| /* |
| * 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_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); |
| |
| |
| static int cache_refcount_updates = 0; |
| |
| static int write_refcount_block(BlockDriverState *bs) |
| { |
| BDRVQcowState *s = bs->opaque; |
| size_t size = s->cluster_size; |
| |
| if (s->refcount_block_cache_offset == 0) { |
| return 0; |
| } |
| |
| BLKDBG_EVENT(bs->file, BLKDBG_REFBLOCK_UPDATE); |
| if (bdrv_pwrite_sync(bs->file, s->refcount_block_cache_offset, |
| s->refcount_block_cache, size) < 0) |
| { |
| return -EIO; |
| } |
| |
| return 0; |
| } |
| |
| /*********************************************************/ |
| /* refcount handling */ |
| |
| int qcow2_refcount_init(BlockDriverState *bs) |
| { |
| BDRVQcowState *s = bs->opaque; |
| int ret, refcount_table_size2, i; |
| |
| s->refcount_block_cache = qemu_malloc(s->cluster_size); |
| refcount_table_size2 = s->refcount_table_size * sizeof(uint64_t); |
| s->refcount_table = qemu_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; |
| qemu_free(s->refcount_block_cache); |
| qemu_free(s->refcount_table); |
| } |
| |
| |
| static int load_refcount_block(BlockDriverState *bs, |
| int64_t refcount_block_offset) |
| { |
| BDRVQcowState *s = bs->opaque; |
| int ret; |
| |
| if (cache_refcount_updates) { |
| ret = write_refcount_block(bs); |
| if (ret < 0) { |
| return ret; |
| } |
| } |
| |
| BLKDBG_EVENT(bs->file, BLKDBG_REFBLOCK_LOAD); |
| ret = bdrv_pread(bs->file, refcount_block_offset, s->refcount_block_cache, |
| s->cluster_size); |
| if (ret < 0) { |
| s->refcount_block_cache_offset = 0; |
| return ret; |
| } |
| |
| s->refcount_block_cache_offset = refcount_block_offset; |
| 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) |
| return 0; |
| refcount_block_offset = s->refcount_table[refcount_table_index]; |
| if (!refcount_block_offset) |
| return 0; |
| if (refcount_block_offset != s->refcount_block_cache_offset) { |
| /* better than nothing: return allocated if read error */ |
| ret = load_refcount_block(bs, refcount_block_offset); |
| if (ret < 0) { |
| return ret; |
| } |
| } |
| block_index = cluster_index & |
| ((1 << (s->cluster_bits - REFCOUNT_SHIFT)) - 1); |
| return be16_to_cpu(s->refcount_block_cache[block_index]); |
| } |
| |
| /* |
| * 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 the offset of the refcount block on success or -errno in error case |
| */ |
| static int64_t alloc_refcount_block(BlockDriverState *bs, int64_t cluster_index) |
| { |
| 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]; |
| |
| /* If it's already there, we're done */ |
| if (refcount_block_offset) { |
| if (refcount_block_offset != s->refcount_block_cache_offset) { |
| ret = load_refcount_block(bs, refcount_block_offset); |
| if (ret < 0) { |
| return ret; |
| } |
| } |
| return refcount_block_offset; |
| } |
| } |
| |
| /* |
| * 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 |
| */ |
| |
| if (cache_refcount_updates) { |
| ret = write_refcount_block(bs); |
| 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 */ |
| memset(s->refcount_block_cache, 0, s->cluster_size); |
| s->refcount_block_cache_offset = new_block; |
| |
| /* The block describes itself, need to update the cache */ |
| int block_index = (new_block >> s->cluster_bits) & |
| ((1 << (s->cluster_bits - REFCOUNT_SHIFT)) - 1); |
| s->refcount_block_cache[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); |
| if (ret < 0) { |
| goto fail_block; |
| } |
| |
| bdrv_flush(bs->file); |
| |
| /* Initialize the new refcount block only after updating its refcount, |
| * update_refcount uses the refcount cache itself */ |
| memset(s->refcount_block_cache, 0, s->cluster_size); |
| s->refcount_block_cache_offset = new_block; |
| } |
| |
| /* Now the new refcount block needs to be written to disk */ |
| BLKDBG_EVENT(bs->file, BLKDBG_REFBLOCK_ALLOC_WRITE); |
| ret = bdrv_pwrite_sync(bs->file, new_block, s->refcount_block_cache, |
| s->cluster_size); |
| 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 new_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); |
| 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 = qemu_mallocz(blocks_clusters * s->cluster_size); |
