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ext4: Use correct locking for ext4_end_io_nolock()

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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>
This commit is contained in:
Tao Ma 2011-10-30 18:26:08 -04:00 committed by Theodore Ts'o
parent 6d6a435190
commit d73d5046a7
2 changed files with 11 additions and 6 deletions
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3
fs/ext4/fsync.c
View File

@ -83,9 +83,6 @@ int ext4_flush_completed_IO(struct inode *inode)
int ret = 0; int ret = 0;
int ret2 = 0; int ret2 = 0;
if (list_empty(&ei->i_completed_io_list))
return ret;
dump_completed_IO(inode); dump_completed_IO(inode);
spin_lock_irqsave(&ei->i_completed_io_lock, flags); spin_lock_irqsave(&ei->i_completed_io_lock, flags);
while (!list_empty(&ei->i_completed_io_list)){ while (!list_empty(&ei->i_completed_io_list)){

14
fs/ext4/page-io.c
View File

@ -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. * 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) 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", "list->prev 0x%p\n",
io, inode->i_ino, io->list.next, io->list.prev); io, inode->i_ino, io->list.next, io->list.prev);
if (list_empty(&io->list))
return ret;
if (!(io->flag & EXT4_IO_END_UNWRITTEN)) if (!(io->flag & EXT4_IO_END_UNWRITTEN))
return ret; return ret;
@ -142,6 +142,13 @@ static void ext4_end_io_work(struct work_struct *work)
unsigned long flags; unsigned long flags;
int ret; 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)) { if (!mutex_trylock(&inode->i_mutex)) {
/* /*
* Requeue the work instead of waiting so that the work * 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); list_del_init(&io->list);
spin_unlock_irqrestore(&ei->i_completed_io_lock, flags); spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
mutex_unlock(&inode->i_mutex); mutex_unlock(&inode->i_mutex);
free:
ext4_free_io_end(io); ext4_free_io_end(io);
} }