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qcow2: extract preallocation calculation function 

Calculating the preallocated image size will be needed to implement
.bdrv_measure().  Extract the code out into a separate function.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Message-id: 20170705125738.8777-4-stefanha@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
This commit is contained in:
Stefan Hajnoczi 2017-07-05 13:57:32 +01:00 committed by Max Reitz
parent a843a22a82
commit 95c67e3bd7
1 changed files with 77 additions and 59 deletions
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94
block/qcow2.c
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@ -2537,44 +2537,19 @@ static int preallocate(BlockDriverState *bs)
return 0;
}
static int qcow2_create2(const char *filename, int64_t total_size,
const char *backing_file, const char *backing_format,
int flags, size_t cluster_size, PreallocMode prealloc,
QemuOpts *opts, int version, int refcount_order,
const char *encryptfmt, Error **errp)
{
int cluster_bits;
QDict *options;
/* Calculate cluster_bits */
cluster_bits = ctz32(cluster_size);
if (cluster_bits < MIN_CLUSTER_BITS || cluster_bits > MAX_CLUSTER_BITS ||
(1 << cluster_bits) != cluster_size)
{
error_setg(errp, "Cluster size must be a power of two between %d and "
"%dk", 1 << MIN_CLUSTER_BITS, 1 << (MAX_CLUSTER_BITS - 10));
return -EINVAL;
}
/*
* Open the image file and write a minimal qcow2 header.
/**
* qcow2_calc_prealloc_size:
* @total_size: virtual disk size in bytes
* @cluster_size: cluster size in bytes
* @refcount_order: refcount bits power-of-2 exponent
*
* We keep things simple and start with a zero-sized image. We also
* do without refcount blocks or a L1 table for now. We'll fix the
* inconsistency later.
*
* We do need a refcount table because growing the refcount table means
* allocating two new refcount blocks - the seconds of which would be at
* 2 GB for 64k clusters, and we don't want to have a 2 GB initial file
* size for any qcow2 image.
* Returns: Total number of bytes required for the fully allocated image
* (including metadata).
*/
BlockBackend *blk;
QCowHeader *header;
uint64_t* refcount_table;
Error *local_err = NULL;
int ret;
if (prealloc == PREALLOC_MODE_FULL || prealloc == PREALLOC_MODE_FALLOC) {
static int64_t qcow2_calc_prealloc_size(int64_t total_size,
size_t cluster_size,
int refcount_order)
{
/* Note: The following calculation does not need to be exact; if it is a
* bit off, either some bytes will be "leaked" (which is fine) or we
* will need to increase the file size by some bytes (which is fine,
@ -2583,6 +2558,7 @@ static int qcow2_create2(const char *filename, int64_t total_size,
int64_t meta_size = 0;
uint64_t nreftablee, nrefblocke, nl1e, nl2e, refblock_count;
int64_t aligned_total_size = align_offset(total_size, cluster_size);
int cluster_bits = ctz32(cluster_size);
int refblock_bits, refblock_size;
/* refcount entry size in bytes */
double rces = (1 << refcount_order) / 8.;
@ -2632,8 +2608,50 @@ static int qcow2_create2(const char *filename, int64_t total_size,
cluster_size / sizeof(uint64_t));
meta_size += nreftablee * sizeof(uint64_t);
qemu_opt_set_number(opts, BLOCK_OPT_SIZE,
aligned_total_size + meta_size, &error_abort);
return meta_size + aligned_total_size;
}
static int qcow2_create2(const char *filename, int64_t total_size,
const char *backing_file, const char *backing_format,
int flags, size_t cluster_size, PreallocMode prealloc,
QemuOpts *opts, int version, int refcount_order,
const char *encryptfmt, Error **errp)
{
int cluster_bits;
QDict *options;
/* Calculate cluster_bits */
cluster_bits = ctz32(cluster_size);
if (cluster_bits < MIN_CLUSTER_BITS || cluster_bits > MAX_CLUSTER_BITS ||
(1 << cluster_bits) != cluster_size)
{
error_setg(errp, "Cluster size must be a power of two between %d and "
"%dk", 1 << MIN_CLUSTER_BITS, 1 << (MAX_CLUSTER_BITS - 10));
return -EINVAL;
}
/*
* Open the image file and write a minimal qcow2 header.
*
* We keep things simple and start with a zero-sized image. We also
* do without refcount blocks or a L1 table for now. We'll fix the
* inconsistency later.
*
* We do need a refcount table because growing the refcount table means
* allocating two new refcount blocks - the seconds of which would be at
* 2 GB for 64k clusters, and we don't want to have a 2 GB initial file
* size for any qcow2 image.
*/
BlockBackend *blk;
QCowHeader *header;
uint64_t* refcount_table;
Error *local_err = NULL;
int ret;
if (prealloc == PREALLOC_MODE_FULL || prealloc == PREALLOC_MODE_FALLOC) {
int64_t prealloc_size =
qcow2_calc_prealloc_size(total_size, cluster_size, refcount_order);
qemu_opt_set_number(opts, BLOCK_OPT_SIZE, prealloc_size, &error_abort);
qemu_opt_set(opts, BLOCK_OPT_PREALLOC, PreallocMode_lookup[prealloc],
&error_abort);
}