| uint64_t *new_table = qemu_mallocz(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); |
| qemu_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++) { |
| cpu_to_be64s(&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; |
| |
| qemu_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)); |
| s->free_cluster_index = old_free_cluster_index; |
| |
| ret = load_refcount_block(bs, new_block); |
| if (ret < 0) { |
| goto fail_block; |
| } |
| |
| return new_block; |
| |
| fail_table: |
| qemu_free(new_table); |
| fail_block: |
| s->refcount_block_cache_offset = 0; |
| return ret; |
| } |
| |
| #define REFCOUNTS_PER_SECTOR (512 >> REFCOUNT_SHIFT) |
| static int write_refcount_block_entries(BlockDriverState *bs, |
| int64_t refcount_block_offset, int first_index, int last_index) |
| { |
| BDRVQcowState *s = bs->opaque; |
| size_t size; |
| int ret; |
| |
| if (cache_refcount_updates) { |
| return 0; |
| } |
| |
| if (first_index < 0) { |
| return 0; |
| } |
| |
| first_index &= ~(REFCOUNTS_PER_SECTOR - 1); |
| last_index = (last_index + REFCOUNTS_PER_SECTOR) |
| & ~(REFCOUNTS_PER_SECTOR - 1); |
| |
| size = (last_index - first_index) << REFCOUNT_SHIFT; |
| |
| BLKDBG_EVENT(bs->file, BLKDBG_REFBLOCK_UPDATE_PART); |
| ret = bdrv_pwrite(bs->file, |
| refcount_block_offset + (first_index << REFCOUNT_SHIFT), |
| &s->refcount_block_cache[first_index], size); |
| if (ret < 0) { |
| return ret; |
| } |
| |
| return 0; |
| } |
| |
| /* XXX: cache several refcount block clusters ? */ |
| static int QEMU_WARN_UNUSED_RESULT update_refcount(BlockDriverState *bs, |
| int64_t offset, int64_t length, int addend) |
| { |
| BDRVQcowState *s = bs->opaque; |
| int64_t start, last, cluster_offset; |
| int64_t refcount_block_offset = 0; |
| int64_t table_index = -1, old_table_index; |
| int first_index = -1, last_index = -1; |
| int ret; |
| |
| #ifdef DEBUG_ALLOC2 |
| printf("update_refcount: offset=%" PRId64 " size=%" PRId64 " addend=%d\n", |
| offset, length, addend); |
| #endif |
| if (length < 0) { |
| return -EINVAL; |
| } else if (length == 0) { |
| return 0; |
| } |
| |
| 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 new_block; |
| |
| /* Only write refcount block to disk when we are done with it */ |
| old_table_index = table_index; |
| table_index = cluster_index >> (s->cluster_bits - REFCOUNT_SHIFT); |
| if ((old_table_index >= 0) && (table_index != old_table_index)) { |
| |
| ret = write_refcount_block_entries(bs, refcount_block_offset, |
| first_index, last_index); |
| if (ret < 0) { |
| return ret; |
| } |
| |
| first_index = -1; |
| last_index = -1; |
| } |
| |
| /* Load the refcount block and allocate it if needed */ |
| new_block = alloc_refcount_block(bs, cluster_index); |
| if (new_block < 0) { |
| ret = new_block; |
| goto fail; |
| } |
| refcount_block_offset = new_block; |
| |
| /* we can update the count and save it */ |
| block_index = cluster_index & |
| ((1 << (s->cluster_bits - REFCOUNT_SHIFT)) - 1); |
| if (first_index == -1 || block_index < first_index) { |
| first_index = block_index; |
| } |
| if (block_index > last_index) { |
| last_index = block_index; |
| } |
| |
| refcount = be16_to_cpu(s->refcount_block_cache[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; |
| } |
| s->refcount_block_cache[block_index] = cpu_to_be16(refcount); |
| } |
| |
| ret = 0; |
| fail: |
| |
| /* Write last changed block to disk */ |
| if (refcount_block_offset != 0) { |
| int wret; |
| wret = write_refcount_block_entries(bs, refcount_block_offset, |
| first_index, last_index); |
| 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); |
| (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) |
| { |
| BDRVQcowState *s = bs->opaque; |
| int ret; |
| |
| ret = update_refcount(bs, cluster_index << s->cluster_bits, 1, addend); |
| if (ret < 0) { |
| return ret; |
| } |
| |
| bdrv_flush(bs->file); |
| |
| 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 |
| printf("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); |
| if (ret < 0) { |
| return ret; |
| } |
| |
| return offset; |
| } |
| |
| /* 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) { |
