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locks: add lock cancel command 

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);