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>

5 files changed, 7 insertions, 30 deletions

diff --git a/fs/ocfs2/aops.c b/fs/ocfs2/aops.c
index aeb44e879c51..ebe44f7dce0b 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 f671e49beb34..6cae155d54df 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 51632c40e896..1673438789fe 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 621fc73bf23d..9f1580b506a5 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 49d84f80f36c..d17145552097 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);