Commit 0e4271b7 authored by Hu Tao's avatar Hu Tao Committed by Kevin Wolf
Browse files

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: default avatarHu Tao <hutao@cn.fujitsu.com>
Reviewed-by: default avatarMax Reitz <mreitz@redhat.com>
Signed-off-by: default avatarKevin Wolf <kwolf@redhat.com>
parent 06247428

block/qcow2.c

+53 −10
Original line number Diff line number Diff line
@@ -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,

qemu-doc.texi

+5 −3
Original line number Diff line number Diff line
@@ -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

qemu-img.texi

+5 −3
Original line number Diff line number Diff line
@@ -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

tests/qemu-iotests/082.out

+27 −27
Original line number Diff line number Diff line
@@ -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