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authorZach Brown <zach.brown@oracle.com>2006-12-10 02:21:01 -0800
committerLinus Torvalds <torvalds@woody.osdl.org>2006-12-10 09:57:21 -0800
commit20258b2b397031649e4a41922fe803d57017df84 (patch)
tree9c5fc96367b4938474cee2789d3c98c5e37586bf
parent0273201e693fd62381f6b1e85b15ffc117d8a46e (diff)
[PATCH] dio: remove duplicate bio wait code
Now that we have a single refcount and waiting path we can reuse it in the async 'should_wait' path. It continues to rely on the fragile link between the conditional in dio_complete_aio() which decides to complete the AIO and the conditional in direct_io_worker() which decides to wait and free. By waiting before dropping the reference we stop dio_bio_end_aio() from calling dio_complete_aio() which used to wake up the waiter after seeing the reference count drop to 0. We hoist this wake up into dio_bio_end_aio() which now notices when it's left a single remaining reference that is held by the waiter. Signed-off-by: Zach Brown <zach.brown@oracle.com> Cc: Badari Pulavarty <pbadari@us.ibm.com> Cc: Suparna Bhattacharya <suparna@in.ibm.com> Acked-by: Jeff Moyer <jmoyer@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
-rw-r--r--fs/direct-io.c41
1 files changed, 12 insertions, 29 deletions
diff --git a/fs/direct-io.c b/fs/direct-io.c
index bc1cbf9149f7..f11f05dc9e61 100644
--- a/fs/direct-io.c
+++ b/fs/direct-io.c
@@ -257,7 +257,6 @@ static int dio_complete(struct dio *dio, loff_t offset, int ret)
*/
static void dio_complete_aio(struct dio *dio)
{
- unsigned long flags;
int ret;
ret = dio_complete(dio, dio->iocb->ki_pos, 0);
@@ -267,14 +266,6 @@ static void dio_complete_aio(struct dio *dio)
((dio->rw == READ) && dio->result)) {
aio_complete(dio->iocb, ret, 0);
kfree(dio);
- } else {
- /*
- * Falling back to buffered
- */
- spin_lock_irqsave(&dio->bio_lock, flags);
- if (dio->waiter)
- wake_up_process(dio->waiter);
- spin_unlock_irqrestore(&dio->bio_lock, flags);
}
}
@@ -285,6 +276,8 @@ static int dio_bio_complete(struct dio *dio, struct bio *bio);
static int dio_bio_end_aio(struct bio *bio, unsigned int bytes_done, int error)
{
struct dio *dio = bio->bi_private;
+ int waiter_holds_ref = 0;
+ int remaining;
if (bio->bi_size)
return 1;
@@ -292,7 +285,12 @@ static int dio_bio_end_aio(struct bio *bio, unsigned int bytes_done, int error)
/* cleanup the bio */
dio_bio_complete(dio, bio);
- if (atomic_dec_and_test(&dio->refcount))
+ waiter_holds_ref = !!dio->waiter;
+ remaining = atomic_sub_return(1, (&dio->refcount));
+ if (remaining == 1 && waiter_holds_ref)
+ wake_up_process(dio->waiter);
+
+ if (remaining == 0)
dio_complete_aio(dio);
return 0;
@@ -1097,30 +1095,15 @@ direct_io_worker(int rw, struct kiocb *iocb, struct inode *inode,
if (ret == 0)
ret = dio->result;
+ if (should_wait)
+ dio_await_completion(dio);
+
/* this can free the dio */
if (atomic_dec_and_test(&dio->refcount))
dio_complete_aio(dio);
- if (should_wait) {
- unsigned long flags;
- /*
- * Wait for already issued I/O to drain out and
- * release its references to user-space pages
- * before returning to fallback on buffered I/O
- */
-
- spin_lock_irqsave(&dio->bio_lock, flags);
- set_current_state(TASK_UNINTERRUPTIBLE);
- while (atomic_read(&dio->refcount)) {
- spin_unlock_irqrestore(&dio->bio_lock, flags);
- io_schedule();
- spin_lock_irqsave(&dio->bio_lock, flags);
- set_current_state(TASK_UNINTERRUPTIBLE);
- }
- spin_unlock_irqrestore(&dio->bio_lock, flags);
- set_current_state(TASK_RUNNING);
+ if (should_wait)
kfree(dio);
- }
} else {
dio_await_completion(dio);