2022-05-03 00:37:02

by Dai Ngo

Subject: [PATCH RFC v25 4/7] fs/lock: add helper locks_owner_has_blockers to check for blockers

Add helper locks_owner_has_blockers to check if there is any blockers
for a given lockowner.

Reviewed-by: J. Bruce Fields <[email protected]>
Signed-off-by: Dai Ngo <[email protected]>
---
fs/locks.c | 28 ++++++++++++++++++++++++++++
include/linux/fs.h | 7 +++++++
2 files changed, 35 insertions(+)

diff --git a/fs/locks.c b/fs/locks.c
index 8c6df10cd9ed..c369841ef7d1 100644
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -300,6 +300,34 @@ void locks_release_private(struct file_lock *fl)
}
EXPORT_SYMBOL_GPL(locks_release_private);

+/**
+ * locks_owner_has_blockers - Check for blocking lock requests
+ * @flctx: file lock context
+ * @owner: lock owner
+ *
+ * Return values:
+ * %true: @owner has at least one blocker
+ * %false: @owner 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_GPL(locks_owner_has_blockers);
+
/* Free a lock which is not in use. */
void locks_free_lock(struct file_lock *fl)
{
diff --git a/include/linux/fs.h b/include/linux/fs.h
index bbde95387a23..b8ed7f974fb4 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1174,6 +1174,8 @@ 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);
+extern bool locks_owner_has_blockers(struct file_lock_context *flctx,
+ fl_owner_t owner);
#else /* !CONFIG_FILE_LOCKING */
static inline int fcntl_getlk(struct file *file, unsigned int cmd,
struct flock __user *user)
@@ -1309,6 +1311,11 @@ 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_owner_has_blockers(struct file_lock_context *flctx,
+ fl_owner_t owner)
+{
+ return false;
+}
#endif /* !CONFIG_FILE_LOCKING */

static inline struct inode *file_inode(const struct file *f)
--
2.9.5

2022-05-09 17:13:00

by Jeff Layton

Subject: Re: [PATCH RFC v25 4/7] fs/lock: add helper locks_owner_has_blockers to check for blockers

On Mon, 2022-05-02 at 14:19 -0700, Dai Ngo wrote:
> Add helper locks_owner_has_blockers to check if there is any blockers
> for a given lockowner.
>
> Reviewed-by: J. Bruce Fields <[email protected]>
> Signed-off-by: Dai Ngo <[email protected]>
> ---
> fs/locks.c | 28 ++++++++++++++++++++++++++++
> include/linux/fs.h | 7 +++++++
> 2 files changed, 35 insertions(+)
>
> diff --git a/fs/locks.c b/fs/locks.c
> index 8c6df10cd9ed..c369841ef7d1 100644
> --- a/fs/locks.c
> +++ b/fs/locks.c
> @@ -300,6 +300,34 @@ void locks_release_private(struct file_lock *fl)
> }
> EXPORT_SYMBOL_GPL(locks_release_private);
>
> +/**
> + * locks_owner_has_blockers - Check for blocking lock requests
> + * @flctx: file lock context
> + * @owner: lock owner
> + *
> + * Return values:
> + * %true: @owner has at least one blocker
> + * %false: @owner 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_GPL(locks_owner_has_blockers);
> +
> /* Free a lock which is not in use. */
> void locks_free_lock(struct file_lock *fl)
> {
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index bbde95387a23..b8ed7f974fb4 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -1174,6 +1174,8 @@ 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);
> +extern bool locks_owner_has_blockers(struct file_lock_context *flctx,
> + fl_owner_t owner);
> #else /* !CONFIG_FILE_LOCKING */
> static inline int fcntl_getlk(struct file *file, unsigned int cmd,
> struct flock __user *user)
> @@ -1309,6 +1311,11 @@ 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_owner_has_blockers(struct file_lock_context *flctx,
> + fl_owner_t owner)
> +{
> + return false;
> +}
> #endif /* !CONFIG_FILE_LOCKING */
>
> static inline struct inode *file_inode(const struct file *f)

Reviewed-by: Jeff Layton <[email protected]>