afr: arbiter xlator

This patch adds the arbiter translator into the tree. This is a server
side xlator used for replica 3 volumes. It sits above posix and will be
loaded on the 3rd (last) brick of every afr subvolume in a replica 3
configuration. It intercepts inode read/write operations: reads are
unwound with ENOTCONN, inode writes are unwound with success without
actually passing them down to posix. Metadata operations are allowed to
pass through.

The CLI for creating a 3 way replica with arbiter is also added but kept
disabled (A 'normal' 3 way replica is created instead).

This patch is a part of the arbiter logic implementation for 3 way AFR,
details of which can be found at http://review.gluster.org/#/c/9656/

Change-Id: I395b81f49d5da52c466daf5c8518f1bbad9c16fa
BUG: 1199985
Signed-off-by: Ravishankar N <ravishankar@redhat.com>
Reviewed-on: http://review.gluster.org/9840
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Pranith Kumar Karampuri <pkarampu@redhat.com>
Reviewed-by: Vijay Bellur <vbellur@redhat.com>

8 files changed, 410 insertions, 1 deletions

diff --git a/xlators/features/Makefile.am b/xlators/features/Makefile.am
index 67d1338ed9e..5f35b37bc8e 100644
--- a/xlators/features/Makefile.am
+++ b/xlators/features/Makefile.am
@@ -1,4 +1,4 @@
-SUBDIRS = locks quota read-only mac-compat quiesce marker index barrier \
+SUBDIRS = locks quota read-only mac-compat quiesce marker index barrier arbiter\
           protect compress changelog changetimerecorder ganesha gfid-access $(GLUPY_SUBDIR) qemu-block \
           upcall snapview-client snapview-server trash #path-converter # filter
 
