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authorRyan Ding <ryan.ding@oracle.com>2016-03-25 14:21:15 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2016-03-25 16:37:42 -0700
commite63890f38ade9497b5609ddeb7f52df0fe55ea15 (patch)
tree6374b96dfa45477fc53cb6033cddc5621d5936c7
parentf1f973ffce96a47c2b3f142e91eccef5bf22f699 (diff)
downloadlinux-sh-e63890f38ade9497b5609ddeb7f52df0fe55ea15.tar.gz
ocfs2: fix ip_unaligned_aio deadlock with dio work queue
In the current implementation of unaligned aio+dio, lock order behave as follow: in user process context: -> call io_submit() -> get i_mutex <== window1 -> get ip_unaligned_aio -> submit direct io to block device -> release i_mutex -> io_submit() return in dio work queue context(the work queue is created in __blockdev_direct_IO): -> release ip_unaligned_aio <== window2 -> get i_mutex -> clear unwritten flag & change i_size -> release i_mutex There is a limitation to the thread number of dio work queue. 256 at default. If all 256 thread are in the above 'window2' stage, and there is a user process in the 'window1' stage, the system will became deadlock. Since the user process hold i_mutex to wait ip_unaligned_aio lock, while there is a direct bio hold ip_unaligned_aio mutex who is waiting for a dio work queue thread to be schedule. But all the dio work queue thread is waiting for i_mutex lock in 'window2'. This case only happened in a test which send a large number(more than 256) of aio at one io_submit() call. My design is to remove ip_unaligned_aio lock. Change it to a sync io instead. Just like ip_unaligned_aio lock, serialize the unaligned aio dio. [akpm@linux-foundation.org: remove OCFS2_IOCB_UNALIGNED_IO, per Junxiao Bi] Signed-off-by: Ryan Ding <ryan.ding@oracle.com> Reviewed-by: Junxiao Bi <junxiao.bi@oracle.com> Cc: Joseph Qi <joseph.qi@huawei.com> Cc: Mark Fasheh <mfasheh@suse.de> Cc: Joel Becker <jlbec@evilplan.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--fs/ocfs2/aops.c6
-rw-r--r--fs/ocfs2/aops.h8
-rw-r--r--fs/ocfs2/file.c27
-rw-r--r--fs/ocfs2/inode.h3
-rw-r--r--fs/ocfs2/super.c1
5 files changed, 9 insertions, 36 deletions
diff --git a/fs/ocfs2/aops.c b/fs/ocfs2/aops.c
index 578ce225cf83..843475793504 100644
--- a/fs/ocfs2/aops.c
+++ b/fs/ocfs2/aops.c
@@ -2391,12 +2391,6 @@ static int ocfs2_dio_end_io(struct kiocb *iocb,
/* this io's submitter should not have unlocked this before we could */
BUG_ON(!ocfs2_iocb_is_rw_locked(iocb));
- if (ocfs2_iocb_is_unaligned_aio(iocb)) {
- ocfs2_iocb_clear_unaligned_aio(iocb);
-
- mutex_unlock(&OCFS2_I(inode)->ip_unaligned_aio);
- }
-
if (private)
ocfs2_dio_end_io_write(inode, private, offset, bytes);
diff --git a/fs/ocfs2/aops.h b/fs/ocfs2/aops.h
index d06b80f58f83..b1c9f28a57b1 100644
--- a/fs/ocfs2/aops.h
+++ b/fs/ocfs2/aops.h
@@ -84,7 +84,6 @@ static inline void ocfs2_iocb_set_rw_locked(struct kiocb *iocb, int level)
enum ocfs2_iocb_lock_bits {
OCFS2_IOCB_RW_LOCK = 0,
OCFS2_IOCB_RW_LOCK_LEVEL,
- OCFS2_IOCB_UNALIGNED_IO,
OCFS2_IOCB_NUM_LOCKS
};
@@ -93,11 +92,4 @@ enum ocfs2_iocb_lock_bits {
#define ocfs2_iocb_rw_locked_level(iocb) \
test_bit(OCFS2_IOCB_RW_LOCK_LEVEL, (unsigned long *)&iocb->private)