| s->free_byte_offset = qcow2_alloc_clusters(bs, s->cluster_size); |
| if (s->free_byte_offset < 0) { |
| return s->free_byte_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); |
| } 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); |
| s->free_byte_offset += size; |
| } else { |
| s->free_byte_offset = offset; |
| goto redo; |
| } |
| } |
| |
| bdrv_flush(bs->file); |
| return offset; |
| } |
| |
| void qcow2_free_clusters(BlockDriverState *bs, |
| int64_t offset, int64_t size) |
| { |
| int ret; |
| |
| BLKDBG_EVENT(bs->file, BLKDBG_CLUSTER_FREE); |
| ret = update_refcount(bs, offset, size, -1); |
| 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_any_clusters |
| * |
| * free clusters according to its type: compressed or not |
| * |
| */ |
| |
| void qcow2_free_any_clusters(BlockDriverState *bs, |
| uint64_t cluster_offset, int nb_clusters) |
| { |
| BDRVQcowState *s = bs->opaque; |
| |
| /* free the cluster */ |
| |
| if (cluster_offset & QCOW_OFLAG_COMPRESSED) { |
| int nb_csectors; |
| nb_csectors = ((cluster_offset >> s->csize_shift) & |
| s->csize_mask) + 1; |
| qcow2_free_clusters(bs, |
| (cluster_offset & s->cluster_offset_mask) & ~511, |
| nb_csectors * 512); |
| return; |
| } |
| |
| qcow2_free_clusters(bs, cluster_offset, nb_clusters << s->cluster_bits); |
| |
| return; |
| } |
| |
| |
| |
| /*********************************************************/ |
| /* snapshots and image creation */ |
| |
| |
| |
| void qcow2_create_refcount_update(QCowCreateState *s, int64_t offset, |
| int64_t size) |
| { |
| int refcount; |
| int64_t start, last, cluster_offset; |
| uint16_t *p; |
| |
| 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) { |
| p = &s->refcount_block[cluster_offset >> s->cluster_bits]; |
| refcount = be16_to_cpu(*p); |
| refcount++; |
| *p = cpu_to_be16(refcount); |
| } |
| } |
| |
| /* 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 l2_size, i, j, l1_modified, l2_modified, nb_csectors, refcount; |
| |
| qcow2_l2_cache_reset(bs); |
| cache_refcount_updates = 1; |
| |
| l2_table = NULL; |
| l1_table = NULL; |
| l1_size2 = l1_size * sizeof(uint64_t); |
| if (l1_table_offset != s->l1_table_offset) { |
| if (l1_size2 != 0) { |
| l1_table = qemu_mallocz(align_offset(l1_size2, 512)); |
| } else { |
| l1_table = NULL; |
| } |
| l1_allocated = 1; |
| 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]); |
| } else { |
| assert(l1_size == s->l1_size); |
| l1_table = s->l1_table; |
| l1_allocated = 0; |
| } |
| |
| l2_size = s->l2_size * sizeof(uint64_t); |
| l2_table = qemu_malloc(l2_size); |
| l1_modified = 0; |
| for(i = 0; i < l1_size; i++) { |
| l2_offset = l1_table[i]; |
| if (l2_offset) { |
| old_l2_offset = l2_offset; |
| l2_offset &= ~QCOW_OFLAG_COPIED; |
| l2_modified = 0; |
| if (bdrv_pread(bs->file, 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) { |
| 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); |
| if (ret < 0) { |
| goto fail; |
| } |
| |
| /* TODO Flushing once for the whole function should |
| * be enough */ |
| bdrv_flush(bs->file); |
| } |
| /* compressed clusters are never modified */ |
| refcount = 2; |
| } else { |
| if (addend != 0) { |
| refcount = update_cluster_refcount(bs, offset >> s->cluster_bits, addend); |
| } else { |
| refcount = get_refcount(bs, offset >> s->cluster_bits); |
| } |
| |
| if (refcount < 0) { |
| goto fail; |
| } |
| } |
| |
| if (refcount == 1) { |
| offset |= QCOW_OFLAG_COPIED; |
| } |
| if (offset != old_offset) { |
| l2_table[j] = cpu_to_be64(offset); |
| l2_modified = 1; |
| } |
| } |
| } |
| if (l2_modified) { |
| if (bdrv_pwrite_sync(bs->file, |
| l2_offset, l2_table, l2_size) < 0) |
| goto fail; |
| } |
| |
| if (addend != 0) { |
| refcount = update_cluster_refcount(bs, l2_offset >> s->cluster_bits, addend); |
| } else { |
| refcount = get_refcount(bs, l2_offset >> s->cluster_bits); |
| } |
| if (refcount < 0) { |
| 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; |
| } |
| } |
| } |
| if (l1_modified) { |
| for(i = 0; i < l1_size; i++) |
| cpu_to_be64s(&l1_table[i]); |
| if (bdrv_pwrite_sync(bs->file, l1_table_offset, l1_table, |
| l1_size2) < 0) |
