diff --git a/block/io.c b/block/io.c index 65b5102714d4d60ff6a5e594ef1b30ae82e06b1e..905db99be4146a661fc526a0c6a4497397c73525 100644 --- a/block/io.c +++ b/block/io.c @@ -1185,7 +1185,8 @@ bdrv_driver_pwritev_compressed(BlockDriverState *bs, uint64_t offset, } static int coroutine_fn bdrv_co_do_copy_on_readv(BdrvChild *child, - int64_t offset, unsigned int bytes, QEMUIOVector *qiov) + int64_t offset, unsigned int bytes, QEMUIOVector *qiov, + int flags) { BlockDriverState *bs = child->bs; @@ -1296,9 +1297,11 @@ static int coroutine_fn bdrv_co_do_copy_on_readv(BdrvChild *child, goto err; } - qemu_iovec_from_buf(qiov, progress, bounce_buffer + skip_bytes, - pnum - skip_bytes); - } else { + if (!(flags & BDRV_REQ_PREFETCH)) { + qemu_iovec_from_buf(qiov, progress, bounce_buffer + skip_bytes, + pnum - skip_bytes); + } + } else if (!(flags & BDRV_REQ_PREFETCH)) { /* Read directly into the destination */ qemu_iovec_init(&local_qiov, qiov->niov); qemu_iovec_concat(&local_qiov, qiov, progress, pnum - skip_bytes); @@ -1349,7 +1352,8 @@ static int coroutine_fn bdrv_aligned_preadv(BdrvChild *child, * potential fallback support, if we ever implement any read flags * to pass through to drivers. For now, there aren't any * passthrough flags. */ - assert(!(flags & ~(BDRV_REQ_NO_SERIALISING | BDRV_REQ_COPY_ON_READ))); + assert(!(flags & ~(BDRV_REQ_NO_SERIALISING | BDRV_REQ_COPY_ON_READ | + BDRV_REQ_PREFETCH))); /* Handle Copy on Read and associated serialisation */ if (flags & BDRV_REQ_COPY_ON_READ) { @@ -1377,7 +1381,9 @@ static int coroutine_fn bdrv_aligned_preadv(BdrvChild *child, } if (!ret || pnum != bytes) { - ret = bdrv_co_do_copy_on_readv(child, offset, bytes, qiov); + ret = bdrv_co_do_copy_on_readv(child, offset, bytes, qiov, flags); + goto out; + } else if (flags & BDRV_REQ_PREFETCH) { goto out; } } diff --git a/include/block/block.h b/include/block/block.h index 50a07c1c33858aeb228215f61ab424ce5a268f55..a9df34ff94b62307063d275d7a3a4b405cd72317 100644 --- a/include/block/block.h +++ b/include/block/block.h @@ -88,8 +88,14 @@ typedef enum { * fallback. */ BDRV_REQ_NO_FALLBACK = 0x100, + /* + * BDRV_REQ_PREFETCH may be used only together with BDRV_REQ_COPY_ON_READ + * on read request and means that caller doesn't really need data to be + * written to qiov parameter which may be NULL. + */ + BDRV_REQ_PREFETCH = 0x200, /* Mask of valid flags */ - BDRV_REQ_MASK = 0x1ff, + BDRV_REQ_MASK = 0x3ff, } BdrvRequestFlags; typedef struct BlockSizes { diff --git a/nbd/server.c b/nbd/server.c index 2d812489675d16d4260c5606b5468f8374252006..1de4d410c8cac13e5e4282ebdd821731d808f350 100644 --- a/nbd/server.c +++ b/nbd/server.c @@ -2104,12 +2104,15 @@ static int nbd_co_receive_request(NBDRequestData *req, NBDRequest *request, return -EINVAL; } - req->data = blk_try_blockalign(client->exp->blk, request->len); - if (req->data == NULL) { - error_setg(errp, "No memory"); - return -ENOMEM; + if (request->type != NBD_CMD_CACHE) { + req->data = blk_try_blockalign(client->exp->blk, request->len); + if (req->data == NULL) { + error_setg(errp, "No memory"); + return -ENOMEM; + } } } + if (request->type == NBD_CMD_WRITE) { if (nbd_read(client->ioc, req->data, request->len, "CMD_WRITE data", errp) < 0) @@ -2194,7 +2197,7 @@ static coroutine_fn int nbd_do_cmd_read(NBDClient *client, NBDRequest *request, int ret; NBDExport *exp = client->exp; - assert(request->type == NBD_CMD_READ || request->type == NBD_CMD_CACHE); + assert(request->type == NBD_CMD_READ); /* XXX: NBD Protocol only documents use of FUA with WRITE */ if (request->flags & NBD_CMD_FLAG_FUA) { @@ -2206,7 +2209,7 @@ static coroutine_fn int nbd_do_cmd_read(NBDClient *client, NBDRequest *request, } if (client->structured_reply && !(request->flags & NBD_CMD_FLAG_DF) && - request->len && request->type != NBD_CMD_CACHE) + request->len) { return nbd_co_send_sparse_read(client, request->handle, request->from, data, request->len, errp); @@ -2214,7 +2217,7 @@ static coroutine_fn int nbd_do_cmd_read(NBDClient *client, NBDRequest *request, ret = blk_pread(exp->blk, request->from + exp->dev_offset, data, request->len); - if (ret < 0 || request->type == NBD_CMD_CACHE) { + if (ret < 0) { return nbd_send_generic_reply(client, request->handle, ret, "reading from file failed", errp); } @@ -2233,6 +2236,28 @@ static coroutine_fn int nbd_do_cmd_read(NBDClient *client, NBDRequest *request, } } +/* + * nbd_do_cmd_cache + * + * Handle NBD_CMD_CACHE request. + * Return -errno if sending fails. Other errors are reported directly to the + * client as an error reply. + */ +static coroutine_fn int nbd_do_cmd_cache(NBDClient *client, NBDRequest *request, + Error **errp) +{ + int ret; + NBDExport *exp = client->exp; + + assert(request->type == NBD_CMD_CACHE); + + ret = blk_co_preadv(exp->blk, request->from + exp->dev_offset, request->len, + NULL, BDRV_REQ_COPY_ON_READ | BDRV_REQ_PREFETCH); + + return nbd_send_generic_reply(client, request->handle, ret, + "caching data failed", errp); +} + /* Handle NBD request. * Return -errno if sending fails. Other errors are reported directly to the * client as an error reply. */ @@ -2246,8 +2271,10 @@ static coroutine_fn int nbd_handle_request(NBDClient *client, char *msg; switch (request->type) { - case NBD_CMD_READ: case NBD_CMD_CACHE: + return nbd_do_cmd_cache(client, request, errp); + + case NBD_CMD_READ: return nbd_do_cmd_read(client, request, data, errp); case NBD_CMD_WRITE: