locks: require that flock->l_pid be set to 0 for file-private locks (90478939) · Commits · 戴 / test

Neil Brown suggested potentially overloading the l_pid value as a "lock context" field for file-private locks. While I don't think we will probably want to do that here, it's probably a good idea to ensure that in the future we could extend this API without breaking existing callers. Typically the l_pid value is ignored for incoming struct flock arguments, serving mainly as a place to return the pid of the owner if there is a conflicting lock. For file-private locks, require that it currently be set to 0 and return EINVAL if it isn't. If we eventually want to make a non-zero l_pid mean something, then this will help ensure that we don't break legacy programs that are using file-private locks. Cc: Neil Brown <neilb@suse.de> Signed-off-by:

Jeff Layton <jlayton@redhat.com>

fs/locks.c

+24 −0

Original line number	Diff line number	Diff line
		@@ -1931,6 +1931,10 @@ int fcntl_getlk(struct file filp, unsigned int cmd, struct flock __user l)
		goto out;

		if (cmd == F_GETLKP) {
		error = -EINVAL;
		if (flock.l_pid != 0)
		goto out;

		cmd = F_GETLK;
		file_lock.fl_flags \|= FL_FILE_PVT;
		file_lock.fl_owner = (fl_owner_t)filp;
		@@ -2062,11 +2066,19 @@ again:
		*/
		switch (cmd) {
		case F_SETLKP:
		error = -EINVAL;
		if (flock.l_pid != 0)
		goto out;

		cmd = F_SETLK;
		file_lock->fl_flags \|= FL_FILE_PVT;
		file_lock->fl_owner = (fl_owner_t)filp;
		break;
		case F_SETLKPW:
		error = -EINVAL;
		if (flock.l_pid != 0)
		goto out;

		cmd = F_SETLKW;
		file_lock->fl_flags \|= FL_FILE_PVT;
		file_lock->fl_owner = (fl_owner_t)filp;
		@@ -2121,6 +2133,10 @@ int fcntl_getlk64(struct file filp, unsigned int cmd, struct flock64 __user l)
		goto out;

		if (cmd == F_GETLKP) {
		error = -EINVAL;
		if (flock.l_pid != 0)
		goto out;

		cmd = F_GETLK64;
		file_lock.fl_flags \|= FL_FILE_PVT;
		file_lock.fl_owner = (fl_owner_t)filp;
		@@ -2185,11 +2201,19 @@ again:
		*/
		switch (cmd) {
		case F_SETLKP:
		error = -EINVAL;
		if (flock.l_pid != 0)
		goto out;

		cmd = F_SETLK64;
		file_lock->fl_flags \|= FL_FILE_PVT;
		file_lock->fl_owner = (fl_owner_t)filp;
		break;
		case F_SETLKPW:
		error = -EINVAL;
		if (flock.l_pid != 0)
		goto out;

		cmd = F_SETLKW64;
		file_lock->fl_flags \|= FL_FILE_PVT;
		file_lock->fl_owner = (fl_owner_t)filp;

Admin message