From f3506eee81d1f700d9ee2d2f4a88fddb669ec032 Mon Sep 17 00:00:00 2001
From: Andreas Gruenbacher <agruenba@redhat.com>
Date: Sat, 6 Nov 2021 00:18:56 +0100
Subject: [PATCH] gfs2: Fix length of holes reported at end-of-file
Git-commit: f3506eee81d1f700d9ee2d2f4a88fddb669ec032
Patch-mainline: v5.16-rc2
References: git-fixes

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>
Acked-by: Anthony Iliopoulos <ailiop@suse.com>

---
 fs/gfs2/bmap.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/gfs2/bmap.c b/fs/gfs2/bmap.c
index 7235d539e969..d67108489148 100644
--- a/fs/gfs2/bmap.c
+++ b/fs/gfs2/bmap.c
@@ -940,7 +940,7 @@ static int __gfs2_iomap_get(struct inode *inode, loff_t pos, loff_t length,
 		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;
 
-- 
2.43.0