Wengang Wang
2014-Feb-19 03:24 UTC
[Ocfs2-devel] [PATCH] [ocfs2]: change ip_unaligned_aio to of type mutex from atomit_t
There is a problem that waitqueue_active() may check stale data thus miss a
wakeup of threads waiting on ip_unaligned_aio.
The valid value of ip_unaligned_aio is only 0 and 1 so we can change it to
be of type mutex thus the above prolem is avoid. Another benifit is that mutex
which works as FIFO is fairer than wake_up_all().
Signed-off-by: Wengang Wang <wen.gang.wang at oracle.com>
---
fs/ocfs2/aops.c | 6 +-----
fs/ocfs2/aops.h | 5 -----
fs/ocfs2/file.c | 15 +++------------
fs/ocfs2/inode.h | 2 +-
fs/ocfs2/super.c | 9 ++-------
5 files changed, 7 insertions(+), 30 deletions(-)
diff --git a/fs/ocfs2/aops.c b/fs/ocfs2/aops.c
index aeb44e8..ebe44f7 100644
--- a/fs/ocfs2/aops.c
+++ b/fs/ocfs2/aops.c
@@ -571,7 +571,6 @@ static void ocfs2_dio_end_io(struct kiocb *iocb,
{
struct inode *inode = file_inode(iocb->ki_filp);
int level;
- wait_queue_head_t *wq = ocfs2_ioend_wq(inode);
/* this io's submitter should not have unlocked this before we could */
BUG_ON(!ocfs2_iocb_is_rw_locked(iocb));
@@ -582,10 +581,7 @@ static void ocfs2_dio_end_io(struct kiocb *iocb,
if (ocfs2_iocb_is_unaligned_aio(iocb)) {
ocfs2_iocb_clear_unaligned_aio(iocb);
- if (atomic_dec_and_test(&OCFS2_I(inode)->ip_unaligned_aio) &&
- waitqueue_active(wq)) {
- wake_up_all(wq);
- }
+ mutex_unlock(&OCFS2_I(inode)->ip_unaligned_aio);
}
ocfs2_iocb_clear_rw_locked(iocb);
diff --git a/fs/ocfs2/aops.h b/fs/ocfs2/aops.h
index f671e49..6cae155 100644
--- a/fs/ocfs2/aops.h
+++ b/fs/ocfs2/aops.h
@@ -102,9 +102,4 @@ enum ocfs2_iocb_lock_bits {
#define ocfs2_iocb_is_unaligned_aio(iocb) \
test_bit(OCFS2_IOCB_UNALIGNED_IO, (unsigned long *)&iocb->private)
-#define OCFS2_IOEND_WQ_HASH_SZ 37
-#define ocfs2_ioend_wq(v) (&ocfs2__ioend_wq[((unsigned long)(v)) %\
- OCFS2_IOEND_WQ_HASH_SZ])
-extern wait_queue_head_t ocfs2__ioend_wq[OCFS2_IOEND_WQ_HASH_SZ];
-
#endif /* OCFS2_FILE_H */
diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
index 8450262bc..51f67cd 100644
--- a/fs/ocfs2/file.c
+++ b/fs/ocfs2/file.c
@@ -2061,13 +2061,6 @@ out:
return ret;
}
-static void ocfs2_aiodio_wait(struct inode *inode)
-{
- wait_queue_head_t *wq = ocfs2_ioend_wq(inode);
-
- wait_event(*wq, (atomic_read(&OCFS2_I(inode)->ip_unaligned_aio) == 0));
-}
-
static int ocfs2_is_io_unaligned(struct inode *inode, size_t count, loff_t pos)
{
int blockmask = inode->i_sb->s_blocksize - 1;
@@ -2345,10 +2338,8 @@ relock:
* Wait on previous unaligned aio to complete before
* proceeding.
*/
- ocfs2_aiodio_wait(inode);
-
- /* Mark the iocb as needing a decrement in ocfs2_dio_end_io */
- atomic_inc(&OCFS2_I(inode)->ip_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);
}
@@ -2428,7 +2419,7 @@ out_dio:
if (unaligned_dio) {
ocfs2_iocb_clear_unaligned_aio(iocb);
- atomic_dec(&OCFS2_I(inode)->ip_unaligned_aio);
+ mutex_unlock(&OCFS2_I(inode)->ip_unaligned_aio);
}
out:
diff --git a/fs/ocfs2/inode.h b/fs/ocfs2/inode.h
index 621fc73..9f1580b 100644
--- a/fs/ocfs2/inode.h
+++ b/fs/ocfs2/inode.h
@@ -44,7 +44,7 @@ struct ocfs2_inode_info
struct rw_semaphore ip_xattr_sem;
/* Number of outstanding AIO's which are not page aligned */
- atomic_t ip_unaligned_aio;
+ struct mutex ip_unaligned_aio;
/* These fields are protected by ip_lock */
spinlock_t ip_lock;
diff --git a/fs/ocfs2/super.c b/fs/ocfs2/super.c
index 49d84f8..d171455 100644
--- a/fs/ocfs2/super.c
+++ b/fs/ocfs2/super.c
@@ -1612,14 +1612,9 @@ static int ocfs2_show_options(struct seq_file *s, struct
dentry *root)
return 0;
}
-wait_queue_head_t ocfs2__ioend_wq[OCFS2_IOEND_WQ_HASH_SZ];
-
static int __init ocfs2_init(void)
{
- int status, i;
-
- for (i = 0; i < OCFS2_IOEND_WQ_HASH_SZ; i++)
- init_waitqueue_head(&ocfs2__ioend_wq[i]);
+ int status;
status = init_ocfs2_uptodate_cache();
if (status < 0)
@@ -1761,7 +1756,7 @@ static void ocfs2_inode_init_once(void *data)
ocfs2_extent_map_init(&oi->vfs_inode);
INIT_LIST_HEAD(&oi->ip_io_markers);
oi->ip_dir_start_lookup = 0;
- atomic_set(&oi->ip_unaligned_aio, 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);
--
1.8.3.1