qemu-img: Allow source cache mode specification
Many qemu-img subcommands only read the source file(s) once. For these
use cases, a full write-back cache is unnecessary and mainly clutters
host cache memory. Though this is generally no concern as cache memory
is freely available and can be scaled by the host OS, it may become a
concern with thin provisioning.
For these cases, it makes sense to allow users to freely specify the
source cache mode (e.g. use no cache at all).
This commit adds a new switch (-T) for the qemu-img subcommands check,
compare, convert and rebase to specify the cache to be used for source
images (the backing file in case of rebase).
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
diff --git a/qemu-img-cmds.hx b/qemu-img-cmds.hx
index d029609..48df0b8 100644
--- a/qemu-img-cmds.hx
+++ b/qemu-img-cmds.hx
@@ -10,9 +10,9 @@
ETEXI
DEF("check", img_check,
- "check [-q] [-f fmt] [--output=ofmt] [-r [leaks | all]] filename")
+ "check [-q] [-f fmt] [--output=ofmt] [-r [leaks | all]] [-T src_cache] filename")
STEXI
-@item check [-q] [-f @var{fmt}] [--output=@var{ofmt}] [-r [leaks | all]] @var{filename}
+@item check [-q] [-f @var{fmt}] [--output=@var{ofmt}] [-r [leaks | all]] [-T @var{src_cache}] @var{filename}
ETEXI
DEF("create", img_create,
@@ -28,15 +28,15 @@
ETEXI
DEF("compare", img_compare,
- "compare [-f fmt] [-F fmt] [-p] [-q] [-s] filename1 filename2")
+ "compare [-f fmt] [-F fmt] [-T src_cache] [-p] [-q] [-s] filename1 filename2")
STEXI
-@item compare [-f @var{fmt}] [-F @var{fmt}] [-p] [-q] [-s] @var{filename1} @var{filename2}
+@item compare [-f @var{fmt}] [-F @var{fmt}] [-T @var{src_cache}] [-p] [-q] [-s] @var{filename1} @var{filename2}
ETEXI
DEF("convert", img_convert,
- "convert [-c] [-p] [-q] [-n] [-f fmt] [-t cache] [-O output_fmt] [-o options] [-s snapshot_id_or_name] [-l snapshot_param] [-S sparse_size] filename [filename2 [...]] output_filename")
+ "convert [-c] [-p] [-q] [-n] [-f fmt] [-t cache] [-T src_cache] [-O output_fmt] [-o options] [-s snapshot_id_or_name] [-l snapshot_param] [-S sparse_size] filename [filename2 [...]] output_filename")
STEXI
-@item convert [-c] [-p] [-q] [-n] [-f @var{fmt}] [-t @var{cache}] [-O @var{output_fmt}] [-o @var{options}] [-s @var{snapshot_id_or_name}] [-l @var{snapshot_param}] [-S @var{sparse_size}] @var{filename} [@var{filename2} [...]] @var{output_filename}
+@item convert [-c] [-p] [-q] [-n] [-f @var{fmt}] [-t @var{cache}] [-T @var{src_cache}] [-O @var{output_fmt}] [-o @var{options}] [-s @var{snapshot_id_or_name}] [-l @var{snapshot_param}] [-S @var{sparse_size}] @var{filename} [@var{filename2} [...]] @var{output_filename}
ETEXI
DEF("info", img_info,
@@ -58,9 +58,9 @@
ETEXI
DEF("rebase", img_rebase,
- "rebase [-q] [-f fmt] [-t cache] [-p] [-u] -b backing_file [-F backing_fmt] filename")
+ "rebase [-q] [-f fmt] [-t cache] [-T src_cache] [-p] [-u] -b backing_file [-F backing_fmt] filename")
STEXI
