diff options
Diffstat (limited to 'contrib/qemu/block/qcow2-refcount.c')
| -rw-r--r-- | contrib/qemu/block/qcow2-refcount.c | 1374 |
1 files changed, 1374 insertions, 0 deletions
diff --git a/contrib/qemu/block/qcow2-refcount.c b/contrib/qemu/block/qcow2-refcount.c new file mode 100644 index 00000000..1244693f --- /dev/null +++ b/contrib/qemu/block/qcow2-refcount.c @@ -0,0 +1,1374 @@ +/* + * Block driver for the QCOW version 2 format + * + * Copyright (c) 2004-2006 Fabrice Bellard + * + * Permission is hereby granted, free of charge, to any person obtaining a copy + * of this software and associated documentation files (the "Software"), to deal + * in the Software without restriction, including without limitation the rights + * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell + * copies of the Software, and to permit persons to whom the Software is + * furnished to do so, subject to the following conditions: + * + * The above copyright notice and this permission notice shall be included in + * all copies or substantial portions of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, + * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN + * THE SOFTWARE. + */ + +#include "qemu-common.h" +#include "block/block_int.h" +#include "block/qcow2.h" + +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, enum qcow2_discard_type type); + + +/*********************************************************/ +/* refcount handling */ + +int qcow2_refcount_init(BlockDriverState *bs) +{ + BDRVQcowState *s = bs->opaque; + int ret, refcount_table_size2, i; + + refcount_table_size2 = s->refcount_table_size * sizeof(uint64_t); + s->refcount_table = g_malloc(refcount_table_size2); + if (s->refcount_table_size > 0) { + BLKDBG_EVENT(bs->file, BLKDBG_REFTABLE_LOAD); + ret = bdrv_pread(bs->file, s->refcount_table_offset, + s->refcount_table, refcount_table_size2); + if (ret != refcount_table_size2) + goto fail; + for(i = 0; i < s->refcount_table_size; i++) + be64_to_cpus(&s->refcount_table[i]); + } + return 0; + fail: + return -ENOMEM; +} + +void qcow2_refcount_close(BlockDriverState *bs) +{ + BDRVQcowState *s = bs->opaque; + g_free(s->refcount_table); +} + + +static int load_refcount_block(BlockDriverState *bs, + int64_t refcount_block_offset, + void **refcount_block) +{ + BDRVQcowState *s = bs->opaque; + int ret; + + BLKDBG_EVENT(bs->file, BLKDBG_REFBLOCK_LOAD); + ret = qcow2_cache_get(bs, s->refcount_block_cache, refcount_block_offset, + refcount_block); + + return ret; +} + +/* + * 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; + uint16_t *refcount_block; + uint16_t refcount; + + refcount_table_index = cluster_index >> (s->cluster_bits - REFCOUNT_SHIFT); + if (refcount_table_index >= s->refcount_table_size) + return 0; + refcount_block_offset = s->refcount_table[refcount_table_index]; + if (!refcount_block_offset) + return 0; + + ret = qcow2_cache_get(bs, s->refcount_block_cache, refcount_block_offset, + (void**) &refcount_block); + if (ret < 0) { + return ret; + } + + block_index = cluster_index & + ((1 << (s->cluster_bits - REFCOUNT_SHIFT)) - 1); + refcount = be16_to_cpu(refcount_block[block_index]); + + ret = qcow2_cache_put(bs, s->refcount_block_cache, + (void**) &refcount_block); + if (ret < 0) { + return ret; + } + + return refcount; +} + +/* + * Rounds the refcount table size up to avoid growing the table for each single + * refcount block that is allocated. + */ +static unsigned int next_refcount_table_size(BDRVQcowState *s, + unsigned int min_size) +{ + unsigned int min_clusters = (min_size >> (s->cluster_bits - 3)) + 1; + unsigned int refcount_table_clusters = + MAX(1, s->refcount_table_size >> (s->cluster_bits - 3)); + + while (min_clusters > refcount_table_clusters) { + refcount_table_clusters = (refcount_table_clusters * 3 + 1) / 2; + } + + return refcount_table_clusters << (s->cluster_bits - 3); +} + + +/* Checks if two offsets are described by the same refcount block */ +static int in_same_refcount_block(BDRVQcowState *s, uint64_t offset_a, + uint64_t offset_b) +{ + uint64_t block_a = offset_a >> (2 * s->cluster_bits - REFCOUNT_SHIFT); + uint64_t block_b = offset_b >> (2 * s->cluster_bits - REFCOUNT_SHIFT); + + return (block_a == block_b); +} + +/* + * Loads a refcount block. If it doesn't exist yet, it is allocated first + * (including growing the