Re: [Qemu-devel] [PATCH V12 4/6] rename qcow2-cache.c to block-cache.c

[Michael Roth <mdroth@linux.vnet.ibm.com>]

On Fri, Aug 10, 2012 at 11:39:43PM +0800, Dong Xu Wang wrote:
> add-cow and qcow2 file format will share the same cache code, so rename
> block-cache.c to block-cache.c. And related structure and qcow2 code also

"qcow2-cache.c to block-cache.c"

But I've scanned through the rest of your patches and can't seem to find
where block-cache.c gets introduced. Did you forget to git add it?

> are changed.
> 
> Signed-off-by: Dong Xu Wang <wdongxu@linux.vnet.ibm.com>
> ---
>  block.h                |    3 +
>  block/Makefile.objs    |    3 +-
>  block/qcow2-cache.c    |  323 ------------------------------------------------
>  block/qcow2-cluster.c  |   66 ++++++----
>  block/qcow2-refcount.c |   66 ++++++-----
>  block/qcow2.c          |   36 +++---
>  block/qcow2.h          |   24 +---
>  trace-events           |   13 +-
>  8 files changed, 109 insertions(+), 425 deletions(-)
>  delete mode 100644 block/qcow2-cache.c
> 
> diff --git a/block.h b/block.h
> index e5dfcd7..c325661 100644
> --- a/block.h
> +++ b/block.h
> @@ -401,6 +401,9 @@ typedef enum {
>      BLKDBG_CLUSTER_ALLOC_BYTES,
>      BLKDBG_CLUSTER_FREE,
> 
> +    BLKDBG_ADD_COW_UPDATE,
> +    BLKDBG_ADD_COW_LOAD,
> +
>      BLKDBG_EVENT_MAX,
>  } BlkDebugEvent;
> 
> diff --git a/block/Makefile.objs b/block/Makefile.objs
> index b5754d3..23bdfc8 100644
> --- a/block/Makefile.objs
> +++ b/block/Makefile.objs
> @@ -1,7 +1,8 @@
>  block-obj-y += raw.o cow.o qcow.o vdi.o vmdk.o cloop.o dmg.o bochs.o vpc.o vvfat.o
> -block-obj-y += qcow2.o qcow2-refcount.o qcow2-cluster.o qcow2-snapshot.o qcow2-cache.o
> +block-obj-y += qcow2.o qcow2-refcount.o qcow2-cluster.o qcow2-snapshot.o
>  block-obj-y += qed.o qed-gencb.o qed-l2-cache.o qed-table.o qed-cluster.o
>  block-obj-y += qed-check.o
> +block-obj-y += block-cache.o
>  block-obj-y += parallels.o nbd.o blkdebug.o sheepdog.o blkverify.o
>  block-obj-y += stream.o
>  block-obj-$(CONFIG_WIN32) += raw-win32.o
> diff --git a/block/qcow2-cache.c b/block/qcow2-cache.c
> deleted file mode 100644
> index 2d4322a..0000000
> --- a/block/qcow2-cache.c
> +++ /dev/null
> @@ -1,323 +0,0 @@
> -/*
> - * L2/refcount table cache for the QCOW2 format
> - *
> - * Copyright (c) 2010 Kevin Wolf <kwolf@redhat.com>
> - *
> - * 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 "block_int.h"
> -#include "qemu-common.h"
> -#include "qcow2.h"
> -#include "trace.h"
> -
> -typedef struct Qcow2CachedTable {
> -    void*   table;
> -    int64_t offset;
> -    bool    dirty;
> -    int     cache_hits;
> -    int     ref;
> -} Qcow2CachedTable;
> -
> -struct Qcow2Cache {
> -    Qcow2CachedTable*       entries;
> -    struct Qcow2Cache*      depends;
> -    int                     size;
> -    bool                    depends_on_flush;
> -};
> -
> -Qcow2Cache *qcow2_cache_create(BlockDriverState *bs, int num_tables)
> -{
> -    BDRVQcowState *s = bs->opaque;
> -    Qcow2Cache *c;
> -    int i;
> -
> -    c = g_malloc0(sizeof(*c));
> -    c->size = num_tables;
> -    c->entries = g_malloc0(sizeof(*c->entries) * num_tables);
