From: Andreas Gruenbacher <agruenba@redhat.com>
Date: Fri, 5 Nov 2021 23:18:56 +0000 (+0100)
Subject: gfs2: Fix length of holes reported at end-of-file
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=f3506eee81d1f700d9ee2d2f4a88fddb669ec032;p=linux.git

gfs2: Fix length of holes reported at end-of-file

Fix the length of holes reported at the end of a file: the length is
relative to the beginning of the extent, not the seek position which is
rounded down to the filesystem block size.

This bug went unnoticed for some time, but is now caught by the
following assertion in iomap_iter_done():

  WARN_ON_ONCE(iter->iomap.offset + iter->iomap.length <= iter->pos)

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
---

diff --git a/fs/gfs2/bmap.c b/fs/gfs2/bmap.c
index 7235d539e9695..d67108489148e 100644
--- a/fs/gfs2/bmap.c
+++ b/fs/gfs2/bmap.c
@@ -940,7 +940,7 @@ do_alloc:
 		else if (height == ip->i_height)
 			ret = gfs2_hole_size(inode, lblock, len, mp, iomap);
 		else
-			iomap->length = size - pos;
+			iomap->length = size - iomap->offset;
 	} else if (flags & IOMAP_WRITE) {
 		u64 alloc_size;