From 38d60cb243e12f05aed9ff7061a3439dd1471cfc Mon Sep 17 00:00:00 2001 From: Federico Simoncelli Date: Tue, 12 Jul 2011 16:06:38 -0300 Subject: [RHEL6 qemu-kvm PATCH 5/8] qemu-img: Add cache command line option RH-Author: Federico Simoncelli Message-id: <1310486798-27936-1-git-send-email-fsimonce@redhat.com> Patchwork-id: 29534 O-Subject: [PATCH RHEL6.2 qemu-img] qemu-img: Add cache command line option Bugzilla: 713743 RH-Acked-by: Kevin Wolf RH-Acked-by: Christoph Hellwig RH-Acked-by: Jes Sorensen qemu-img currently writes disk images using writeback and filling up the cache buffers which are then flushed by the kernel preventing other processes from accessing the storage. This is particularly bad in cluster environments where time-based algorithms might be in place and accessing the storage within certain timeouts is critical. This patch adds the option to choose a cache method when writing disk images. Signed-off-by: Federico Simoncelli Bugzilla: 713743 Upstream status: accepted into block branch, not yet in master --- qemu-img-cmds.hx | 6 ++-- qemu-img.c | 80 +++++++++++++++++++++++++++++++++++++++++++++--------- 2 files changed, 70 insertions(+), 16 deletions(-) Signed-off-by: Eduardo Habkost --- qemu-img-cmds.hx | 6 ++-- qemu-img.c | 80 +++++++++++++++++++++++++++++++++++++++++++++--------- 2 files changed, 70 insertions(+), 16 deletions(-) diff --git a/qemu-img-cmds.hx b/qemu-img-cmds.hx index 995852a..b4fb880 100644 --- a/qemu-img-cmds.hx +++ b/qemu-img-cmds.hx @@ -22,13 +22,13 @@ STEXI ETEXI DEF("commit", img_commit, - "commit [-f fmt] filename") + "commit [-f fmt] [-t cache] filename") STEXI @item commit [-f @var{fmt}] @var{filename} ETEXI DEF("convert", img_convert, - "convert [-c] [-p] [-f fmt] [-O output_fmt] [-o options] filename [filename2 [...]] output_filename") + "convert [-c] [-p] [-f fmt] [-t cache] [-O output_fmt] [-o options] filename [filename2 [...]] output_filename") STEXI @item convert [-c] [-f @var{fmt}] [-O @var{output_fmt}] [-o @var{options}] @var{filename} [@var{filename2} [...]] @var{output_filename} ETEXI @@ -46,7 +46,7 @@ STEXI ETEXI DEF("rebase", img_rebase, - "rebase [-f fmt] [-p] [-u] -b backing_file [-F backing_fmt] filename") + "rebase [-f fmt] [-t cache] [-p] [-u] -b backing_file [-F backing_fmt] filename") STEXI @item rebase [-f @var{fmt}] [-u] -b @var{backing_file} [-F @var{backing_fmt}] @var{filename} ETEXI diff --git a/qemu-img.c b/qemu-img.c index 6a1f1d7..ced2635 100644 --- a/qemu-img.c +++ b/qemu-img.c @@ -38,6 +38,7 @@ typedef struct img_cmd_t { /* Default to cache=writeback as data integrity is not important for qemu-tcg. */ #define BDRV_O_FLAGS BDRV_O_CACHE_WB +#define BDRV_DEFAULT_CACHE "writeback" static void error(const char *fmt, ...) { @@ -71,6 +72,8 @@ static void help(void) "Command parameters:\n" " 'filename' is a disk image filename\n" " 'fmt' is the disk image format. It is guessed automatically in most cases\n" + " 'cache' is the cache mode used to write the output disk image, the valid\n" + " options are: 'none', 'writeback' (default), 'writethrough' and 'unsafe'\n" " 'size' is the disk image size in bytes. Optional suffixes\n" " 'k' or 'K' (kilobyte, 1024), 'M' (megabyte, 1024k), 'G' (gigabyte, 1024M)\n" " and T (terabyte, 1024G) are supported. 'b' is ignored.