[PATCH v4 12/13] locks: report l_pid as -1 for FL_FILE_PVT locks

From: Jeff Layton
Date: Thu Dec 19 2013 - 08:35:53 EST


FL_FILE_PVT locks are no longer tied to a particular pid, and are
instead inheritable by child processes. Report a l_pid of '-1' for
these sorts of locks since the pid is somewhat meaningless for them.

This precedent comes from FreeBSD. There, POSIX and flock() locks can
conflict with one another. If fcntl(F_GETLK, ...) returns a lock set
with flock() then the l_pid member cannot be a process ID because the
lock is not held by a process as such.

Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
---
fs/locks.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/locks.c b/fs/locks.c
index 995583b..013b177 100644
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -1863,7 +1863,7 @@ EXPORT_SYMBOL_GPL(vfs_test_lock);

static int posix_lock_to_flock(struct flock *flock, struct file_lock *fl)
{
- flock->l_pid = fl->fl_pid;
+ flock->l_pid = IS_FILE_PVT(fl) ? -1 : fl->fl_pid;
#if BITS_PER_LONG == 32
/*
* Make sure we can represent the posix lock via
@@ -1885,7 +1885,7 @@ static int posix_lock_to_flock(struct flock *flock, struct file_lock *fl)
#if BITS_PER_LONG == 32
static void posix_lock_to_flock64(struct flock64 *flock, struct file_lock *fl)
{
- flock->l_pid = fl->fl_pid;
+ flock->l_pid = IS_FILE_PVT(fl) ? -1 : fl->fl_pid;
flock->l_start = fl->fl_start;
flock->l_len = fl->fl_end == OFFSET_MAX ? 0 :
fl->fl_end - fl->fl_start + 1;
--
1.8.4.2

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