refcount table if needed). + * + * Returns 0 on success or -errno in error case + */ +static int alloc_refcount_block(BlockDriverState *bs, + int64_t cluster_index, uint16_t **refcount_block) +{ + BDRVQcowState *s = bs->opaque; + unsigned int refcount_table_index; + int ret; + + BLKDBG_EVENT(bs->file, BLKDBG_REFBLOCK_ALLOC); + + /* Find the refcount block for the given cluster */ + refcount_table_index = cluster_index >> (s->cluster_bits - REFCOUNT_SHIFT); + + if (refcount_table_index < s->refcount_table_size) { + + uint64_t refcount_block_offset = + s->refcount_table[refcount_table_index] & REFT_OFFSET_MASK; + + /* If it's already there, we're done */ + if (refcount_block_offset) { + return load_refcount_block(bs, refcount_block_offset, + (void**) refcount_block); + } + } + + /* + * If we came here, we need to allocate something. Something is at least + * a cluster for the new refcount block. It may also include a new refcount + * table if the old refcount table is too small. + * + * Note that allocating clusters here needs some special care: + * + * - We can't use the normal qcow2_alloc_clusters(), it would try to + * increase the refcount and very likely we would end up with an endless + * recursion. Instead we must place the refcount blocks in a way that + * they can describe them themselves. + * + * - We need to consider that at this point we are inside update_refcounts + * and doing the initial refcount increase. This means that some clusters + * have already been allocated by the caller, but their refcount isn't + * accurate yet. free_cluster_index tells us where this allocation ends + * as long as we don't overwrite it by freeing clusters. + * + * - alloc_clusters_noref and qcow2_free_clusters may load a different + * refcount block into the cache + */ + + *refcount_block = NULL; + + /* We write to the refcount table, so we might depend on L2 tables */ + ret = qcow2_cache_flush(bs, s->l2_table_cache); + if (ret < 0) { + return ret; + } + + /* Allocate the refcount block itself and mark it as used */ + int64_t new_block = alloc_clusters_noref(bs, s->cluster_size); + if (new_block < 0) { + return new_block; + } + +#ifdef DEBUG_ALLOC2 + fprintf(stderr, "qcow2: Allocate refcount block %d for %" PRIx64 + " at %" PRIx64 "\n", + refcount_table_index, cluster_index << s->cluster_bits, new_block); +#endif + + if (in_same_refcount_block(s, new_block, cluster_index << s->cluster_bits)) { + /* Zero the new refcount block before updating it */ + ret = qcow2_cache_get_empty(bs, s->refcount_block_cache, new_block, + (void**) refcount_block); + if (ret < 0) { + goto fail_block; + } + + memset(*refcount_block, 0, s->cluster_size); + + /* The block describes itself, need to update the cache */ + int block_index = (new_block >> s->cluster_bits) & + ((1 << (s->cluster_bits - REFCOUNT_SHIFT)) - 1); + (*refcount_block)[block_index] = cpu_to_be16(1); + } 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, + QCOW2_DISCARD_NEVER); + if (ret < 0) { + goto fail_block; + } + + ret = qcow2_cache_flush(bs, s->refcount_block_cache); + if (ret < 0) { + goto fail_block; + } + + /* Initialize the new refcount block only after updating its refcount, + * update_refcount uses the refcount cache itself */ + ret = qcow2_cache_get_empty(bs, s->refcount_block_cache, new_block, + (void**) refcount_block); + if (ret < 0) { + goto fail_block; + } + + memset(*refcount_block, 0, s->cluster_size); + } + + /* Now the new refcount block needs to be written to disk */ + BLKDBG_EVENT(bs->file, BLKDBG_REFBLOCK_ALLOC_WRITE); + qcow2_cache_entry_mark_dirty(s->refcount_block_cache, *refcount_block); + ret = qcow2_cache_flush(bs, s->refcount_block_cache); + if (ret < 0) { + goto fail_block; + } + + /* If the refcount table is big enough, just hook the block up there */ + if (refcount_table_index < s->refcount_table_size) { + uint64_t data64 = cpu_to_be64(new_block); + BLKDBG_EVENT(bs->file, BLKDBG_REFBLOCK_ALLOC_HOOKUP); + ret = bdrv_pwrite_sync(bs->file, + s->refcount_table_offset + refcount_table_index * sizeof(uint64_t), + &data64, sizeof(data64)); + if (ret < 0) { + goto fail_block; + } + + s->refcount_table[refcount_table_index] = new_block; + return 0; + } + + ret = qcow2_cache_put(bs, s->refcount_block_cache, (void**) refcount_block); + if (ret < 0) { + goto fail_block; + } + + /* + * If we come