[sheepdog] [PATCH v4] sheepdog: selectable object size support
Liu Yuan
namei.unix at gmail.com
Tue Feb 10 11:35:58 CET 2015
On Tue, Feb 10, 2015 at 06:56:33PM +0900, Teruaki Ishizaki wrote:
> (2015/02/10 17:58), Liu Yuan wrote:
> >On Tue, Feb 10, 2015 at 05:22:02PM +0900, Teruaki Ishizaki wrote:
> >>(2015/02/10 12:10), Liu Yuan wrote:
> >>>On Tue, Jan 27, 2015 at 05:35:27PM +0900, Teruaki Ishizaki wrote:
> >>>>Previously, qemu block driver of sheepdog used hard-coded VDI object size.
> >>>>This patch enables users to handle "block_size_shift" value for
> >>>>calculating VDI object size.
> >>>>
> >>>>When you start qemu, you don't need to specify additional command option.
> >>>>
> >>>>But when you create the VDI which doesn't have default object size
> >>>>with qemu-img command, you specify block_size_shift option.
> >>>>
> >>>>If you want to create a VDI of 8MB(1 << 23) object size,
> >>>>you need to specify following command option.
> >>>>
> >>>> # qemu-img create -o block_size_shift=23 sheepdog:test1 100M
> >>>>
> >>>>In addition, when you don't specify qemu-img command option,
> >>>>a default value of sheepdog cluster is used for creating VDI.
> >>>>
> >>>> # qemu-img create sheepdog:test2 100M
> >>>>
> >>>>Signed-off-by: Teruaki Ishizaki <ishizaki.teruaki at lab.ntt.co.jp>
> >>>>---
> >>>>V4:
> >>>> - Limit a read/write buffer size for creating a preallocated VDI.
> >>>> - Replace a parse function for the block_size_shift option.
> >>>> - Fix an error message.
> >>>>
> >>>>V3:
> >>>> - Delete the needless operation of buffer.
> >>>> - Delete the needless operations of request header.
> >>>> for SD_OP_GET_CLUSTER_DEFAULT.
> >>>> - Fix coding style problems.
> >>>>
> >>>>V2:
> >>>> - Fix coding style problem (white space).
> >>>> - Add members, store_policy and block_size_shift to struct SheepdogVdiReq.
> >>>> - Initialize request header to use block_size_shift specified by user.
> >>>>---
> >>>> block/sheepdog.c | 138 ++++++++++++++++++++++++++++++++++++++-------
> >>>> include/block/block_int.h | 1 +
> >>>> 2 files changed, 119 insertions(+), 20 deletions(-)
> >>>>
> >>>>diff --git a/block/sheepdog.c b/block/sheepdog.c
> >>>>index be3176f..a43b947 100644
> >>>>--- a/block/sheepdog.c
> >>>>+++ b/block/sheepdog.c
> >>>>@@ -37,6 +37,7 @@
> >>>> #define SD_OP_READ_VDIS 0x15
> >>>> #define SD_OP_FLUSH_VDI 0x16
> >>>> #define SD_OP_DEL_VDI 0x17
> >>>>+#define SD_OP_GET_CLUSTER_DEFAULT 0x18
> >>>>
> >>>> #define SD_FLAG_CMD_WRITE 0x01
> >>>> #define SD_FLAG_CMD_COW 0x02
