NFS: Fix a potential busy wait in nfs_page_group_lock
We cannot allow nfs_page_group_lock to use TASK_KILLABLE here, since the loop would cause a busy wait if somebody kills the task. Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
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@ -138,6 +138,12 @@ nfs_iocounter_wait(struct nfs_io_counter *c)
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return __nfs_iocounter_wait(c);
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}
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static int nfs_wait_bit_uninterruptible(void *word)
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{
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io_schedule();
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return 0;
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}
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/*
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* nfs_page_group_lock - lock the head of the page group
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* @req - request in group that is to be locked
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@ -148,13 +154,12 @@ void
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nfs_page_group_lock(struct nfs_page *req)
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{
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struct nfs_page *head = req->wb_head;
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int err = -EAGAIN;
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WARN_ON_ONCE(head != head->wb_head);
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while (err)
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err = wait_on_bit_lock(&head->wb_flags, PG_HEADLOCK,
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nfs_wait_bit_killable, TASK_KILLABLE);
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wait_on_bit_lock(&head->wb_flags, PG_HEADLOCK,
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nfs_wait_bit_uninterruptible,
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TASK_UNINTERRUPTIBLE);
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}
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/*
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@ -410,12 +415,6 @@ void nfs_release_request(struct nfs_page *req)
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kref_put(&req->wb_kref, nfs_page_group_destroy);
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}
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static int nfs_wait_bit_uninterruptible(void *word)
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{
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io_schedule();
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return 0;
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}
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/**
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* nfs_wait_on_request - Wait for a request to complete.
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* @req: request to wait upon.
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