[PATCH 06/12] locks: use properly initialized file_lock when unlocking.

NeilBrown
2018-11-05T01:32:20Z

Both locks_remove_posix() and locks_remove_flock() use a
struct file_lock without calling locks_init_lock() on it.
This means the various list_heads are not initialized, which
will become a problem with a later patch.

So change them both to initialize properly. For flock locks,
this involves using flock_make_lock(), and changing it to
allow a file_lock to be passed in, so memory allocation isn't
always needed.

Signed-off-by: NeilBrown <neilb@suse.com>
---
fs/locks.c | 21 +++++++++------------
1 file changed, 9 insertions(+), 12 deletions(-)

diff --git a/fs/locks.c b/fs/locks.c
index b8f33792a0a6..ea999ce0e93c 100644
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -418,15 +418,15 @@ static inline int flock_translate_cmd(int cmd) {

/* Fill in a file_lock structure with an appropriate FLOCK lock. */
static struct file_lock *
-flock_make_lock(struct file *filp, unsigned int cmd)
+flock_make_lock(struct file *filp, unsigned int cmd, struct file_lock *fl)
{
- struct file_lock *fl;
int type = flock_translate_cmd(cmd);

if (type < 0)
return ERR_PTR(type);

- fl = locks_alloc_lock();
+ if (fl == NULL)
+ fl = locks_alloc_lock();
if (fl == NULL)
return ERR_PTR(-ENOMEM);

@@ -2008,7 +2008,7 @@ SYSCALL_DEFINE2(flock, unsigned int, fd, unsigned int, cmd)
!(f.file->f_mode & (FMODE_READ|FMODE_WRITE)))
goto out_putf;

- lock = flock_make_lock(f.file, cmd);
+ lock = flock_make_lock(f.file, cmd, NULL);
if (IS_ERR(lock)) {
error = PTR_ERR(lock);
goto out_putf;
@@ -2483,6 +2483,7 @@ void locks_remove_posix(struct file *filp, fl_owner_t owner)
if (!ctx || list_empty(&ctx->flc_posix))
return;

+ locks_init_lock(&lock);
lock.fl_type = F_UNLCK;
lock.fl_flags = FL_POSIX | FL_CLOSE;
lock.fl_start = 0;
@@ -2506,19 +2507,15 @@ EXPORT_SYMBOL(locks_remove_posix);
static void
locks_remove_flock(struct file *filp, struct file_lock_context *flctx)
{
- struct file_lock fl = {
- .fl_owner = filp,
- .fl_pid = current->tgid,
- .fl_file = filp,
- .fl_flags = FL_FLOCK | FL_CLOSE,
- .fl_type = F_UNLCK,
- .fl_end = OFFSET_MAX,
- };
+ struct file_lock fl;
struct inode *inode = locks_inode(filp);

if (list_empty(&flctx->flc_flock))
return;

+ flock_make_lock(filp, LOCK_UN, &fl);
+ fl.fl_flags |= FL_CLOSE;
+
if (filp->f_op->flock)
filp->f_op->flock(filp, F_SETLKW, &fl);
else