From: Marc Eshel <eshel@xxxxxxxxxxxxxxx> - unquoted
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: "J. Bruce Fields" <bfields@xxxxxxxxxxxxxx>
---
fs/locks.c | 17 +++++++++++++++++
include/linux/fcntl.h | 4 ++++
include/linux/fs.h | 1 +
3 files changed, 22 insertions(+), 0 deletions(-)
diff --git a/fs/locks.c b/fs/locks.c
index 485b38a..68ae4d4 100644
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -2041,6 +2041,23 @@ 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);
+ else
+ return posix_unblock_lock(filp, fl);
+}
+
+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;
diff --git a/include/linux/fcntl.h b/include/linux/fcntl.h
index 996f561..40b9326 100644
--- a/include/linux/fcntl.h
+++ b/include/linux/fcntl.h
@@ -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)
diff --git a/include/linux/fs.h b/include/linux/fs.h
index bec1dbe..c58690d 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -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);
--
1.5.0.rc1.gf4b6c
-
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