[PATCH 2/7] xfs: add nowait support for xfs_seek_iomap_begin()

[Hao Xu <hao.xu@linux.dev>]

From: Hao Xu <howeyxu@tencent.com>

To support nowait llseek(), IOMAP_NOWAIT semantics should be respected.
In xfs, xfs_seek_iomap_begin() is the only place which may be blocked
by ilock and extent loading. Let's turn it into trylock logic just like
what we've done in xfs_readdir().

Signed-off-by: Hao Xu <howeyxu@tencent.com>
---
 fs/xfs/xfs_iomap.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
index 18c8f168b153..bbd7c6b27701 100644
--- a/fs/xfs/xfs_iomap.c
+++ b/fs/xfs/xfs_iomap.c
@@ -1294,7 +1294,9 @@ xfs_seek_iomap_begin(
 	if (xfs_is_shutdown(mp))
 		return -EIO;
 
-	lockmode = xfs_ilock_data_map_shared(ip);
+	lockmode = xfs_ilock_data_map_shared_generic(ip, flags & IOMAP_NOWAIT);
+	if (!lockmode)
+		return -EAGAIN;
 	error = xfs_iread_extents(NULL, ip, XFS_DATA_FORK);
 	if (error)
 		goto out_unlock;
-- 
2.25.1