Commit 6cfcb9b8 authored by Kevin Wolf's avatar Kevin Wolf Committed by Stefan Hajnoczi
Browse files

qcow2: Add refcount update reason to all callers 



This adds a refcount update reason to all callers of update_refcounts(),
so that a follow-up patch can use this information to decide whether
clusters that reach a refcount of 0 should be discarded in the image
file.

Signed-off-by: default avatarKevin Wolf <kwolf@redhat.com>
Signed-off-by: default avatarStefan Hajnoczi <stefanha@redhat.com>
parent 492fdc6f

block/qcow2-cluster.c

+13 −6
Original line number Diff line number Diff line
@@ -98,14 +98,16 @@ int qcow2_grow_l1_table(BlockDriverState *bs, uint64_t min_size, 
        goto fail;

    }

    g_free(s->l1_table);

    qcow2_free_clusters(bs, s->l1_table_offset, s->l1_size * sizeof(uint64_t));

    qcow2_free_clusters(bs, s->l1_table_offset, s->l1_size * sizeof(uint64_t),

                        QCOW2_DISCARD_OTHER);

    s->l1_table_offset = new_l1_table_offset;

    s->l1_table = new_l1_table;

    s->l1_size = new_l1_size;

    return 0;

 fail:

    g_free(new_l1_table);

    qcow2_free_clusters(bs, new_l1_table_offset, new_l1_size2);

    qcow2_free_clusters(bs, new_l1_table_offset, new_l1_size2,

                        QCOW2_DISCARD_OTHER);

    return ret;

}
@@ -548,7 +550,8 @@ static int get_cluster_table(BlockDriverState *bs, uint64_t offset, 


        /* Then decrease the refcount of the old table */

        if (l2_offset) {

            qcow2_free_clusters(bs, l2_offset, s->l2_size * sizeof(uint64_t));

            qcow2_free_clusters(bs, l2_offset, s->l2_size * sizeof(uint64_t),

                                QCOW2_DISCARD_OTHER);

        }

    }
@@ -715,10 +718,14 @@ int qcow2_alloc_cluster_link_l2(BlockDriverState *bs, QCowL2Meta *m) 
    /*

     * If this was a COW, we need to decrease the refcount of the old cluster.

     * Also flush bs->file to get the right order for L2 and refcount update.

     *

     * Don't discard clusters that reach a refcount of 0 (e.g. compressed

     * clusters), the next write will reuse them anyway.

     */

    if (j != 0) {

        for (i = 0; i < j; i++) {

            qcow2_free_any_clusters(bs, be64_to_cpu(old_cluster[i]), 1);

            qcow2_free_any_clusters(bs, be64_to_cpu(old_cluster[i]), 1,

                                    QCOW2_DISCARD_NEVER);

        }

    }
@@ -1339,7 +1346,7 @@ static int discard_single_l2(BlockDriverState *bs, uint64_t offset, 
        l2_table[l2_index + i] = cpu_to_be64(0);



        /* Then decrease the refcount */

        qcow2_free_any_clusters(bs, old_offset, 1);

        qcow2_free_any_clusters(bs, old_offset, 1, QCOW2_DISCARD_REQUEST);

    }



    ret = qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table);
@@ -1415,7 +1422,7 @@ static int zero_single_l2(BlockDriverState *bs, uint64_t offset, 
        qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_table);

        if (old_offset & QCOW_OFLAG_COMPRESSED) {

            l2_table[l2_index + i] = cpu_to_be64(QCOW_OFLAG_ZERO);

            qcow2_free_any_clusters(bs, old_offset, 1);

            qcow2_free_any_clusters(bs, old_offset, 1, QCOW2_DISCARD_REQUEST);

        } else {

            l2_table[l2_index + i] |= cpu_to_be64(QCOW_OFLAG_ZERO);

