/*
* nfs_page_group_lock - lock the head of the page group
* @req - request in group that is to be locked
+ * @nonblock - if true don't block waiting for lock
*
* 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 wait)
+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 (wait && 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;
}
/*
{
bool ret;
- nfs_page_group_lock(req, true);
+ nfs_page_group_lock(req, false);
ret = nfs_page_group_sync_on_bit_locked(req, bit);
nfs_page_group_unlock(req);
struct nfs_page *subreq;
unsigned int bytes_left = 0;
unsigned int offset, pgbase;
- int ret;
- ret = nfs_page_group_lock(req, false);
- if (ret < 0) {
- desc->pg_error = ret;
- return 0;
- }
+ nfs_page_group_lock(req, false);
subreq = req;
bytes_left = subreq->wb_bytes;
if (desc->pg_recoalesce)
return 0;
/* retry add_request for this subreq */
- ret = nfs_page_group_lock(req, false);
- if (ret < 0) {
- desc->pg_error = ret;
- return 0;
- }
+ nfs_page_group_lock(req, false);
continue;
}