diff --git a/xlators/features/arbiter/Makefile.am b/xlators/features/arbiter/Makefile.am
new file mode 100644
index 00000000000..a985f42a877
--- /dev/null
+++ b/xlators/features/arbiter/Makefile.am
@@ -0,0 +1,3 @@
+SUBDIRS = src
+
+CLEANFILES =
diff --git a/xlators/features/arbiter/src/Makefile.am b/xlators/features/arbiter/src/Makefile.am
new file mode 100644
index 00000000000..edec57b892c
--- /dev/null
+++ b/xlators/features/arbiter/src/Makefile.am
@@ -0,0 +1,16 @@
+xlator_LTLIBRARIES = arbiter.la
+xlatordir = $(libdir)/glusterfs/$(PACKAGE_VERSION)/xlator/features
+
+arbiter_la_LDFLAGS = -module -avoid-version
+
+arbiter_la_SOURCES = arbiter.c
+_la_LIBADD = $(top_builddir)/libglusterfs/src/libglusterfs.la
+arbiter_la_LIBADD = $(top_builddir)/libglusterfs/src/libglusterfs.la
+
+noinst_HEADERS = arbiter.h arbiter-mem-types.h
+
+AM_CPPFLAGS = $(GF_CPPFLAGS) -I$(top_srcdir)/libglusterfs/src
+
+AM_CFLAGS = -Wall $(GF_CFLAGS)
+
+CLEANFILES =
diff --git a/xlators/features/arbiter/src/arbiter-mem-types.h b/xlators/features/arbiter/src/arbiter-mem-types.h
new file mode 100644
index 00000000000..200b59de695
--- /dev/null
+++ b/xlators/features/arbiter/src/arbiter-mem-types.h
@@ -0,0 +1,19 @@
+/*
+  Copyright (c) 2015 Red Hat, Inc. <http://www.redhat.com>
+  This file is part of GlusterFS.
+  This file is licensed to you under your choice of the GNU Lesser
+  General Public License, version 3 or any later version (LGPLv3 or
+  later), or the GNU General Public License, version 2 (GPLv2), in all
+  cases as published by the Free Software Foundation.
+*/
+
+#ifndef __ARBITER_MEM_TYPES_H__
+#define __ARBITER_MEM_TYPES_H__
+#include "mem-types.h"
+
+typedef enum gf_arbiter_mem_types_ {
+        gf_arbiter_mt_inode_ctx_t =  gf_common_mt_end + 1,
+        gf_arbiter_mt_iatt,
+        gf_arbiter_mt_end
+} gf_arbiter_mem_types_t;
+#endif
diff --git a/xlators/features/arbiter/src/arbiter.c b/xlators/features/arbiter/src/arbiter.c
new file mode 100644
index 00000000000..87145da5680
--- /dev/null
+++ b/xlators/features/arbiter/src/arbiter.c
@@ -0,0 +1,324 @@
+/*
+  Copyright (c) 2015 Red Hat, Inc. <http://www.redhat.com>
+  This file is part of GlusterFS.
+
+  This file is licensed to you under your choice of the GNU Lesser
+  General Public License, version 3 or any later version (LGPLv3 or
+  later), or the GNU General Public License, version 2 (GPLv2), in all
+  cases as published by the Free Software Foundation.
+*/
+
+#ifndef _CONFIG_H
+#define _CONFIG_H
+#include "config.h"
+#endif
+
+#include "arbiter.h"
+#include "arbiter-mem-types.h"
+#include "glusterfs.h"
+#include "xlator.h"
+#include "logging.h"
+
+void
+arbiter_inode_ctx_destroy (arbiter_inode_ctx_t *ctx)
+{
+        if (!ctx)
+                return;
+        GF_FREE (ctx->iattbuf);
+        GF_FREE (ctx);
+}
+
+static arbiter_inode_ctx_t *
+__arbiter_inode_ctx_get (inode_t *inode, xlator_t *this)
+{
+
+        arbiter_inode_ctx_t *ctx = NULL;
+        int ret = 0;
+        uint64_t ctx_addr = 0;
+
+        ret = __inode_ctx_get (inode, this, &ctx_addr);
+        if (ret == 0) {
+                ctx = (arbiter_inode_ctx_t *) (long) ctx_addr;
+                goto out;
+        }
+
+        ctx = GF_CALLOC (1, sizeof (*ctx), gf_arbiter_mt_inode_ctx_t);
+        if (!ctx)
+                goto fail;
+        ctx->iattbuf = GF_CALLOC (1, sizeof (*ctx->iattbuf),
+                                  gf_arbiter_mt_iatt);
+        if (!ctx->iattbuf)
+                goto fail;
+        ret = __inode_ctx_put (inode, this, (uint64_t)ctx);
+        if (ret) {
+                gf_log_callingfn (this->name, GF_LOG_ERROR, "failed to "
+                                  "set the inode ctx (%s)",
+                                  uuid_utoa (inode->gfid));
+                goto fail;
+        }
+out:
+        return ctx;
+fail:
+        arbiter_inode_ctx_destroy (ctx);
+        return NULL;
+}
+
+static arbiter_inode_ctx_t *
+arbiter_inode_ctx_get (inode_t *inode, xlator_t *this)
+{
+        arbiter_inode_ctx_t *ctx = NULL;
+
+        LOCK(&inode->lock);
+        {
+                ctx = __arbiter_inode_ctx_get (inode, this);
+        }
+        UNLOCK(&inode->lock);
+        return ctx;
+}
+
+int32_t
+arbiter_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)
+{
+        arbiter_inode_ctx_t *ctx = NULL;
+
+        if (op_ret != 0)
+                goto unwind;
+        ctx = arbiter_inode_ctx_get (inode, this);
+        if (!ctx) {
+                op_ret = -1;
+                op_errno = ENOMEM;
+                goto unwind;
+        }
+        memcpy (ctx->iattbuf, buf, sizeof (*ctx->iattbuf));
+
+unwind:
+        STACK_UNWIND_STRICT (lookup, frame, op_ret, op_errno, inode, buf,
+                             xdata, postparent);
+        return 0;
+}
+
+int32_t
+arbiter_lookup (call_frame_t *frame, xlator_t *this, loc_t *loc, dict_t *xdata)
+{
+        STACK_WIND (frame, arbiter_lookup_cbk, FIRST_CHILD(this),
+                         FIRST_CHILD(this)->fops->lookup, loc, xdata);
+        return 0;
+}
+
+int32_t
+arbiter_readv (call_frame_t *frame,  xlator_t *this, fd_t *fd, size_t size,
+               off_t offset, uint32_t flags, dict_t *xdata)
+{
+        STACK_UNWIND_STRICT (readv, frame, -1, ENOTCONN, NULL, 0, NULL, NULL,
+                             NULL);
+        return 0;
+}
+
+int32_t
+arbiter_truncate (call_frame_t *frame, xlator_t *this, loc_t *loc, off_t offset,
+                  dict_t *xdata)
+{
+        arbiter_inode_ctx_t *ctx      = NULL;
+        struct iatt         *buf      = NULL;
+        int32_t              op_ret   = 0;
+        int32_t              op_errno = 0;
+
+        ctx = arbiter_inode_ctx_get (loc->inode, this);
+        if (!ctx) {
+                op_ret = -1;
+                op_errno = ENOMEM;
+                goto unwind;
+        }
+        buf = ctx->iattbuf;
+unwind:
+        STACK_UNWIND_STRICT (truncate, frame, op_ret, op_errno, buf, buf,
+                             xdata);
+        return 0;
+}
+
+int32_t
+arbiter_ftruncate (call_frame_t *frame, xlator_t *this, fd_t *fd, off_t offset,
+                   dict_t *xdata)
+
+{