here, we need to grow the refcount table. Again, a new + * refcount table needs some space and we can't simply allocate to avoid + * endless recursion. + * + * Therefore let's grab new refcount blocks at the end of the image, which + * will describe themselves and the new refcount table. This way we can + * reference them only in the new table and do the switch to the new + * refcount table at once without producing an inconsistent state in + * between. + */ + BLKDBG_EVENT(bs->file, BLKDBG_REFTABLE_GROW); + + /* Calculate the number of refcount blocks needed so far */ + uint64_t refcount_block_clusters = 1 << (s->cluster_bits - REFCOUNT_SHIFT); + uint64_t blocks_used = (s->free_cluster_index + + refcount_block_clusters - 1) / refcount_block_clusters; + + /* And now we need at least one block more for the new metadata */ + uint64_t table_size = next_refcount_table_size(s, blocks_used + 1); + uint64_t last_table_size; + uint64_t blocks_clusters; + do { + uint64_t table_clusters = + size_to_clusters(s, table_size * sizeof(uint64_t)); + blocks_clusters = 1 + + ((table_clusters + refcount_block_clusters - 1) + / refcount_block_clusters); + uint64_t meta_clusters = table_clusters + blocks_clusters; + + last_table_size = table_size; + table_size = next_refcount_table_size(s, blocks_used + + ((meta_clusters + refcount_block_clusters - 1) + / refcount_block_clusters)); + + } while (last_table_size != table_size); + +#ifdef DEBUG_ALLOC2 + fprintf(stderr, "qcow2: Grow refcount table %" PRId32 " => %" PRId64 "\n", + s->refcount_table_size, table_size); +#endif + + /* Create the new refcount table and blocks */ + uint64_t meta_offset = (blocks_used * refcount_block_clusters) * + s->cluster_size; + uint64_t table_offset = meta_offset + blocks_clusters * s->cluster_size; + uint16_t *new_blocks = g_malloc0(blocks_clusters * s->cluster_size); + uint64_t *new_table = g_malloc0(table_size * sizeof(uint64_t)); + + assert(meta_offset >= (s->free_cluster_index * s->cluster_size)); + + /* Fill the new refcount table */ + memcpy(new_table, s->refcount_table, + s->refcount_table_size * sizeof(uint64_t)); + new_table[refcount_table_index] = new_block; + + int i; + for (i = 0; i < blocks_clusters; i++) { + new_table[blocks_used + i] = meta_offset + (i * s->cluster_size); + } + + /* Fill the refcount blocks */ + uint64_t table_clusters = size_to_clusters(s, table_size * sizeof(uint64_t)); + int block = 0; + for (i = 0; i < table_clusters + blocks_clusters; i++) { + new_blocks[block++] = cpu_to_be16(1); + } + + /* Write refcount blocks to disk */ + BLKDBG_EVENT(bs->file, BLKDBG_REFBLOCK_ALLOC_WRITE_BLOCKS); + ret = bdrv_pwrite_sync(bs->file, meta_offset, new_blocks, + blocks_clusters * s->cluster_size); + g_free(new_blocks); + if (ret < 0) { + goto fail_table; + } + + /* Write refcount table to disk */ + for(i = 0; i < table_size; i++) { + cpu_to_be64s(&new_table[i]); + } + + BLKDBG_EVENT(bs->file, BLKDBG_REFBLOCK_ALLOC_WRITE_TABLE); + ret = bdrv_pwrite_sync(bs->file, table_offset, new_table, + table_size * sizeof(uint64_t)); + if (ret < 0) { + goto fail_table; + } + + for(i = 0; i < table_size; i++) { + be64_to_cpus(&new_table[i]); + } + + /* Hook up the new refcount table in the qcow2 header */ + uint8_t data[12]; + cpu_to_be64w((uint64_t*)data, table_offset); + cpu_to_be32w((uint32_t*)(data + 8), table_clusters); + BLKDBG_EVENT(bs->file, BLKDBG_REFBLOCK_ALLOC_SWITCH_TABLE); + ret = bdrv_pwrite_sync(bs->file, offsetof(QCowHeader, refcount_table_offset), + data, sizeof(data)); + if (ret < 0) { + goto fail_table; + } + + /* And switch it in memory */ + uint64_t old_table_offset = s->refcount_table_offset; + uint64_t old_table_size = s->refcount_table_size; + + g_free(s->refcount_table); + s->refcount_table = new_table; + s->refcount_table_size = table_size; + s->refcount_table_offset = table_offset; + + /* 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_DISCARD_OTHER); + s->free_cluster_index = old_free_cluster_index; + + ret = load_refcount_block(bs, new_block, (void**) refcount_block); + if (ret < 0) { + return ret; + } + + return 0; + +fail_table: + g_free(new_table); +fail_block: + if (*refcount_block != NULL) { + qcow2_cache_put(bs, s->refcount_block_cache, (void**) refcount_block); + } + return ret; +} + +void qcow2_process_discards(BlockDriverState *bs, int ret) +{ + BDRVQcowState *s = bs->opaque; + Qcow2DiscardRegion *d, *next; + + QTAILQ_FOREACH_SAFE(d, &s->discards, next, next) { + QTAILQ_REMOVE(&s->discards, d, next); + + /* Discard is optional, ignore the return value */ + if (ret >= 0) { + bdrv_discard(bs->file, + d->offset >> BDRV_SECTOR_BITS, + d->bytes >> BDRV_SECTOR_BITS); + } + + g_free(d); + } +} + +static void update_refcount_discard(BlockDriverState *bs, + uint64_t offset, uint64_t length) +{ + BDRVQcowState *s = bs->opaque; + Qcow2DiscardRegion *d, *p, *next; + + QTAILQ_FOREACH(d, &s->discards, next) { + uint64_t new_start = MIN(offset, d->offset); + uint64_t new_end = MAX(offset + length, d->offset + d->bytes); + + if (new_end - new_start <= length + d->bytes) { + /* There can't be any overlap, areas ending up here have no + * references any more and therefore shouldn't get freed another + * time. */ + assert(d->bytes + length == new_end - new_start); + d->offset = new_start; + d->bytes = new_end - new_start; + goto found; + } + } + + d = g_malloc(sizeof(*d)); + *d = (Qcow2DiscardRegion) { + .bs = bs, + .offset = offset, + .bytes = length, + }; + QTAILQ_INSERT_TAIL(&s->discards, d, next); + +found: + /* Merge discard requests if they are adjacent now */ + QTAILQ_FOREACH_SAFE(p, &s->discards, next, next) { + if (p == d + || p->offset > d->offset + d->bytes + || d->offset > p->offset + p->bytes) + { + continue; + } + + /* Still no overlap possible */ + assert(p->offset == d->offset + d->bytes + || d->offset == p->offset + p->bytes); + + QTAILQ_REMOVE(&s->discards, p, next); + d->offset = MIN(d->offset, p->offset); + d->bytes += p->bytes; + } +} + +/* XXX: cache several refcount block clusters ? */ +static int QEMU_WARN_UNUSED_RESULT update_refcount(BlockDriverState *bs, + int64_t offset, int64_t length, int addend, enum qcow2_discard_type type) +{ + BDRVQcowState *s = bs->opaque; + int64_t start, last, cluster_offset; + uint16_t *refcount_block = NULL; + int64_t old_table_index = -1; + int ret; + +#ifdef DEBUG_ALLOC2 + fprintf(stderr, "update_refcount: offset=%" PRId64 " size=%" PRId64 " addend=%d\n", + offset, length, addend); +#endif + if (length < 0) { + return -EINVAL; + } else if (length == 0) { + return 0; + } + + if (addend < 0) { + qcow2_cache_set_dependency(bs, s->refcount_block_cache, + s->l2_table_cache); + } + + start = offset & ~(s->cluster_size - 1); + last = (offset + length - 1) & ~(s->cluster_size - 1); + for(cluster_offset = start; cluster_offset <= last; + cluster_offset += s->cluster_size) + { + int block_index, refcount; + int64_t cluster_index = cluster_offset >> s->cluster_bits; + int64_t table_index = + cluster_index >> (s->cluster_bits - REFCOUNT_SHIFT); + + /* Load the refcount block and allocate it if needed */ + if (table_index != old_table_index) { + if (refcount_block) { + ret = qcow2_cache_put(bs, s->refcount_block_cache, + (void**) &refcount_block); + if (ret < 0) { + goto fail; + } + } + + ret = alloc_refcount_block(bs, cluster_index, &refcount_block); + if (ret < 0) { + goto fail; + } + } + old_table_index = table_index; + + qcow2_cache_entry_mark_dirty(s->refcount_block_cache, refcount_block); + + /* we can update the count and save it */ + block_index = cluster_index & + ((1 << (s->cluster_bits - REFCOUNT_SHIFT)) - 1); + + refcount = be16_to_cpu(refcount_block[block_index]); + refcount += addend; + if (refcount < 0 || refcount > 0xffff) { + ret = -EINVAL; + goto fail; + } + if (refcount == 0 && cluster_index < s->free_cluster_index) { + s->free_cluster_index = cluster_index; + } + refcount_block[block_index] = cpu_to_be16(refcount); + + if (refcount == 0 && s->discard_passthrough[type]) { + update_refcount_discard(bs, cluster_offset, s->cluster_size); + } + } + + ret = 0; +fail: + if (!s->cache_discards) { + qcow2_process_discards(bs, ret); + } + + /* Write last changed block to disk */ + if (refcount_block) { + int wret; + wret = qcow2_cache_put(bs, s->refcount_block_cache, + (void**) &refcount_block); + if (wret < 0) { + return ret < 0 ? ret : wret; + } + } + + /* + * Try do undo any updates if an error is returned (This may succeed in + * some cases like ENOSPC for allocating a new refcount block) + */ + if (ret < 0) { + int dummy; + dummy = update_refcount(bs, offset, cluster_offset - offset, -addend, + QCOW2_DISCARD_NEVER); + (void)dummy; + } + + return ret; +} + +/* + * 