nfs: fix nonblocking calls to nfs_page_group_lock (bc8a309e) · Commits · 戴 / test

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:

Weston Andros Adamson <dros@primarydata.com> Reviewed-by:

Peng Tao <tao.peng@primarydata.com> Signed-off-by:

Trond Myklebust <trond.myklebust@primarydata.com>

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;
		}

		/*

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