fsck -l: fix racing between unlock/unlink and open

[yumkam@gmail.com (Yuriy M. Kaminskiy)]

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Probably, there are better solutions, but I prefer KISS.

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>From fcb97ddcbc336bc8860828c47cdaf21c7b1ca655 Mon Sep 17 00:00:00 2001
From: "Yuriy M. Kaminskiy" <yumkam@gmail.com>
Date: Fri, 8 Apr 2016 00:38:56 +0300
Subject: [PATCH] fsck: fix racing between unlock/unlink and open

Process A	Process B	Process C
open()
[creates file]
lock()
[succeed]
		open()
		[open existing]
		lock()...
running()
close()
		[...succeed]
unlink()
		running()
				open()
				[creates file] {BAD!}
				lock()
				[succeed] {BAD!}
				running() {BAD!}
		close()

Cons: leaves empty (unlocked/harmless) .lock files in /run/fsck/
Signed-off-by: Yuriy M. Kaminskiy <yumkam@gmail.com>
---
 disk-utils/fsck.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/disk-utils/fsck.c b/disk-utils/fsck.c
index 05cfbc4..84d2dcc 100644
--- a/disk-utils/fsck.c
+++ b/disk-utils/fsck.c
@@ -410,7 +410,6 @@ static void unlock_disk(struct fsck_instance *inst)
 		printf(_("Unlocking %s.\n"), inst->lockpath);
 
 	close(inst->lock);			/* unlock */
-	unlink(inst->lockpath);
 
 	free(inst->lockpath);
 
-- 
2.1.4