ -142,6 +142,13 @@ static void ext4_end_io_work(struct work_struct *work) unsigned long flags; int ret; + spin_lock_irqsave(&ei->i_completed_io_lock, flags); + if (list_empty(&io->list)) { + spin_unlock_irqrestore(&ei->i_completed_io_lock, flags); + goto free; + } + spin_unlock_irqrestore(&ei->i_completed_io_lock, flags); + if (!mutex_trylock(&inode->i_mutex)) { /* * Requeue the work instead of waiting so that the work @@ -170,6 +177,7 @@ static void ext4_end_io_work(struct work_struct *work) list_del_init(&io->list); spin_unlock_irqrestore(&ei->i_completed_io_lock, flags); mutex_unlock(&inode->i_mutex); +free: ext4_free_io_end(io); } |