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, + enum qcow2_discard_type type) +{ + BDRVQcowState *s = bs->opaque; + int ret; + + ret = update_refcount(bs, cluster_index << s->cluster_bits, 1, addend, + type); + if (ret < 0) { + return ret; + } + + return get_refcount(bs, cluster_index); +} + + + +/*********************************************************/ +/* cluster allocation functions */ + + + +/* return < 0 if error */ +static int64_t alloc_clusters_noref(BlockDriverState *bs, int64_t size) +{ + BDRVQcowState *s = bs->opaque; + int i, nb_clusters, refcount; + + nb_clusters = size_to_clusters(s, size); +retry: + for(i = 0; i < nb_clusters; i++) { + int64_t next_cluster_index = s->free_cluster_index++; + refcount = get_refcount(bs, next_cluster_index); + + if (refcount < 0) { + return refcount; + } else if (refcount != 0) { + goto retry; + } + } +#ifdef DEBUG_ALLOC2 + fprintf(stderr, "alloc_clusters: size=%" PRId64 " -> %" PRId64 "\n", + size, + (s->free_cluster_index - nb_clusters) << s->cluster_bits); +#endif + return (s->free_cluster_index - nb_clusters) << s->cluster_bits; +} + +int64_t qcow2_alloc_clusters(BlockDriverState *bs, int64_t size) +{ + int64_t offset; + int ret; + + BLKDBG_EVENT(bs->file, BLKDBG_CLUSTER_ALLOC); + offset = alloc_clusters_noref(bs, size); + if (offset < 0) { + return offset; + } + + ret = update_refcount(bs, offset, size, 1, QCOW2_DISCARD_NEVER); + if (ret < 0) { + return ret; + } + + return offset; +} + +int qcow2_alloc_clusters_at(BlockDriverState *bs, uint64_t offset, + int nb_clusters) +{ + BDRVQcowState *s = bs->opaque; + uint64_t cluster_index; + uint64_t old_free_cluster_index; + int i, refcount, ret; + + /* Check how many clusters there are free */ + cluster_index = offset >> s->cluster_bits; + for(i = 0; i < nb_clusters; i++) { + refcount = get_refcount(bs, cluster_index++); + + if (refcount < 0) { + return refcount; + } else if (refcount != 0) { + break; + } + } + + /* And then allocate them */ + 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, + QCOW2_DISCARD_NEVER); + if (ret < 0) { + return ret; + } + + s->free_cluster_index = old_free_cluster_index; + + return i; +} + +/* only used to allocate compressed sectors. We try to allocate + contiguous sectors. size must be <= cluster_size */ +int64_t qcow2_alloc_bytes(BlockDriverState *bs, int size) +{ + BDRVQcowState *s = bs->opaque; + int64_t offset, cluster_offset; + int free_in_cluster; + + BLKDBG_EVENT(bs->file, BLKDBG_CLUSTER_ALLOC_BYTES); + assert(size > 0 && size <= s->cluster_size); + if (s->free_byte_offset == 0) { + offset = qcow2_alloc_clusters(bs, s->cluster_size); + if (offset < 0) { + return offset; + } + s->free_byte_offset = offset; + } + redo: + free_in_cluster = s->cluster_size - + (s->free_byte_offset & (s->cluster_size - 1)); + if (size <= free_in_cluster) { + /* enough space in current cluster */ + offset = s->free_byte_offset; + s->free_byte_offset += size; + free_in_cluster -= 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, + QCOW2_DISCARD_NEVER); + } else { + offset = qcow2_alloc_clusters(bs, s->cluster_size); + if (offset < 0) { + return offset; + } + cluster_offset = s->free_byte_offset & ~(s->cluster_size - 1); + 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, + QCOW2_DISCARD_NEVER); + s->free_byte_offset += size; + } else { + s->free_byte_offset = offset; + goto redo; + } + } + + /* The cluster refcount was incremented, either by qcow2_alloc_clusters() + * or explicitly by update_cluster_refcount(). Refcount blocks must be + * flushed before the caller's L2 table updates. + */ + qcow2_cache_set_dependency(bs, s->l2_table_cache, s->refcount_block_cache); + return offset; +} + +void qcow2_free_clusters(BlockDriverState *bs, + 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, 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 */ + } +} + +/* + * 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, enum qcow2_discard_type type) +{ + BDRVQcowState *s = bs->opaque; + + switch (qcow2_get_cluster_type(l2_entry)) { + case QCOW2_CLUSTER_COMPRESSED: + { + int nb_csectors; + nb_csectors = ((l2_entry >> s->csize_shift) & + s->csize_mask) + 1; + qcow2_free_clusters(bs, + (l2_entry & s->cluster_offset_mask) & ~511, + nb_csectors * 512, type); + } + break; + case QCOW2_CLUSTER_NORMAL: + qcow2_free_clusters(bs, l2_entry & L2E_OFFSET_MASK, + nb_clusters << s->cluster_bits, type); + break; + case QCOW2_CLUSTER_UNALLOCATED: + case QCOW2_CLUSTER_ZERO: + break; + default: + abort(); + } +} + + + +/*********************************************************/ +/* snapshots and image creation */ + + + +/* update the refcounts of snapshots and the copied flag */ +int qcow2_update_snapshot_refcount(BlockDriverState *bs, + int64_t l1_table_offset, int l1_size, int addend) +{ + BDRVQcowState *s = bs->opaque; + uint64_t *l1_table, *l2_table, l2_offset, offset, l1_size2, l1_allocated; + int64_t old_offset, old_l2_offset; + int i, j, l1_modified = 0, nb_csectors, refcount; + int ret; + + l2_table = NULL; + l1_table = NULL; + l1_size2 = l1_size * sizeof(uint64_t); + + s->cache_discards = true; + + /* WARNING: qcow2_snapshot_goto relies on this function not using the + * l1_table_offset when it is the current s->l1_table_offset! Be careful + * when changing this! */ + if (l1_table_offset != s->l1_table_offset) { + l1_table = g_malloc0(align_offset(l1_size2, 512)); + l1_allocated = 1; + + ret = bdrv_pread(bs->file, l1_table_offset, l1_table, l1_size2); + if (ret < 0) { + goto fail; + } + + for(i = 0;i < l1_size; i++) + be64_to_cpus(&l1_table[i]); + } else { + assert(l1_size == s->l1_size); + l1_table = s->l1_table; + l1_allocated = 0; + } + + for(i = 0; i < l1_size; i++) { + l2_offset = l1_table[i]; + if (l2_offset) { + old_l2_offset = l2_offset; + l2_offset &= L1E_OFFSET_MASK; + + ret = qcow2_cache_get(bs, s->l2_table_cache, l2_offset, + (void**) &l2_table); + if (ret < 0) { + goto fail; + } + + for(j = 0; j < s->l2_size; j++) { + offset = be64_to_cpu(l2_table[j]); + if (offset != 0) { + old_offset = offset; + offset &= ~QCOW_OFLAG_COPIED; + if (offset & QCOW_OFLAG_COMPRESSED) { + nb_csectors = ((offset >> s->csize_shift) & + s->csize_mask) + 1; + if (addend != 0) { + int ret; + ret = update_refcount(bs, + (offset & s->cluster_offset_mask) & ~511, + nb_csectors * 512, addend, + QCOW2_DISCARD_SNAPSHOT); + if (ret < 0) { + goto fail; + } + } + /* compressed clusters are never modified */ + refcount = 2; + } else { + uint64_t cluster_index = (offset & L2E_OFFSET_MASK) >> s->cluster_bits; + if (addend != 0) { + refcount = update_cluster_refcount(bs, cluster_index, addend, + QCOW2_DISCARD_SNAPSHOT); + } else { + refcount = get_refcount(bs, cluster_index); + } + + if (refcount < 0) { + ret = refcount; + goto fail; + } + } + + if (refcount == 1) { + offset |= QCOW_OFLAG_COPIED; + } + if (offset != old_offset) { + if (addend > 0) { + qcow2_cache_set_dependency(bs, s->l2_table_cache, + s->refcount_block_cache); + } + l2_table[j] = cpu_to_be64(offset); + qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_table); + } + } + } + + ret = qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table); + if (ret < 0) { + goto fail; + } + + + if (addend != 0) { + refcount = update_cluster_refcount(bs, l2_offset >> s->cluster_bits, addend, + QCOW2_DISCARD_SNAPSHOT); + } else { + refcount = get_refcount(bs, l2_offset >> s->cluster_bits); + } + if (refcount < 0) { + ret = refcount; + goto fail; + } else if (refcount == 1) { + l2_offset |= QCOW_OFLAG_COPIED; + } + if (l2_offset != old_l2_offset) { + l1_table[i] = l2_offset; + l1_modified = 1; + } + } + } + + ret = bdrv_flush(bs); +fail: + if (l2_table) { + qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table); + } + + s->cache_discards = false; + qcow2_process_discards(bs, ret); + + /* Update L1 only if it isn't deleted anyway (addend = -1) */ + if (ret == 0 && addend >= 0 && l1_modified) { + for (i = 0; i < l1_size; i++) { + cpu_to_be64s(&l1_table[i]); + } + + ret = bdrv_pwrite_sync(bs->file, l1_table_offset, l1_table, l1_size2); + + for (i = 0; i < l1_size; i++) { + be64_to_cpus(&l1_table[i]); + } + } + if (l1_allocated) + g_free(l1_table); + return ret; +} + + + + +/*********************************************************/ +/* refcount checking functions */ + + + +/* + * Increases the refcount for a range of clusters in a given refcount table. + * This is used to construct a temporary refcount table out of L1 and L2 tables + * which can be compared the the refcount table saved in the image. + * + * Modifies the number of errors in res. + */ +static void inc_refcounts(BlockDriverState *bs, + BdrvCheckResult *res, + uint16_t *refcount_table, + int