Re: [Qemu-devel] [PATCH v3 4/8] qcow2-refcount: Move OFLAG_COPIED checks

[Max Reitz]

Am 30.08.2013 10:48, schrieb Kevin Wolf:
> Am 30.08.2013 um 09:46 hat Max Reitz geschrieben:
> > Move the OFLAG_COPIED checks out of check_refcounts_l1 and
> > check_refcounts_l2 and after the actual refcount checks/fixes (since the
> > refcounts might actually change there).
> >
> > Signed-off-by: Max Reitz <address@hidden>
> > ---
> >   block/qcow2-refcount.c | 99 +++++++++++++++++++++++++++++++++-----------------
> >   1 file changed, 65 insertions(+), 34 deletions(-)
> >
> > diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c
> > index 310efcc..fdc0f86 100644
> > --- a/block/qcow2-refcount.c
> > +++ b/block/qcow2-refcount.c
> > @@ -1035,7 +1035,7 @@ static int check_refcounts_l2(BlockDriverState *bs, 
> > BdrvCheckResult *res,
> >       BDRVQcowState *s = bs->opaque;
> >       uint64_t *l2_table, l2_entry;
> >       uint64_t next_contiguous_offset = 0;
> > -    int i, l2_size, nb_csectors, refcount;
> > +    int i, l2_size, nb_csectors;
> >   
> >       /* Read L2 table from disk */
> >       l2_size = s->l2_size * sizeof(uint64_t);
> > @@ -1087,23 +1087,8 @@ static int check_refcounts_l2(BlockDriverState *bs, 
> > BdrvCheckResult *res,
> >   
> >           case QCOW2_CLUSTER_NORMAL:
> >           {
> > -            /* QCOW_OFLAG_COPIED must be set iff refcount == 1 */
> >               uint64_t offset = l2_entry & L2E_OFFSET_MASK;
> >   
> > -            if (flags & CHECK_OFLAG_COPIED) {
> > -                refcount = get_refcount(bs, offset >> s->cluster_bits);
> > -                if (refcount < 0) {
> > -                    fprintf(stderr, "Can't get refcount for offset %"
> > -                        PRIx64 ": %s\n", l2_entry, strerror(-refcount));
> > -                    goto fail;
> > -                }
> > -                if ((refcount == 1) != ((l2_entry & QCOW_OFLAG_COPIED) != 0)) {
> > -                    fprintf(stderr, "ERROR OFLAG_COPIED: offset=%"
> > -                        PRIx64 " refcount=%d\n", l2_entry, refcount);
> > -                    res->corruptions++;
> > -                }
> > -            }
> > -
> >               if (flags & CHECK_FRAG_INFO) {
> >                   res->bfi.allocated_clusters++;
> >                   if (next_contiguous_offset &&
> > @@ -1160,7 +1145,7 @@ static int check_refcounts_l1(BlockDriverState *bs,
> >   {
> >       BDRVQcowState *s = bs->opaque;
> >       uint64_t *l1_table, l2_offset, l1_size2;
> > -    int i, refcount, ret;
> > +    int i, ret;
> >   
> >       l1_size2 = l1_size * sizeof(uint64_t);
> >   
> > @@ -1184,22 +1169,6 @@ static int check_refcounts_l1(BlockDriverState *bs,
> >       for(i = 0; i < l1_size; i++) {
> >           l2_offset = l1_table[i];
> >           if (l2_offset) {
> > -            /* QCOW_OFLAG_COPIED must be set iff refcount == 1 */
> > -            if (flags & CHECK_OFLAG_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));
> > -                    goto fail;
> > -                }
> > -                if ((refcount == 1) != ((l2_offset & QCOW_OFLAG_COPIED) != 0)) 
> > {
> > -                    fprintf(stderr, "ERROR OFLAG_COPIED: l2_offset=%" PRIx64
> > -                        " refcount=%d\n", l2_offset, refcount);
> > -                    res->corruptions++;
> > -                }
> > -            }
> > -
> >               /* Mark L2 table as used */
> >               l2_offset &= L1E_OFFSET_MASK;
> >               inc_refcounts(bs, res, refcount_table, refcount_table_size,
> > @@ -1241,7 +1210,8 @@ int qcow2_check_refcounts(BlockDriverState *bs, 
> > BdrvCheckResult *res,
> >   {
> >       BDRVQcowState *s = bs->opaque;
> >       int64_t size, i, highest_cluster;
> > -    int nb_clusters, refcount1, refcount2;
> > +    uint64_t *l2_table = NULL;
> > +    int nb_clusters, refcount1, refcount2, j;
> >       QCowSnapshot *sn;
> >       uint16_t *refcount_table;
> >       int ret;
> > @@ -1365,10 +1335,71 @@ int qcow2_check_refcounts(BlockDriverState *bs, 
> > BdrvCheckResult *res,
> >           }
> >       }
> >   
> > +    l2_table = qemu_blockalign(bs, s->cluster_size);
> > +
> > +    /* check OFLAG_COPIED */
> > +    for (i = 0; i < s->l1_size; i++) {
> > +        uint64_t l1_entry = s->l1_table[i];
> > +        uint64_t l2_offset = l1_entry & L1E_OFFSET_MASK;
> > +        int refcount;
> > +
> > +        if (!l2_offset) {
> > +            continue;
> > +        }
> > +
> > +        refcount = get_refcount(bs, l2_offset >> s->cluster_bits);
> > +        if (refcount < 0) {
> > +            /* don't print message nor increment check_errors, since the above
> > +             * loop will have done this already */
> > +            continue;
> > +        }
> > +        if ((refcount == 1) != ((l1_entry & QCOW_OFLAG_COPIED) != 0)) {
> > +            fprintf(stderr, "ERROR OFLAG_COPIED L2 cluster: l1_entry=%" PRIx64
> > +                    " refcount=%d\n",
> > +                    l1_entry, refcount);
> In theory, code motion patches shouldn't change much else, but as you're
> already changing the message here, I wouldn't mind if you also sneaked
> in the L1 index. ;-)
Okay, I'll do that.

