Le Tuesday 29 Oct 2013 à 16:25:52 (+0800), Liu Yuan a écrit : > 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) > > E.g, to convert a vdi into sheepdog vdi 'test' with 8:3 erasure coding scheme > > $ qemu-img convert -o redundancy=8:3 linux-0.2.img sheepdog:test > > Cc: Kevin Wolf <kw...@redhat.com> > Cc: Stefan Hajnoczi <stefa...@redhat.com> > Signed-off-by: Liu Yuan <namei.u...@gmail.com> > --- > block/sheepdog.c | 78 > ++++++++++++++++++++++++++++++++++++++++++++- > include/block/block_int.h | 1 + > 2 files changed, 78 insertions(+), 1 deletion(-) > > diff --git a/block/sheepdog.c b/block/sheepdog.c > index e66d2f8..bd7cfd6 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 dats trips 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 > @@ -1446,6 +1454,65 @@ out: > return ret; > } > > +static int64_t is_numeric(const char *s) > +{ > + char *end; > + return strtosz_suffix(s, &end, STRTOSZ_DEFSUFFIX_B); > +} > + > +/* > + * 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; > + uint8_t copy, parity; > + char p[10]; > + > + strncpy(p, opt, sizeof(p)); > + n1 = strtok(p, ":"); > + n2 = strtok(NULL, ":"); > + > + if ((n1 && !is_numeric(n1)) || (n2 && !is_numeric(n2))) { > + return -EINVAL; > + } > + > + copy = strtol(n1, NULL, 10); > + if (copy > SD_MAX_COPIES) { > + return -EINVAL; > + } > + if (!n2) { > + inode->copy_policy = 0; > + inode->nr_copies = copy; > + } > + > + if (copy != 2 && copy != 4 && copy != 8 && copy != 16) { > + return -EINVAL; > + } > + > + parity = strtol(n2, NULL, 10); > + if (parity >= SD_EC_MAX_STRIP || parity == 0) { > + 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) > { > @@ -1486,6 +1553,11 @@ 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++; > } > @@ -1528,7 +1600,6 @@ 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; > @@ -2332,6 +2403,11 @@ 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 } > }; > > diff --git a/include/block/block_int.h b/include/block/block_int.h > index a48731d..b90862f 100644 > --- a/include/block/block_int.h > +++ b/include/block/block_int.h > @@ -53,6 +53,7 @@ > #define BLOCK_OPT_COMPAT_LEVEL "compat" > #define BLOCK_OPT_LAZY_REFCOUNTS "lazy_refcounts" > #define BLOCK_OPT_ADAPTER_TYPE "adapter_type" > +#define BLOCK_OPT_REDUNDANCY "redundancy" > > typedef struct BdrvTrackedRequest { > BlockDriverState *bs; > -- > 1.7.9.5 > >
Hi, Perhaps it would be better to implement theses options with the new block driver options mechanism that Kevin implemented. >From a user perspective it look like this. -drive if=virtio,file.driver=quorum,\ file.children.0.file.filename=1.qcow2,\ file.children.1.file.filename=2.qcow2,\ file.children.2.file.filename=3.qcow2,\ file.vote_threshold=3 I don't know if it would work with protocols but that would uniformize the options passing style accross multiple block drivers. I have an under review patch on the list using this mechanism, see: "[PATCH V9 11/11] quorum: Add quorum_open() and quorum_close()." Best regards Benoît