-@item rebase [-q] [-f @var{fmt}] [-t @var{cache}] [-p] [-u] -b @var{backing_file} [-F @var{backing_fmt}] @var{filename}
+@item rebase [-q] [-f @var{fmt}] [-t @var{cache}] [-T @var{src_cache}] [-p] [-u] -b @var{backing_file} [-F @var{backing_fmt}] @var{filename}
ETEXI
DEF("resize", img_resize,
diff --git a/qemu-img.c b/qemu-img.c
index 18caa4b..df85405 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -109,6 +109,7 @@
" 'cache' is the cache mode used to write the output disk image, the valid\n"
" options are: 'none', 'writeback' (default, except for convert), 'writethrough',\n"
" 'directsync' and 'unsafe' (default for convert)\n"
+ " 'src_cache' in contrast is the cache mode used to read input disk images\n"
" 'size' is the disk image size in bytes. Optional suffixes\n"
" 'k' or 'K' (kilobyte, 1024), 'M' (megabyte, 1024k), 'G' (gigabyte, 1024M),\n"
" 'T' (terabyte, 1024G), 'P' (petabyte, 1024T) and 'E' (exabyte, 1024P) are\n"
@@ -591,7 +592,7 @@
{
int c, ret;
OutputFormat output_format = OFORMAT_HUMAN;
- const char *filename, *fmt, *output;
+ const char *filename, *fmt, *output, *cache;
BlockDriverState *bs;
int fix = 0;
int flags = BDRV_O_FLAGS | BDRV_O_CHECK;
@@ -600,6 +601,7 @@
fmt = NULL;
output = NULL;
+ cache = BDRV_DEFAULT_CACHE;
for(;;) {
int option_index = 0;
static const struct option long_options[] = {
@@ -609,7 +611,7 @@
{"output", required_argument, 0, OPTION_OUTPUT},
{0, 0, 0, 0}
};
- c = getopt_long(argc, argv, "f:hr:q",
+ c = getopt_long(argc, argv, "hf:r:T:q",
long_options, &option_index);
if (c == -1) {
break;
@@ -637,6 +639,9 @@
case OPTION_OUTPUT:
output = optarg;
break;
+ case 'T':
+ cache = optarg;
+ break;
case 'q':
quiet = true;
break;
@@ -656,6 +661,12 @@
return 1;
}
+ ret = bdrv_parse_cache_flags(cache, &flags);
+ if (ret < 0) {
+ error_report("Invalid source cache option: %s", cache);
+ return 1;
+ }
+
bs = bdrv_new_open("image", filename, fmt, flags, true, quiet);
if (!bs) {
return 1;
@@ -948,7 +959,7 @@
*/
static int img_compare(int argc, char **argv)
{
- const char *fmt1 = NULL, *fmt2 = NULL, *filename1, *filename2;
+ const char *fmt1 = NULL, *fmt2 = NULL, *cache, *filename1, *filename2;
BlockDriverState *bs1, *bs2;
int64_t total_sectors1, total_sectors2;
uint8_t *buf1 = NULL, *buf2 = NULL;
@@ -956,14 +967,16 @@
int allocated1, allocated2;
int ret = 0; /* return value - 0 Ident, 1 Different, >1 Error */
bool progress = false, quiet = false, strict = false;
+ int flags;
int64_t total_sectors;
int64_t sector_num = 0;
int64_t nb_sectors;
int c, pnum;
uint64_t progress_base;
+ cache = BDRV_DEFAULT_CACHE;
for (;;) {
- c = getopt(argc, argv, "hpf:F:sq");
+ c = getopt(argc, argv, "hf:F:T:pqs");
if (c == -1) {
break;
}
@@ -978,6 +991,9 @@
case 'F':
fmt2 = optarg;
break;
+ case 'T':
+ cache = optarg;
+ break;
case 'p':
progress = true;
break;
@@ -1002,17 +1018,25 @@
filename1 = argv[optind++];
filename2 = argv[optind++];
+ flags = BDRV_O_FLAGS;
+ ret = bdrv_parse_cache_flags(cache, &flags);
+ if (ret < 0) {
+ error_report("Invalid source cache option: %s", cache);
