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authorZach Brown <zach.brown@oracle.com>2006-12-10 05:21:01 -0500
committerLinus Torvalds <torvalds@woody.osdl.org>2006-12-10 12:57:21 -0500
commit20258b2b397031649e4a41922fe803d57017df84 (patch)
tree9c5fc96367b4938474cee2789d3c98c5e37586bf /fs/direct-io.c
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>
Diffstat (limited to 'fs/direct-io.c')
-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)
257 */ 257 */
258static void dio_complete_aio(struct dio *dio) 258static void dio_complete_aio(struct dio *dio)
259{ 259{
260 unsigned long flags;
261 int ret; 260 int ret;
262 261
263 ret = dio_complete(dio, dio->iocb->ki_pos, 0); 262 ret = dio_complete(dio, dio->iocb->ki_pos, 0);
@@ -267,14 +266,6 @@ static void dio_complete_aio(struct dio *dio)
267 ((dio->rw == READ) && dio->result)) { 266 ((dio->rw == READ) && dio->result)) {
268 aio_complete(dio->iocb, ret, 0); 267 aio_complete(dio->iocb, ret, 0);
269 kfree(dio); 268 kfree(dio);
270 } else {
271 /*
272 * Falling back to buffered
273 */
274 spin_lock_irqsave(&dio->bio_lock, flags);
275 if (dio->waiter)
276 wake_up_process(dio->waiter);
277 spin_unlock_irqrestore(&dio->bio_lock, flags);
278 } 269 }
279} 270}
280 271
@@ -285,6 +276,8 @@ static int dio_bio_complete(struct dio *dio, struct bio *bio);
285static int dio_bio_end_aio(struct bio *bio, unsigned int bytes_done, int error) 276static int dio_bio_end_aio(struct bio *bio, unsigned int bytes_done, int error)
286{ 277{
287 struct dio *dio = bio->bi_private; 278 struct dio *dio = bio->bi_private;
279 int waiter_holds_ref = 0;
280 int remaining;
288 281
289 if (bio->bi_size) 282 if (bio->bi_size)
290 return 1; 283 return 1;
@@ -292,7 +285,12 @@ static int dio_bio_end_aio(struct bio *bio, unsigned int bytes_done, int error)
292 /* cleanup the bio */ 285 /* cleanup the bio */
293 dio_bio_complete(dio, bio); 286 dio_bio_complete(dio, bio);
294 287
295 if (atomic_dec_and_test(&dio->refcount)) 288 waiter_holds_ref = !!dio->waiter;
289 remaining = atomic_sub_return(1, (&dio->refcount));
290 if (remaining == 1 && waiter_holds_ref)
291 wake_up_process(dio->waiter);
292
293 if (remaining == 0)
296 dio_complete_aio(dio); 294 dio_complete_aio(dio);
297 295
298 return 0; 296 return 0;
@@ -1097,30 +1095,15 @@ direct_io_worker(int rw, struct kiocb *iocb, struct inode *inode,
1097 if (ret == 0) 1095 if (ret == 0)
1098 ret = dio->result; 1096 ret = dio->result;
1099 1097
1098 if (should_wait)
1099 dio_await_completion(dio);
1100
1100 /* this can free the dio */ 1101 /* this can free the dio */
1101 if (atomic_dec_and_test(&dio->refcount)) 1102 if (atomic_dec_and_test(&dio->refcount))
1102 dio_complete_aio(dio); 1103 dio_complete_aio(dio);
1103 1104
1104 if (should_wait) { 1105 if (should_wait)
1105 unsigned long flags;
1106 /*
1107 * Wait for already issued I/O to drain out and
1108 * release its references to user-space pages
1109 * before returning to fallback on buffered I/O
1110 */
1111
1112 spin_lock_irqsave(&dio->bio_lock, flags);
1113 set_current_state(TASK_UNINTERRUPTIBLE);
1114 while (atomic_read(&dio->refcount)) {
1115 spin_unlock_irqrestore(&dio->bio_lock, flags);
1116 io_schedule();
1117 spin_lock_irqsave(&dio->bio_lock, flags);
1118 set_current_state(TASK_UNINTERRUPTIBLE);
1119 }
1120 spin_unlock_irqrestore(&dio->bio_lock, flags);
1121 set_current_state(TASK_RUNNING);
1122 kfree(dio); 1106 kfree(dio);
1123 }
1124 } else { 1107 } else {
1125 dio_await_completion(dio); 1108 dio_await_completion(dio);
1126 1109