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authorMiklos Szeredi <mszeredi@suse.cz>2008-07-25 01:48:57 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2008-07-25 10:53:47 -0700
commitbde74e4bc64415b142e556a34d295a52a1b7da9d (patch)
treeb6bd229307ccab9b1ad03ffbc75f1f9960cd49e4 /include
parentcc77b1521d06be07c9bb1a4a3e1f775dcaa15093 (diff)
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locks: add special return value for asynchronous locks
Use a special error value FILE_LOCK_DEFERRED to mean that a locking operation returned asynchronously. This is returned by posix_lock_file() for sleeping locks to mean that the lock has been queued on the block list, and will be woken up when it might become available and needs to be retried (either fl_lmops->fl_notify() is called or fl_wait is woken up). f_op->lock() to mean either the above, or that the filesystem will call back with fl_lmops->fl_grant() when the result of the locking operation is known. The filesystem can do this for sleeping as well as non-sleeping locks. This is to make sure, that return values of -EAGAIN and -EINPROGRESS by filesystems are not mistaken to mean an asynchronous locking. This also makes error handling in fs/locks.c and lockd/svclock.c slightly cleaner. Signed-off-by: Miklos Szeredi <mszeredi@suse.cz> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Cc: "J. Bruce Fields" <bfields@fieldses.org> Cc: Matthew Wilcox <matthew@wil.cx> Cc: David Teigland <teigland@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include')
-rw-r--r--include/linux/fs.h6
1 files changed, 6 insertions, 0 deletions
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 4b86f806014..49d8eb7a71b 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -886,6 +886,12 @@ static inline int file_check_writeable(struct file *filp)
#define FL_SLEEP 128 /* A blocking lock */
/*
+ * Special return value from posix_lock_file() and vfs_lock_file() for
+ * asynchronous locking.
+ */
+#define FILE_LOCK_DEFERRED 1
+
+/*
* The POSIX file lock owner is determined by
* the "struct files_struct" in the thread group
* (or NULL for no owner - BSD locks).