+ ret = 2;
+ goto out3;
+ }
+
/* Initialize before goto out */
qemu_progress_init(progress, 2.0);
- bs1 = bdrv_new_open("image 1", filename1, fmt1, BDRV_O_FLAGS, true, quiet);
+ bs1 = bdrv_new_open("image 1", filename1, fmt1, flags, true, quiet);
if (!bs1) {
error_report("Can't open file %s", filename1);
ret = 2;
goto out3;
}
- bs2 = bdrv_new_open("image 2", filename2, fmt2, BDRV_O_FLAGS, true, quiet);
+ bs2 = bdrv_new_open("image 2", filename2, fmt2, flags, true, quiet);
if (!bs2) {
error_report("Can't open file %s", filename2);
ret = 2;
@@ -1191,8 +1215,8 @@
{
int c, n, n1, bs_n, bs_i, compress, cluster_sectors, skip_create;
int64_t ret = 0;
- int progress = 0, flags;
- const char *fmt, *out_fmt, *cache, *out_baseimg, *out_filename;
+ int progress = 0, flags, src_flags;
+ const char *fmt, *out_fmt, *cache, *src_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;
@@ -1214,11 +1238,12 @@
fmt = NULL;
out_fmt = "raw";
cache = "unsafe";
+ src_cache = BDRV_DEFAULT_CACHE;
out_baseimg = NULL;
compress = 0;
skip_create = 0;
for(;;) {
- c = getopt(argc, argv, "f:O:B:s:hce6o:pS:t:qnl:");
+ c = getopt(argc, argv, "hf:O:B:ce6o:s:l:S:pt:T:qn");
if (c == -1) {
break;
}
@@ -1299,6 +1324,9 @@
case 't':
cache = optarg;
break;
+ case 'T':
+ src_cache = optarg;
+ break;
case 'q':
quiet = true;
break;
@@ -1335,6 +1363,13 @@
goto out;
}
+ src_flags = BDRV_O_FLAGS;
+ ret = bdrv_parse_cache_flags(src_cache, &src_flags);
+ if (ret < 0) {
+ error_report("Invalid source cache option: %s", src_cache);
+ goto out;
+ }
+
qemu_progress_print(0, 100);
bs = g_new0(BlockDriverState *, bs_n);
@@ -1344,7 +1379,7 @@
for (bs_i = 0; bs_i < bs_n; bs_i++) {
char *id = bs_n > 1 ? g_strdup_printf("source %d", bs_i)
: g_strdup("source");
- bs[bs_i] = bdrv_new_open(id, argv[optind + bs_i], fmt, BDRV_O_FLAGS,
+ bs[bs_i] = bdrv_new_open(id, argv[optind + bs_i], fmt, src_flags,
true, quiet);
g_free(id);
if (!bs[bs_i]) {
@@ -2291,8 +2326,8 @@
BlockDriverState *bs, *bs_old_backing = NULL, *bs_new_backing = NULL;
BlockDriver *old_backing_drv, *new_backing_drv;
char *filename;
- const char *fmt, *cache, *out_basefmt, *out_baseimg;
- int c, flags, ret;
+ const char *fmt, *cache, *src_cache, *out_basefmt, *out_baseimg;
+ int c, flags, src_flags, ret;
int unsafe = 0;
int progress = 0;
bool quiet = false;
@@ -2301,10 +2336,11 @@
/* Parse commandline parameters */
fmt = NULL;
cache = BDRV_DEFAULT_CACHE;
+ src_cache = BDRV_DEFAULT_CACHE;
out_baseimg = NULL;
out_basefmt = NULL;
for(;;) {
- c = getopt(argc, argv, "uhf:F:b:pt:q");
+ c = getopt(argc, argv, "hf:F:b:upt:T:q");
if (c == -1) {
break;
}
@@ -2331,6 +2367,9 @@
case 't':
cache = optarg;
break;
+ case 'T':
+ src_cache = optarg;
+ break;
case 'q':
quiet = true;
break;
@@ -2359,6 +2398,13 @@
return -1;
}
+ src_flags = BDRV_O_FLAGS;
+ ret = bdrv_parse_cache_flags(src_cache, &src_flags);
+ if (ret < 0) {
+ error_report("Invalid source cache option: %s", src_cache);
+ return -1;
+ }
+
/*
* Open the images.
