update sources to ceph Nautilus 14.2.1

[ceph.git] / ceph / doc / dev / mds_internals / data-structures.rst

diff --git a/ceph/doc/dev/mds_internals/data-structures.rst b/ceph/doc/dev/mds_internals/data-structures.rst
index 1197b62f3a4b9175ee4320d573338aff66717c5d..c77175a16fca5e9bbce8f1e345d067ee5eb98b3a 100644 (file)
--- a/ceph/doc/dev/mds_internals/data-structures.rst
+++ b/ceph/doc/dev/mds_internals/data-structures.rst
@@ -34,3 +34,11 @@ As this doc is being written, size of CInode is about 1400 bytes, size of CDentr
 is about 400 bytes, size of CDir is about 700 bytes. These data structures are
 quite large. Please be careful if you want to add new fields to them.
 
+*OpenFileTable*
+  Open file table tracks open files and their ancestor directories. Recovering
+  MDS can easily get open files' paths, significantly reducing the time of
+  loading inodes for open files. Each entry in the table corresponds to an inode,
+  it records linkage information (parent inode and dentry name) of the inode. MDS
+  can constructs the inode's path by recursively lookup parent inode's linkage.
+  Open file table is stored in omap of RADOS objects, table entries correspond to
+  KV pairs in omap.