+        arbiter_inode_ctx_t *ctx      = NULL;
+        struct iatt         *buf      = NULL;
+        int32_t              op_ret   = 0;
+        int32_t              op_errno = 0;
+
+        ctx = arbiter_inode_ctx_get (fd->inode, this);
+        if (!ctx) {
+                op_ret = -1;
+                op_errno = ENOMEM;
+                goto unwind;
+        }
+        buf = ctx->iattbuf;
+unwind:
+        STACK_UNWIND_STRICT (ftruncate, frame, op_ret, op_errno, buf, buf,
+                             xdata);
+        return 0;
+}
+
+int32_t
+arbiter_writev (call_frame_t *frame, xlator_t *this, fd_t *fd,
+                struct iovec *vector, int32_t count, off_t off, uint32_t flags,
+                struct iobref *iobref, dict_t *xdata)
+{
+        arbiter_inode_ctx_t *ctx      = NULL;
+        struct iatt         *buf      = NULL;
+        int                  op_ret   = 0;
+        int                  op_errno = 0;
+
+        ctx = arbiter_inode_ctx_get (fd->inode, this);
+        if (!ctx) {
+                op_ret = -1;
+                op_errno = ENOMEM;
+                goto unwind;
+        }
+        buf = ctx->iattbuf;
+        op_ret = iov_length (vector, count);
+unwind:
+        STACK_UNWIND_STRICT (writev, frame, op_ret, op_errno, buf, buf, xdata);
+        return 0;
+}
+
+int32_t
+arbiter_fallocate (call_frame_t *frame, xlator_t *this, fd_t *fd,
+                  int32_t keep_size, off_t offset, size_t len, dict_t *xdata)
+{
+        arbiter_inode_ctx_t *ctx      = NULL;
+        struct iatt         *buf      = NULL;
+        int                  op_ret   = 0;
+        int                  op_errno = 0;
+
+        ctx = arbiter_inode_ctx_get (fd->inode, this);
+        if (!ctx) {
+                op_ret = -1;
+                op_errno = ENOMEM;
+                goto unwind;
+        }
+        buf = ctx->iattbuf;
+unwind:
+        STACK_UNWIND_STRICT(fallocate, frame, op_ret, op_errno, buf, buf,
+                            xdata);
+        return 0;
+}
+
+int32_t
+arbiter_discard (call_frame_t *frame, xlator_t *this, fd_t *fd,
+                off_t offset, size_t len, dict_t *xdata)
+{
+        arbiter_inode_ctx_t *ctx      = NULL;
+        struct iatt         *buf      = NULL;
+        int                  op_ret   = 0;
+        int                  op_errno = 0;
+
+        ctx = arbiter_inode_ctx_get (fd->inode, this);
+        if (!ctx) {
+                op_ret = -1;
+                op_errno = ENOMEM;
+                goto unwind;
+        }
+        buf = ctx->iattbuf;
+unwind:
+        STACK_UNWIND_STRICT(discard, frame, op_ret, op_errno, buf, buf, xdata);
+        return 0;
+}
+
+int32_t
+arbiter_zerofill (call_frame_t *frame, xlator_t *this, fd_t *fd,
+                  off_t offset, off_t len, dict_t *xdata)
+{
+        arbiter_inode_ctx_t *ctx      = NULL;
+        struct iatt         *buf      = NULL;
+        int                  op_ret   = 0;
+        int                  op_errno = 0;
+
+        ctx = arbiter_inode_ctx_get (fd->inode, this);
+        if (!ctx) {
+                op_ret = -1;
+                op_errno = ENOMEM;
+                goto unwind;
+        }
+        buf = ctx->iattbuf;
+unwind:
+        STACK_UNWIND_STRICT(zerofill, frame, op_ret, op_errno, buf, buf, xdata);
+        return 0;
+}
+
+int32_t
+mem_acct_init (xlator_t *this)
+{
+        int ret = -1;
+
+        ret = xlator_mem_acct_init (this, gf_arbiter_mt_end + 1);
+        if (ret)
+                gf_log (this->name, GF_LOG_ERROR, "Memory accounting "
+                        "initialization failed.");
+        return ret;
+}
+
+int
+reconfigure (xlator_t *this, dict_t *options)
+{
+
+        return 0;
+}
+
+int
+arbiter_forget (xlator_t *this, inode_t *inode)
+{
+        arbiter_inode_ctx_t *ctx = NULL;
+        uint64_t ctx_addr = 0;
+
+        inode_ctx_del (inode, this, &ctx_addr);
+        if (!ctx_addr)
+                return 0;
+        ctx = (arbiter_inode_ctx_t *) (long) ctx_addr;
+        GF_FREE (ctx);
+        return 0;
+}
+
+int32_t
+init (xlator_t *this)
+{
+
+        if (!this->children || this->children->next) {
+                gf_log (this->name, GF_LOG_ERROR,
+                        "'arbiter' not configured with exactly one child");
+                return -1;
+        }
+
+        if (!this->parents)
+                gf_log (this->name, GF_LOG_ERROR,
+                        "dangling volume. check volfile ");
+
+        return 0;
+}
+
+void
+fini (xlator_t *this)
+{
+        return;
+}
+
+struct xlator_fops fops = {
+        .lookup = arbiter_lookup,
+        .readv  = arbiter_readv,
+        .truncate = arbiter_truncate,
+        .writev = arbiter_writev,
+        .ftruncate = arbiter_ftruncate,
+        .fallocate = arbiter_fallocate,
+        .discard = arbiter_discard,
+        .zerofill = arbiter_zerofill,
+};
+
+struct xlator_cbks cbks = {
+        .forget = arbiter_forget,
+};
+
+struct volume_options options[] = {
+        { .key  = {NULL} },
+};
diff --git a/xlators/features/arbiter/src/arbiter.h b/xlators/features/arbiter/src/arbiter.h
new file mode 100644
index 00000000000..69ce9cb4fa3
--- /dev/null
+++ b/xlators/features/arbiter/src/arbiter.h
@@ -0,0 +1,26 @@
+/*
+  Copyright (c) 2015 Red Hat, Inc. <http://www.redhat.com>
+  This file is part of GlusterFS.
+
+  This file is licensed to you under your choice of the GNU Lesser
+  General Public License, version 3 or any later version (LGPLv3 or
+  later), or the GNU General Public License, version 2 (GPLv2), in all
+  cases as published by the Free Software Foundation.
+*/
+
+#ifndef _ARBITER_H
+#define _ARBITER_H
+
+#ifndef _CONFIG_H
+#define _CONFIG_H
+#include "config.h"
+#endif
+
+#include "locking.h"
+#include "common-utils.h"
+
+typedef struct arbiter_inode_ctx_ {
+        struct iatt *iattbuf;
+} arbiter_inode_ctx_t;
+
+#endif /* _ARBITER_H */
diff --git a/xlators/mgmt/glusterd/src/glusterd-volgen.c b/xlators/mgmt/glusterd/src/glusterd-volgen.c
index 79da432bafe..6f6d1095edb 100644
--- a/xlators/mgmt/glusterd/src/glusterd-volgen.c
+++ b/xlators/mgmt/glusterd/src/glusterd-volgen.c
@@ -1496,6 +1496,25 @@ out:
 }
 
