Commit ab1ddef9 authored by Jeff Layton's avatar Jeff Layton
Browse files

filelock: new helper: vfs_inode_has_locks 



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.

Reviewed-by: default avatarXiubo Li <xiubli@redhat.com>
Reviewed-by: default avatarChristoph Hellwig <hch@infradead.org>
Signed-off-by: default avatarJeff Layton <jlayton@kernel.org>
parent 7e8e5cc8

fs/locks.c

+23 −0
Original line number Diff line number Diff line
@@ -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>

include/linux/fs.h

+6 −0
Original line number Diff line number Diff line
@@ -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);
@@ -1284,6 +1285,11 @@ static inline int vfs_cancel_lock(struct file *filp, struct file_lock *fl) 
	return 0;

}



static inline bool vfs_inode_has_locks(struct inode *inode)

{

	return false;

}



static inline int locks_lock_inode_wait(struct inode *inode, struct file_lock *fl)

{

	return -ENOLCK;