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qcow2: Add falloc and full preallocation option 

preallocation=falloc allocates disk space by posix_fallocate(),
preallocation=full allocates disk space by writing zeros to disk.
Both modes imply preallocation=metadata.

Signed-off-by: Hu Tao <hutao@cn.fujitsu.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Hu Tao 2014-09-10 17:05:49 +08:00 committed by Kevin Wolf
parent 06247428be
commit 0e4271b711
4 changed files with 90 additions and 43 deletions
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63
block/qcow2.c
View File

@ -1772,6 +1772,56 @@ static int qcow2_create2(const char *filename, int64_t total_size,
Error *local_err = NULL;
int ret;
if (prealloc == PREALLOC_MODE_FULL || prealloc == PREALLOC_MODE_FALLOC) {
int64_t meta_size = 0;
uint64_t nreftablee, nrefblocke, nl1e, nl2e;
int64_t aligned_total_size = align_offset(total_size, cluster_size);
/* header: 1 cluster */
meta_size += cluster_size;
/* total size of L2 tables */
nl2e = aligned_total_size / cluster_size;
nl2e = align_offset(nl2e, cluster_size / sizeof(uint64_t));
meta_size += nl2e * sizeof(uint64_t);
/* total size of L1 tables */
nl1e = nl2e * sizeof(uint64_t) / cluster_size;
nl1e = align_offset(nl1e, cluster_size / sizeof(uint64_t));
meta_size += nl1e * sizeof(uint64_t);
/* total size of refcount blocks
*
* note: every host cluster is reference-counted, including metadata
* (even refcount blocks are recursively included).
* Let:
* a = total_size (this is the guest disk size)
* m = meta size not including refcount blocks and refcount tables
* c = cluster size
* y1 = number of refcount blocks entries
* y2 = meta size including everything
* then,
* y1 = (y2 + a)/c
* y2 = y1 * sizeof(u16) + y1 * sizeof(u16) * sizeof(u64) / c + m
* we can get y1:
* y1 = (a + m) / (c - sizeof(u16) - sizeof(u16) * sizeof(u64) / c)
*/
nrefblocke = (aligned_total_size + meta_size + cluster_size) /
(cluster_size - sizeof(uint16_t) -
1.0 * sizeof(uint16_t) * sizeof(uint64_t) / cluster_size);
nrefblocke = align_offset(nrefblocke, cluster_size / sizeof(uint16_t));
meta_size += nrefblocke * sizeof(uint16_t);
/* total size of refcount tables */
nreftablee = nrefblocke * sizeof(uint16_t) / cluster_size;
nreftablee = align_offset(nreftablee, cluster_size / sizeof(uint64_t));
meta_size += nreftablee * sizeof(uint64_t);
qemu_opt_set_number(opts, BLOCK_OPT_SIZE,
aligned_total_size + meta_size);
qemu_opt_set(opts, BLOCK_OPT_PREALLOC, PreallocMode_lookup[prealloc]);
}
ret = bdrv_create_file(filename, opts, &local_err);
if (ret < 0) {
error_propagate(errp, local_err);
@ -1877,7 +1927,7 @@ static int qcow2_create2(const char *filename, int64_t total_size,
}
/* And if we're supposed to preallocate metadata, do that now */
if (prealloc == PREALLOC_MODE_METADATA) {
if (prealloc != PREALLOC_MODE_OFF) {
BDRVQcowState *s = bs->opaque;
qemu_co_mutex_lock(&s->lock);
ret = preallocate(bs);
@ -1958,14 +2008,6 @@ static int qcow2_create(const char *filename, QemuOpts *opts, Error **errp)
flags |= BLOCK_FLAG_LAZY_REFCOUNTS;
}
if (prealloc != PREALLOC_MODE_OFF &&
prealloc != PREALLOC_MODE_METADATA) {
ret = -EINVAL;
error_setg(errp, "Unsupported preallocate mode: %s",
PreallocMode_lookup[prealloc]);
goto finish;
}
if (backing_file && prealloc != PREALLOC_MODE_OFF) {
error_setg(errp, "Backing file and preallocation cannot be used at "
"the same time");
@ -2526,7 +2568,8 @@ static QemuOptsList qcow2_create_opts = {
{
.name = BLOCK_OPT_PREALLOC,
.type = QEMU_OPT_STRING,
.help = "Preallocation mode (allowed values: off, metadata)"
.help = "Preallocation mode (allowed values: off, metadata, "
"falloc, full)"
},
{
.name = BLOCK_OPT_LAZY_REFCOUNTS,

