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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: Xiubo Li <xiubli@redhat.com>
Reviewed-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
This commit is contained in:
Jeff Layton 2022-11-14 08:33:09 -05:00
parent 7e8e5cc818
commit ab1ddef98a
2 changed files with 29 additions and 0 deletions
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23
fs/locks.c
View File

@ -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>

6
include/linux/fs.h
View File

@ -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;