diff options
Diffstat (limited to 'block')
-rw-r--r-- | block/sheepdog.c | 74 |
1 files changed, 73 insertions, 1 deletions
diff --git a/block/sheepdog.c b/block/sheepdog.c index ae43675..b4ae50f 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 } }; |