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List:       linux-stable-commits
Subject:    patch leases-can-be-hidden-by-flocks.patch queued to -stable tree
From:       <gregkh () suse ! de>
Date:       2007-09-21 22:19:29
Message-ID: 20070921221850.3135A1449FC0 () imap ! suse ! de
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This is a note to let you know that we have just queued up the patch titled

     Subject: Leases can be hidden by flocks

to the 2.6.22-stable tree.  Its filename is

     leases-can-be-hidden-by-flocks.patch

A git repo of this tree can be found at 
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary


From stable-bounces@linux.kernel.org Tue Sep 11 15:29:11 2007
From: Pavel Emelyanov <xemul@openvz.org>
Date: Tue, 11 Sep 2007 15:24:01 -0700
Subject: Leases can be hidden by flocks
To: torvalds@linux-foundation.org
Cc: bfields@fieldses.org, akpm@linux-foundation.org, trond.myklebust@fys.uio.no, \
                stable@kernel.org, xemul@openvz.org
Message-ID: <200709112224.l8BMO2NQ000334@imap1.linux-foundation.org>


From: Pavel Emelyanov <xemul@openvz.org>

commit 0e2f6db88a6900bc9db576d6b478b12ee60d61f7 in mainline.

The inode->i_flock list contains the leases, flocks and posix
locks in the specified order. However, the flocks are added in
the head of this list thus hiding the leases from F_GETLEASE
command, from time_out_leases() and other code that expects
the leases to come first.

The following example will demonstrate this:

#define _GNU_SOURCE

#include <unistd.h>
#include <fcntl.h>
#include <stdio.h>
#include <sys/file.h>

static void show_lease(int fd)
{
        int res;

        res = fcntl(fd, F_GETLEASE);
        switch (res) {
                case F_RDLCK:
                        printf("Read lease\n");
                        break;
                case F_WRLCK:
                        printf("Write lease\n");
                        break;
                case F_UNLCK:
                        printf("No leases\n");
                        break;
                default:
                        printf("Some shit\n");
                        break;
        }
}

int main(int argc, char **argv)
{
        int fd, res;

        fd = open(argv[1], O_RDONLY);
        if (fd == -1) {
                perror("Can't open file");
                return 1;
        }

        res = fcntl(fd, F_SETLEASE, F_WRLCK);
        if (res == -1) {
                perror("Can't set lease");
                return 1;
        }

        show_lease(fd);

        if (flock(fd, LOCK_SH) == -1) {
                perror("Can't flock shared");
                return 1;
        }

        show_lease(fd);

        return 0;
}

The first call to show_lease() will show the write lease set, but
the second will show no leases.

Fix the flock adding so that the leases always stay in the head
of this list.

Found during making the flocks pid-namespaces aware.

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Acked-by: "J. Bruce Fields" <bfields@fieldses.org>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

--- a/fs/locks.c~leases-can-be-hidden-by-flocks
+++ a/fs/locks.c
@@ -782,7 +782,7 @@ find_conflict:
 	if (request->fl_flags & FL_ACCESS)
 		goto out;
 	locks_copy_lock(new_fl, request);
-	locks_insert_lock(&inode->i_flock, new_fl);
+	locks_insert_lock(before, new_fl);
 	new_fl = NULL;
 	error = 0;
 
_

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Patches currently in stable-queue which might be from xemul@openvz.org are

queue-2.6.22/leases-can-be-hidden-by-flocks.patch
-
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