bd: Add support to create clone, snapshot and merge of LV images.

Special xattr names "clone" & "snapshot" can be used to create full and
linked clone of the LV images. GFID of destination posix file (to be
mapped) is passed as a value to the xattr. Destination posix file must
exist before running this operation.

These operations form a basis for offloading storage related operations
from QEMU to GlusterFS.

Syntax for full clone: xattr name: "clone" value: "gfid-of-dest-file"
Syntax for linked clone: xattr name: "snapshot" value: "gfid-of-dest-file"
Syntax for merging: xattr name: "merge" value: "path-to-snapshot-file"

Example:
	setfattr -n clone -v <gfid-of-dest-file> /media/source
	setfattr -n snapshot -v <gfid-of-dest-file> /media/source
	setfattr -n merge -v "/media/sn" /media/sn

Change-Id: Id9f984a709d4c2e52a64ae75bb12a8ecb01f8776
BUG: 1028672
Signed-off-by: M. Mohan Kumar <mohan@in.ibm.com>
Reviewed-on: http://review.gluster.org/5626
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Anand Avati <avati@redhat.com>

4 files changed, 47 insertions, 10 deletions

diff --git a/xlators/mgmt/glusterd/src/glusterd-brick-ops.c b/xlators/mgmt/glusterd/src/glusterd-brick-ops.c
index cc425353516..df6087659ef 100644
--- a/xlators/mgmt/glusterd/src/glusterd-brick-ops.c
+++ b/xlators/mgmt/glusterd/src/glusterd-brick-ops.c
@@ -1109,7 +1109,8 @@ glusterd_op_perform_add_bricks (glusterd_volinfo_t *volinfo, int32_t count,
                 brick = strtok_r (brick_list+1, " \n", &saveptr);
 #ifdef HAVE_BD_XLATOR
         if (brickinfo->vg[0])
-                caps = CAPS_BD | CAPS_THIN;
+                caps = CAPS_BD | CAPS_THIN |
+                        CAPS_OFFLOAD_COPY | CAPS_OFFLOAD_SNAPSHOT;
 #endif
 
         while (i <= count) {
diff --git a/xlators/mgmt/glusterd/src/glusterd-handler.c b/xlators/mgmt/glusterd/src/glusterd-handler.c
index 181b8fcf1a9..fcffccc07b8 100644
--- a/xlators/mgmt/glusterd/src/glusterd-handler.c
+++ b/xlators/mgmt/glusterd/src/glusterd-handler.c
@@ -335,7 +335,7 @@ glusterd_add_volume_detail_to_dict (glusterd_volinfo_t *volinfo,
         char                    *volume_id_str  = NULL;
         struct args_pack        pack = {0,};
         xlator_t                *this = NULL;
-
+        int                     caps = 0;
 
         GF_ASSERT (volinfo);
         GF_ASSERT (volumes);
@@ -401,6 +401,7 @@ glusterd_add_volume_detail_to_dict (glusterd_volinfo_t *volinfo,
 
 #ifdef HAVE_BD_XLATOR
         if (volinfo->caps) {
+                caps = 0;
                 snprintf (key, 256, "volume%d.xlator0", count);
                 buf = GF_MALLOC (256, gf_common_mt_char);
                 if (!buf) {
@@ -416,7 +417,8 @@ glusterd_add_volume_detail_to_dict (glusterd_volinfo_t *volinfo,
                 }
 
