From a8599bd821d084d04a3290fffae1071624ec00ea Mon Sep 17 00:00:00 2001 From: Sage Weil Date: Tue, 6 Oct 2009 11:31:12 -0700 Subject: [PATCH] ceph: capability management The Ceph metadata servers control client access to inode metadata and file data by issuing capabilities, granting clients permission to read and/or write both inode field and file data to OSDs (storage nodes). Each capability consists of a set of bits indicating which operations are allowed. If the client holds a *_SHARED cap, the client has a coherent value that can be safely read from the cached inode. In the case of a *_EXCL (exclusive) or FILE_WR capabilities, the client is allowed to change inode attributes (e.g., file size, mtime), note its dirty state in the ceph_cap, and asynchronously flush that metadata change to the MDS. In the event of a conflicting operation (perhaps by another client), the MDS will revoke the conflicting client capabilities. In order for a client to cache an inode, it must hold a capability with at least one MDS server. When inodes are released, release notifications are batched and periodically sent en masse to the MDS cluster to release server state. Signed-off-by: Sage Weil --- Reading git-format-patch failed