aboutsummaryrefslogtreecommitdiffstats
path: root/fs
diff options
context:
space:
mode:
authorZach Brown <zach.brown@oracle.com>2005-11-13 19:07:33 -0500
committerLinus Torvalds <torvalds@g5.osdl.org>2005-11-13 21:14:16 -0500
commit20dcae32439384b6863c626bb3b2a09bed65b33e (patch)
tree9750c39119447fb32963448bf1935e1ba22b2f9d /fs
parent4557398f8cbaf9f254cff747534b4724c7f75c4f (diff)
[PATCH] aio: remove kioctx from mm_struct
Sync iocbs have a life cycle that don't need a kioctx. Their retrying, if any, is done in the context of their owner who has allocated them on the stack. The sole user of a sync iocb's ctx reference was aio_complete() checking for an elevated iocb ref count that could never happen. No path which grabs an iocb ref has access to sync iocbs. If we were to implement sync iocb cancelation it would be done by the owner of the iocb using its on-stack reference. Removing this chunk from aio_complete allows us to remove the entire kioctx instance from mm_struct, reducing its size by a third. On a i386 testing box the slab size went from 768 to 504 bytes and from 5 to 8 per page. Signed-off-by: Zach Brown <zach.brown@oracle.com> Acked-by: Benjamin LaHaise <bcrl@kvack.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'fs')
-rw-r--r--fs/aio.c27
1 files changed, 9 insertions, 18 deletions
diff --git a/fs/aio.c b/fs/aio.c
index 20bb919eb195..e7cd40b626b7 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -937,28 +937,19 @@ int fastcall aio_complete(struct kiocb *iocb, long res, long res2)
937 unsigned long tail; 937 unsigned long tail;
938 int ret; 938 int ret;
939 939
940 /* Special case handling for sync iocbs: events go directly 940 /*
941 * into the iocb for fast handling. Note that this will not 941 * Special case handling for sync iocbs:
942 * work if we allow sync kiocbs to be cancelled. in which 942 * - events go directly into the iocb for fast handling
943 * case the usage count checks will have to move under ctx_lock 943 * - the sync task with the iocb in its stack holds the single iocb
944 * for all cases. 944 * ref, no other paths have a way to get another ref
945 * - the sync task helpfully left a reference to itself in the iocb
945 */ 946 */
946 if (is_sync_kiocb(iocb)) { 947 if (is_sync_kiocb(iocb)) {
947 int ret; 948 BUG_ON(iocb->ki_users != 1);
948
949 iocb->ki_user_data = res; 949 iocb->ki_user_data = res;
950 if (iocb->ki_users == 1) { 950 iocb->ki_users = 0;
951 iocb->ki_users = 0;
952 ret = 1;
953 } else {
954 spin_lock_irq(&ctx->ctx_lock);
955 iocb->ki_users--;
956 ret = (0 == iocb->ki_users);
957 spin_unlock_irq(&ctx->ctx_lock);
958 }
959 /* sync iocbs put the task here for us */
960 wake_up_process(iocb->ki_obj.tsk); 951 wake_up_process(iocb->ki_obj.tsk);
961 return ret; 952 return 1;
962 } 953 }
963 954
964 info = &ctx->ring_info; 955 info = &ctx->ring_info;