Commit 9cf35f67 authored Sep 11, 2019 by Goldwyn Rodrigues Committed by David Sterba Nov 18, 2019

btrfs: simplify inode locking for RWF_NOWAIT



This is similar to 942491c9 ("xfs: fix AIM7 regression"). Apparently
our current rwsem code doesn't like doing the trylock, then lock for
real scheme. This causes extra contention on the lock and can be
measured eg. by AIM7 benchmark.  So change our read/write methods to
just do the trylock for the RWF_NOWAIT case.

Fixes: edf064e7 ("btrfs: nowait aio support")
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ update changelog ]
Signed-off-by: David Sterba <dsterba@suse.com>

parent af42d346

fs/btrfs/file.c

+3 −2

Original line number	Diff line number	Diff line
		@@ -1903,9 +1903,10 @@ static ssize_t btrfs_file_write_iter(struct kiocb *iocb,
		(iocb->ki_flags & IOCB_NOWAIT))
		return -EOPNOTSUPP;

		if (!inode_trylock(inode)) {
		if (iocb->ki_flags & IOCB_NOWAIT)
		if (iocb->ki_flags & IOCB_NOWAIT) {
		if (!inode_trylock(inode))
		return -EAGAIN;
		} else {
		inode_lock(inode);
		}

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