[Sheepdog] [PATCH] sheep: add snapshot tag support

[MORITA Kazutaka]

This patch enables us to add a snapshot name when creating a snapshot.

This is mutually depends on the client patch I'll send later to the
qemu-devel.  You can also get these from the latest git tree:

  server:
    git://sheepdog.git.sourceforge.net/gitroot/sheepdog/sheepdog next
  client:
    git://sheepdog.git.sourceforge.net/gitroot/sheepdog/qemu for-block

usage:
  $ qemu-img snapshot -c tagname sheepdog:linux

  $ ./collie/collie vdi list
    name        id    size    used  shared    creation time   vdi id
  ------------------------------------------------------------------
  s linux        1  2.0 GB   48 MB  0.0 MB 2010-06-18 20:40   a5d05d
    linux        2  2.0 GB  0.0 MB   48 MB 2010-06-18 21:23   a5d05e

  $ qemu-img snapshot -l sheepdog:linux
  Snapshot list:
  ID        TAG                 VM SIZE                DATE       VM CLOCK
  1         tagname                   0 2010-06-18 21:23:32   00:00:00.000

Signed-off-by: MORITA Kazutaka <morita.kazutaka at lab.ntt.co.jp>
---
 include/sheepdog_proto.h |    2 ++
 sheep/vdi.c              |   32 ++++++++++++++++++++++----------
 2 files changed, 24 insertions(+), 10 deletions(-)

diff --git a/include/sheepdog_proto.h b/include/sheepdog_proto.h
index 5a16982..1e321a8 100644
--- a/include/sheepdog_proto.h
+++ b/include/sheepdog_proto.h
@@ -74,6 +74,7 @@
 #define MAX_DATA_OBJS (1ULL << 20)
 #define MAX_CHILDREN 1024
 #define SD_MAX_VDI_LEN 256
+#define SD_MAX_VDI_TAG_LEN 256
 #define SD_NR_VDIS   (1U << 24)
 #define SD_DATA_OBJ_SIZE (UINT64_C(1) << 22)
 
@@ -156,6 +157,7 @@ struct sd_vdi_rsp {
 
 struct sheepdog_inode {
 	char name[SD_MAX_VDI_LEN];
+	char tag[SD_MAX_VDI_TAG_LEN];
 	uint64_t ctime;
 	uint64_t snap_ctime;
 	uint64_t vm_clock_nsec;
diff --git a/sheep/vdi.c b/sheep/vdi.c
index 7a894a3..102d956 100644
--- a/sheep/vdi.c
+++ b/sheep/vdi.c
@@ -117,14 +117,14 @@ static int create_vdi_obj(uint32_t epoch, char *name, uint32_t new_vid, uint64_t
 }
 
 static int find_first_vdi(uint32_t epoch, unsigned long start, unsigned long end,
-			  char *name, int namelen, uint32_t snapid, uint32_t *vid,
+			  char *name, char *tag, uint32_t snapid, uint32_t *vid,
 			  unsigned long *deleted_nr, uint32_t *next_snap)
 {
 	struct sheepdog_node_list_entry entries[SD_MAX_NODES];
 	static struct sheepdog_inode inode;
 	unsigned long i;
 	int nr_nodes, nr_reqs;
-	int ret;
+	int ret, vdi_found = 0;
 
 	nr_nodes = get_ordered_sd_node_list(entries);
 
@@ -145,6 +145,10 @@ static int find_first_vdi(uint32_t epoch, unsigned long start, unsigned long end
 		}
 
 		if (!strncmp(inode.name, name, strlen(inode.name))) {
+			vdi_found = 1;
+			if (tag && tag[0] &&
+			    strncmp(inode.tag, tag, sizeof(inode.tag)) != 0)
+				continue;
 			if (snapid && snapid != inode.snap_id)
 				continue;
 
@@ -153,12 +157,16 @@ static int find_first_vdi(uint32_t epoch, unsigned long start, unsigned long end
 			return SD_RES_SUCCESS;
 		}
 	}
+
+	if (vdi_found)
+		return SD_RES_NO_TAG;
+
 	return SD_RES_NO_VDI;
 }
 
 
 static int do_lookup_vdi(uint32_t epoch, char *name, int namelen, uint32_t *vid,
-			 uint32_t snapid, uint32_t *next_snapid,
+			 char *tag, uint32_t snapid, uint32_t *next_snapid,
 			 unsigned long *right_nr,  unsigned long *deleted_nr)
 {
 	int ret;
@@ -176,7 +184,7 @@ static int do_lookup_vdi(uint32_t epoch, char *name, int namelen, uint32_t *vid,
 	} else if (nr < SD_NR_VDIS) {
 	right_side:
 		/* look up on the right side of the hash point */
-		ret = find_first_vdi(epoch, nr - 1, start_nr, name, namelen, snapid, vid,
+		ret = find_first_vdi(epoch, nr - 1, start_nr, name, tag, snapid, vid,
 				     deleted_nr, next_snapid);
 		return ret;
 	} else {
@@ -187,7 +195,7 @@ static int do_lookup_vdi(uint32_t epoch, char *name, int namelen, uint32_t *vid,
 			return SD_RES_FULL_VDI;
 		else if (nr) {
 			/* look up on the left side of the hash point */
-			ret = find_first_vdi(epoch, nr - 1, 0, name, namelen, snapid, vid,
+			ret = find_first_vdi(epoch, nr - 1, 0, name, tag, snapid, vid,
 					     deleted_nr, next_snapid);
 			if (ret == SD_RES_NO_VDI)
 				; /* we need to go to the right side */
@@ -202,14 +210,18 @@ static int do_lookup_vdi(uint32_t epoch, char *name, int namelen, uint32_t *vid,
 
 int lookup_vdi(uint32_t epoch, char *data, int data_len, uint32_t *vid, uint32_t snapid)
 {
-	char *name = data;
+	char *name = data, *tag;
 	uint32_t dummy0;
 	unsigned long dummy1, dummy2;
 
-	if (data_len != SD_MAX_VDI_LEN)
+	if (data_len == SD_MAX_VDI_LEN + SD_MAX_VDI_TAG_LEN)
+		tag = data + SD_MAX_VDI_LEN;
+	else if (data_len == SD_MAX_VDI_LEN)
+		tag = NULL;
+	else
 		return SD_RES_INVALID_PARMS;
 
-	return do_lookup_vdi(epoch, name, strlen(name), vid, snapid,
+	return do_lookup_vdi(epoch, name, strlen(name), vid, tag, snapid,
 			     &dummy0, &dummy1, &dummy2);
 }
 
@@ -227,7 +239,7 @@ int add_vdi(uint32_t epoch, char *data, int data_len, uint64_t size,
 
 	name = data;
 
-	ret = do_lookup_vdi(epoch, name, strlen(name), &cur_vid, 0, &next_snapid,
+	ret = do_lookup_vdi(epoch, name, strlen(name), &cur_vid, NULL, 0, &next_snapid,
 			    &right_nr, &deleted_nr);
 
 	if (is_snapshot) {
@@ -287,7 +299,7 @@ int del_vdi(uint32_t epoch, char *data, int data_len, uint32_t snapid)
 	if (data_len != SD_MAX_VDI_LEN)
 		return SD_RES_INVALID_PARMS;
 
-	ret = do_lookup_vdi(epoch, name, strlen(name), &vid, snapid,
+	ret = do_lookup_vdi(epoch, name, strlen(name), &vid, NULL, snapid,
 			     &dummy0, &dummy1, &dummy2);
 	if (ret != SD_RES_SUCCESS)
 		return ret;
-- 
1.5.6.5