> > +            res->corruptions++;
> > +        }
> > +
> > +        ret = bdrv_pread(bs->file, l2_offset, l2_table,
> > +                s->l2_size * sizeof(uint64_t));
> Indentation: s would usually be aligned to the same column as bs.
>
> > +        if (ret < 0) {
> > +            fprintf(stderr, "ERROR: Could not read L2 table: %s\n",
> > +                    strerror(-ret));
> > +            res->check_errors++;
> > +            goto fail;
> > +        }
> > +
> > +        for (j = 0; j < s->l2_size; j++) {
> > +            uint64_t l2_entry = be64_to_cpu(l2_table[j]);
> > +            uint64_t data_offset;
> > +
> > +            if (qcow2_get_cluster_type(l2_entry) != QCOW2_CLUSTER_NORMAL) {
> > +                continue;
> > +            }
> You're removing the check for QCOW2_CLUSTER_ZERO, which was a
> fall-through case in the original code.
Oh, right. I keep forgetting preallocations… :-/

> > +
> > +            data_offset = l2_entry & L2E_OFFSET_MASK;
> > +
> > +            refcount = get_refcount(bs, data_offset >> s->cluster_bits);
> > +            if (refcount < 0) {
> > +                /* don't print message nor increment check_errors, since the
> > +                 * above loop will have done this already */
> > +                continue;
> > +            }
> > +            if ((refcount == 1) != ((l2_entry & QCOW_OFLAG_COPIED) != 0)) {
> > +                fprintf(stderr, "ERROR OFLAG_COPIED data cluster: l2_entry=%"
> > +                        PRIx64 " refcount=%d\n",
> > +                        l2_entry, refcount);
> > +                res->corruptions++;
> > +            }
> > +        }
> > +    }
> I think it's long enough that it deserves a separate function.
Okay.

> > +
> >       res->image_end_offset = (highest_cluster + 1) * s->cluster_size;
> >       ret = 0;
> >   
> >   fail:
> > +    qemu_vfree(l2_table);
> >       g_free(refcount_table);
> >   
> >       return ret;
> Kevin

Max