8
qemu-doc.texi
View File

@ -584,9 +584,11 @@ sizes can improve the image file size whereas larger cluster sizes generally
provide better performance.
@item preallocation
Preallocation mode (allowed values: off, metadata). An image with preallocated
metadata is initially larger but can improve performance when the image needs
to grow.
Preallocation mode (allowed values: @code{off}, @code{metadata}, @code{falloc},
@code{full}). An image with preallocated metadata is initially larger but can
improve performance when the image needs to grow. @code{falloc} and @code{full}
preallocations are like the same options of @code{raw} format, but sets up
metadata also.
@item lazy_refcounts
If this option is set to @code{on}, reference count updates are postponed with

8
qemu-img.texi
View File

@ -476,9 +476,11 @@ sizes can improve the image file size whereas larger cluster sizes generally
provide better performance.
@item preallocation
Preallocation mode (allowed values: off, metadata). An image with preallocated
metadata is initially larger but can improve performance when the image needs
to grow.
Preallocation mode (allowed values: @code{off}, @code{metadata}, @code{falloc},
@code{full}). An image with preallocated metadata is initially larger but can
improve performance when the image needs to grow. @code{falloc} and @code{full}
preallocations are like the same options of @code{raw} format, but sets up
metadata also.
@item lazy_refcounts
If this option is set to @code{on}, reference count updates are postponed with