> -
> -    for (i = 0; i < c->size; i++) {
> -        c->entries[i].table = qemu_blockalign(bs, s->cluster_size);
> -    }
> -
> -    return c;
> -}
> -
> -int qcow2_cache_destroy(BlockDriverState* bs, Qcow2Cache *c)
> -{
> -    int i;
> -
> -    for (i = 0; i < c->size; i++) {
> -        assert(c->entries[i].ref == 0);
> -        qemu_vfree(c->entries[i].table);
> -    }
> -
> -    g_free(c->entries);
> -    g_free(c);
> -
> -    return 0;
> -}
> -
> -static int qcow2_cache_flush_dependency(BlockDriverState *bs, Qcow2Cache *c)
> -{
> -    int ret;
> -
> -    ret = qcow2_cache_flush(bs, c->depends);
> -    if (ret < 0) {
> -        return ret;
> -    }
> -
> -    c->depends = NULL;
> -    c->depends_on_flush = false;
> -
> -    return 0;
> -}
> -
> -static int qcow2_cache_entry_flush(BlockDriverState *bs, Qcow2Cache *c, int i)
> -{
> -    BDRVQcowState *s = bs->opaque;
> -    int ret = 0;
> -
> -    if (!c->entries[i].dirty || !c->entries[i].offset) {
> -        return 0;
> -    }
> -
> -    trace_qcow2_cache_entry_flush(qemu_coroutine_self(),
> -                                  c == s->l2_table_cache, i);
> -
> -    if (c->depends) {
> -        ret = qcow2_cache_flush_dependency(bs, c);
> -    } else if (c->depends_on_flush) {
> -        ret = bdrv_flush(bs->file);
> -        if (ret >= 0) {
> -            c->depends_on_flush = false;
> -        }
> -    }
> -
> -    if (ret < 0) {
> -        return ret;
> -    }
> -
> -    if (c == s->refcount_block_cache) {
> -        BLKDBG_EVENT(bs->file, BLKDBG_REFBLOCK_UPDATE_PART);
> -    } else if (c == s->l2_table_cache) {
> -        BLKDBG_EVENT(bs->file, BLKDBG_L2_UPDATE);
> -    }
> -
> -    ret = bdrv_pwrite(bs->file, c->entries[i].offset, c->entries[i].table,
> -        s->cluster_size);
> -    if (ret < 0) {
> -        return ret;
> -    }
> -
> -    c->entries[i].dirty = false;
> -
> -    return 0;
> -}
> -
> -int qcow2_cache_flush(BlockDriverState *bs, Qcow2Cache *c)
> -{
> -    BDRVQcowState *s = bs->opaque;
> -    int result = 0;
> -    int ret;
> -    int i;
> -
> -    trace_qcow2_cache_flush(qemu_coroutine_self(), c == s->l2_table_cache);
> -
> -    for (i = 0; i < c->size; i++) {
> -        ret = qcow2_cache_entry_flush(bs, c, i);
> -        if (ret < 0 && result != -ENOSPC) {
> -            result = ret;
> -        }
> -    }
> -
> -    if (result == 0) {
> -        ret = bdrv_flush(bs->file);
> -        if (ret < 0) {
> -            result = ret;
> -        }
> -    }
> -
> -    return result;
> -}
> -
> -int qcow2_cache_set_dependency(BlockDriverState *bs, Qcow2Cache *c,
> -    Qcow2Cache *dependency)
> -{
> -    int ret;
> -
> -    if (dependency->depends) {
> -        ret = qcow2_cache_flush_dependency(bs, dependency);
> -        if (ret < 0) {
> -            return ret;
> -        }
> -    }
> -
> -    if (c->depends && (c->depends != dependency)) {
> -        ret = qcow2_cache_flush_dependency(bs, c);
> -        if (ret < 0) {
> -            return ret;
> -        }
> -    }
> -
> -    c->depends = dependency;
> -    return 0;
> -}
> -
> -void qcow2_cache_depends_on_flush(Qcow2Cache *c)
> -{
