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Commit bc8a309e authored by Weston Andros Adamson's avatar Weston Andros Adamson Committed by Trond Myklebust
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nfs: fix nonblocking calls to nfs_page_group_lock 



nfs_page_group_lock was calling wait_on_bit_lock even when told not to
block. Fix by first trying test_and_set_bit, followed by wait_on_bit_lock
if and only if blocking is allowed.  Return -EAGAIN if nonblocking and the
test_and_set of the bit was already locked.

Signed-off-by: default avatarWeston Andros Adamson <dros@primarydata.com>
Reviewed-by: default avatarPeng Tao <tao.peng@primarydata.com>
Signed-off-by: default avatarTrond Myklebust <trond.myklebust@primarydata.com>
parent fd2f3a06

fs/nfs/pagelist.c

+13 −8
Original line number Diff line number Diff line
@@ -143,23 +143,28 @@ nfs_iocounter_wait(struct nfs_io_counter *c) 
 *

 * this lock must be held if modifying the page group list

 *

 * returns result from wait_on_bit_lock: 0 on success, < 0 on error

 * return 0 on success, < 0 on error: -EDELAY if nonblocking or the

 * result from wait_on_bit_lock

 *

 * NOTE: calling with nonblock=false should always have set the

 *       lock bit (see fs/buffer.c and other uses of wait_on_bit_lock

 *       with TASK_UNINTERRUPTIBLE), so there is no need to check the result.

 */

int

nfs_page_group_lock(struct nfs_page *req, bool nonblock)

{

	struct nfs_page *head = req->wb_head;

	int ret;



	WARN_ON_ONCE(head != head->wb_head);



	do {

		ret = wait_on_bit_lock(&head->wb_flags, PG_HEADLOCK,

	if (!test_and_set_bit(PG_HEADLOCK, &head->wb_flags))

		return 0;



	if (!nonblock)

		return wait_on_bit_lock(&head->wb_flags, PG_HEADLOCK,

				TASK_UNINTERRUPTIBLE);

	} while (!nonblock && ret != 0);



	WARN_ON_ONCE(ret > 0);

	return ret;

	return -EAGAIN;

}



/*