xfs: don't start out with the exclusive ilock for direct I/O

There is no reason to take the ilock exclusively at the start of
xfs_file_iomap_begin for direct I/O, given that it will be demoted
just before calling xfs_iomap_write_direct anyway.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
index 4e771e0..ee01859 100644 (file)
--- a/fs/xfs/xfs_iomap.c
+++ b/fs/xfs/xfs_iomap.c
@@ -965,13 +965,11 @@ static inline bool needs_cow_for_zeroing(struct xfs_bmbt_irec *imap, int nimaps)
 static inline bool need_excl_ilock(struct xfs_inode *ip, unsigned flags)
 {
        /*
-        * COW writes will allocate delalloc space, so we need to make sure
-        * to take the lock exclusively here.
+        * COW writes may allocate delalloc space or convert unwritten COW
+        * extents, so we need to make sure to take the lock exclusively here.
         */
        if (xfs_is_reflink_inode(ip) && (flags & (IOMAP_WRITE | IOMAP_ZERO)))
                return true;
-       if ((flags & IOMAP_DIRECT) && (flags & IOMAP_WRITE))
-               return true;
        return false;
 }