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qcow2: Allow different cluster sizes

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Add an option to specify the cluster size of a newly created qcow2 image.
Default is 4k which is the same value that was hard-coded before.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
This commit is contained in:
Kevin Wolf 2009-05-19 17:57:21 +02:00 committed by Anthony Liguori
parent efa84d43cc
commit 73c632edc4
2 changed files with 49 additions and 5 deletions
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53
block/qcow2.c
View File

@ -62,6 +62,9 @@
#define REFCOUNT_SHIFT 1 /* refcount size is 2 bytes */
#define MIN_CLUSTER_BITS 9
#define MAX_CLUSTER_BITS 16
typedef struct QCowHeader {
uint32_t magic;
uint32_t version;
@ -300,8 +303,8 @@ static int qcow_open(BlockDriverState *bs, const char *filename, int flags)
if (header.magic != QCOW_MAGIC || header.version != QCOW_VERSION)
goto fail;
if (header.size <= 1 ||
header.cluster_bits < 9 ||
header.cluster_bits > 16)
header.cluster_bits < MIN_CLUSTER_BITS ||
header.cluster_bits > MAX_CLUSTER_BITS)
goto fail;
if (header.crypt_method > QCOW_CRYPT_AES)
goto fail;
@ -1583,9 +1586,30 @@ static void create_refcount_update(QCowCreateState *s,
}
}
static int get_bits_from_size(size_t size)
{
int res = 0;
if (size == 0) {
return -1;
}
while (size != 1) {
/* Not a power of two */
if (size & 1) {
return -1;
}
size >>= 1;
res++;
}
return res;
}
static int qcow_create2(const char *filename, int64_t total_size,
const char *backing_file, const char *backing_format,
int flags)
int flags, size_t cluster_size)
{
int fd, header_size, backing_filename_len, l1_size, i, shift, l2_bits;
@ -1619,8 +1643,20 @@ static int qcow_create2(const char *filename, int64_t total_size,
header.backing_file_size = cpu_to_be32(backing_filename_len);
header_size += backing_filename_len;
}
s->cluster_bits = 12; /* 4 KB clusters */
/* Cluster size */
s->cluster_bits = get_bits_from_size(cluster_size);
if (s->cluster_bits < MIN_CLUSTER_BITS ||
s->cluster_bits > MAX_CLUSTER_BITS)
{
fprintf(stderr, "Cluster size must be a power of two between "
"%d and %dk\n",
1 << MIN_CLUSTER_BITS,
1 << (MAX_CLUSTER_BITS - 10));
return -EINVAL;
}
s->cluster_size = 1 << s->cluster_bits;
header.cluster_bits = cpu_to_be32(s->cluster_bits);
header_size = (header_size + 7) & ~7;
if (flags & BLOCK_FLAG_ENCRYPT) {
@ -1702,6 +1738,7 @@ static int qcow_create(const char *filename, QEMUOptionParameter *options)
const char *backing_fmt = NULL;
uint64_t sectors = 0;
int flags = 0;
size_t cluster_size = 4096;
/* Read out options */
while (options && options->name) {
@ -1713,11 +1750,16 @@ static int qcow_create(const char *filename, QEMUOptionParameter *options)
backing_fmt = options->value.s;
} else if (!strcmp(options->name, BLOCK_OPT_ENCRYPT)) {
flags |= options->value.n ? BLOCK_FLAG_ENCRYPT : 0;
} else if (!strcmp(options->name, BLOCK_OPT_CLUSTER_SIZE)) {
if (options->value.n) {
cluster_size = options->value.n;
}
}
options++;
}
return qcow_create2(filename, sectors, backing_file, backing_fmt, flags);
return qcow_create2(filename, sectors, backing_file, backing_fmt, flags,
cluster_size);
}
static int qcow_make_empty(BlockDriverState *bs)
@ -2920,6 +2962,7 @@ static QEMUOptionParameter qcow_create_options[] = {
{ BLOCK_OPT_BACKING_FILE, OPT_STRING },
{ BLOCK_OPT_BACKING_FMT, OPT_STRING },
{ BLOCK_OPT_ENCRYPT, OPT_FLAG },
{ BLOCK_OPT_CLUSTER_SIZE, OPT_SIZE },
{ NULL }
};

1
block_int.h
View File

@ -36,6 +36,7 @@
#define BLOCK_OPT_COMPAT6 "compat6"
#define BLOCK_OPT_BACKING_FILE "backing_file"
#define BLOCK_OPT_BACKING_FMT "backing_fmt"
#define BLOCK_OPT_CLUSTER_SIZE "cluster_size"
typedef struct AIOPool {
void (*cancel)(BlockDriverAIOCB *acb);