From: Benjamin LaHaise <bcrl@kvack.org>
Implement a per-kiocb lock to serialise retry operations and cancel. This
is done using wait_on_bit_lock() on the KIF_LOCKED bit of kiocb->ki_flags.
Also, make the cancellation path lock the kiocb and subsequently release
all references to it if the cancel was successful.
Signed-off-by: Benjamin LaHaise <benjamin.c.lahaise@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
---
fs/aio.c | 23 +++++++++++++++++++++++
1 files changed, 23 insertions(+)
diff -puN fs/aio.c~aio-kiocb-locking-to-serialise-retry-and-cancel fs/aio.c
--- devel/fs/aio.c~aio-kiocb-locking-to-serialise-retry-and-cancel 2005-08-21 23:48:35.000000000 -0700
+++ devel-akpm/fs/aio.c 2005-08-21 23:48:35.000000000 -0700
@@ -546,6 +546,24 @@ struct kioctx *lookup_ioctx(unsigned lon
return ioctx;
}
+static int lock_kiocb_action(void *param)
+{
+ schedule();
+ return 0;
+}
+
+static inline void lock_kiocb(struct kiocb *iocb)
+{
+ wait_on_bit_lock(&iocb->ki_flags, KIF_LOCKED, lock_kiocb_action,
+ TASK_UNINTERRUPTIBLE);
+}
+
+static inline void unlock_kiocb(struct kiocb *iocb)
+{
+ kiocbClearLocked(iocb);
+ wake_up_bit(&iocb->ki_flags, KIF_LOCKED);
+}
+
/*
* use_mm
* Makes the calling kernel thread take on the specified
@@ -786,7 +804,9 @@ static int __aio_run_iocbs(struct kioctx
* Hold an extra reference while retrying i/o.
*/
iocb->ki_users++; /* grab extra reference */
+ lock_kiocb(iocb);
aio_run_iocb(iocb);
+ unlock_kiocb(iocb);
if (__aio_put_req(ctx, iocb)) /* drop extra ref */
put_ioctx(ctx);
}
@@ -1536,6 +1556,7 @@ int fastcall io_submit_one(struct kioctx
;
}
spin_unlock_irq(&ctx->ctx_lock);
+ unlock_kiocb(req);
aio_put_req(req); /* drop extra ref to req */
return 0;
@@ -1661,6 +1682,7 @@ asmlinkage long sys_io_cancel(aio_contex
if (NULL != cancel) {
struct io_event tmp;
pr_debug("calling cancel\n");
+ lock_kiocb(kiocb);
memset(&tmp, 0, sizeof(tmp));
tmp.obj = (u64)(unsigned long)kiocb->ki_obj.user;
tmp.data = kiocb->ki_user_data;
@@ -1672,6 +1694,7 @@ asmlinkage long sys_io_cancel(aio_contex
if (copy_to_user(result, &tmp, sizeof(tmp)))
ret = -EFAULT;
}
+ unlock_kiocb(kiocb);
} else
ret = -ENOSYS;
_