refcount_table_size, + int64_t offset, int64_t size) +{ + BDRVQcowState *s = bs->opaque; + int64_t start, last, cluster_offset; + int k; + + if (size <= 0) + return; + + start = offset & ~(s->cluster_size - 1); + last = (offset + size - 1) & ~(s->cluster_size - 1); + for(cluster_offset = start; cluster_offset <= last; + cluster_offset += s->cluster_size) { + k = cluster_offset >> s->cluster_bits; + if (k < 0) { + fprintf(stderr, "ERROR: invalid cluster offset=0x%" PRIx64 "\n", + cluster_offset); + res->corruptions++; + } else if (k >= refcount_table_size) { + fprintf(stderr, "Warning: cluster offset=0x%" PRIx64 " is after " + "the end of the image file, can't properly check refcounts.\n", + cluster_offset); + res->check_errors++; + } else { + if (++refcount_table[k] == 0) { + fprintf(stderr, "ERROR: overflow cluster offset=0x%" PRIx64 + "\n", cluster_offset); + res->corruptions++; + } + } + } +} + +/* Flags for check_refcounts_l1() and check_refcounts_l2() */ +enum { + CHECK_OFLAG_COPIED = 0x1, /* check QCOW_OFLAG_COPIED matches refcount */ + CHECK_FRAG_INFO = 0x2, /* update BlockFragInfo counters */ +}; + +/* + * 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, BdrvCheckResult *res, + uint16_t *refcount_table, int refcount_table_size, int64_t l2_offset, + int flags) +{ + BDRVQcowState *s = bs->opaque; + uint64_t *l2_table, l2_entry; + uint64_t next_contiguous_offset = 0; + int i, l2_size, nb_csectors, refcount; + + /* Read L2 table from disk */ + l2_size = s->l2_size * sizeof(uint64_t); + l2_table = g_malloc(l2_size); + + if (bdrv_pread(bs->file, l2_offset, l2_table, l2_size) != l2_size) + goto fail; + + /* Do the actual checks */ + for(i = 0; i < s->l2_size; i++) { + l2_entry = be64_to_cpu(l2_table[i]); + + switch (qcow2_get_cluster_type(l2_entry)) { + case QCOW2_CLUSTER_COMPRESSED: + /* Compressed clusters don't have QCOW_OFLAG_COPIED */ + if (l2_entry & QCOW_OFLAG_COPIED) { + fprintf(stderr, "ERROR: cluster %" PRId64 ": " + "copied flag must never be set for compressed " + "clusters\n", l2_entry >> s->cluster_bits); + l2_entry &= ~QCOW_OFLAG_COPIED; + res->corruptions++; + } + + /* Mark cluster as used */ + nb_csectors = ((l2_entry >> s->csize_shift) & + s->csize_mask) + 1; + l2_entry &= s->cluster_offset_mask; + inc_refcounts(bs, res, refcount_table, refcount_table_size, + l2_entry & ~511, nb_csectors * 512); + + if (flags & CHECK_FRAG_INFO) { + res->bfi.allocated_clusters++; + res->bfi.compressed_clusters++; + + /* Compressed clusters are fragmented by nature. Since they + * take up sub-sector space but we only have sector granularity + * I/O we need to re-read the same sectors even for adjacent + * compressed clusters. + */ + res->bfi.fragmented_clusters++; + } + break; + + case QCOW2_CLUSTER_ZERO: + if ((l2_entry & L2E_OFFSET_MASK) == 0) { + break; + } + /* fall through */ + + 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 && + offset != next_contiguous_offset) { + res->bfi.fragmented_clusters++; + } + next_contiguous_offset = offset + s->cluster_size; + } + + /* Mark cluster as used */ + inc_refcounts(bs, res, refcount_table,refcount_table_size, + offset, s->cluster_size); + + /* Correct offsets are cluster aligned */ + if (offset & (s->cluster_size - 1)) { + fprintf(stderr, "ERROR offset=%" PRIx64 ": Cluster is not " + "properly aligned; L2 entry corrupted.\n", offset); + res->corruptions++; + } + break; + } + + case QCOW2_CLUSTER_UNALLOCATED: + break; + + default: + abort(); + } + } + + g_free(l2_table); + return 0; + +fail: + fprintf(stderr, "ERROR: I/O error in check_refcounts_l2\n"); + g_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, + BdrvCheckResult *res, + uint16_t *refcount_table, + int refcount_table_size, + int64_t l1_table_offset, int l1_size, + int flags) +{ + BDRVQcowState *s = bs->opaque; + uint64_t *l1_table, l2_offset, l1_size2; + int i, refcount, ret; + + l1_size2 = l1_size * sizeof(uint64_t); + + /* Mark L1 table as used */ + inc_refcounts(bs, res, refcount_table, refcount_table_size, + l1_table_offset, l1_size2); + + /* Read L1 table entries from disk */ + if (l1_size2 == 0) { + l1_table = NULL; + } else { + l1_table = g_malloc(l1_size2); + if (bdrv_pread(bs->file, l1_table_offset, + l1_table, l1_size2) != l1_size2) + goto fail; + for(i = 0;i < l1_size; i++) + be64_to_cpus(&l1_table[i]); + } + + /* 