 static int
+brick_graph_add_arbiter (volgen_graph_t *graph, glusterd_volinfo_t *volinfo,
+                         dict_t *set_dict, glusterd_brickinfo_t *brickinfo)
+{
+        xlator_t *xl = NULL;
+        int ret = -1;
+
+        if (volinfo->arbiter_count != 1)
+                return 0;
+        /*TODO: Parse brickinfo and add the arbiter xlator only if brick is the
+         * last brick (i.e. 3rd brick) of the replcia pair.*/
+        xl = volgen_graph_add (graph, "features/arbiter", volinfo->volname);
+        if (!xl)
+                goto out;
+        ret = 0;
+out:
+        return ret;
+}
+
+static int
 brick_graph_add_bd (volgen_graph_t *graph, glusterd_volinfo_t *volinfo,
                      dict_t *set_dict, glusterd_brickinfo_t *brickinfo)
 {
@@ -2140,6 +2159,7 @@ static volgen_brick_xlator_t server_graph_table[] = {
         {brick_graph_add_changetimerecorder, "changetimerecorder"},
         {brick_graph_add_bd, "bd"},
         {brick_graph_add_trash, "trash"},
+        {brick_graph_add_arbiter, "arbiter"},
         {brick_graph_add_posix, "posix"},
 };
 
diff --git a/xlators/mgmt/glusterd/src/glusterd.h b/xlators/mgmt/glusterd/src/glusterd.h
index bac1598598b..2dd6348ac7f 100644
--- a/xlators/mgmt/glusterd/src/glusterd.h
+++ b/xlators/mgmt/glusterd/src/glusterd.h
@@ -340,6 +340,7 @@ struct glusterd_volinfo_ {
         int                       sub_count;  /* backward compatibility */
         int                       stripe_count;
         int                       replica_count;
+        int                       arbiter_count;
         int                       disperse_count;
         int                       redundancy_count;
         int                       subvol_count; /* Number of subvolumes in a