Ceph has a need to know whether a particular inode has any locks set on
it. It's currently tracking that by a num_locks field in its
filp->private_data, but that's problematic as it tries to decrement this
field when releasing locks and that can race with the file being torn
down.
Add a new vfs_inode_has_locks helper that just returns whether any locks
are currently held on the inode.
Cc: Xiubo Li <xiubli@xxxxxxxxxx>
Reviewed-by: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
---
fs/locks.c | 23 +++++++++++++++++++++++
include/linux/fs.h | 1 +
2 files changed, 24 insertions(+)
diff --git a/fs/locks.c b/fs/locks.c
index 5876c8ff0edc..9ccf89b6c95d 100644
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -2672,6 +2672,29 @@ int vfs_cancel_lock(struct file *filp, struct file_lock *fl)
}
EXPORT_SYMBOL_GPL(vfs_cancel_lock);
+/**
+ * vfs_inode_has_locks - are any file locks held on @inode?
+ * @inode: inode to check for locks
+ *
+ * Return true if there are any FL_POSIX or FL_FLOCK locks currently
+ * set on @inode.
+ */
+bool vfs_inode_has_locks(struct inode *inode)
+{
+ struct file_lock_context *ctx;
+ bool ret;
+
+ ctx = smp_load_acquire(&inode->i_flctx);
+ if (!ctx)
+ return false;
+
+ spin_lock(&ctx->flc_lock);
+ ret = !list_empty(&ctx->flc_posix) || !list_empty(&ctx->flc_flock);
+ spin_unlock(&ctx->flc_lock);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(vfs_inode_has_locks);
+
#ifdef CONFIG_PROC_FS
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
diff --git a/include/linux/fs.h b/include/linux/fs.h
index e654435f1651..d6cb42b7e91c 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1170,6 +1170,7 @@ extern int locks_delete_block(struct file_lock *);
extern int vfs_test_lock(struct file *, struct file_lock *);
extern int vfs_lock_file(struct file *, unsigned int, struct file_lock *, struct file_lock *);
extern int vfs_cancel_lock(struct file *filp, struct file_lock *fl);
+bool vfs_inode_has_locks(struct inode *inode);
extern int locks_lock_inode_wait(struct inode *inode, struct file_lock *fl);
extern int __break_lease(struct inode *inode, unsigned int flags, unsigned int type);
extern void lease_get_mtime(struct inode *, struct timespec64 *time);
--
2.38.1
