From:   Sasha Levin <sashal@kernel.org>
To:     linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc:     Andreas Gruenbacher <agruenba@redhat.com>,
        Sasha Levin <sashal@kernel.org>, rpeterso@redhat.com,
        cluster-devel@redhat.com
Subject: [PATCH AUTOSEL 5.15 02/39] gfs2: Fix length of holes reported at end-of-file
Date:   Thu, 25 Nov 2021 21:31:19 -0500
Message-Id: <20211126023156.441292-2-sashal@kernel.org>
In-Reply-To: <20211126023156.441292-1-sashal@kernel.org>
References: <20211126023156.441292-1-sashal@kernel.org>
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From: Andreas Gruenbacher <agruenba@redhat.com>

[ Upstream commit f3506eee81d1f700d9ee2d2f4a88fddb669ec032 ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 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 5414c2c335809..fba32141a651b 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;
 
-- 
2.33.0