> >>>>@@ -167,7 +168,8 @@ typedef struct SheepdogVdiReq {
> >>>> uint32_t base_vdi_id;
> >>>> uint8_t copies;
> >>>> uint8_t copy_policy;
> >>>>- uint8_t reserved[2];
> >>>>+ uint8_t store_policy;
> >>>>+ uint8_t block_size_shift;
> >>>> uint32_t snapid;
> >>>> uint32_t type;
> >>>> uint32_t pad[2];
> >>>>@@ -186,6 +188,21 @@ typedef struct SheepdogVdiRsp {
> >>>> uint32_t pad[5];
> >>>> } SheepdogVdiRsp;
> >>>>
> >>>>+typedef struct SheepdogClusterRsp {
> >>>>+ uint8_t proto_ver;
> >>>>+ uint8_t opcode;
> >>>>+ uint16_t flags;
> >>>>+ uint32_t epoch;
> >>>>+ uint32_t id;
> >>>>+ uint32_t data_length;
> >>>>+ uint32_t result;
> >>>>+ uint8_t nr_copies;
> >>>>+ uint8_t copy_policy;
> >>>>+ uint8_t block_size_shift;
> >>>>+ uint8_t __pad1;
> >>>>+ uint32_t __pad2[6];
> >>>>+} SheepdogClusterRsp;
> >>>>+
> >>>> typedef struct SheepdogInode {
> >>>> char name[SD_MAX_VDI_LEN];
> >>>> char tag[SD_MAX_VDI_TAG_LEN];
> >>>>@@ -1544,6 +1561,7 @@ static int do_sd_create(BDRVSheepdogState *s, uint32_t *vdi_id, int snapshot,
> >>>> hdr.vdi_size = s->inode.vdi_size;
> >>>> hdr.copy_policy = s->inode.copy_policy;
> >>>> hdr.copies = s->inode.nr_copies;
> >>>>+ hdr.block_size_shift = s->inode.block_size_shift;
> >>>>
> >>>> ret = do_req(fd, s->aio_context, (SheepdogReq *)&hdr, buf, &wlen, &rlen);
> >>>>
> >>>>@@ -1569,9 +1587,12 @@ static int do_sd_create(BDRVSheepdogState *s, uint32_t *vdi_id, int snapshot,
> >>>> static int sd_prealloc(const char *filename, Error **errp)
> >>>> {
> >>>> BlockDriverState *bs = NULL;
> >>>>+ BDRVSheepdogState *base = NULL;
> >>>>+ unsigned long buf_size;
> >>>> uint32_t idx, max_idx;
> >>>>+ uint32_t object_size;
> >>>> int64_t vdi_size;
> >>>>- void *buf = g_malloc0(SD_DATA_OBJ_SIZE);
> >>>>+ void *buf = NULL;
> >>>> int ret;
> >>>>
> >>>> ret = bdrv_open(&bs, filename, NULL, NULL, BDRV_O_RDWR | BDRV_O_PROTOCOL,
> >>>>@@ -1585,18 +1606,24 @@ static int sd_prealloc(const char *filename, Error **errp)
> >>>> ret = vdi_size;
> >>>> goto out;
> >>>> }
> >>>>- max_idx = DIV_ROUND_UP(vdi_size, SD_DATA_OBJ_SIZE);
> >>>>+
> >>>>+ base = bs->opaque;
> >>>>+ object_size = (UINT32_C(1) << base->inode.block_size_shift);
> >>>>+ buf_size = MIN(object_size, SD_DATA_OBJ_SIZE);
> >>>>+ buf = g_malloc0(buf_size);
> >>>>+
> >>>>+ max_idx = DIV_ROUND_UP(vdi_size, buf_size);
> >>>>
> >>>> for (idx = 0; idx < max_idx; idx++) {
> >>>> /*
> >>>> * The created image can be a cloned image, so we need to read
> >>>> * a data from the source image.
