From: Karel Zak <kzak@redhat.com>
Date: Tue, 9 Jan 2024 11:59:24 +0000 (+0100)
Subject: hardlink: fix fiemap use
X-Git-Tag: v2.40-rc1~61
X-Git-Url: http://git.ipfire.org/?p=thirdparty%2Futil-linux.git;a=commitdiff_plain;h=d829e785f218714102f23940e68dc71be20cfbd4

hardlink: fix fiemap use

Handle cases where the number of fm_mapped_extents is zero by ignoring
the fm_extents array, as zero is a valid value.

Fixes: https://github.com/util-linux/util-linux/issues/2687
Signed-off-by: Karel Zak <kzak@redhat.com>
---

diff --git a/misc-utils/hardlink.c b/misc-utils/hardlink.c
index 98c9f8d291..f9d3d09ac6 100644
--- a/misc-utils/hardlink.c
+++ b/misc-utils/hardlink.c
@@ -991,7 +991,8 @@ static int is_reflink(struct file *xa, struct file *xb)
 		if (ioctl(bf, FS_IOC_FIEMAP, (unsigned long) bmap) < 0)
 			goto done;
 
-		if (amap->fm_mapped_extents != bmap->fm_mapped_extents)
+		if (amap->fm_mapped_extents == 0 ||
+		    amap->fm_mapped_extents != bmap->fm_mapped_extents)
 			goto done;
 
 		for (i = 0; i < amap->fm_mapped_extents; i++) {