                 if (volinfo->caps & CAPS_THIN) {
-                        snprintf (key, 256, "volume%d.xlator0.caps0", count);
+                        snprintf (key, 256, "volume%d.xlator0.caps%d", count,
+                                  caps++);
                         buf = GF_MALLOC (256, gf_common_mt_char);
                         if (!buf) {
                                 ret = ENOMEM;
@@ -429,6 +431,39 @@ glusterd_add_volume_detail_to_dict (glusterd_volinfo_t *volinfo,
                                 goto out;
                         }
                 }
+
+                if (volinfo->caps & CAPS_OFFLOAD_COPY) {
+                        snprintf (key, 256, "volume%d.xlator0.caps%d", count,
+                                  caps++);
+                        buf = GF_MALLOC (256, gf_common_mt_char);
+                        if (!buf) {
+                                ret = ENOMEM;
+                                goto out;
+                        }
+                        snprintf (buf, 256, "offload_copy");
+                        ret = dict_set_dynstr (volumes, key, buf);
+                        if (ret) {
+                                GF_FREE (buf);
+                                goto out;
+                        }
+                }
+
+                if (volinfo->caps & CAPS_OFFLOAD_SNAPSHOT) {
+                        snprintf (key, 256, "volume%d.xlator0.caps%d", count,
+                                  caps++);
+                        buf = GF_MALLOC (256, gf_common_mt_char);
+                        if (!buf) {
+                                ret = ENOMEM;
+                                goto out;
+                        }
+                        snprintf (buf, 256, "offload_snapshot");
+                        ret = dict_set_dynstr (volumes, key, buf);
+                        if (ret)  {
+                                GF_FREE (buf);
+                                goto out;
+                        }
+                }
+
         }
 #endif
 
diff --git a/xlators/mgmt/glusterd/src/glusterd-volume-ops.c b/xlators/mgmt/glusterd/src/glusterd-volume-ops.c
index a2bd7334c93..561ff652d81 100644
--- a/xlators/mgmt/glusterd/src/glusterd-volume-ops.c
+++ b/xlators/mgmt/glusterd/src/glusterd-volume-ops.c
@@ -665,7 +665,7 @@ glusterd_is_valid_vg (glusterd_brickinfo_t *brick, int check_tag, char *msg)
         }
 next:
 
-        brick->caps = CAPS_BD;
+        brick->caps = CAPS_BD | CAPS_OFFLOAD_COPY | CAPS_OFFLOAD_SNAPSHOT;
 
         dm_lvlist = lvm_vg_list_lvs (vg);
         if (!dm_lvlist)
@@ -953,7 +953,6 @@ glusterd_op_stage_start_volume (dict_t *dict, char **op_errstr)
                 }
         }
 
-
         list_for_each_entry (brickinfo, &volinfo->bricks, brick_list) {
                 ret = glusterd_resolve_brick (brickinfo);
                 if (ret) {
@@ -1011,8 +1010,8 @@ glusterd_op_stage_start_volume (dict_t *dict, char **op_errstr)
                 }
 #ifdef HAVE_BD_XLATOR
                 if (brickinfo->vg[0])
-                        caps = CAPS_BD | CAPS_THIN;
-
+                        caps = CAPS_BD | CAPS_THIN |
+                                CAPS_OFFLOAD_COPY | CAPS_OFFLOAD_SNAPSHOT;
                 /* Check for VG/thin pool if its BD volume */
                 if (brickinfo->vg[0]) {
                         ret = glusterd_is_valid_vg (brickinfo, 0, msg);
@@ -1602,7 +1601,7 @@ glusterd_op_create_volume (dict_t *dict, char **op_errstr)
 
         if (count)
                 brick = strtok_r (brick_list+1, " \n", &saveptr);
-        caps = CAPS_BD | CAPS_THIN;
+        caps = CAPS_BD | CAPS_THIN | CAPS_OFFLOAD_COPY | CAPS_OFFLOAD_SNAPSHOT;
 
         while ( i <= count) {
                 ret = glusterd_brickinfo_new_from_brick (brick, &brickinfo);
diff --git a/xlators/mgmt/glusterd/src/glusterd.h b/xlators/mgmt/glusterd/src/glusterd.h
index 6423d5a8154..ad63682e55e 100644
--- a/xlators/mgmt/glusterd/src/glusterd.h
+++ b/xlators/mgmt/glusterd/src/glusterd.h
@@ -234,8 +234,10 @@ struct _auth {
 typedef struct _auth auth_t;
 
 /* Capabilities of xlator */
-#define CAPS_BD           0x00000001
-#define CAPS_THIN         0x00000010
+#define CAPS_BD               0x00000001
+#define CAPS_THIN             0x00000002
+#define CAPS_OFFLOAD_COPY     0x00000004
+#define CAPS_OFFLOAD_SNAPSHOT 0x00000008
 
 struct glusterd_rebalance_ {
         gf_defrag_status_t       defrag_status;