From: Darrick J. Wong <djwong@kernel.org>
Date: Wed, 20 Dec 2023 16:53:43 +0000 (-0800)
Subject: xfs_copy: distinguish short writes to EOD from runtime errors
X-Git-Tag: v6.6.0~6^2~2
X-Git-Url: http://git.ipfire.org/?p=thirdparty%2Fxfsprogs-dev.git;a=commitdiff_plain;h=603850fe94cdb6a586eb75cb33bcb9e24e204b18

xfs_copy: distinguish short writes to EOD from runtime errors

Detect short writes to the end of the destination device and report
them.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---

diff --git a/copy/xfs_copy.c b/copy/xfs_copy.c
index 6e692e4f7..2cfb7519e 100644
--- a/copy/xfs_copy.c
+++ b/copy/xfs_copy.c
@@ -884,18 +884,28 @@ main(int argc, char **argv)
 		} else  {
 			char	*lb[XFS_MAX_SECTORSIZE] = { NULL };
 			off64_t	off;
+			ssize_t	len;
 
 			/* ensure device files are sufficiently large */
 
 			off = mp->m_sb.sb_dblocks * source_blocksize;
 			off -= sizeof(lb);
-			if (pwrite(target[i].fd, lb, sizeof(lb), off) < 0)  {
+			len = pwrite(target[i].fd, lb, XFS_MAX_SECTORSIZE, off);
+			if (len < 0) {
 				do_log(_("%s:  failed to write last block\n"),
 					progname);
 				do_log(_("\tIs target \"%s\" too small?\n"),
 					target[i].name);
 				die_perror();
 			}
+			if (len != XFS_MAX_SECTORSIZE) {
+				do_log(
+ _("%s:  short write to last block: %zd bytes, %zu expected\n"),
+					progname, len, XFS_MAX_SECTORSIZE);
+				do_log(_("\tIs target \"%s\" too small?\n"),
+					target[i].name);
+				exit(1);
+			}
 		}
 	}