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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@oracle.com>
Cc: Mark Fasheh <mfasheh@suse.com>
Cc: Joel Becker <jlbec@evilplan.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Wengang Wang 2014-04-03 14:46:46 -07:00 committed by Linus Torvalds
parent 181a9a043b
commit c18ceab012
5 changed files with 7 additions and 30 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
fs/ocfs2/aops.c
View File

@ -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);

5
fs/ocfs2/aops.h
View File

@ -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 */

15
fs/ocfs2/file.c
View File

@ -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:

2
fs/ocfs2/inode.h
View File

@ -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;

9
fs/ocfs2/super.c
View File

@ -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);