*
@@ -2402,7 +2448,7 @@
bs_old_backing = bdrv_new("old_backing", &error_abort);
bdrv_get_backing_filename(bs, backing_name, sizeof(backing_name));
- ret = bdrv_open(&bs_old_backing, backing_name, NULL, NULL, BDRV_O_FLAGS,
+ ret = bdrv_open(&bs_old_backing, backing_name, NULL, NULL, src_flags,
old_backing_drv, &local_err);
if (ret) {
error_report("Could not open old backing file '%s': %s",
@@ -2412,8 +2458,8 @@
}
if (out_baseimg[0]) {
bs_new_backing = bdrv_new("new_backing", &error_abort);
- ret = bdrv_open(&bs_new_backing, out_baseimg, NULL, NULL,
- BDRV_O_FLAGS, new_backing_drv, &local_err);
+ ret = bdrv_open(&bs_new_backing, out_baseimg, NULL, NULL, src_flags,
+ new_backing_drv, &local_err);
if (ret) {
error_report("Could not open new backing file '%s': %s",
out_baseimg, error_get_pretty(local_err));
diff --git a/qemu-img.texi b/qemu-img.texi
index 514be90..688b28d 100644
--- a/qemu-img.texi
+++ b/qemu-img.texi
@@ -72,6 +72,9 @@
specifies the cache mode that should be used with the (destination) file. See
the documentation of the emulator's @code{-drive cache=...} option for allowed
values.
+@item -T @var{src_cache}
+in contrast specifies the cache mode that should be used with the source
+file(s).
@end table
Parameters to snapshot subcommand:
@@ -113,7 +116,7 @@
Command description:
@table @option
-@item check [-f @var{fmt}] [--output=@var{ofmt}] [-r [leaks | all]] @var{filename}
+@item check [-f @var{fmt}] [--output=@var{ofmt}] [-r [leaks | all]] [-T @var{src_cache}] @var{filename}
Perform a consistency check on the disk image @var{filename}. The command can
output in the format @var{ofmt} which is either @code{human} or @code{json}.
@@ -172,7 +175,7 @@
backing file to match the size of the smaller snapshot, you can safely truncate
it yourself once the commit operation successfully completes.
-@item compare [-f @var{fmt}] [-F @var{fmt}] [-p] [-s] [-q] @var{filename1} @var{filename2}
+@item compare [-f @var{fmt}] [-F @var{fmt}] [-T @var{src_cache}] [-p] [-s] [-q] @var{filename1} @var{filename2}
Check if two images have the same content. You can compare images with
different format or settings.
@@ -213,7 +216,7 @@
@end table
-@item convert [-c] [-p] [-n] [-f @var{fmt}] [-t @var{cache}] [-O @var{output_fmt}] [-o @var{options}] [-s @var{snapshot_id_or_name}] [-l @var{snapshot_param}] [-S @var{sparse_size}] @var{filename} [@var{filename2} [...]] @var{output_filename}
+@item convert [-c] [-p] [-n] [-f @var{fmt}] [-t @var{cache}] [-T @var{src_cache}] [-O @var{output_fmt}] [-o @var{options}] [-s @var{snapshot_id_or_name}] [-l @var{snapshot_param}] [-S @var{sparse_size}] @var{filename} [@var{filename2} [...]] @var{output_filename}
Convert the disk image @var{filename} or a snapshot @var{snapshot_param}(@var{snapshot_id_or_name} is deprecated)
to disk image @var{output_filename} using format @var{output_fmt}. It can be optionally compressed (@code{-c}
@@ -325,7 +328,7 @@
List, apply, create or delete snapshots in image @var{filename}.
-@item rebase [-f @var{fmt}] [-t @var{cache}] [-p] [-u] -b @var{backing_file} [-F @var{backing_fmt}] @var{filename}
+@item rebase [-f @var{fmt}] [-t @var{cache}] [-T @var{src_cache}] [-p] [-u] -b @var{backing_file} [-F @var{backing_fmt}] @var{filename}
Changes the backing file of an image. Only the formats @code{qcow2} and
@code{qed} support changing the backing file.
@@ -336,6 +339,9 @@
string), then the image is rebased onto no backing file (i.e. it will exist
independently of any backing file).
+@var{cache} specifies the cache mode to be used for @var{filename}, whereas
+@var{src_cache} specifies the cache mode for reading the new backing file.
+
There are two different modes in which @code{rebase} can operate:
@table @option
@item Safe mode
