[stgt] [PATCH v2 1/3] bs_sheepdog.c: mock the behavior of QEMU's sheepdog driver in a correct manner
Hitoshi Mitake
mitake.hitoshi at lab.ntt.co.jp
Wed Oct 16 10:42:06 CEST 2013
Current bs_sheepdog.c doesn't mock the behavior of QEMU's sheepdog
driver in a correct manner when it opens snapshot VDIs. It treats the
snapshot VDIs as read-only disks, but this behavior is different from
the QEMU's driver. This patch lets bs_sheepdog.c mock the original
behavior (delete an original VDI of the snapshot -> create a new non
snapshot VDI based on the snapshot and open it). This patch also
removes confusing notations of --backing-store option of
bs_sheepdog.c.
Signed-off-by: Hitoshi Mitake <mitake.hitoshi at lab.ntt.co.jp>
---
usr/bs_sheepdog.c | 109 +++++++++++++++++++++++++++++++++++++----------------
1 file changed, 76 insertions(+), 33 deletions(-)
diff --git a/usr/bs_sheepdog.c b/usr/bs_sheepdog.c
index 4f7cde0..11ddce6 100644
--- a/usr/bs_sheepdog.c
+++ b/usr/bs_sheepdog.c
@@ -622,8 +622,11 @@ static int reload_inode(struct sheepdog_access_info *ai)
if (ret)
return -1;
- read_object(ai, (char *)&ai->inode, vid_to_vdi_oid(vid),
- ai->inode.nr_copies, SD_INODE_SIZE, 0);
+ ret = read_object(ai, (char *)&ai->inode, vid_to_vdi_oid(vid),
+ ai->inode.nr_copies, SD_INODE_SIZE, 0);
+ if (ret)
+ return -1;
+
return 0;
}
@@ -917,9 +920,9 @@ static int sd_open(struct sheepdog_access_info *ai, char *filename, int flags)
enum {
EXPECT_PROTO,
EXPECT_PATH,
- EXPECT_VDI,
- EXPECT_HOST_OR_PORT,
+ EXPECT_HOST,
EXPECT_PORT,
+ EXPECT_VDI,
EXPECT_TAG_OR_SNAP,
EXPECT_NOTHING,
} parse_state = EXPECT_PROTO;
@@ -942,9 +945,6 @@ static int sd_open(struct sheepdog_access_info *ai, char *filename, int flags)
* tcp:<host>:<port>:<vdi>
* tcp:<host>:<port>:<vdi>:<tag>
* tcp:<host>:<port>:<vdi>:<snapid>
- * tcp:<port>:<vdi>
- * tcp:<port>:<vdi>:<tag>
- * tcp:<port>:<vdi>:<snapid>
*/
result = strtok_r(filename, ":", &saveptr);
@@ -957,7 +957,7 @@ static int sd_open(struct sheepdog_access_info *ai, char *filename, int flags)
parse_state = EXPECT_PATH;
} else if (!strcmp("tcp", result)) {
ai->is_unix = 0;
- parse_state = EXPECT_HOST_OR_PORT;
+ parse_state = EXPECT_HOST;
} else {
eprintf("unknown protocol of sheepdog vdi:"\
" %s\n", result);
@@ -968,26 +968,14 @@ static int sd_open(struct sheepdog_access_info *ai, char *filename, int flags)
strncpy(ai->uds_path, result, UNIX_PATH_MAX);
parse_state = EXPECT_VDI;
break;
- case EXPECT_HOST_OR_PORT:
- len = strlen(result);
- for (i = 0; i < len; i++) {
- if (!isdigit(result[i])) {
- /* result is a hostname */
- strncpy(ai->hostname, result,
- HOST_NAME_MAX);
- parse_state = EXPECT_PORT;
- goto next_token;
- }
- }
-
- /* result is a port, use localhost as hostname */
- strncpy(ai->hostname, "localhost", strlen("localhost"));
-set_port:
+ case EXPECT_HOST:
+ strncpy(ai->hostname, result, HOST_NAME_MAX);