| goto fail; |
| for(i = 0; i < l1_size; i++) |
| be64_to_cpus(&l1_table[i]); |
| } |
| if (l1_allocated) |
| qemu_free(l1_table); |
| qemu_free(l2_table); |
| cache_refcount_updates = 0; |
| write_refcount_block(bs); |
| return 0; |
| fail: |
| if (l1_allocated) |
| qemu_free(l1_table); |
| qemu_free(l2_table); |
| cache_refcount_updates = 0; |
| write_refcount_block(bs); |
| return -EIO; |
| } |
| |
| |
| |
| |
| /*********************************************************/ |
| /* 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++; |
| } |
| } |
| } |
| } |
| |
| /* |
| * 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 check_copied) |
| { |
| BDRVQcowState *s = bs->opaque; |
| uint64_t *l2_table, offset; |
| int i, l2_size, nb_csectors, refcount; |
| |
| /* Read L2 table from disk */ |
| l2_size = s->l2_size * sizeof(uint64_t); |
| l2_table = qemu_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++) { |
| 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; |
| res->corruptions++; |
| } |
| |
| /* Mark cluster as used */ |
| nb_csectors = ((offset >> s->csize_shift) & |
| s->csize_mask) + 1; |
| offset &= s->cluster_offset_mask; |
| inc_refcounts(bs, res, 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 < 0) { |
| fprintf(stderr, "Can't get refcount for offset %" |
| PRIx64 ": %s\n", entry, strerror(-refcount)); |
| goto fail; |
| } |
| if ((refcount == 1) != ((entry & QCOW_OFLAG_COPIED) != 0)) { |
| fprintf(stderr, "ERROR OFLAG_COPIED: offset=%" |
| PRIx64 " refcount=%d\n", entry, refcount); |
| res->corruptions++; |
| } |
| } |
| |
| /* Mark cluster as used */ |
| offset &= ~QCOW_OFLAG_COPIED; |
| 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++; |
| } |
| } |
| } |
| } |
| |
| qemu_free(l2_table); |
| return 0; |
| |
| fail: |
| fprintf(stderr, "ERROR: I/O error in check_refcounts_l2\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, |
| BdrvCheckResult *res, |
| uint16_t *refcount_table, |
| int refcount_table_size, |
| int64_t l1_table_offset, int l1_size, |
| int check_copied) |
| { |
| 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 = qemu_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 (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)); |
| 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 &= ~QCOW_OFLAG_COPIED; |
| 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, check_copied); |
| if (ret < 0) { |
| goto fail; |
| } |
| } |
| } |
| qemu_free(l1_table); |
| return 0; |
| |
| fail: |
| fprintf(stderr, "ERROR: I/O error in check_refcounts_l1\n"); |
| res->check_errors++; |
| qemu_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 occured. |
| */ |
| int qcow2_check_refcounts(BlockDriverState *bs, BdrvCheckResult *res) |
| { |
| BDRVQcowState *s = bs->opaque; |
| int64_t size; |
| int nb_clusters, refcount1, refcount2, i; |
| QCowSnapshot *sn; |
| uint16_t *refcount_table; |
| int ret; |
| |
| size = bdrv_getlength(bs->file); |
| nb_clusters = size_to_clusters(s, size); |
| refcount_table = qemu_mallocz(nb_clusters * sizeof(uint16_t)); |
| |
| /* 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, 1); |
| if (ret < 0) { |
| return ret; |
| } |
| |
| /* 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) { |
| return ret; |
| } |
| } |
| 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 %d is not " |
| "cluster aligned; refcount table entry corrupted\n", i); |
| res->corruptions++; |
| continue; |
| } |
| |
| if (cluster >= nb_clusters) { |
| fprintf(stderr, "ERROR refcount block %d 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 %d refcount=%d\n", |
| i, refcount_table[cluster]); |
| res->corruptions++; |
| } |
| } |
| } |
| |
| /* 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)); |
| res->check_errors++; |
| continue; |
| } |
| |
| refcount2 = refcount_table[i]; |
| if (refcount1 != refcount2) { |
| fprintf(stderr, "%s cluster %d refcount=%d reference=%d\n", |
| refcount1 < refcount2 ? "ERROR" : "Leaked", |
| i, refcount1, refcount2); |
| if (refcount1 < refcount2) { |
| res->corruptions++; |
| } else { |
| res->leaks++; |
| } |
| } |
| } |
| |
| qemu_free(refcount_table); |
| |
| return 0; |
| } |
| |