> >>>> */
> >>>>- ret = bdrv_pread(bs, idx * SD_DATA_OBJ_SIZE, buf, SD_DATA_OBJ_SIZE);
> >>>>+ ret = bdrv_pread(bs, idx * buf_size, buf, buf_size);
> >>>> if (ret < 0) {
> >>>> goto out;
> >>>> }
> >>>>- ret = bdrv_pwrite(bs, idx * SD_DATA_OBJ_SIZE, buf, SD_DATA_OBJ_SIZE);
> >>>>+ ret = bdrv_pwrite(bs, idx * buf_size, buf, buf_size);
> >>>> if (ret < 0) {
> >>>> goto out;
> >>>> }
> >>>>@@ -1669,6 +1696,21 @@ static int parse_redundancy(BDRVSheepdogState *s, const char *opt)
> >>>> return 0;
> >>>> }
> >>>>
> >>>>+static int parse_block_size_shift(BDRVSheepdogState *s, QemuOpts *opt)
> >>>>+{
> >>>>+ struct SheepdogInode *inode = &s->inode;
> >>>>+ inode->block_size_shift =
> >>>>+ (uint8_t)qemu_opt_get_number_del(opt, "block_size_shift", 0);
> >>>>+ if (inode->block_size_shift == 0) {
> >>>>+ /* block_size_shift is set for cluster default value by sheepdog */
> >>>>+ return 0;
> >>>>+ } else if (inode->block_size_shift < 20 || inode->block_size_shift > 31) {
> >>>>+ return -EINVAL;
> >>>>+ }
> >>>>+
> >>>>+ return 0;
> >>>>+}
> >>>>+
> >>>> static int sd_create(const char *filename, QemuOpts *opts,
> >>>> Error **errp)
> >>>> {
> >>>>@@ -1679,6 +1721,7 @@ static int sd_create(const char *filename, QemuOpts *opts,
> >>>> BDRVSheepdogState *s;
> >>>> char tag[SD_MAX_VDI_TAG_LEN];
> >>>> uint32_t snapid;
> >>>>+ uint64_t max_vdi_size;
> >>>> bool prealloc = false;
> >>>>
> >>>> s = g_new0(BDRVSheepdogState, 1);
> >>>>@@ -1718,9 +1761,10 @@ static int sd_create(const char *filename, QemuOpts *opts,
> >>>> }
> >>>> }
> >>>>
> >>>>- if (s->inode.vdi_size > SD_MAX_VDI_SIZE) {
> >>>>- error_setg(errp, "too big image size");
> >>>>- ret = -EINVAL;
> >>>>+ ret = parse_block_size_shift(s, opts);
> >>>>+ if (ret < 0) {
> >>>>+ error_setg(errp, "Invalid block_size_shift:"
> >>>>+ " '%s'. please use 20-31", buf);
> >>>> goto out;
> >>>> }
> >>>>
> >>>>@@ -1757,6 +1801,47 @@ static int sd_create(const char *filename, QemuOpts *opts,
> >>>> }
> >>>>
> >>>> s->aio_context = qemu_get_aio_context();
> >>>>+
> >>>>+ /* if block_size_shift is not specified, get cluster default value */
> >>>>+ if (s->inode.block_size_shift == 0) {
> >>>
> >>>Seems that we don't keep backward compatibility for new QEMU and old sheep that
> >>>doesn't support SD_OP_GET_CLUSTER_DEFAULT.
> >>Then, I'll add the operation that if block_size_shift from
> >>SD_OP_GET_CLUSTER_DEFAULT is zero, block_size_shift is set to 22.
> >>Is it OK?
> >
> >If sheep doesn't support SD_OP_GET_CLUSTER_DEFAULT, sheep will return
> >SD_RES_INVALID_PARMS. So to keep backward compatibility, we shouldn't issue
> >SD_OP_GET_CLUSTER_DEFAULT to sheep daemon.
> OK, I think that the way is better.
> >
> >My point is that, after user upgrading the sheep and still stick with old QEMU,
> >(I guess many users will), any operations in the past sholudn't fail right after
> >upgrading.
> >
> >>
> >>>
> >>>What will happen if old QEMU with new sheep that support block_size_shift? Most
> >>>distributions will ship the old stable qemu that wouldn't be aware of
> >>>block_size_shift.
> >>If old QEMU with new sheep is used, VDI is created with cluster default
> >>block_size_shift and accessed as 4MB object_size.
> >>So I think that for backward compatibility, users must do cluster
> >>format command with default block_size_shift 22 equal to
> >>4MB object_size.
> >
> >how old QEMU know about block_size_shift? For old QEMU, block_size_shift is
> >encoded as 0 and then send the create request to sheep. Does sheep can handle
> >block_size_shift = 0? You know, we can't pass any value to old QEMU for
> >block_size_shift.
> Sheep can handle block_size_shift = 0, when users create new VDI.
> Old QEMU does do_sd_create() without setting hdr.block_size_shift and
> sends a request SD_OP_NEW_VDI.
> If block_size_shift is set to zero, new sheep sets cluster default value
> in cluster_new_vdi() like copies and copy_policy.
Okay, so new sheep can handle old QEMU request. By the way, how about the
suggestion in my last email? (x + 1) * 4MB stuff...
Thanks
Yuan
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