diff options
Diffstat (limited to 'block')
| -rw-r--r-- | block/qcow2-cluster.c | 5 | ||||
| -rw-r--r-- | block/qcow2.c | 123 | ||||
| -rw-r--r-- | block/qcow2.h | 21 |
3 files changed, 141 insertions, 8 deletions
diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c index d7e0e19d9c..e179211c57 100644 --- a/block/qcow2-cluster.c +++ b/block/qcow2-cluster.c @@ -662,7 +662,10 @@ int qcow2_alloc_cluster_link_l2(BlockDriverState *bs, QCowL2Meta *m) qcow2_cache_depends_on_flush(s->l2_table_cache); } - qcow2_cache_set_dependency(bs, s->l2_table_cache, s->refcount_block_cache); + if (qcow2_need_accurate_refcounts(s)) { + qcow2_cache_set_dependency(bs, s->l2_table_cache, + s->refcount_block_cache); + } ret = get_cluster_table(bs, m->offset, &l2_table, &l2_index); if (ret < 0) { goto err; diff --git a/block/qcow2.c b/block/qcow2.c index 870148ddf8..fd5e214431 100644 --- a/block/qcow2.c +++ b/block/qcow2.c @@ -214,6 +214,62 @@ static void report_unsupported_feature(BlockDriverState *bs, } } +/* + * Sets the dirty bit and flushes afterwards if necessary. + * + * The incompatible_features bit is only set if the image file header was + * updated successfully. Therefore it is not required to check the return + * value of this function. + */ +static int qcow2_mark_dirty(BlockDriverState *bs) +{ + BDRVQcowState *s = bs->opaque; + uint64_t val; + int ret; + + assert(s->qcow_version >= 3); + + if (s->incompatible_features & QCOW2_INCOMPAT_DIRTY) { + return 0; /* already dirty */ + } + + val = cpu_to_be64(s->incompatible_features | QCOW2_INCOMPAT_DIRTY); + ret = bdrv_pwrite(bs->file, offsetof(QCowHeader, incompatible_features), + &val, sizeof(val)); + if (ret < 0) { + return ret; + } + ret = bdrv_flush(bs->file); + if (ret < 0) { + return ret; + } + + /* Only treat image as dirty if the header was updated successfully */ + s->incompatible_features |= QCOW2_INCOMPAT_DIRTY; + return 0; +} + +/* + * Clears the dirty bit and flushes before if necessary. Only call this + * function when there are no pending requests, it does not guard against + * concurrent requests dirtying the image. + */ +static int qcow2_mark_clean(BlockDriverState *bs) +{ + BDRVQcowState *s = bs->opaque; + + if (s->incompatible_features & QCOW2_INCOMPAT_DIRTY) { + int ret = bdrv_flush(bs); + if (ret < 0) { + return ret; + } + + s->incompatible_features &= ~QCOW2_INCOMPAT_DIRTY; + return qcow2_update_header(bs); + } + return 0; +} + static int qcow2_open(BlockDriverState *bs, int flags) { BDRVQcowState *s = bs->opaque; @@ -287,12 +343,13 @@ static int qcow2_open(BlockDriverState *bs, int flags) s->compatible_features = header.compatible_features; s->autoclear_features = header.autoclear_features; - if (s->incompatible_features != 0) { + if (s->incompatible_features & ~QCOW2_INCOMPAT_MASK) { void *feature_table = NULL; qcow2_read_extensions(bs, header.header_length, ext_end, &feature_table); report_unsupported_feature(bs, feature_table, - s->incompatible_features); + s->incompatible_features & + ~QCOW2_INCOMPAT_MASK); ret = -ENOTSUP; goto fail; } @@ -412,6 +469,22 @@ static int qcow2_open(BlockDriverState *bs, int flags) /* Initialise locks */ qemu_co_mutex_init(&s->lock); + /* Repair image if dirty */ + if ((s->incompatible_features & QCOW2_INCOMPAT_DIRTY) && + !bs->read_only) { + BdrvCheckResult result = {0}; + + ret = qcow2_check_refcounts(bs, &result, BDRV_FIX_ERRORS); + if (ret < 0) { + goto fail; + } + + ret = qcow2_mark_clean(bs); + if (ret < 0) { + goto fail; + } + } + #ifdef DEBUG_ALLOC { BdrvCheckResult result = {0}; @@ -714,6 +787,11 @@ static coroutine_fn int qcow2_co_writev(BlockDriverState *bs, goto fail; } + if (l2meta.nb_clusters > 0 && + (s->compatible_features & QCOW2_COMPAT_LAZY_REFCOUNTS)) { + qcow2_mark_dirty(bs); + } + cluster_offset = l2meta.cluster_offset; assert((cluster_offset & 511) == 0); @@ -785,6 +863,8 @@ static void qcow2_close(BlockDriverState *bs) qcow2_cache_flush(bs, s->l2_table_cache); qcow2_cache_flush(bs, s->refcount_block_cache); + qcow2_mark_clean(bs); + qcow2_cache_destroy(bs, s->l2_table_cache); qcow2_cache_destroy(bs, s->refcount_block_cache); @@ -949,7 +1029,16 @@ int qcow2_update_header(BlockDriverState *bs) /* Feature table */ Qcow2Feature features[] = { - /* no feature defined yet */ + { + .type = QCOW2_FEAT_TYPE_INCOMPATIBLE, + .bit = QCOW2_INCOMPAT_DIRTY_BITNR, + .name = "dirty bit", + }, + { + .type = QCOW2_FEAT_TYPE_COMPATIBLE, + .bit = QCOW2_COMPAT_LAZY_REFCOUNTS_BITNR, + .name = "lazy refcounts", + }, }; ret = header_ext_add(buf, QCOW2_EXT_MAGIC_FEATURE_TABLE, @@ -1132,6 +1221,11 @@ static int qcow2_create2(const char *filename, int64_t total_size, header.crypt_method = cpu_to_be32(QCOW_CRYPT_NONE); } + if (flags & BLOCK_FLAG_LAZY_REFCOUNTS) { + header.compatible_features |= + cpu_to_be64(QCOW2_COMPAT_LAZY_REFCOUNTS); + } + ret = bdrv_pwrite(bs, 0, &header, sizeof(header)); if (ret < 0) { goto out; @@ -1245,6 +1339,8 @@ static int qcow2_create(const char *filename, QEMUOptionParameter *options) options->value.s); return -EINVAL; } + } else if (!strcmp(options->name, BLOCK_OPT_LAZY_REFCOUNTS)) { + flags |= options->value.n ? BLOCK_FLAG_LAZY_REFCOUNTS : 0; } options++; } @@ -1255,6 +1351,12 @@ static int qcow2_create(const char *filename, QEMUOptionParameter *options) return -EINVAL; } + if (version < 3 && (flags & BLOCK_FLAG_LAZY_REFCOUNTS)) { + fprintf(stderr, "Lazy refcounts only supported with compatibility " + "level 1.1 and above (use compat=1.1 or greater)\n"); + return -EINVAL; + } + return qcow2_create2(filename, sectors, backing_file, backing_fmt, flags, cluster_size, prealloc, options, version); } @@ -1441,10 +1543,12 @@ static coroutine_fn int qcow2_co_flush_to_os(BlockDriverState *bs) return ret; } - ret = qcow2_cache_flush(bs, s->refcount_block_cache); - if (ret < 0) { - qemu_co_mutex_unlock(&s->lock); - return ret; + if (qcow2_need_accurate_refcounts(s)) { + ret = qcow2_cache_flush(bs, s->refcount_block_cache); + if (ret < 0) { + qemu_co_mutex_unlock(&s->lock); + return ret; + } } qemu_co_mutex_unlock(&s->lock); @@ -1559,6 +1663,11 @@ static QEMUOptionParameter qcow2_create_options[] = { .type = OPT_STRING, .help = "Preallocation mode (allowed values: off, metadata)" }, + { + .name = BLOCK_OPT_LAZY_REFCOUNTS, + .type = OPT_FLAG, + .help = "Postpone refcount updates", + }, { NULL } }; diff --git a/block/qcow2.h b/block/qcow2.h index 455b6d7cfe..b4eb65470e 100644 --- a/block/qcow2.h +++ b/block/qcow2.h @@ -110,6 +110,22 @@ enum { QCOW2_FEAT_TYPE_AUTOCLEAR = 2, }; +/* Incompatible feature bits */ +enum { + QCOW2_INCOMPAT_DIRTY_BITNR = 0, + QCOW2_INCOMPAT_DIRTY = 1 << QCOW2_INCOMPAT_DIRTY_BITNR, + + QCOW2_INCOMPAT_MASK = QCOW2_INCOMPAT_DIRTY, +}; + +/* Compatible feature bits */ +enum { + QCOW2_COMPAT_LAZY_REFCOUNTS_BITNR = 0, + QCOW2_COMPAT_LAZY_REFCOUNTS = 1 << QCOW2_COMPAT_LAZY_REFCOUNTS_BITNR, + + QCOW2_COMPAT_FEAT_MASK = QCOW2_COMPAT_LAZY_REFCOUNTS, +}; + typedef struct Qcow2Feature { uint8_t type; uint8_t bit; @@ -237,6 +253,11 @@ static inline int qcow2_get_cluster_type(uint64_t l2_entry) } } +/* Check whether refcounts are eager or lazy */ +static inline bool qcow2_need_accurate_refcounts(BDRVQcowState *s) +{ + return !(s->incompatible_features & QCOW2_INCOMPAT_DIRTY); +} // FIXME Need qcow2_ prefix to global functions |