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authorPavel Emelyanov <xemul@openvz.org>2007-09-11 15:24:01 -0700
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-09-11 17:21:27 -0700
commit0e2f6db88a6900bc9db576d6b478b12ee60d61f7 (patch)
treebd26a78ea79286622785191afa6f8e1c81f58c2d /fs
parent4740622c5c805d88c63a50747a2d05537dd233cf (diff)
downloadlinux-linaro-0e2f6db88a6900bc9db576d6b478b12ee60d61f7.tar.gz
Leases can be hidden by flocks
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> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs')
-rw-r--r--fs/locks.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/fs/locks.c b/fs/locks.c
index 50857d2d340..c795eaaf6c4 100644
--- a/fs/locks.c
+++ b/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;