        }

block/qcow2-refcount.c

+34 −21
Original line number Diff line number Diff line
@@ -29,7 +29,7 @@ 
static int64_t alloc_clusters_noref(BlockDriverState *bs, int64_t size);

static int QEMU_WARN_UNUSED_RESULT update_refcount(BlockDriverState *bs,

                            int64_t offset, int64_t length,

                            int addend);

                            int addend, enum qcow2_discard_type type);





/*********************************************************/
@@ -235,7 +235,8 @@ static int alloc_refcount_block(BlockDriverState *bs, 
    } else {

        /* Described somewhere else. This can recurse at most twice before we

         * arrive at a block that describes itself. */

        ret = update_refcount(bs, new_block, s->cluster_size, 1);

        ret = update_refcount(bs, new_block, s->cluster_size, 1,

                              QCOW2_DISCARD_NEVER);

        if (ret < 0) {

            goto fail_block;

        }
@@ -399,7 +400,8 @@ static int alloc_refcount_block(BlockDriverState *bs, 


    /* Free old table. Remember, we must not change free_cluster_index */

    uint64_t old_free_cluster_index = s->free_cluster_index;

    qcow2_free_clusters(bs, old_table_offset, old_table_size * sizeof(uint64_t));

    qcow2_free_clusters(bs, old_table_offset, old_table_size * sizeof(uint64_t),

                        QCOW2_DISCARD_OTHER);

    s->free_cluster_index = old_free_cluster_index;



    ret = load_refcount_block(bs, new_block, (void**) refcount_block);
@@ -420,7 +422,7 @@ fail_block: 


/* XXX: cache several refcount block clusters ? */

static int QEMU_WARN_UNUSED_RESULT update_refcount(BlockDriverState *bs,

    int64_t offset, int64_t length, int addend)

    int64_t offset, int64_t length, int addend, enum qcow2_discard_type type)

{

    BDRVQcowState *s = bs->opaque;

    int64_t start, last, cluster_offset;
@@ -506,7 +508,8 @@ fail: 
     */

    if (ret < 0) {

        int dummy;

        dummy = update_refcount(bs, offset, cluster_offset - offset, -addend);

        dummy = update_refcount(bs, offset, cluster_offset - offset, -addend,

                                QCOW2_DISCARD_NEVER);

        (void)dummy;

    }
@@ -522,12 +525,14 @@ fail: 
 */

static int update_cluster_refcount(BlockDriverState *bs,

                                   int64_t cluster_index,

                                   int addend)

                                   int addend,

                                   enum qcow2_discard_type type)

{

    BDRVQcowState *s = bs->opaque;

    int ret;



    ret = update_refcount(bs, cluster_index << s->cluster_bits, 1, addend);

    ret = update_refcount(bs, cluster_index << s->cluster_bits, 1, addend,

                          type);

    if (ret < 0) {

        return ret;

    }
@@ -579,7 +584,7 @@ int64_t qcow2_alloc_clusters(BlockDriverState *bs, int64_t size) 
        return offset;

    }



    ret = update_refcount(bs, offset, size, 1);

    ret = update_refcount(bs, offset, size, 1, QCOW2_DISCARD_NEVER);

    if (ret < 0) {

        return ret;

    }
@@ -611,7 +616,8 @@ int qcow2_alloc_clusters_at(BlockDriverState *bs, uint64_t offset, 
    old_free_cluster_index = s->free_cluster_index;

    s->free_cluster_index = cluster_index + i;



    ret = update_refcount(bs, offset, i << s->cluster_bits, 1);

    ret = update_refcount(bs, offset, i << s->cluster_bits, 1,

                          QCOW2_DISCARD_NEVER);

    if (ret < 0) {

        return ret;

    }
@@ -649,7 +655,8 @@ int64_t qcow2_alloc_bytes(BlockDriverState *bs, int size) 
        if (free_in_cluster == 0)

            s->free_byte_offset = 0;

        if ((offset & (s->cluster_size - 1)) != 0)

            update_cluster_refcount(bs, offset >> s->cluster_bits, 1);

            update_cluster_refcount(bs, offset >> s->cluster_bits, 1,

                                    QCOW2_DISCARD_NEVER);