54
tests/qemu-iotests/082.out
View File

@ -64,7 +64,7 @@ backing_file File name of a base image
backing_fmt Image format of the base image
encryption Encrypt the image
cluster_size qcow2 cluster size
preallocation Preallocation mode (allowed values: off, metadata)
preallocation Preallocation mode (allowed values: off, metadata, falloc, full)
lazy_refcounts Postpone refcount updates
nocow Turn off copy-on-write (valid only on btrfs)
@ -76,7 +76,7 @@ backing_file File name of a base image
backing_fmt Image format of the base image
encryption Encrypt the image
cluster_size qcow2 cluster size
preallocation Preallocation mode (allowed values: off, metadata)
preallocation Preallocation mode (allowed values: off, metadata, falloc, full)
lazy_refcounts Postpone refcount updates
nocow Turn off copy-on-write (valid only on btrfs)
@ -88,7 +88,7 @@ backing_file File name of a base image
backing_fmt Image format of the base image
encryption Encrypt the image
cluster_size qcow2 cluster size
preallocation Preallocation mode (allowed values: off, metadata)
preallocation Preallocation mode (allowed values: off, metadata, falloc, full)
lazy_refcounts Postpone refcount updates
nocow Turn off copy-on-write (valid only on btrfs)
@ -100,7 +100,7 @@ backing_file File name of a base image
backing_fmt Image format of the base image
encryption Encrypt the image
cluster_size qcow2 cluster size
preallocation Preallocation mode (allowed values: off, metadata)
preallocation Preallocation mode (allowed values: off, metadata, falloc, full)
lazy_refcounts Postpone refcount updates
nocow Turn off copy-on-write (valid only on btrfs)
@ -112,7 +112,7 @@ backing_file File name of a base image
backing_fmt Image format of the base image
encryption Encrypt the image
cluster_size qcow2 cluster size
preallocation Preallocation mode (allowed values: off, metadata)
preallocation Preallocation mode (allowed values: off, metadata, falloc, full)
lazy_refcounts Postpone refcount updates
nocow Turn off copy-on-write (valid only on btrfs)
@ -124,7 +124,7 @@ backing_file File name of a base image
backing_fmt Image format of the base image
encryption Encrypt the image
cluster_size qcow2 cluster size
preallocation Preallocation mode (allowed values: off, metadata)
preallocation Preallocation mode (allowed values: off, metadata, falloc, full)
lazy_refcounts Postpone refcount updates
nocow Turn off copy-on-write (valid only on btrfs)
@ -136,7 +136,7 @@ backing_file File name of a base image
backing_fmt Image format of the base image
encryption Encrypt the image
cluster_size qcow2 cluster size
preallocation Preallocation mode (allowed values: off, metadata)
preallocation Preallocation mode (allowed values: off, metadata, falloc, full)
lazy_refcounts Postpone refcount updates
nocow Turn off copy-on-write (valid only on btrfs)
@ -148,7 +148,7 @@ backing_file File name of a base image
backing_fmt Image format of the base image
encryption Encrypt the image
cluster_size qcow2 cluster size
preallocation Preallocation mode (allowed values: off, metadata)
preallocation Preallocation mode (allowed values: off, metadata, falloc, full)
lazy_refcounts Postpone refcount updates
nocow Turn off copy-on-write (valid only on btrfs)
@ -175,7 +175,7 @@ backing_file File name of a base image
backing_fmt Image format of the base image
encryption Encrypt the image
cluster_size qcow2 cluster size
preallocation Preallocation mode (allowed values: off, metadata)
preallocation Preallocation mode (allowed values: off, metadata, falloc, full)
lazy_refcounts Postpone refcount updates
Testing: create -o help
@ -253,7 +253,7 @@ backing_file File name of a base image
backing_fmt Image format of the base image
encryption Encrypt the image
cluster_size qcow2 cluster size
preallocation Preallocation mode (allowed values: off, metadata)
preallocation Preallocation mode (allowed values: off, metadata, falloc, full)
lazy_refcounts Postpone refcount updates
nocow Turn off copy-on-write (valid only on btrfs)
@ -265,7 +265,7 @@ backing_file File name of a base image
backing_fmt Image format of the base image
encryption Encrypt the image
cluster_size qcow2 cluster size
preallocation Preallocation mode (allowed values: off, metadata)
preallocation Preallocation mode (allowed values: off, metadata, falloc, full)
lazy_refcounts Postpone refcount updates
nocow Turn off copy-on-write (valid only on btrfs)
@ -277,7 +277,7 @@ backing_file File name of a base image
backing_fmt Image format of the base image
encryption Encrypt the image
cluster_size qcow2 cluster size
preallocation Preallocation mode (allowed values: off, metadata)
preallocation Preallocation mode (allowed values: off, metadata, falloc, full)
lazy_refcounts Postpone refcount updates
nocow Turn off copy-on-write (valid only on btrfs)
@ -289,7 +289,7 @@ backing_file File name of a base image
backing_fmt Image format of the base image
encryption Encrypt the image
cluster_size qcow2 cluster size
preallocation Preallocation mode (allowed values: off, metadata)
preallocation Preallocation mode (allowed values: off, metadata, falloc, full)
lazy_refcounts Postpone refcount updates
nocow Turn off copy-on-write (valid only on btrfs)
@ -301,7 +301,7 @@ backing_file File name of a base image
backing_fmt Image format of the base image
encryption Encrypt the image
cluster_size qcow2 cluster size
