From ae2f14af54b089f793fcd1f5635dcb57a569adef Mon Sep 17 00:00:00 2001 From: aliguori Date: Tue, 21 Apr 2009 23:11:58 +0000 Subject: qcow2: Refcount checking code cleanup (Kevin Wolf) This is purely cosmetical changes to make the code easier to read. Move L2 table processing from a deeply nested block to its own function, add some comments. Patch v2: Fix misplaced bracket causing false positives Signed-off-by: Kevin Wolf Signed-off-by: Anthony Liguori git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@7216 c046a42c-6fe2-441c-8c8c-71466251a162 --- block-qcow2.c | 149 +++++++++++++++++++++++++++++++++++++++++----------------- 1 file changed, 105 insertions(+), 44 deletions(-) diff --git a/block-qcow2.c b/block-qcow2.c index cbadcd0cb3..eacac4d35d 100644 --- a/block-qcow2.c +++ b/block-qcow2.c @@ -2603,6 +2603,90 @@ static int inc_refcounts(BlockDriverState *bs, return errors; } +/* + * Increases the refcount in the given refcount table for the all clusters + * referenced in the L2 table. While doing so, performs some checks on L2 + * entries. + * + * Returns the number of errors found by the checks or -errno if an internal + * error occurred. + */ +static int check_refcounts_l2(BlockDriverState *bs, + uint16_t *refcount_table, int refcount_table_size, int64_t l2_offset, + int check_copied) +{ + BDRVQcowState *s = bs->opaque; + uint64_t *l2_table, offset; + int i, l2_size, nb_csectors, refcount; + int errors = 0; + + /* Read L2 table from disk */ + l2_size = s->l2_size * sizeof(uint64_t); + l2_table = qemu_malloc(l2_size); + + if (bdrv_pread(s->hd, l2_offset, l2_table, l2_size) != l2_size) + goto fail; + + /* Do the actual checks */ + for(i = 0; i < s->l2_size; i++) { + offset = be64_to_cpu(l2_table[i]); + if (offset != 0) { + if (offset & QCOW_OFLAG_COMPRESSED) { + /* Compressed clusters don't have QCOW_OFLAG_COPIED */ + if (offset & QCOW_OFLAG_COPIED) { + fprintf(stderr, "ERROR: cluster %" PRId64 ": " + "copied flag must never be set for compressed " + "clusters\n", offset >> s->cluster_bits); + offset &= ~QCOW_OFLAG_COPIED; + errors++; + } + + /* Mark cluster as used */ + nb_csectors = ((offset >> s->csize_shift) & + s->csize_mask) + 1; + offset &= s->cluster_offset_mask; + errors += inc_refcounts(bs, refcount_table, + refcount_table_size, + offset & ~511, nb_csectors * 512); + } else { + /* QCOW_OFLAG_COPIED must be set iff refcount == 1 */ + if (check_copied) { + uint64_t entry = offset; + offset &= ~QCOW_OFLAG_COPIED; + refcount = get_refcount(bs, offset >> s->cluster_bits); + if ((refcount == 1) != ((entry & QCOW_OFLAG_COPIED) != 0)) { + fprintf(stderr, "ERROR OFLAG_COPIED: offset=%" + PRIx64 " refcount=%d\n", entry, refcount); + errors++; + } + } + + /* Mark cluster as used */ + offset &= ~QCOW_OFLAG_COPIED; + errors += inc_refcounts(bs, refcount_table, + refcount_table_size, + offset, s->cluster_size); + } + } + } + + qemu_free(l2_table); + return errors; + +fail: + fprintf(stderr, "ERROR: I/O error in check_refcounts_l1\n"); + qemu_free(l2_table); + return -EIO; +} + +/* + * Increases the refcount for the L1 table, its L2 tables and all referenced + * clusters in the given refcount table. While doing so, performs some checks + * on L1 and L2 entries. + * + * Returns the number of errors found by the checks or -errno if an internal + * error occurred. + */ static int check_refcounts_l1(BlockDriverState *bs, uint16_t *refcount_table, int refcount_table_size, @@ -2610,16 +2694,17 @@ static int check_refcounts_l1(BlockDriverState *bs, int check_copied) { BDRVQcowState *s = bs->opaque; - uint64_t *l1_table, *l2_table, l2_offset, offset, l1_size2; - int l2_size, i, j, nb_csectors, refcount; + uint64_t *l1_table, l2_offset, l1_size2; + int i, refcount, ret; int errors = 0; - l2_table = NULL; l1_size2 = l1_size * sizeof(uint64_t); + /* Mark L1 table as used */ errors += inc_refcounts(bs, refcount_table, refcount_table_size, l1_table_offset, l1_size2); + /* Read L1 table entries from disk */ l1_table = qemu_malloc(l1_size2); if (bdrv_pread(s->hd, l1_table_offset, l1_table, l1_size2) != l1_size2) @@ -2627,68 +2712,43 @@ static int check_refcounts_l1(BlockDriverState *bs, for(i = 0;i < l1_size; i++) be64_to_cpus(&l1_table[i]); - l2_size = s->l2_size * sizeof(uint64_t); - l2_table = qemu_malloc(l2_size); + /* Do the actual checks */ 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 (check_copied) { - refcount = get_refcount(bs, (l2_offset & ~QCOW_OFLAG_COPIED) >> s->cluster_bits); + refcount = get_refcount(bs, (l2_offset & ~QCOW_OFLAG_COPIED) + >> s->cluster_bits); if ((refcount == 1) != ((l2_offset & QCOW_OFLAG_COPIED) != 0)) { fprintf(stderr, "ERROR OFLAG_COPIED: l2_offset=%" PRIx64 " refcount=%d\n", l2_offset, refcount); errors++; } } + + /* Mark L2 table as used */ l2_offset &= ~QCOW_OFLAG_COPIED; - if (bdrv_pread(s->hd, l2_offset, l2_table, l2_size) != l2_size) - goto fail; - for(j = 0; j < s->l2_size; j++) { - offset = be64_to_cpu(l2_table[j]); - if (offset != 0) { - if (offset & QCOW_OFLAG_COMPRESSED) { - if (offset & QCOW_OFLAG_COPIED) { - fprintf(stderr, "ERROR: cluster %" PRId64 ": " - "copied flag must never be set for compressed " - "clusters\n", offset >> s->cluster_bits); - offset &= ~QCOW_OFLAG_COPIED; - errors++; - } - nb_csectors = ((offset >> s->csize_shift) & - s->csize_mask) + 1; - offset &= s->cluster_offset_mask; - errors += inc_refcounts(bs, refcount_table, - refcount_table_size, - offset & ~511, nb_csectors * 512); - } else { - if (check_copied) { - refcount = get_refcount(bs, (offset & ~QCOW_OFLAG_COPIED) >> s->cluster_bits); - if ((refcount == 1) != ((offset & QCOW_OFLAG_COPIED) != 0)) { - fprintf(stderr, "ERROR OFLAG_COPIED: offset=%" - PRIx64 " refcount=%d\n", offset, refcount); - errors++; - } - } - offset &= ~QCOW_OFLAG_COPIED; - errors += inc_refcounts(bs, refcount_table, - refcount_table_size, - offset, s->cluster_size); - } - } - } errors += inc_refcounts(bs, refcount_table, refcount_table_size, l2_offset, s->cluster_size); + + /* Process and check L2 entries */ + ret = check_refcounts_l2(bs, refcount_table, refcount_table_size, + l2_offset, check_copied); + if (ret < 0) { + goto fail; + } + errors += ret; } } qemu_free(l1_table); - qemu_free(l2_table); return errors; - fail: + +fail: fprintf(stderr, "ERROR: I/O error in check_refcounts_l1\n"); qemu_free(l1_table); - qemu_free(l2_table); return -EIO; } @@ -2715,6 +2775,7 @@ static int check_refcounts(BlockDriverState *bs) errors += inc_refcounts(bs, refcount_table, nb_clusters, 0, s->cluster_size); + /* current L1 table */ ret = check_refcounts_l1(bs, refcount_table, nb_clusters, s->l1_table_offset, s->l1_size, 1); if (ret < 0) { -- cgit v1.2.1