[PATCH fs/locks 1 of 3] Fix miscompare in __posix_lock_file

[PATCH fs/locks 1 of 3] Fix miscompare in __posix_lock_file

[Olaf Kirch]

# Subject: Fix miscompare in __posix_lock_file
# 
# If an application requests the same lock twice, the
# kernel should just leave the existing lock in place.
# Currently, it will install a second lock of the same type.
# 
# Signed-off-by: Olaf Kirch <okir@suse.de>

Index: linux-2.6.12/fs/locks.c
===================================================================
--- linux-2.6.12.orig/fs/locks.c	2005-07-11 12:15:59.000000000 +0200
+++ linux-2.6.12/fs/locks.c	2005-07-11 12:16:41.000000000 +0200
@@ -828,12 +828,16 @@ static int __posix_lock_file(struct inod
 		/* Detect adjacent or overlapping regions (if same lock type)
 		 */
 		if (request->fl_type == fl->fl_type) {
+			/* In all comparisons of start vs end, use
+			 * "start - 1" rather than "end + 1". If end
+			 * is OFFSET_MAX, end + 1 will become negative.
+			 */
 			if (fl->fl_end < request->fl_start - 1)
 				goto next_lock;
 			/* If the next lock in the list has entirely bigger
 			 * addresses than the new one, insert the lock here.
 			 */
-			if (fl->fl_start > request->fl_end + 1)
+			if (fl->fl_start - 1 > request->fl_end)
 				break;
 
 			/* If we come here, the new and old lock are of the
-- 
Olaf Kirch   |  --- o --- Nous sommes du soleil we love when we play
okir@suse.de |    / | \   sol.dhoop.naytheet.ah kin.ir.samse.qurax


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