\n" @@ -187,6 +190,27 @@ static int read_password(char *buf, int buf_size) } #endif +static int set_cache_flag(const char *mode, int *flags) +{ + *flags &= ~BDRV_O_CACHE_MASK; + + if (!strcmp(mode, "none") || !strcmp(mode, "off")) { + *flags |= BDRV_O_CACHE_WB; + *flags |= BDRV_O_NOCACHE; + } else if (!strcmp(mode, "writeback")) { + *flags |= BDRV_O_CACHE_WB; + } else if (!strcmp(mode, "unsafe")) { + *flags |= BDRV_O_CACHE_WB; + *flags |= BDRV_O_NO_FLUSH; + } else if (!strcmp(mode, "writethrough")) { + /* this is the default */ + } else { + return -1; + } + + return 0; +} + static int print_block_option_help(const char *filename, const char *fmt) { BlockDriver *drv, *proto_drv; @@ -445,13 +469,14 @@ static int img_check(int argc, char **argv) static int img_commit(int argc, char **argv) { - int c, ret; - const char *filename, *fmt; + int c, ret, flags; + const char *filename, *fmt, *cache; BlockDriverState *bs; fmt = NULL; + cache = BDRV_DEFAULT_CACHE; for(;;) { - c = getopt(argc, argv, "f:h"); + c = getopt(argc, argv, "f:ht:"); if (c == -1) { break; } @@ -463,6 +488,9 @@ static int img_commit(int argc, char **argv) case 'f': fmt = optarg; break; + case 't': + cache = optarg; + break; } } if (optind >= argc) { @@ -470,7 +498,14 @@ static int img_commit(int argc, char **argv) } filename = argv[optind++]; - bs = bdrv_new_open(filename, fmt, BDRV_O_FLAGS | BDRV_O_RDWR); + flags = BDRV_O_RDWR; + ret = set_cache_flag(cache, &flags); + if (ret < 0) { + error("Invalid cache option: %s\n", cache); + return -1; + } + + bs = bdrv_new_open(filename, fmt, flags); if (!bs) { return 1; } @@ -572,8 +607,8 @@ static int compare_sectors(const uint8_t *buf1, const uint8_t *buf2, int n, static int img_convert(int argc, char **argv) { int c, ret = 0, n, n1, bs_n, bs_i, compress, cluster_size, cluster_sectors; - int progress = 0; - const char *fmt, *out_fmt, *out_baseimg, *out_filename; + int progress = 0, flags; + const char *fmt, *out_fmt, *cache, *out_baseimg, *out_filename; BlockDriver *drv, *proto_drv; BlockDriverState **bs = NULL, *out_bs = NULL; int64_t total_sectors, nb_sectors, sector_num, bs_offset; @@ -587,10 +622,11 @@ static int img_convert(int argc, char **argv) fmt = NULL; out_fmt = "raw"; + cache = "unsafe"; out_baseimg = NULL; compress = 0; for(;;) { - c = getopt(argc, argv, "f:O:B:hce6o:p"); + c = getopt(argc, argv, "f:O:B:s:hce6o:pt:"); if (c == -1) { break; } @@ -625,6 +661,9 @@ static int img_convert(int argc, char **argv) case 'p': progress = 1; break; + case 't': + cache = optarg; + break; } } @@ -731,8 +770,14 @@ static int img_convert(int argc, char **argv) goto out; } - out_bs = bdrv_new_open(out_filename, out_fmt, - BDRV_O_FLAGS | BDRV_O_RDWR | BDRV_O_NO_FLUSH); + flags = BDRV_O_RDWR; + ret = set_cache_flag(cache, &flags); + if (ret < 0) { + error("Invalid cache option: %s\n", cache); + return -1; + } + + out_bs = bdrv_new_open(out_filename, out_fmt, flags); if (!out_bs) { ret = -1; goto out; @@ -1177,18 +1222,18 @@ static int img_rebase(int argc, char **argv) BlockDriverState *bs, *bs_old_backing = NULL, *bs_new_backing = NULL; BlockDriver *old_backing_drv, *new_backing_drv; char *filename; - const char *fmt, *out_basefmt, *out_baseimg; + const char *fmt, *cache, *out_basefmt, *out_baseimg; int c, flags, ret; int unsafe = 0; int progress = 0; /* Parse commandline parameters */ fmt = NULL; + cache = BDRV_DEFAULT_CACHE; out_baseimg = NULL; out_basefmt = NULL; - for(;;) { - c = getopt(argc, argv, "uhf:F:b:p"); + c = getopt(argc, argv, "uhf:F:b:pt:"); if (c == -1) { break; } @@ -1212,6 +1257,9 @@ static int img_rebase(int argc, char **argv) case 'p': progress = 1; break; + case 't': + cache = optarg; + break; } } @@ -1223,13 +1271,19 @@ static int img_rebase(int argc, char **argv) qemu_progress_init(progress, 2.0); qemu_progress_print(0, 100); + flags = BDRV_O_RDWR | (unsafe ? BDRV_O_NO_BACKING : 0); + ret = set_cache_flag(cache, &flags); + if (ret < 0) { + error("Invalid cache option: %s\n", cache); + return -1; + } + /* * Open the images. * * Ignore the old backing file for unsafe rebase in case we want to correct * the reference to a renamed or moved backing file. */ - flags = BDRV_O_FLAGS | BDRV_O_RDWR | (unsafe ? BDRV_O_NO_BACKING : 0); bs = bdrv_new_open(filename, fmt, flags); if (!bs) { return 1; -- 1.7.3.2