From: Gero Treuner <gero@70t.de>
Date: Thu, 10 Sep 2020 19:43:03 +0000 (+0200)
Subject: fallocate: fix --dig-holes at end of files
X-Git-Tag: v2.36.1~51
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=ed423e56ec43e6cdd5a8475e698f693b56512a63;p=thirdparty%2Futil-linux.git

fallocate: fix --dig-holes at end of files

I discovered that making a file sparse with "fallocate -d filename"
fails on the last block of a file, because - usually being partial -
the system call only zeroes that part instead of deallocating the
block. See man fallocate(2) - section "Deallocating file space".

The expected call is punching the whole block beyond eof, which
doesn't change the file length because of flag FALLOC_FL_KEEP_SIZE.

Signed-off-by: Karel Zak <kzak@redhat.com>
---

diff --git a/sys-utils/fallocate.c b/sys-utils/fallocate.c
index 014b946247..ba97092fcf 100644
--- a/sys-utils/fallocate.c
+++ b/sys-utils/fallocate.c
@@ -264,8 +264,11 @@ static void dig_holes(int fd, off_t file_off, off_t len)
 			off += rsz;
 		}
 		if (hole_sz) {
+			off_t alloc_sz = hole_sz;
+			if (off >= end)
+				alloc_sz += st.st_blksize;		/* meet block boundary */
 			xfallocate(fd, FALLOC_FL_PUNCH_HOLE|FALLOC_FL_KEEP_SIZE,
-					hole_start, hole_sz);
+					hole_start, alloc_sz);
 			ct += hole_sz;
 		}
 		file_off = off;