preallocation Preallocation mode (allowed values: off, metadata)
preallocation Preallocation mode (allowed values: off, metadata, falloc, full)
lazy_refcounts Postpone refcount updates
nocow Turn off copy-on-write (valid only on btrfs)
@ -313,7 +313,7 @@ backing_file File name of a base image
backing_fmt Image format of the base image
encryption Encrypt the image
cluster_size qcow2 cluster size
preallocation Preallocation mode (allowed values: off, metadata)
preallocation Preallocation mode (allowed values: off, metadata, falloc, full)
lazy_refcounts Postpone refcount updates
nocow Turn off copy-on-write (valid only on btrfs)
@ -325,7 +325,7 @@ backing_file File name of a base image
backing_fmt Image format of the base image
encryption Encrypt the image
cluster_size qcow2 cluster size
preallocation Preallocation mode (allowed values: off, metadata)
preallocation Preallocation mode (allowed values: off, metadata, falloc, full)
lazy_refcounts Postpone refcount updates
nocow Turn off copy-on-write (valid only on btrfs)
@ -337,7 +337,7 @@ backing_file File name of a base image
backing_fmt Image format of the base image
encryption Encrypt the image
cluster_size qcow2 cluster size
preallocation Preallocation mode (allowed values: off, metadata)
preallocation Preallocation mode (allowed values: off, metadata, falloc, full)
lazy_refcounts Postpone refcount updates
nocow Turn off copy-on-write (valid only on btrfs)
@ -364,7 +364,7 @@ backing_file File name of a base image
backing_fmt Image format of the base image
encryption Encrypt the image
cluster_size qcow2 cluster size
preallocation Preallocation mode (allowed values: off, metadata)
preallocation Preallocation mode (allowed values: off, metadata, falloc, full)
lazy_refcounts Postpone refcount updates
Testing: convert -o help
@ -431,7 +431,7 @@ backing_file File name of a base image
backing_fmt Image format of the base image
encryption Encrypt the image
cluster_size qcow2 cluster size
preallocation Preallocation mode (allowed values: off, metadata)
preallocation Preallocation mode (allowed values: off, metadata, falloc, full)
lazy_refcounts Postpone refcount updates
nocow Turn off copy-on-write (valid only on btrfs)
@ -443,7 +443,7 @@ backing_file File name of a base image
backing_fmt Image format of the base image
encryption Encrypt the image
cluster_size qcow2 cluster size
preallocation Preallocation mode (allowed values: off, metadata)
preallocation Preallocation mode (allowed values: off, metadata, falloc, full)
lazy_refcounts Postpone refcount updates
nocow Turn off copy-on-write (valid only on btrfs)
@ -455,7 +455,7 @@ backing_file File name of a base image
backing_fmt Image format of the base image
encryption Encrypt the image
cluster_size qcow2 cluster size
preallocation Preallocation mode (allowed values: off, metadata)
preallocation Preallocation mode (allowed values: off, metadata, falloc, full)
lazy_refcounts Postpone refcount updates
nocow Turn off copy-on-write (valid only on btrfs)
@ -467,7 +467,7 @@ backing_file File name of a base image
backing_fmt Image format of the base image
encryption Encrypt the image
cluster_size qcow2 cluster size
preallocation Preallocation mode (allowed values: off, metadata)
preallocation Preallocation mode (allowed values: off, metadata, falloc, full)
lazy_refcounts Postpone refcount updates
nocow Turn off copy-on-write (valid only on btrfs)
@ -479,7 +479,7 @@ backing_file File name of a base image
backing_fmt Image format of the base image
encryption Encrypt the image
cluster_size qcow2 cluster size
preallocation Preallocation mode (allowed values: off, metadata)
preallocation Preallocation mode (allowed values: off, metadata, falloc, full)
lazy_refcounts Postpone refcount updates
nocow Turn off copy-on-write (valid only on btrfs)
@ -491,7 +491,7 @@ backing_file File name of a base image
backing_fmt Image format of the base image
encryption Encrypt the image
cluster_size qcow2 cluster size
preallocation Preallocation mode (allowed values: off, metadata)
preallocation Preallocation mode (allowed values: off, metadata, falloc, full)
lazy_refcounts Postpone refcount updates
nocow Turn off copy-on-write (valid only on btrfs)
@ -503,7 +503,7 @@ backing_file File name of a base image
backing_fmt Image format of the base image
encryption Encrypt the image
cluster_size qcow2 cluster size
preallocation Preallocation mode (allowed values: off, metadata)
preallocation Preallocation mode (allowed values: off, metadata, falloc, full)
lazy_refcounts Postpone refcount updates
nocow Turn off copy-on-write (valid only on btrfs)
@ -515,7 +515,7 @@ backing_file File name of a base image
backing_fmt Image format of the base image
encryption Encrypt the image
cluster_size qcow2 cluster size
preallocation Preallocation mode (allowed values: off, metadata)
preallocation Preallocation mode (allowed values: off, metadata, falloc, full)
lazy_refcounts Postpone refcount updates
nocow Turn off copy-on-write (valid only on btrfs)
@ -544,7 +544,7 @@ backing_file File name of a base image
backing_fmt Image format of the base image
encryption Encrypt the image
cluster_size qcow2 cluster size
preallocation Preallocation mode (allowed values: off, metadata)
preallocation Preallocation mode (allowed values: off, metadata, falloc, full)
lazy_refcounts Postpone refcount updates
Testing: convert -o help