LUDOC-276 protocol: Document RPCs for setattr

[doc/protocol.git] / lustre_file_ids.txt

diff --git a/lustre_file_ids.txt b/lustre_file_ids.txt
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+Lustre File IDs
+^^^^^^^^^^^^^^^
+[[file-id]]
+
+Each resource stored on a target is assigned an identifier that is
+unique to that resource.
+
+----
+struct lu_fid {
+       __u64 f_seq;
+       __u32 f_oid;
+       __u32 f_ver;
+};
+----
+
+The 'f_seq' field identifies the target. That is, all the resources
+with a common 'f_seq' will be on the same target. A target can have
+more than one 'f_seq' value assigned to it.
+
+The 'f_oid' gives the specific value for a given resource that is
+unique to that resource on that target.
+
+The 'f_ver' value identifies which version of a resource is being
+identified, in the event that the resource is being updated, and
+different hosts might be referring to different versions of the same
+resource.