Commit 018faafd authored by Kevin Wolf's avatar Kevin Wolf
Browse files

qcow2: Allow get_refcount to return errors 



get_refcount might need to load a refcount block from disk, so errors may
happen. Return the error code instead of assuming a refcount of 1 and change
the callers to respect error return values.

Signed-off-by: default avatarKevin Wolf <kwolf@redhat.com>
parent 6c6ea921

block/qcow2-refcount.c

+37 −4
Original line number Diff line number Diff line
@@ -105,11 +105,17 @@ static int load_refcount_block(BlockDriverState *bs, 
    return 0;

}



/*

 * Returns the refcount of the cluster given by its index. Any non-negative

 * return value is the refcount of the cluster, negative values are -errno

 * and indicate an error.

 */

static int get_refcount(BlockDriverState *bs, int64_t cluster_index)

{

    BDRVQcowState *s = bs->opaque;

    int refcount_table_index, block_index;

    int64_t refcount_block_offset;

    int ret;



    refcount_table_index = cluster_index >> (s->cluster_bits - REFCOUNT_SHIFT);

    if (refcount_table_index >= s->refcount_table_size)
@@ -119,8 +125,10 @@ static int get_refcount(BlockDriverState *bs, int64_t cluster_index) 
        return 0;

    if (refcount_block_offset != s->refcount_block_cache_offset) {

        /* better than nothing: return allocated if read error */

        if (load_refcount_block(bs, refcount_block_offset) < 0)

            return 1;

        ret = load_refcount_block(bs, refcount_block_offset);

        if (ret < 0) {

            return ret;

        }

    }

    block_index = cluster_index &

        ((1 << (s->cluster_bits - REFCOUNT_SHIFT)) - 1);
@@ -538,7 +546,13 @@ fail: 
    return ret;

}



/* addend must be 1 or -1 */

/*

 * Increases or decreases the refcount of a given cluster by one.

 * addend must be 1 or -1.

 *

 * If the return value is non-negative, it is the new refcount of the cluster.

 * If it is negative, it is -errno and indicates an error.

 */

static int update_cluster_refcount(BlockDriverState *bs,

                                   int64_t cluster_index,

                                   int addend)
@@ -779,6 +793,10 @@ int qcow2_update_snapshot_refcount(BlockDriverState *bs, 
                        } else {

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

                        }



                        if (refcount < 0) {

                            goto fail;

                        }

                    }



                    if (refcount == 1) {
@@ -801,7 +819,9 @@ int qcow2_update_snapshot_refcount(BlockDriverState *bs, 
            } else {

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

            }

            if (refcount == 1) {

            if (refcount < 0) {

                goto fail;

            } else if (refcount == 1) {

                l2_offset |= QCOW_OFLAG_COPIED;

            }

            if (l2_offset != old_l2_offset) {
@@ -934,6 +954,10 @@ static int check_refcounts_l2(BlockDriverState *bs, 
                    uint64_t entry = offset;

                    offset &= ~QCOW_OFLAG_COPIED;

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

                    if (refcount < 0) {

                        fprintf(stderr, "Can't get refcount for offset %"

                            PRIx64 ": %s\n", entry, strerror(-refcount));

                    }

                    if ((refcount == 1) != ((entry & QCOW_OFLAG_COPIED) != 0)) {

                        fprintf(stderr, "ERROR OFLAG_COPIED: offset=%"

                            PRIx64 " refcount=%d\n", entry, refcount);
@@ -1011,6 +1035,10 @@ static int check_refcounts_l1(BlockDriverState *bs, 
            if (check_copied) {

                refcount = get_refcount(bs, (l2_offset & ~QCOW_OFLAG_COPIED)

                    >> s->cluster_bits);

                if (refcount < 0) {

                    fprintf(stderr, "Can't get refcount for l2_offset %"

                        PRIx64 ": %s\n", l2_offset, strerror(-refcount));

                }

                if ((refcount == 1) != ((l2_offset & QCOW_OFLAG_COPIED) != 0)) {

                    fprintf(stderr, "ERROR OFLAG_COPIED: l2_offset=%" PRIx64

                        " refcount=%d\n", l2_offset, refcount);
@@ -1118,6 +1146,11 @@ int qcow2_check_refcounts(BlockDriverState *bs) 
    /* compare ref counts */

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

        refcount1 = get_refcount(bs, i);

        if (refcount1 < 0) {

            fprintf(stderr, "Can't get refcount for cluster %d: %s\n",

                i, strerror(-refcount1));

        }



        refcount2 = refcount_table[i];

        if (refcount1 != refcount2) {

            fprintf(stderr, "ERROR cluster %d refcount=%d reference=%d\n",