From: Marc Eshel Date: Wed, 6 Dec 2006 04:31:28 +0000 (-0500) Subject: locks: add fl_grant callback for asynchronous lock return X-Git-Tag: v2.6.22-rc1~818^2~7 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=2beb6614f5e36c6165b704c167d82ef3e4ceaa0c;p=pandora-kernel.git locks: add fl_grant callback for asynchronous lock return Acquiring a lock on a cluster filesystem may require communication with remote hosts, and to avoid blocking lockd or nfsd threads during such communication, we allow the results to be returned asynchronously. When a ->lock() call needs to block, the file system will return -EINPROGRESS, and then later return the results with a call to the routine in the fl_grant field of the lock_manager_operations struct. This differs from the case when ->lock returns -EAGAIN to a blocking lock request; in that case, the filesystem calls fl_notify when the lock is granted, and the caller retries the original lock. So while fl_notify is merely a hint to the caller that it should retry, fl_grant actually communicates the final result of the lock operation (with the lock already acquired in the succesful case). Therefore fl_grant takes a lock, a status and, for the test lock case, a conflicting lock. We also allow fl_grant to return an error to the filesystem, to handle the case where the fl_grant requests arrives after the lock manager has already given up waiting for it. Signed-off-by: Marc Eshel Signed-off-by: J. Bruce Fields --- Reading git-diff-tree failed