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-rw-r--r--block/sheepdog.c74
1 files changed, 73 insertions, 1 deletions
diff --git a/block/sheepdog.c b/block/sheepdog.c
index ae436754f8..b4ae50f44d 100644
--- a/block/sheepdog.c
+++ b/block/sheepdog.c
@@ -91,6 +91,14 @@
#define SD_NR_VDIS (1U << 24)
#define SD_DATA_OBJ_SIZE (UINT64_C(1) << 22)
#define SD_MAX_VDI_SIZE (SD_DATA_OBJ_SIZE * MAX_DATA_OBJS)
+/*
+ * For erasure coding, we use at most SD_EC_MAX_STRIP for data strips and
+ * (SD_EC_MAX_STRIP - 1) for parity strips
+ *
+ * SD_MAX_COPIES is sum of number of data strips and parity strips.
+ */
+#define SD_EC_MAX_STRIP 16
+#define SD_MAX_COPIES (SD_EC_MAX_STRIP * 2 - 1)
#define SD_INODE_SIZE (sizeof(SheepdogInode))
#define CURRENT_VDI_ID 0
@@ -1495,6 +1503,7 @@ static int do_sd_create(BDRVSheepdogState *s, uint32_t *vdi_id, int snapshot)
hdr.data_length = wlen;
hdr.vdi_size = s->inode.vdi_size;
hdr.copy_policy = s->inode.copy_policy;
+ hdr.copies = s->inode.nr_copies;
ret = do_req(fd, (SheepdogReq *)&hdr, buf, &wlen, &rlen);
@@ -1562,6 +1571,60 @@ out:
return ret;
}
+/*
+ * Sheepdog support two kinds of redundancy, full replication and erasure
+ * coding.
+ *
+ * # create a fully replicated vdi with x copies
+ * -o redundancy=x (1 <= x <= SD_MAX_COPIES)
+ *
+ * # create a erasure coded vdi with x data strips and y parity strips
+ * -o redundancy=x:y (x must be one of {2,4,8,16} and 1 <= y < SD_EC_MAX_STRIP)
+ */
+static int parse_redundancy(BDRVSheepdogState *s, const char *opt)
+{
+ struct SheepdogInode *inode = &s->inode;
+ const char *n1, *n2;
+ long copy, parity;
+ char p[10];
+
+ pstrcpy(p, sizeof(p), opt);
+ n1 = strtok(p, ":");
+ n2 = strtok(NULL, ":");
+
+ if (!n1) {
+ return -EINVAL;
+ }
+
+ copy = strtol(n1, NULL, 10);
+ if (copy > SD_MAX_COPIES || copy < 1) {
+ return -EINVAL;
+ }
+ if (!n2) {
+ inode->copy_policy = 0;
+ inode->nr_copies = copy;
+ return 0;
+ }
+
+ if (copy != 2 && copy != 4 && copy != 8 && copy != 16) {
+ return -EINVAL;
+ }
+
+ parity = strtol(n2, NULL, 10);
+ if (parity >= SD_EC_MAX_STRIP || parity < 1) {
+ return -EINVAL;
+ }
+
+ /*
+ * 4 bits for parity and 4 bits for data.
+ * We have to compress upper data bits because it can't represent 16
+ */
+ inode->copy_policy = ((copy / 2) << 4) + parity;
+ inode->nr_copies = copy + parity;
+
+ return 0;
+}
+
static int sd_create(const char *filename, QEMUOptionParameter *options,
Error **errp)
{
@@ -1602,6 +1665,11 @@ static int sd_create(const char *filename, QEMUOptionParameter *options,
ret = -EINVAL;
goto out;
}
+ } else if (!strcmp(options->name, BLOCK_OPT_REDUNDANCY)) {
+ ret = parse_redundancy(s, options->value.s);
+ if (ret < 0) {
+ goto out;
+ }
}
options++;
}
@@ -1644,7 +1712,6 @@ static int sd_create(const char *filename, QEMUOptionParameter *options,
bdrv_unref(bs);
}
- /* TODO: allow users to specify copy number */
ret = do_sd_create(s, &vid, 0);
if (!prealloc || ret) {
goto out;
@@ -2432,6 +2499,11 @@ static QEMUOptionParameter sd_create_options[] = {
.type = OPT_STRING,
.help = "Preallocation mode (allowed values: off, full)"
},
+ {
+ .name = BLOCK_OPT_REDUNDANCY,
+ .type = OPT_STRING,
+ .help = "Redundancy of the image"
+ },
{ NULL }
};