Commit b6c24694 authored by Alberto Garcia's avatar Alberto Garcia Committed by Kevin Wolf
Browse files

qcow2: Define and use QCOW2_COMPRESSED_SECTOR_SIZE 



When an L2 table entry points to a compressed cluster the space used
by the data is specified in 512-byte sectors. This size is independent
from BDRV_SECTOR_SIZE and is specific to the qcow2 file format.

The QCOW2_COMPRESSED_SECTOR_SIZE constant defined in this patch makes
this explicit.

Signed-off-by: default avatarAlberto Garcia <berto@igalia.com>
Signed-off-by: default avatarKevin Wolf <kwolf@redhat.com>
parent 50ba5b2d

block/qcow2-cluster.c

+3 −2
Original line number Diff line number Diff line
@@ -796,8 +796,9 @@ int qcow2_alloc_compressed_cluster_offset(BlockDriverState *bs, 
        return cluster_offset;

    }



    nb_csectors = ((cluster_offset + compressed_size - 1) >> 9) -

                  (cluster_offset >> 9);

    nb_csectors =

        (cluster_offset + compressed_size - 1) / QCOW2_COMPRESSED_SECTOR_SIZE -

        (cluster_offset / QCOW2_COMPRESSED_SECTOR_SIZE);



    cluster_offset |= QCOW_OFLAG_COMPRESSED |

                      ((uint64_t)nb_csectors << s->csize_shift);

block/qcow2-refcount.c

+14 −11
Original line number Diff line number Diff line
@@ -1172,12 +1172,11 @@ void qcow2_free_any_clusters(BlockDriverState *bs, uint64_t l2_entry, 
    switch (ctype) {

    case QCOW2_CLUSTER_COMPRESSED:

        {

            int nb_csectors;

            nb_csectors = ((l2_entry >> s->csize_shift) &

                           s->csize_mask) + 1;

            qcow2_free_clusters(bs,

                (l2_entry & s->cluster_offset_mask) & ~511,

                nb_csectors * 512, type);

            int64_t offset = (l2_entry & s->cluster_offset_mask)

                & QCOW2_COMPRESSED_SECTOR_MASK;

            int size = QCOW2_COMPRESSED_SECTOR_SIZE *

                (((l2_entry >> s->csize_shift) & s->csize_mask) + 1);

            qcow2_free_clusters(bs, offset, size, type);

        }

        break;

    case QCOW2_CLUSTER_NORMAL:
@@ -1317,9 +1316,12 @@ int qcow2_update_snapshot_refcount(BlockDriverState *bs, 
                        nb_csectors = ((entry >> s->csize_shift) &

                                       s->csize_mask) + 1;

                        if (addend != 0) {

                            uint64_t coffset = (entry & s->cluster_offset_mask)

                                & QCOW2_COMPRESSED_SECTOR_MASK;

                            ret = update_refcount(

                                bs, (entry & s->cluster_offset_mask) & ~511,

                                nb_csectors * 512, abs(addend), addend < 0,

                                bs, coffset,

                                nb_csectors * QCOW2_COMPRESSED_SECTOR_SIZE,

                                abs(addend), addend < 0,

                                QCOW2_DISCARD_SNAPSHOT);

                            if (ret < 0) {

                                goto fail;
@@ -1635,9 +1637,10 @@ static int check_refcounts_l2(BlockDriverState *bs, BdrvCheckResult *res, 
            nb_csectors = ((l2_entry >> s->csize_shift) &

                           s->csize_mask) + 1;

            l2_entry &= s->cluster_offset_mask;

            ret = qcow2_inc_refcounts_imrt(bs, res,

                                           refcount_table, refcount_table_size,

                                           l2_entry & ~511, nb_csectors * 512);

            ret = qcow2_inc_refcounts_imrt(

                bs, res, refcount_table, refcount_table_size,

                l2_entry & QCOW2_COMPRESSED_SECTOR_MASK,

                nb_csectors * QCOW2_COMPRESSED_SECTOR_SIZE);

            if (ret < 0) {

                goto fail;

            }

block/qcow2.c

+2 −1
Original line number Diff line number Diff line
@@ -4187,7 +4187,8 @@ qcow2_co_preadv_compressed(BlockDriverState *bs, 


    coffset = file_cluster_offset & s->cluster_offset_mask;

    nb_csectors = ((file_cluster_offset >> s->csize_shift) & s->csize_mask) + 1;

    csize = nb_csectors * 512 - (coffset & 511);

    csize = nb_csectors * QCOW2_COMPRESSED_SECTOR_SIZE -

        (coffset & ~QCOW2_COMPRESSED_SECTOR_MASK);



    buf = g_try_malloc(csize);

    if (!buf) {

block/qcow2.h

+4 −0
Original line number Diff line number Diff line
@@ -74,6 +74,10 @@ 
#define MIN_CLUSTER_BITS 9

#define MAX_CLUSTER_BITS 21



/* Defined in the qcow2 spec (compressed cluster descriptor) */

#define QCOW2_COMPRESSED_SECTOR_SIZE 512U

#define QCOW2_COMPRESSED_SECTOR_MASK (~(QCOW2_COMPRESSED_SECTOR_SIZE - 1))



/* Must be at least 2 to cover COW */

#define MIN_L2_CACHE_SIZE 2 /* cache entries */