> -    c->depends_on_flush = true;
> -}
> -
> -static int qcow2_cache_find_entry_to_replace(Qcow2Cache *c)
> -{
> -    int i;
> -    int min_count = INT_MAX;
> -    int min_index = -1;
> -
> -
> -    for (i = 0; i < c->size; i++) {
> -        if (c->entries[i].ref) {
> -            continue;
> -        }
> -
> -        if (c->entries[i].cache_hits < min_count) {
> -            min_index = i;
> -            min_count = c->entries[i].cache_hits;
> -        }
> -
> -        /* Give newer hits priority */
> -        /* TODO Check how to optimize the replacement strategy */
> -        c->entries[i].cache_hits /= 2;
> -    }
> -
> -    if (min_index == -1) {
> -        /* This can't happen in current synchronous code, but leave the check
> -         * here as a reminder for whoever starts using AIO with the cache */
> -        abort();
> -    }
> -    return min_index;
> -}
> -
> -static int qcow2_cache_do_get(BlockDriverState *bs, Qcow2Cache *c,
> -    uint64_t offset, void **table, bool read_from_disk)
> -{
> -    BDRVQcowState *s = bs->opaque;
> -    int i;
> -    int ret;
> -
> -    trace_qcow2_cache_get(qemu_coroutine_self(), c == s->l2_table_cache,
> -                          offset, read_from_disk);
> -
> -    /* Check if the table is already cached */
> -    for (i = 0; i < c->size; i++) {
> -        if (c->entries[i].offset == offset) {
> -            goto found;
> -        }
> -    }
> -
> -    /* If not, write a table back and replace it */
> -    i = qcow2_cache_find_entry_to_replace(c);
> -    trace_qcow2_cache_get_replace_entry(qemu_coroutine_self(),
> -                                        c == s->l2_table_cache, i);
> -    if (i < 0) {
> -        return i;
> -    }
> -
> -    ret = qcow2_cache_entry_flush(bs, c, i);
> -    if (ret < 0) {
> -        return ret;
> -    }
> -
> -    trace_qcow2_cache_get_read(qemu_coroutine_self(),
> -                               c == s->l2_table_cache, i);
> -    c->entries[i].offset = 0;
> -    if (read_from_disk) {
> -        if (c == s->l2_table_cache) {
> -            BLKDBG_EVENT(bs->file, BLKDBG_L2_LOAD);
> -        }
> -
> -        ret = bdrv_pread(bs->file, offset, c->entries[i].table, s->cluster_size);
> -        if (ret < 0) {
> -            return ret;
> -        }
> -    }
> -
> -    /* Give the table some hits for the start so that it won't be replaced
> -     * immediately. The number 32 is completely arbitrary. */
> -    c->entries[i].cache_hits = 32;
> -    c->entries[i].offset = offset;
> -
> -    /* And return the right table */
> -found:
> -    c->entries[i].cache_hits++;
> -    c->entries[i].ref++;
> -    *table = c->entries[i].table;
> -
> -    trace_qcow2_cache_get_done(qemu_coroutine_self(),
> -                               c == s->l2_table_cache, i);
> -
> -    return 0;
> -}
> -
> -int qcow2_cache_get(BlockDriverState *bs, Qcow2Cache *c, uint64_t offset,
> -    void **table)
> -{
> -    return qcow2_cache_do_get(bs, c, offset, table, true);
> -}
> -
> -int qcow2_cache_get_empty(BlockDriverState *bs, Qcow2Cache *c, uint64_t offset,
> -    void **table)
> -{
> -    return qcow2_cache_do_get(bs, c, offset, table, false);
