Re: [syzbot] [iomap?] [xfs?] WARNING in iomap_write_begin

[Julian Sun]

The patch passed test locally, and the patch in the link 
appears to be messed up. Please retest.

#syz test: upstream ee9a43b7cfe2

diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
index 72c981e3dc92..6216c31aa3cc 100644
--- a/fs/xfs/xfs_iomap.c
+++ b/fs/xfs/xfs_iomap.c
@@ -1162,6 +1162,9 @@ xfs_buffered_write_iomap_begin(
 	if (error)
 		goto out_unlock;
 
+	/* Get extent info that may updated by xfs_bmapi_reserve_delalloc() */
+	xfs_iext_lookup_extent(ip, &ip->i_df, offset_fsb, &icur, &imap);
+
 	/*
 	 * Flag newly allocated delalloc blocks with IOMAP_F_NEW so we punch
 	 * them out if the write happens to fail.