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 (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, + l2_offset, s->cluster_size); + + /* L2 tables are cluster aligned */ + if (l2_offset & (s->cluster_size - 1)) { + fprintf(stderr, "ERROR l2_offset=%" PRIx64 ": Table is not " + "cluster aligned; L1 entry corrupted\n", l2_offset); + res->corruptions++; + } + + /* Process and check L2 entries */ + ret = check_refcounts_l2(bs, res, refcount_table, + refcount_table_size, l2_offset, flags); + if (ret < 0) { + goto fail; + } + } + } + g_free(l1_table); + return 0; + +fail: + fprintf(stderr, "ERROR: I/O error in check_refcounts_l1\n"); + res->check_errors++; + g_free(l1_table); + return -EIO; +} + +/* + * Checks an image for refcount consistency. + * + * Returns 0 if no errors are found, the number of errors in case the image is + * detected as corrupted, and -errno when an internal error occurred. + */ +int qcow2_check_refcounts(BlockDriverState *bs, BdrvCheckResult *res, + BdrvCheckMode fix) +{ + BDRVQcowState *s = bs->opaque; + int64_t size, i, highest_cluster; + int nb_clusters, refcount1, refcount2; + QCowSnapshot *sn; + uint16_t *refcount_table; + int ret; + + size = bdrv_getlength(bs->file); + nb_clusters = size_to_clusters(s, size); + refcount_table = g_malloc0(nb_clusters * sizeof(uint16_t)); + + res->bfi.total_clusters = + size_to_clusters(s, bs->total_sectors * BDRV_SECTOR_SIZE); + + /* header */ + inc_refcounts(bs, res, refcount_table, nb_clusters, + 0, s->cluster_size); + + /* current L1 table */ + ret = check_refcounts_l1(bs, res, refcount_table, nb_clusters, + s->l1_table_offset, s->l1_size, + CHECK_OFLAG_COPIED | CHECK_FRAG_INFO); + if (ret < 0) { + goto fail; + } + + /* snapshots */ + for(i = 0; i < s->nb_snapshots; i++) { + sn = s->snapshots + i; + ret = check_refcounts_l1(bs, res, refcount_table, nb_clusters, + sn->l1_table_offset, sn->l1_size, 0); + if (ret < 0) { + goto fail; + } + } + inc_refcounts(bs, res, refcount_table, nb_clusters, + s->snapshots_offset, s->snapshots_size); + + /* refcount data */ + inc_refcounts(bs, res, refcount_table, nb_clusters, + s->refcount_table_offset, + s->refcount_table_size * sizeof(uint64_t)); + + for(i = 0; i < s->refcount_table_size; i++) { + uint64_t offset, cluster; + offset = s->refcount_table[i]; + cluster = offset >> s->cluster_bits; + + /* Refcount blocks are cluster aligned */ + if (offset & (s->cluster_size - 1)) { + fprintf(stderr, "ERROR refcount block %" PRId64 " is not " + "cluster aligned; refcount table entry corrupted\n", i); + res->corruptions++; + continue; + } + + if (cluster >= nb_clusters) { + fprintf(stderr, "ERROR refcount block %" PRId64 + " is outside image\n", i); + res->corruptions++; + continue; + } + + if (offset != 0) { + inc_refcounts(bs, res, refcount_table, nb_clusters, + offset, s->cluster_size); + if (refcount_table[cluster] != 1) { + fprintf(stderr, "ERROR refcount block %" PRId64 + " refcount=%d\n", + i, refcount_table[cluster]); + res->corruptions++; + } + } + } + + /* compare ref counts */ + for (i = 0, highest_cluster = 0; i < nb_clusters; i++) { + refcount1 = get_refcount(bs, i); + if (refcount1 < 0) { + fprintf(stderr, "Can't get refcount for cluster %" PRId64 ": %s\n", + i, strerror(-refcount1)); + res->check_errors++; + continue; + } + + refcount2 = refcount_table[i]; + + if (refcount1 > 0 || refcount2 > 0) { + highest_cluster = i; + } + + if (refcount1 != refcount2) { + + /* Check if we're allowed to fix the mismatch */ + int *num_fixed = NULL; + if (refcount1 > refcount2 && (fix & BDRV_FIX_LEAKS)) { + num_fixed = &res->leaks_fixed; + } else if (refcount1 < refcount2 && (fix & BDRV_FIX_ERRORS)) { + num_fixed = &res->corruptions_fixed; + } + + fprintf(stderr, "%s cluster %" PRId64 " refcount=%d reference=%d\n", + num_fixed != NULL ? "Repairing" : + refcount1 < refcount2 ? "ERROR" : + "Leaked", + i, refcount1, refcount2); + + if (num_fixed) { + ret = update_refcount(bs, i << s->cluster_bits, 1, + refcount2 - refcount1, + QCOW2_DISCARD_ALWAYS); + if (ret >= 0) { + (*num_fixed)++; + continue; + } + } + + /* And if we couldn't, print an error */ + if (refcount1 < refcount2) { + res->corruptions++; + } else { + res->leaks++; + } + } + } + + res->image_end_offset = (highest_cluster + 1) * s->cluster_size; + ret = 0; + +fail: + g_free(refcount_table); + + return ret; +} + |