> -}
> -
> -int qcow2_cache_put(BlockDriverState *bs, Qcow2Cache *c, void **table)
> -{
> -    int i;
> -
> -    for (i = 0; i < c->size; i++) {
> -        if (c->entries[i].table == *table) {
> -            goto found;
> -        }
> -    }
> -    return -ENOENT;
> -
> -found:
> -    c->entries[i].ref--;
> -    *table = NULL;
> -
> -    assert(c->entries[i].ref >= 0);
> -    return 0;
> -}
> -
> -void qcow2_cache_entry_mark_dirty(Qcow2Cache *c, void *table)
> -{
> -    int i;
> -
> -    for (i = 0; i < c->size; i++) {
> -        if (c->entries[i].table == table) {
> -            goto found;
> -        }
> -    }
> -    abort();
> -
> -found:
> -    c->entries[i].dirty = true;
> -}
> diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c
> index e179211..335dc7a 100644
> --- a/block/qcow2-cluster.c
> +++ b/block/qcow2-cluster.c
> @@ -28,6 +28,7 @@
>  #include "block_int.h"
>  #include "block/qcow2.h"
>  #include "trace.h"
> +#include "block-cache.h"
> 
>  int qcow2_grow_l1_table(BlockDriverState *bs, int min_size, bool exact_size)
>  {
> @@ -69,7 +70,8 @@ int qcow2_grow_l1_table(BlockDriverState *bs, int min_size, bool exact_size)
>          return new_l1_table_offset;
>      }
> 
> -    ret = qcow2_cache_flush(bs, s->refcount_block_cache);
> +    ret = block_cache_flush(bs, s->refcount_block_cache,
> +        BLOCK_TABLE_REF, s->cluster_size);
>      if (ret < 0) {
>          goto fail;
>      }
> @@ -119,7 +121,8 @@ static int l2_load(BlockDriverState *bs, uint64_t l2_offset,
>      BDRVQcowState *s = bs->opaque;
>      int ret;
> 
> -    ret = qcow2_cache_get(bs, s->l2_table_cache, l2_offset, (void**) l2_table);
> +    ret = block_cache_get(bs, s->l2_table_cache, l2_offset,
> +        (void **) l2_table, BLOCK_TABLE_L2, s->cluster_size);
> 
>      return ret;
>  }
> @@ -180,7 +183,8 @@ static int l2_allocate(BlockDriverState *bs, int l1_index, uint64_t **table)
>          return l2_offset;
>      }
> 
> -    ret = qcow2_cache_flush(bs, s->refcount_block_cache);
> +    ret = block_cache_flush(bs, s->refcount_block_cache,
> +        BLOCK_TABLE_REF, s->cluster_size);
>      if (ret < 0) {
>          goto fail;
>      }
> @@ -188,7 +192,8 @@ static int l2_allocate(BlockDriverState *bs, int l1_index, uint64_t **table)
>      /* allocate a new entry in the l2 cache */
> 
>      trace_qcow2_l2_allocate_get_empty(bs, l1_index);
> -    ret = qcow2_cache_get_empty(bs, s->l2_table_cache, l2_offset, (void**) table);
> +    ret = block_cache_get_empty(bs, s->l2_table_cache, l2_offset,
> +        (void **) table, BLOCK_TABLE_L2, s->cluster_size);
>      if (ret < 0) {
>          return ret;
>      }
> @@ -203,16 +208,17 @@ static int l2_allocate(BlockDriverState *bs, int l1_index, uint64_t **table)
> 
>          /* if there was an old l2 table, read it from the disk */
>          BLKDBG_EVENT(bs->file, BLKDBG_L2_ALLOC_COW_READ);
> -        ret = qcow2_cache_get(bs, s->l2_table_cache,
> +        ret = block_cache_get(bs, s->l2_table_cache,
>              old_l2_offset & L1E_OFFSET_MASK,
> -            (void**) &old_table);
> +            (void **) &old_table, BLOCK_TABLE_L2, s->cluster_size);