-#define ocfs2_iocb_set_unaligned_aio(iocb) \
- set_bit(OCFS2_IOCB_UNALIGNED_IO, (unsigned long *)&iocb->private)
-#define ocfs2_iocb_clear_unaligned_aio(iocb) \
- clear_bit(OCFS2_IOCB_UNALIGNED_IO, (unsigned long *)&iocb->private)
-#define ocfs2_iocb_is_unaligned_aio(iocb) \
- test_bit(OCFS2_IOCB_UNALIGNED_IO, (unsigned long *)&iocb->private)
-
#endif /* OCFS2_FILE_H */
diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
index 1ab182321b18..c18ab45f8d21 100644
--- a/fs/ocfs2/file.c
+++ b/fs/ocfs2/file.c
@@ -2178,7 +2178,7 @@ static ssize_t ocfs2_file_write_iter(struct kiocb *iocb,
struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
int full_coherency = !(osb->s_mount_opt &
OCFS2_MOUNT_COHERENCY_BUFFERED);
- int unaligned_dio = 0;
+ void *saved_ki_complete = NULL;
int append_write = ((iocb->ki_pos + count) >=
i_size_read(inode) ? 1 : 0);
@@ -2241,17 +2241,12 @@ static ssize_t ocfs2_file_write_iter(struct kiocb *iocb,
goto out;
}
- if (direct_io && !is_sync_kiocb(iocb))
- unaligned_dio = ocfs2_is_io_unaligned(inode, count, iocb->ki_pos);
-
- if (unaligned_dio) {
+ if (direct_io && !is_sync_kiocb(iocb) &&
+ ocfs2_is_io_unaligned(inode, count, iocb->ki_pos)) {
/*
- * Wait on previous unaligned aio to complete before
- * proceeding.
+ * Make it a sync io if it's an unaligned aio.
*/
- mutex_lock(&OCFS2_I(inode)->ip_unaligned_aio);
- /* Mark the iocb as needing an unlock in ocfs2_dio_end_io */
- ocfs2_iocb_set_unaligned_aio(iocb);
+ saved_ki_complete = xchg(&iocb->ki_complete, NULL);
}
/* communicate with ocfs2_dio_end_io */
@@ -2272,11 +2267,10 @@ static ssize_t ocfs2_file_write_iter(struct kiocb *iocb,
*/
if ((written == -EIOCBQUEUED) || (!ocfs2_iocb_is_rw_locked(iocb))) {
rw_level = -1;
- unaligned_dio = 0;
}
if (unlikely(written <= 0))
- goto no_sync;
+ goto out;
if (((file->f_flags & O_DSYNC) && !direct_io) ||
IS_SYNC(inode)) {
@@ -2298,13 +2292,10 @@ static ssize_t ocfs2_file_write_iter(struct kiocb *iocb,
iocb->ki_pos - 1);
}
-no_sync:
- if (unaligned_dio && ocfs2_iocb_is_unaligned_aio(iocb)) {
- ocfs2_iocb_clear_unaligned_aio(iocb);
- mutex_unlock(&OCFS2_I(inode)->ip_unaligned_aio);
- }
-
out:
+ if (saved_ki_complete)
+ xchg(&iocb->ki_complete, saved_ki_complete);
+
if (rw_level != -1)
ocfs2_rw_unlock(inode, rw_level);
diff --git a/fs/ocfs2/inode.h b/fs/ocfs2/inode.h
index 68e8cf9bda97..d8f3fc8d2551 100644
--- a/fs/ocfs2/inode.h
+++ b/fs/ocfs2/inode.h
@@ -43,9 +43,6 @@ struct ocfs2_inode_info
/* protects extended attribute changes on this inode */
struct rw_semaphore ip_xattr_sem;
- /* Number of outstanding AIO's which are not page aligned */
- struct mutex ip_unaligned_aio;
-
/* These fields are protected by ip_lock */
spinlock_t ip_lock;
u32 ip_open_count;
diff --git a/fs/ocfs2/super.c b/fs/ocfs2/super.c
index d142fb75740e..e2c4e3839d7b 100644
--- a/fs/ocfs2/super.c
+++ b/fs/ocfs2/super.c
@@ -1747,7 +1747,6 @@ static void ocfs2_inode_init_once(void *data)
INIT_LIST_HEAD(&oi->ip_io_markers);
INIT_LIST_HEAD(&oi->ip_unwritten_list);
oi->ip_dir_start_lookup = 0;
- mutex_init(&oi->ip_unaligned_aio);
init_rwsem(&oi->ip_alloc_sem);
init_rwsem(&oi->ip_xattr_sem);
mutex_init(&oi->ip_io_mutex);