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qemu-img: add a "map" subcommand 

This command dumps the metadata of an entire chain, in either tabular or JSON
format.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Paolo Bonzini 2013-09-04 19:00:33 +02:00 committed by Stefan Hajnoczi
parent f0ad5712d5
commit 4c93a13b5d
2 changed files with 197 additions and 0 deletions
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6
qemu-img-cmds.hx
View File

@ -45,6 +45,12 @@ STEXI
@item info [-f @var{fmt}] [--output=@var{ofmt}] [--backing-chain] @var{filename}
ETEXI
DEF("map", img_map,
"map [-f fmt] [--output=ofmt] filename")
STEXI
@item map [-f @var{fmt}] [--output=@var{ofmt}] @var{filename}
ETEXI
DEF("snapshot", img_snapshot,
"snapshot [-q] [-l | -a snapshot | -c snapshot | -d snapshot] filename")
STEXI

191
qemu-img.c
View File

@ -1801,6 +1801,197 @@ static int img_info(int argc, char **argv)
return 0;
}
typedef struct MapEntry {
int flags;
int depth;
int64_t start;
int64_t length;
int64_t offset;
BlockDriverState *bs;
} MapEntry;
static void dump_map_entry(OutputFormat output_format, MapEntry *e,
MapEntry *next)
{
switch (output_format) {
case OFORMAT_HUMAN:
if ((e->flags & BDRV_BLOCK_DATA) &&
!(e->flags & BDRV_BLOCK_OFFSET_VALID)) {
error_report("File contains external, encrypted or compressed clusters.");
exit(1);
}
if ((e->flags & (BDRV_BLOCK_DATA|BDRV_BLOCK_ZERO)) == BDRV_BLOCK_DATA) {
printf("%#-16"PRIx64"%#-16"PRIx64"%#-16"PRIx64"%s\n",
e->start, e->length, e->offset, e->bs->filename);
}
/* This format ignores the distinction between 0, ZERO and ZERO|DATA.
* Modify the flags here to allow more coalescing.
*/
if (next &&
(next->flags & (BDRV_BLOCK_DATA|BDRV_BLOCK_ZERO)) != BDRV_BLOCK_DATA) {
next->flags &= ~BDRV_BLOCK_DATA;
next->flags |= BDRV_BLOCK_ZERO;
}
break;
case OFORMAT_JSON:
printf("%s{ \"start\": %"PRId64", \"length\": %"PRId64", \"depth\": %d,"
" \"zero\": %s, \"data\": %s",
(e->start == 0 ? "[" : ",\n"),
e->start, e->length, e->depth,
(e->flags & BDRV_BLOCK_ZERO) ? "true" : "false",
(e->flags & BDRV_BLOCK_DATA) ? "true" : "false");
if (e->flags & BDRV_BLOCK_OFFSET_VALID) {
printf(", 'offset': %"PRId64"", e->offset);
}
putchar('}');
if (!next) {
printf("]\n");
}
break;
}
}
static int get_block_status(BlockDriverState *bs, int64_t sector_num,
int nb_sectors, MapEntry *e)
{
int64_t ret;
int depth;
/* As an optimization, we could cache the current range of unallocated
* clusters in each file of the chain, and avoid querying the same
* range repeatedly.
*/
depth = 0;
for (;;) {
ret = bdrv_get_block_status(bs, sector_num, nb_sectors, &nb_sectors);
if (ret < 0) {
return ret;
}
assert(nb_sectors);
if (ret & (BDRV_BLOCK_ZERO|BDRV_BLOCK_DATA)) {
break;
}
bs = bs->backing_hd;
if (bs == NULL) {
ret = 0;
break;
}
depth++;
}
e->start = sector_num * BDRV_SECTOR_SIZE;
e->length = nb_sectors * BDRV_SECTOR_SIZE;
e->flags = ret & ~BDRV_BLOCK_OFFSET_MASK;
e->offset = ret & BDRV_BLOCK_OFFSET_MASK;
e->depth = depth;
e->bs = bs;
return 0;
}
static int img_map(int argc, char **argv)
{
int c;
OutputFormat output_format = OFORMAT_HUMAN;
BlockDriverState *bs;
const char *filename, *fmt, *output;
int64_t length;
MapEntry curr = { .length = 0 }, next;
int ret = 0;
fmt = NULL;
output = NULL;
for (;;) {
int option_index = 0;
static const struct option long_options[] = {
{"help", no_argument, 0, 'h'},
{"format", required_argument, 0, 'f'},
{"output", required_argument, 0, OPTION_OUTPUT},
{0, 0, 0, 0}
};
c = getopt_long(argc, argv, "f:h",
long_options, &option_index);
if (c == -1) {
break;
}
switch (c) {
case '?':
case 'h':
help();
break;
case 'f':
fmt = optarg;
break;
case OPTION_OUTPUT:
output = optarg;
break;
}
}
if (optind >= argc) {
help();
}
filename = argv[optind++];
if (output && !strcmp(output, "json")) {
output_format = OFORMAT_JSON;
} else if (output && !strcmp(output, "human")) {
output_format = OFORMAT_HUMAN;
} else if (output) {
error_report("--output must be used with human or json as argument.");
return 1;
}
bs = bdrv_new_open(filename, fmt, BDRV_O_FLAGS, true, false);
if (!bs) {
return 1;
}
if (output_format == OFORMAT_HUMAN) {
printf("%-16s%-16s%-16s%s\n", "Offset", "Length", "Mapped to", "File");
}
length = bdrv_getlength(bs);
while (curr.start + curr.length < length) {
int64_t nsectors_left;
int64_t sector_num;
int n;
sector_num = (curr.start + curr.length) >> BDRV_SECTOR_BITS;
/* Probe up to 1 GiB at a time. */
nsectors_left = DIV_ROUND_UP(length, BDRV_SECTOR_SIZE) - sector_num;
n = MIN(1 << (30 - BDRV_SECTOR_BITS), nsectors_left);
ret = get_block_status(bs, sector_num, n, &next);
if (ret < 0) {
error_report("Could not read file metadata: %s", strerror(-ret));
goto out;
}
if (curr.length != 0 && curr.flags == next.flags &&
curr.depth == next.depth &&
((curr.flags & BDRV_BLOCK_OFFSET_VALID) == 0 ||
curr.offset + curr.length == next.offset)) {
curr.length += next.length;
continue;
}
if (curr.length > 0) {
dump_map_entry(output_format, &curr, &next);
}
curr = next;
}
dump_map_entry(output_format, &curr, NULL);
out:
bdrv_unref(bs);
return ret < 0;
}
#define SNAPSHOT_LIST 1
#define SNAPSHOT_CREATE 2
#define SNAPSHOT_APPLY 3