>          if (ret < 0) {
>              goto fail;
>          }
> 
>          memcpy(l2_table, old_table, s->cluster_size);
> 
> -        ret = qcow2_cache_put(bs, s->l2_table_cache, (void**) &old_table);
> +        ret = block_cache_put(bs, s->l2_table_cache,
> +            (void **) &old_table, BLOCK_TABLE_L2);
>          if (ret < 0) {
>              goto fail;
>          }
> @@ -222,8 +228,9 @@ static int l2_allocate(BlockDriverState *bs, int l1_index, uint64_t **table)
>      BLKDBG_EVENT(bs->file, BLKDBG_L2_ALLOC_WRITE);
> 
>      trace_qcow2_l2_allocate_write_l2(bs, l1_index);
> -    qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_table);
> -    ret = qcow2_cache_flush(bs, s->l2_table_cache);
> +    block_cache_entry_mark_dirty(s->l2_table_cache, l2_table);
> +    ret = block_cache_flush(bs, s->l2_table_cache,
> +        BLOCK_TABLE_L2, s->cluster_size);
>      if (ret < 0) {
>          goto fail;
>      }
> @@ -242,7 +249,7 @@ static int l2_allocate(BlockDriverState *bs, int l1_index, uint64_t **table)
> 
>  fail:
>      trace_qcow2_l2_allocate_done(bs, l1_index, ret);
> -    qcow2_cache_put(bs, s->l2_table_cache, (void**) table);
> +    block_cache_put(bs, s->l2_table_cache, (void **) table, BLOCK_TABLE_L2);
>      s->l1_table[l1_index] = old_l2_offset;
>      return ret;
>  }
> @@ -475,7 +482,7 @@ int qcow2_get_cluster_offset(BlockDriverState *bs, uint64_t offset,
>          abort();
>      }
> 
> -    qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table);
> +    block_cache_put(bs, s->l2_table_cache, (void **) &l2_table, BLOCK_TABLE_L2);
> 
>      nb_available = (c * s->cluster_sectors);
> 
> @@ -584,13 +591,15 @@ uint64_t qcow2_alloc_compressed_cluster_offset(BlockDriverState *bs,
>       * allocated. */
>      cluster_offset = be64_to_cpu(l2_table[l2_index]);
>      if (cluster_offset & L2E_OFFSET_MASK) {
> -        qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table);
> +        block_cache_put(bs, s->l2_table_cache,
> +            (void **) &l2_table, BLOCK_TABLE_L2);
>          return 0;
>      }
> 
>      cluster_offset = qcow2_alloc_bytes(bs, compressed_size);
>      if (cluster_offset < 0) {
> -        qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table);
> +        block_cache_put(bs, s->l2_table_cache,
> +            (void **) &l2_table, BLOCK_TABLE_L2);
>          return 0;
>      }
> 
> @@ -605,9 +614,10 @@ uint64_t qcow2_alloc_compressed_cluster_offset(BlockDriverState *bs,
>      /* compressed clusters never have the copied flag */
> 
>      BLKDBG_EVENT(bs->file, BLKDBG_L2_UPDATE_COMPRESSED);
> -    qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_table);
> +    block_cache_entry_mark_dirty(s->l2_table_cache, l2_table);
>      l2_table[l2_index] = cpu_to_be64(cluster_offset);
> -    ret = qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table);
> +    ret = block_cache_put(bs, s->l2_table_cache,
> +        (void **) &l2_table, BLOCK_TABLE_L2);
>      if (ret < 0) {
>          return 0;
>      }
> @@ -659,18 +669,16 @@ int qcow2_alloc_cluster_link_l2(BlockDriverState *bs, QCowL2Meta *m)
>       * handled.
