From eddbf3a23392ca47a697779167c61b4ab790732b Mon Sep 17 00:00:00 2001
From: Sheena Artrip <sheenobu@fb.com>
Date: Wed, 29 Jan 2020 15:12:17 -0800
Subject: metadisp: new translator for data and metadata separation

Summary:

feature/metadisp is an xlator for performing "metadata dispersal" across
multiple children. it does this by flattening the complex
POSIX paths into /$GFID style paths, then forwarding the
metadata operations to its first child and forwarding the
data operations to its second child.

The purpose of this xlator is to allow separation of data and metadata,
in cases where metadata might be stored in another format (embedded kv?),
on another disk (ssd), on another host (dht2).

Change-Id: I392c8bd0c867a3237d144aea327323f700a2728d
Updates: #816
Signed-Off-By: Sheena Artrip <sheenobu@fb.com>
Tested-By: Amar Tumballi <amar@kadalu.io>
---
 xlators/features/metadisp/src/gen-fops.py | 160 ++++++++++++++++++++++++++++++
 1 file changed, 160 insertions(+)
 create mode 100644 xlators/features/metadisp/src/gen-fops.py

(limited to 'xlators/features/metadisp/src/gen-fops.py')

diff --git a/xlators/features/metadisp/src/gen-fops.py b/xlators/features/metadisp/src/gen-fops.py
new file mode 100644
index 00000000000..8b5e120fdec
--- /dev/null
+++ b/xlators/features/metadisp/src/gen-fops.py
@@ -0,0 +1,160 @@
+#!/usr/bin/python
+
+import sys
+from generator import fop_subs, generate
+
+FN_METADATA_CHILD_GENERIC = """
+int32_t
+metadisp_@NAME@ (call_frame_t *frame, xlator_t *this,
+                 @LONG_ARGS@)
+{
+  METADISP_TRACE("@NAME@ metadata");
+  STACK_WIND (frame, default_@NAME@_cbk,
+              METADATA_CHILD(this), METADATA_CHILD(this)->fops->@NAME@,
+              @SHORT_ARGS@);
+  return 0;
+}
+"""
+
+FN_GENERIC_TEMPLATE = """
+int32_t
+metadisp_@NAME@ (call_frame_t *frame, xlator_t *this,
+                          @LONG_ARGS@)
+{
+  METADISP_TRACE("@NAME@ generic");
+  STACK_WIND (frame, default_@NAME@_cbk,
+                          DATA_CHILD(this), DATA_CHILD(this)->fops->@NAME@,
+                          @SHORT_ARGS@);
+  return 0;
+}
+"""
+
+FN_DATAFD_TEMPLATE = """
+int32_t
+metadisp_@NAME@ (call_frame_t *frame, xlator_t *this,
+                          @LONG_ARGS@)
+{
+  METADISP_TRACE("@NAME@ datafd");
+  xlator_t *child = NULL;
+  child = DATA_CHILD(this);
+  STACK_WIND (frame, default_@NAME@_cbk,
+                          child, child->fops->@NAME@,
+                          @SHORT_ARGS@);
+  return 0;
+}
+"""
+
+FN_DATALOC_TEMPLATE = """
+int32_t
+metadisp_@NAME@ (call_frame_t *frame, xlator_t *this,
+                          @LONG_ARGS@)
+{
+  METADISP_TRACE("@NAME@ dataloc");
+  loc_t backend_loc = {
+      0,
+  };
+  if (build_backend_loc(loc->gfid, loc, &backend_loc)) {
+      goto unwind;
+  }
+  xlator_t *child = NULL;
+  child = DATA_CHILD(this);
+  STACK_WIND (frame, default_@NAME@_cbk,
+                          child, child->fops->@NAME@,
+                          @SHORT_ARGS@);
+  return 0;
+
+unwind:
+  STACK_UNWIND_STRICT(lookup, frame, -1, EINVAL, NULL, NULL, NULL, NULL);
+  return 0;
+}
+"""
+
+FOPS_LINE_TEMPLATE = "\t.@NAME@ = metadisp_@NAME@,"
+
+skipped = [
+    "readdir",
+    "readdirp",
+    "lookup",
+    "fsync",
+    "stat",
+    "open",
+    "create",
+    "unlink",
+    "setattr",
+    # TODO: implement "inodelk",
+]
+
+
+def gen_fops():
+    done = skipped
+
+    #
+    # these are fops that wind to the DATA_CHILD
+    #
+    # NOTE: re-written in order from google doc:
+    #          https://docs.google.com/document/d/1KEwVtSNvDhs4qb63gWx2ulCp5GJjge77NGJk4p_Ms4Q
+    for name in [
+        "writev",
+        "readv",
+        "ftruncate",
+        "zerofill",
+        "discard",
+        "seek",
+        "fstat",
+    ]:
+        done = done + [name]
+        print(generate(FN_DATAFD_TEMPLATE, name, fop_subs))
+
+    for name in ["truncate"]:
+        done = done + [name]
+        print(generate(FN_DATALOC_TEMPLATE, name, fop_subs))
+
+    # these are fops that operate solely on dentries, folders,
+    # or extended attributes. Therefore, they must always
+    # wind to METADATA_CHILD and should never perform
+    # any path rewriting
+    #
+    # NOTE: re-written in order from google doc:
+    #          https://docs.google.com/document/d/1KEwVtSNvDhs4qb63gWx2ulCp5GJjge77NGJk4p_Ms4Q
+    for name in [
+        "mkdir",
+        "symlink",
+        "link",
+        "rename",
+        "mknod",
+        "opendir",
+        # "readdir,  # special-cased
+        # "readdirp, # special-cased
+        "fsyncdir",
+        # "setattr", # special-cased
+        "readlink",
+        "fentrylk",
+        "access",
+        # TODO: these wind to both,
+        # data for backend-attributes and metadata for the rest
+        "xattrop",
+        "setxattr",
+        "getxattr",
+        "removexattr",
+        "fgetxattr",
+        "fsetxattr",
+        "fremovexattr",
+    ]:
+
+        done = done + [name]
+        print(generate(FN_METADATA_CHILD_GENERIC, name, fop_subs))
+
+    print("struct xlator_fops fops = {")
+    for name in done:
+        print(generate(FOPS_LINE_TEMPLATE, name, fop_subs))
+
+    print("};")
+
+
+for l in open(sys.argv[1], "r").readlines():
+    if l.find("#pragma generate") != -1:
+        print("/* BEGIN GENERATED CODE - DO NOT MODIFY */")
+        gen_fops()
+        print("/* END GENERATED CODE */")
+    else:
+        print(l[:-1])
-- 
cgit