NLM: don't unlock on cancel requests (5996a298) · Commits · 戴 / test

Currently when lockd gets an NLM_CANCEL request, it also does an unlock for the same range. This is incorrect. The Open Group documentation says that "This procedure cancels an *outstanding* blocked lock request." (Emphasis mine.) Also, consider a client that holds a lock on the first byte of a file, and requests a lock on the entire file. If the client cancels that request (perhaps because the requesting process is signalled), the server shouldn't apply perform an unlock on the entire file, since that will also remove the previous lock that the client was already granted. Or consider a lock request that actually *downgraded* an exclusive lock to a shared lock. Signed-off-by:

J. Bruce Fields <bfields@citi.umich.edu> Signed-off-by:

Trond Myklebust <Trond.Myklebust@netapp.com>

fs/lockd/svclock.c

+0 −5

Original line number	Diff line number	Diff line
		@@ -240,11 +240,6 @@ nlmsvc_delete_block(struct nlm_block *block, int unlock)
		nlmsvc_remove_block(block);
		if (fl->fl_next)
		posix_unblock_lock(file->f_file, fl);
		if (unlock) {
		fl->fl_type = F_UNLCK;
		posix_lock_file(file->f_file, fl);
		block->b_granted = 0;
		}

		/* If the block is in the middle of a GRANT callback,
		* don't kill it yet. */

fs/locks.c

+2 −11

Original line number	Diff line number	Diff line
		@@ -1961,19 +1961,10 @@ EXPORT_SYMBOL(posix_block_lock);
		void
		posix_unblock_lock(struct file filp, struct file_lock waiter)
		{
		/*
		* A remote machine may cancel the lock request after it's been
		* granted locally. If that happens, we need to delete the lock.
		*/
		lock_kernel();
		if (waiter->fl_next) {
		if (waiter->fl_next)
		__locks_delete_block(waiter);
		unlock_kernel();
		} else {
		unlock_kernel();
		waiter->fl_type = F_UNLCK;
		posix_lock_file(filp, waiter);
		}
		}

		EXPORT_SYMBOL(posix_unblock_lock);

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