Commit bc8a309e authored by Weston Andros Adamson's avatar Weston Andros Adamson Committed by Trond Myklebust
Browse files

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
......@@ -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,
TASK_UNINTERRUPTIBLE);
} while (!nonblock && ret != 0);
if (!test_and_set_bit(PG_HEADLOCK, &head->wb_flags))
return 0;
WARN_ON_ONCE(ret > 0);
return ret;
if (!nonblock)
return wait_on_bit_lock(&head->wb_flags, PG_HEADLOCK,
TASK_UNINTERRUPTIBLE);
return -EAGAIN;
}
/*
......
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