    } else {

        offset = qcow2_alloc_clusters(bs, s->cluster_size);

        if (offset < 0) {
@@ -659,7 +666,8 @@ int64_t qcow2_alloc_bytes(BlockDriverState *bs, int size) 
        if ((cluster_offset + s->cluster_size) == offset) {

            /* we are lucky: contiguous data */

            offset = s->free_byte_offset;

            update_cluster_refcount(bs, offset >> s->cluster_bits, 1);

            update_cluster_refcount(bs, offset >> s->cluster_bits, 1,

                                    QCOW2_DISCARD_NEVER);

            s->free_byte_offset += size;

        } else {

            s->free_byte_offset = offset;
@@ -676,12 +684,13 @@ int64_t qcow2_alloc_bytes(BlockDriverState *bs, int size) 
}



void qcow2_free_clusters(BlockDriverState *bs,

                          int64_t offset, int64_t size)

                          int64_t offset, int64_t size,

                          enum qcow2_discard_type type)

{

    int ret;



    BLKDBG_EVENT(bs->file, BLKDBG_CLUSTER_FREE);

    ret = update_refcount(bs, offset, size, -1);

    ret = update_refcount(bs, offset, size, -1, type);

    if (ret < 0) {

        fprintf(stderr, "qcow2_free_clusters failed: %s\n", strerror(-ret));

        /* TODO Remember the clusters to free them later and avoid leaking */
@@ -692,8 +701,8 @@ void qcow2_free_clusters(BlockDriverState *bs, 
 * Free a cluster using its L2 entry (handles clusters of all types, e.g.

 * normal cluster, compressed cluster, etc.)

 */

void qcow2_free_any_clusters(BlockDriverState *bs,

    uint64_t l2_entry, int nb_clusters)

void qcow2_free_any_clusters(BlockDriverState *bs, uint64_t l2_entry,

                             int nb_clusters, enum qcow2_discard_type type)

{

    BDRVQcowState *s = bs->opaque;
@@ -705,12 +714,12 @@ void qcow2_free_any_clusters(BlockDriverState *bs, 
                           s->csize_mask) + 1;

            qcow2_free_clusters(bs,

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

                nb_csectors * 512);

                nb_csectors * 512, type);

        }

        break;

    case QCOW2_CLUSTER_NORMAL:

        qcow2_free_clusters(bs, l2_entry & L2E_OFFSET_MASK,

                            nb_clusters << s->cluster_bits);

                            nb_clusters << s->cluster_bits, type);

        break;

    case QCOW2_CLUSTER_UNALLOCATED:

    case QCOW2_CLUSTER_ZERO:
@@ -785,7 +794,8 @@ int qcow2_update_snapshot_refcount(BlockDriverState *bs, 
                            int ret;

                            ret = update_refcount(bs,

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

                                nb_csectors * 512, addend);

                                nb_csectors * 512, addend,

                                QCOW2_DISCARD_SNAPSHOT);

                            if (ret < 0) {

                                goto fail;

                            }
@@ -795,7 +805,8 @@ int qcow2_update_snapshot_refcount(BlockDriverState *bs, 
                    } else {

                        uint64_t cluster_index = (offset & L2E_OFFSET_MASK) >> s->cluster_bits;

                        if (addend != 0) {

                            refcount = update_cluster_refcount(bs, cluster_index, addend);

                            refcount = update_cluster_refcount(bs, cluster_index, addend,

                                                               QCOW2_DISCARD_SNAPSHOT);

                        } else {

                            refcount = get_refcount(bs, cluster_index);

                        }
@@ -827,7 +838,8 @@ int qcow2_update_snapshot_refcount(BlockDriverState *bs, 




            if (addend != 0) {

                refcount = update_cluster_refcount(bs, l2_offset >> s->cluster_bits, addend);

                refcount = update_cluster_refcount(bs, l2_offset >> s->cluster_bits, addend,

                                                   QCOW2_DISCARD_SNAPSHOT);

