> On Mar 4, 2022, at 7:37 PM, Dai Ngo <dai.ngo@xxxxxxxxxx> wrote:
>
> Add helper locks_any_blockers to check if there is any blockers
> for a file_lock.
>
> Signed-off-by: Dai Ngo <dai.ngo@xxxxxxxxxx>
> ---
> include/linux/fs.h | 10 ++++++++++
> 1 file changed, 10 insertions(+)
>
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index 831b20430d6e..7f5756bfcc13 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -1200,6 +1200,11 @@ extern void lease_unregister_notifier(struct notifier_block *);
> struct files_struct;
> extern void show_fd_locks(struct seq_file *f,
> struct file *filp, struct files_struct *files);
> +
> +static inline bool locks_has_blockers_locked(struct file_lock *lck)
> +{
> + return !list_empty(&lck->fl_blocked_requests);
> +}
> #else /* !CONFIG_FILE_LOCKING */
> static inline int fcntl_getlk(struct file *file, unsigned int cmd,
> struct flock __user *user)
> @@ -1335,6 +1340,11 @@ static inline int lease_modify(struct file_lock *fl, int arg,
> struct files_struct;
> static inline void show_fd_locks(struct seq_file *f,
> struct file *filp, struct files_struct *files) {}
> +
> +static inline bool locks_has_blockers_locked(struct file_lock *lck)
> +{
> + return false;
> +}
> #endif /* !CONFIG_FILE_LOCKING */
>
> static inline struct inode *file_inode(const struct file *f)
Hm. This is not exactly what I had in mind.
In order to be more kABI friendly, fl_blocked_requests should be
dereferenced only in fs/locks.c. IMO you want to take the inner
loop in nfs4_lockowner_has_blockers() and make that a function
that lives in fs/locks.c. Something akin to:
fs/locks.c:
/**
* locks_owner_has_blockers - Check for blocking lock requests
* @flctx: file lock context
* @owner: lock owner
*
* Return values:
* %true: @ctx has at least one blocker
* %false: @ctx has no blockers
*/
bool locks_owner_has_blockers(struct file_lock_context *flctx,
fl_owner_t owner)
{
struct file_lock *fl;
spin_lock(&flctx->flc_lock);
list_for_each_entry(fl, &flctx->flc_posix, fl_list) {
if (fl->fl_owner != owner)
continue;
if (!list_empty(&fl->fl_blocked_requests)) {
spin_unlock(&flctx->flc_lock);
return true;
}
}
spin_unlock(&flctx->flc_lock);
return false;
}
EXPORT_SYMBOL(locks_owner_has_blockers);
As a subsequent clean up (which anyone can do at a later point),
a similar change could be done to check_for_locks(). This bit of
code seems to appear in several other filesystems, for example:
7643 inode = locks_inode(nf->nf_file);
7644 flctx = inode->i_flctx;
7645
7646 if (flctx && !list_empty_careful(&flctx->flc_posix)) {
7647 spin_lock(&flctx->flc_lock);
7648 list_for_each_entry(fl, &flctx->flc_posix, fl_list) {
7649 if (fl->fl_owner == (fl_owner_t)lowner) {
7650 status = true;
7651 break;
7652 }
7653 }
7654 spin_unlock(&flctx->flc_lock);
7655 }
--
Chuck Lever
