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locks: add lock cancel command

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Lock managers need to be able to cancel pending lock requests.  In the case
where the exported filesystem manages its own locks, it's not sufficient just
to call posix_unblock_lock(); we need to let the filesystem know what's
happening too.

We do this by adding a new fcntl lock command: FL_CANCELLK.  Some day this
might also be made available to userspace applications that could benefit from
an asynchronous locking api.

Signed-off-by: Marc Eshel <eshel@almaden.ibm.com>
Signed-off-by: "J. Bruce Fields" <bfields@citi.umich.edu>
This commit is contained in:
Marc Eshel 2007-01-18 17:52:58 -05:00 committed by J. Bruce Fields
parent 150b393456
commit 9b9d2ab415
3 changed files with 21 additions and 0 deletions
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16
fs/locks.c
View file

@ -2028,6 +2028,22 @@ posix_unblock_lock(struct file *filp, struct file_lock *waiter)
EXPORT_SYMBOL(posix_unblock_lock);
/**
* vfs_cancel_lock - file byte range unblock lock
* @filp: The file to apply the unblock to
* @fl: The lock to be unblocked
*
* Used by lock managers to cancel blocked requests
*/
int vfs_cancel_lock(struct file *filp, struct file_lock *fl)
{
if (filp->f_op && filp->f_op->lock)
return filp->f_op->lock(filp, F_CANCELLK, fl);
return 0;
}
EXPORT_SYMBOL_GPL(vfs_cancel_lock);
static void lock_get_status(char* out, struct file_lock *fl, int id, char *pfx)
{
struct inode *inode = NULL;

4
include/linux/fcntl.h
View file

@ -3,6 +3,10 @@
#include <asm/fcntl.h>
/* Cancel a blocking posix lock; internal use only until we expose an
* asynchronous lock api to userspace: */
#define F_CANCELLK (F_LINUX_SPECIFIC_BASE+5)
#define F_SETLEASE (F_LINUX_SPECIFIC_BASE+0)
#define F_GETLEASE (F_LINUX_SPECIFIC_BASE+1)

1
include/linux/fs.h
View file

@ -857,6 +857,7 @@ extern int posix_lock_file_wait(struct file *, struct file_lock *);
extern int posix_unblock_lock(struct file *, 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);
extern int flock_lock_file_wait(struct file *filp, struct file_lock *fl);
extern int __break_lease(struct inode *inode, unsigned int flags);
extern void lease_get_mtime(struct inode *, struct timespec *time);