            } else {

                refcount = get_refcount(bs, l2_offset >> s->cluster_bits);

            }
@@ -1253,7 +1265,8 @@ int qcow2_check_refcounts(BlockDriverState *bs, BdrvCheckResult *res, 


            if (num_fixed) {

                ret = update_refcount(bs, i << s->cluster_bits, 1,

                                      refcount2 - refcount1);

                                      refcount2 - refcount1,

                                      QCOW2_DISCARD_ALWAYS);

                if (ret >= 0) {

                    (*num_fixed)++;

                    continue;

block/qcow2-snapshot.c

+4 −2
Original line number Diff line number Diff line
@@ -262,7 +262,8 @@ static int qcow2_write_snapshots(BlockDriverState *bs) 
    }



    /* free the old snapshot table */

    qcow2_free_clusters(bs, s->snapshots_offset, s->snapshots_size);

    qcow2_free_clusters(bs, s->snapshots_offset, s->snapshots_size,

                        QCOW2_DISCARD_SNAPSHOT);

    s->snapshots_offset = snapshots_offset;

    s->snapshots_size = snapshots_size;

    return 0;
@@ -569,7 +570,8 @@ int qcow2_snapshot_delete(BlockDriverState *bs, const char *snapshot_id) 
    if (ret < 0) {

        return ret;

    }

    qcow2_free_clusters(bs, sn.l1_table_offset, sn.l1_size * sizeof(uint64_t));

    qcow2_free_clusters(bs, sn.l1_table_offset, sn.l1_size * sizeof(uint64_t),

                        QCOW2_DISCARD_SNAPSHOT);



    /* must update the copied flag on the current cluster offsets */

    ret = qcow2_update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, 0);

block/qcow2.c

+2 −1
Original line number Diff line number Diff line
@@ -1196,7 +1196,8 @@ static int preallocate(BlockDriverState *bs) 


        ret = qcow2_alloc_cluster_link_l2(bs, meta);

        if (ret < 0) {

            qcow2_free_any_clusters(bs, meta->alloc_offset, meta->nb_clusters);

            qcow2_free_any_clusters(bs, meta->alloc_offset, meta->nb_clusters,

                                    QCOW2_DISCARD_NEVER);

            return ret;

        }

block/qcow2.h

+13 −3
Original line number Diff line number Diff line
@@ -129,6 +129,15 @@ enum { 
    QCOW2_COMPAT_FEAT_MASK            = QCOW2_COMPAT_LAZY_REFCOUNTS,

};



enum qcow2_discard_type {

    QCOW2_DISCARD_NEVER = 0,

    QCOW2_DISCARD_ALWAYS,

    QCOW2_DISCARD_REQUEST,

    QCOW2_DISCARD_SNAPSHOT,

    QCOW2_DISCARD_OTHER,

    QCOW2_DISCARD_MAX

};



typedef struct Qcow2Feature {

    uint8_t type;

    uint8_t bit;
@@ -349,9 +358,10 @@ int qcow2_alloc_clusters_at(BlockDriverState *bs, uint64_t offset, 
    int nb_clusters);

int64_t qcow2_alloc_bytes(BlockDriverState *bs, int size);

void qcow2_free_clusters(BlockDriverState *bs,

    int64_t offset, int64_t size);

void qcow2_free_any_clusters(BlockDriverState *bs,

    uint64_t cluster_offset, int nb_clusters);

                          int64_t offset, int64_t size,

                          enum qcow2_discard_type type);

void qcow2_free_any_clusters(BlockDriverState *bs, uint64_t l2_entry,

                             int nb_clusters, enum qcow2_discard_type type);



int qcow2_update_snapshot_refcount(BlockDriverState *bs,

    int64_t l1_table_offset, int l1_size, int addend);