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/metadisp-lookup.c | 90 +++++++++++++++++++++++++
 1 file changed, 90 insertions(+)
 create mode 100644 xlators/features/metadisp/src/metadisp-lookup.c

(limited to 'xlators/features/metadisp/src/metadisp-lookup.c')

diff --git a/xlators/features/metadisp/src/metadisp-lookup.c b/xlators/features/metadisp/src/metadisp-lookup.c
new file mode 100644
index 00000000000..27d90c9f746
--- /dev/null
+++ b/xlators/features/metadisp/src/metadisp-lookup.c
@@ -0,0 +1,90 @@
+#include "metadisp.h"
+#include <glusterfs/call-stub.h>
+
+/**
+ * Lookup, like stat, is a two-step process for grabbing the metadata details
+ * as well as the data details.
+ */
+
+int32_t
+metadisp_backend_lookup_cbk(call_frame_t *frame, void *cookie, xlator_t *this,
+                            int32_t op_ret, int32_t op_errno, inode_t *inode,
+                            struct iatt *buf, dict_t *xdata,
+                            struct iatt *postparent)
+{
+    METADISP_TRACE("backend_lookup_cbk");
+    if (op_errno == ENOENT) {
+        op_errno = ENODATA;
+        op_ret = -1;
+    }
+    STACK_UNWIND_STRICT(lookup, frame, op_ret, op_errno, inode, buf, xdata,
+                        postparent);
+    return 0;
+}
+
+int32_t
+metadisp_backend_lookup_resume(call_frame_t *frame, xlator_t *this, loc_t *loc,
+                               dict_t *xdata)
+{
+    METADISP_TRACE("backend_lookup_resume");
+    loc_t backend_loc = {
+        0,
+    };
+    if (build_backend_loc(loc->gfid, loc, &backend_loc)) {
+        goto unwind;
+    }
+
+    STACK_WIND(frame, metadisp_backend_lookup_cbk, DATA_CHILD(this),
+               DATA_CHILD(this)->fops->lookup, &backend_loc, xdata);
+    return 0;
+
+unwind:
+    STACK_UNWIND_STRICT(lookup, frame, -1, EINVAL, NULL, NULL, NULL, NULL);
+    return 0;
+}
+
+int32_t
+metadisp_lookup_cbk(call_frame_t *frame, void *cookie, xlator_t *this,
+                    int32_t op_ret, int32_t op_errno, inode_t *inode,
+                    struct iatt *buf, dict_t *xdata, struct iatt *postparent)
+{
+    METADISP_TRACE("%d %d", op_ret, op_errno);
+    call_stub_t *stub = NULL;
+    stub = cookie;
+
+    if (op_ret != 0) {
+        goto unwind;
+    }
+
+    if (!IA_ISREG(buf->ia_type)) {
+        goto unwind;
+    } else if (!stub) {
+        op_errno = EINVAL;
+        goto unwind;
+    }
+
+    METADISP_TRACE("resuming stub");
+
+    // memcpy(stub->args.loc.gfid, buf->ia_gfid, sizeof(uuid_t));
+    call_resume(stub);
+    return 0;
+unwind:
+    METADISP_TRACE("unwinding %d %d", op_ret, op_errno);
+    STACK_UNWIND_STRICT(lookup, frame, op_ret, op_errno, inode, buf, xdata,
+                        postparent);
+    if (stub) {
+        call_stub_destroy(stub);
+    }
+    return 0;
+}
+
+int32_t
+metadisp_lookup(call_frame_t *frame, xlator_t *this, loc_t *loc, dict_t *xdata)
+{
+    METADISP_TRACE("lookup");
+    call_stub_t *stub = NULL;
+    stub = fop_lookup_stub(frame, metadisp_backend_lookup_resume, loc, xdata);
+    STACK_WIND_COOKIE(frame, metadisp_lookup_cbk, stub, METADATA_CHILD(this),
+                      METADATA_CHILD(this)->fops->lookup, loc, xdata);
+    return 0;
+}
-- 
cgit