[{"id":3683379,"web_url":"http://patchwork.ozlabs.org/comment/3683379/","msgid":"<2b383d39-4107-49d7-a106-e442a822d8a3@virtuozzo.com>","list_archive_url":null,"date":"2026-04-28T10:59:26","subject":"Re: [PATCH 2/4] qemu-io: Add 'aio_discard' command","submitter":{"id":68167,"url":"http://patchwork.ozlabs.org/api/people/68167/","name":"Denis V. Lunev","email":"den@virtuozzo.com"},"content":"On 4/27/26 19:05, Kevin Wolf wrote:\n> Testing interactions between multiple requests that include discard\n> requests require that qemu-io can do the discard asynchronously, like it\n> already does for reads and writes. To this effect, add an 'aio_discard'\n> command.\n>\n> Signed-off-by: Kevin Wolf \n> ---\n> qemu-io-cmds.c | 113 +++++++++++++++++++++++++++++++++++++++++++++++++\n> 1 file changed, 113 insertions(+)\n>\n> diff --git a/qemu-io-cmds.c b/qemu-io-cmds.c\n> index 13e03301624..0f5baa70f94 100644\n> --- a/qemu-io-cmds.c\n> +++ b/qemu-io-cmds.c\n> @@ -2218,6 +2218,118 @@ static int discard_f(BlockBackend *blk, int argc, char **argv)\n> return 0;\n> }\n> \n> +static void aio_discard_help(void)\n> +{\n> + printf(\n> +\"\\n\"\n> +\" asynchronously discards a range of bytes from the given offset\\n\"\n> +\"\\n\"\n> +\" Example:\\n\"\n> +\" 'aio_discard 512 1k' - discards 1 kilobyte from 512 bytes into the file\\n\"\n> +\"\\n\"\n> +\" Discards a segment of the currently open file.\\n\"\n> +\" -C, -- report statistics in a machine parsable format\\n\"\n> +\" -q, -- quiet mode, do not show I/O statistics\\n\"\n> +\" The discard is performed asynchronously and the aio_flush command must be\\n\"\n> +\" used to ensure all outstanding aio requests have been completed.\\n\"\n> +\" Note that due to its asynchronous nature, this command will be\\n\"\n> +\" considered successful once the request is submitted, independently\\n\"\n> +\" of potential I/O errors.\\n\"\n> +\"\\n\");\n> +}\n> +\n> +static int aio_discard_f(BlockBackend *blk, int argc, char **argv);\n> +\n> +static const cmdinfo_t aio_discard_cmd = {\n> + .name = \"aio_discard\",\n> + .cfunc = aio_discard_f,\n> + .perm = BLK_PERM_WRITE,\n> + .argmin = 2,\n> + .argmax = -1,\n> + .args = \"[-Cq] off len\",\n> + .oneline = \"asynchronously discards a number of bytes\",\n> + .help = aio_discard_help,\n> +};\n> +\n> +static void aio_discard_done(void *opaque, int ret)\n> +{\n> + struct aio_ctx *ctx = opaque;\n> + struct timespec t2;\n> +\n> + clock_gettime(CLOCK_MONOTONIC, &t2);\n> +\n> + if (ret < 0) {\n> + printf(\"aio_discard failed: %s\\n\", strerror(-ret));\n> + block_acct_failed(blk_get_stats(ctx->blk), &ctx->acct);\n> + goto out;\n> + }\n> +\n> + block_acct_done(blk_get_stats(ctx->blk), &ctx->acct);\n> +\n> + if (ctx->qflag) {\n> + goto out;\n> + }\n> +\n> + /* Finally, report back -- -C gives a parsable format */\n> + t2 = tsub(t2, ctx->t1);\n> + print_report(\"discarded \", &t2, ctx->offset, ctx->qiov.size,\n> + ctx->qiov.size, 1, ctx->Cflag);\n> +out:\n> + g_free(ctx);\n> +}\n> +\n> +static int aio_discard_f(BlockBackend *blk, int argc, char **argv)\n> +{\n> + int c, ret;\n> + int64_t count;\n> + struct aio_ctx *ctx = g_new0(struct aio_ctx, 1);\n> +\n> + ctx->blk = blk;\n> +\n> + while ((c = getopt(argc, argv, \"Cq\")) != -1) {\n> + switch (c) {\n> + case 'C':\n> + ctx->Cflag = true;\n> + break;\n> + case 'q':\n> + ctx->qflag = true;\n> + break;\n> + default:\n> + qemuio_command_usage(&aio_discard_cmd);\nleaked ctx\n\n> + return -EINVAL;\n> + }\n> + }\n> +\n> + if (optind != argc - 2) {\n> + qemuio_command_usage(&aio_discard_cmd);\nleaked ctx\n\n> + return -EINVAL;\n> + }\n> +\n> + ctx->offset = cvtnum(argv[optind]);\n> + if (ctx->offset < 0) {\n> + ret = ctx->offset;\n> + print_cvtnum_err(ret, argv[optind]);\n> + g_free(ctx);\n> + return ret;\n> + }\n> + optind++;\n> +\n> + count = cvtnum(argv[optind]);\n> + if (count < 0) {\n> + print_cvtnum_err(count, argv[optind]);\n> + g_free(ctx);\n> + return count;\n> + }\n> +\n> + clock_gettime(CLOCK_MONOTONIC, &ctx->t1);\n> + ctx->qiov.size = count;\n> + block_acct_start(blk_get_stats(blk), &ctx->acct, ctx->qiov.size,\n> + BLOCK_ACCT_UNMAP);\n> + blk_aio_pdiscard(blk, ctx->offset, count, aio_discard_done, ctx);\n> +\n> + return 0;\n> +}\n> +\n> static int alloc_f(BlockBackend *blk, int argc, char **argv)\n> {\n> BlockDriverState *bs = blk_bs(blk);\n> @@ -2800,6 +2912,7 @@ static void __attribute((constructor)) init_qemuio_commands(void)\n> qemuio_add_command(&length_cmd);\n> qemuio_add_command(&info_cmd);\n> qemuio_add_command(&discard_cmd);\n> + qemuio_add_command(&aio_discard_cmd);\n> qemuio_add_command(&alloc_cmd);\n> qemuio_add_command(&map_cmd);\n> qemuio_add_command(&reopen_cmd);","headers":{"Return-Path":"","X-Original-To":"incoming@patchwork.ozlabs.org","Delivered-To":"patchwork-incoming@legolas.ozlabs.org","Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=virtuozzo.com header.i=@virtuozzo.com\n header.a=rsa-sha256 header.s=selector2 header.b=wMX+bn6k;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=nongnu.org\n (client-ip=209.51.188.17; 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