+ parse_state = EXPECT_PORT;
+ break;
+ case EXPECT_PORT:
ai->port = atoi(result);
parse_state = EXPECT_VDI;
break;
- case EXPECT_PORT:
- goto set_port;
case EXPECT_VDI:
strncpy(vdi_name, result, SD_MAX_VDI_LEN);
parse_state = EXPECT_TAG_OR_SNAP;
@@ -1017,8 +1005,6 @@ trans_to_expect_nothing:
parse_state);
exit(1);
}
-
-next_token:;
} while ((result = strtok_r(NULL, ":", &saveptr)) != NULL);
if (parse_state != EXPECT_NOTHING &&
@@ -1039,7 +1025,8 @@ next_token:;
else
dprintf("snapid: %d\n", snapid);
- ai->is_snapshot = !(snapid == -1) && strlen(tag);
+ dprintf("VDI name: %s\n", vdi_name);
+ ai->is_snapshot = !(snapid == -1) || strlen(tag);
ret = find_vdi_name(ai, vdi_name, snapid == -1 ? 0 : snapid, tag, &vid,
ai->is_snapshot);
if (ret)
@@ -1087,6 +1074,53 @@ static void set_medium_error(int *result, uint8_t *key, uint16_t *asc)
*asc = ASC_READ_ERROR;
}
+static int create_branch(struct sheepdog_access_info *ai)
+{
+ struct sheepdog_vdi_req hdr;
+ struct sheepdog_vdi_rsp *rsp = (struct sheepdog_vdi_rsp *)&hdr;
+ unsigned int wlen = 0, rlen;
+ int ret;
+
+ hdr.opcode = SD_OP_DEL_VDI;
+ hdr.vdi_id = ai->inode.vdi_id;
+ hdr.flags = SD_FLAG_CMD_WRITE;
+ wlen = SD_MAX_VDI_LEN;
+ hdr.data_length = wlen;
+
+ ret = do_req(ai, (struct sheepdog_req *)&hdr, ai->inode.name,
+ &wlen, &rlen);
+ if (ret) {
+ eprintf("deleting snapshot VDI for creating branch failed\n");
+ return -1;
+ }
+
+ memset(&hdr, 0, sizeof(hdr));
+ hdr.opcode = SD_OP_NEW_VDI;
+ hdr.vdi_id = ai->inode.vdi_id;
+
+ hdr.flags = SD_FLAG_CMD_WRITE;
+ wlen = SD_MAX_VDI_LEN;
+ hdr.data_length = wlen;
+ hdr.vdi_size = ai->inode.vdi_size;
+ ret = do_req(ai, (struct sheepdog_req *)&hdr, ai->inode.name,
+ &wlen, &rlen);
+ if (ret) {
+ eprintf("creating new VDI for creating branch failed\n");
+ return -1;
+ }
+
+ ret = read_object(ai, (char *)&ai->inode, vid_to_vdi_oid(rsp->vdi_id),
+ ai->inode.nr_copies, SD_INODE_SIZE, 0);
+ if (ret) {
+ eprintf("reloading new inode object failed");
+ return -1;
+ }
+
+ dprintf("creating branch from snapshot, new VDI ID: %x\n", rsp->vdi_id);
+
+ return 0;
+}
+
static void bs_sheepdog_request(struct scsi_cmd *cmd)
{
int ret = 0;
@@ -1110,11 +1144,20 @@ static void bs_sheepdog_request(struct scsi_cmd *cmd)
case WRITE_12:
case WRITE_16:
if (ai->is_snapshot) {
- length = scsi_get_out_length(cmd);
- ret = sd_io(ai, 1, scsi_get_out_buffer(cmd),
- length, cmd->offset);
- } else
- ret = -1;
+ ret = create_branch(ai);
+ if (ret) {
+ eprintf("creating writable VDI from"\
+ " snapshot failed\n");
+ set_medium_error(&result, &key, &asc);
+
+ return;
+ }
+ ai->is_snapshot = 0;
+ }
+
+ length = scsi_get_out_length(cmd);
+ ret = sd_io(ai, 1, scsi_get_out_buffer(cmd),
+ length, cmd->offset);
if (ret)
set_medium_error(&result, &key, &asc);
--
1.7.10.4
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