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: Weston Andros Adamson <dros@primarydata.com> Reviewed-by: Peng Tao <tao.peng@primarydata.com> Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
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fd2f3a06d3
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bc8a309e88
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@ -143,23 +143,28 @@ nfs_iocounter_wait(struct nfs_io_counter *c)
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*
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* this lock must be held if modifying the page group list
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*
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* returns result from wait_on_bit_lock: 0 on success, < 0 on error
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* return 0 on success, < 0 on error: -EDELAY if nonblocking or the
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* result from wait_on_bit_lock
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*
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* NOTE: calling with nonblock=false should always have set the
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* lock bit (see fs/buffer.c and other uses of wait_on_bit_lock
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* with TASK_UNINTERRUPTIBLE), so there is no need to check the result.
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*/
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int
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nfs_page_group_lock(struct nfs_page *req, bool nonblock)
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{
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struct nfs_page *head = req->wb_head;
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int ret;
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WARN_ON_ONCE(head != head->wb_head);
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do {
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ret = wait_on_bit_lock(&head->wb_flags, PG_HEADLOCK,
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TASK_UNINTERRUPTIBLE);
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} while (!nonblock && ret != 0);
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if (!test_and_set_bit(PG_HEADLOCK, &head->wb_flags))
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return 0;
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WARN_ON_ONCE(ret > 0);
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return ret;
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if (!nonblock)
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return wait_on_bit_lock(&head->wb_flags, PG_HEADLOCK,
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TASK_UNINTERRUPTIBLE);
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return -EAGAIN;
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}
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/*
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