>       */
>      if (cow) {
> -        qcow2_cache_depends_on_flush(s->l2_table_cache);
> +        block_cache_depends_on_flush(s->l2_table_cache);
>      }
> 
> -    if (qcow2_need_accurate_refcounts(s)) {
> -        qcow2_cache_set_dependency(bs, s->l2_table_cache,
> -                                   s->refcount_block_cache);
> -    }
> +    block_cache_set_dependency(bs, s->l2_table_cache, BLOCK_TABLE_L2,
> +        s->refcount_block_cache, s->cluster_size);
>      ret = get_cluster_table(bs, m->offset, &l2_table, &l2_index);
>      if (ret < 0) {
>          goto err;
>      }
> -    qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_table);
> +    block_cache_entry_mark_dirty(s->l2_table_cache, l2_table);
> 
>      for (i = 0; i < m->nb_clusters; i++) {
>          /* if two concurrent writes happen to the same unallocated cluster
> @@ -687,7 +695,8 @@ int qcow2_alloc_cluster_link_l2(BlockDriverState *bs, QCowL2Meta *m)
>       }
> 
> 
> -    ret = qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table);
> +    ret = block_cache_put(bs, s->l2_table_cache,
> +        (void **) &l2_table, BLOCK_TABLE_L2);
>      if (ret < 0) {
>          goto err;
>      }
> @@ -913,7 +922,8 @@ again:
>       * request to complete. If we still had the reference, we could use up the
>       * whole cache with sleeping requests.
>       */
> -    ret = qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table);
> +    ret = block_cache_put(bs, s->l2_table_cache,
> +        (void **) &l2_table, BLOCK_TABLE_L2);
>      if (ret < 0) {
>          return ret;
>      }
> @@ -1077,14 +1087,15 @@ static int discard_single_l2(BlockDriverState *bs, uint64_t offset,
>          }
> 
>          /* First remove L2 entries */
> -        qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_table);
> +        block_cache_entry_mark_dirty(s->l2_table_cache, l2_table);
>          l2_table[l2_index + i] = cpu_to_be64(0);
> 
>          /* Then decrease the refcount */
>          qcow2_free_any_clusters(bs, old_offset, 1);
>      }
> 
> -    ret = qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table);
> +    ret = block_cache_put(bs, s->l2_table_cache,
> +        (void **) &l2_table, BLOCK_TABLE_L2);
>      if (ret < 0) {
>          return ret;
>      }
> @@ -1154,7 +1165,7 @@ static int zero_single_l2(BlockDriverState *bs, uint64_t offset,
>          old_offset = be64_to_cpu(l2_table[l2_index + i]);
> 
>          /* Update L2 entries */
> -        qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_table);
> +        block_cache_entry_mark_dirty(s->l2_table_cache, l2_table);
>          if (old_offset & QCOW_OFLAG_COMPRESSED) {
>              l2_table[l2_index + i] = cpu_to_be64(QCOW_OFLAG_ZERO);
>              qcow2_free_any_clusters(bs, old_offset, 1);
> @@ -1163,7 +1174,8 @@ static int zero_single_l2(BlockDriverState *bs, uint64_t offset,
>          }
>      }
> 
> -    ret = qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table);
> +    ret = block_cache_put(bs, s->l2_table_cache,
> +        (void **) &l2_table, BLOCK_TABLE_L2);
>      if (ret < 0) {
>          return ret;
>      }
> diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c
> index 5e3f915..728bfc1 100644
> --- a/block/qcow2-refcount.c
> +++ b/block/qcow2-refcount.c
> @@ -25,6 +25,7 @@
>  #include "qemu-common.h"
>  #include "block_int.h"
>  #include "block/qcow2.h"
> +#include "block-cache.h"
> 
>  static int64_t alloc_clusters_noref(BlockDriverState *bs, int64_t size);
>  static int QEMU_WARN_UNUSED_RESULT update_refcount(BlockDriverState *bs,
> @@ -71,8 +72,8 @@ static int load_refcount_block(BlockDriverState *bs,
>      int ret;
> 
>      BLKDBG_EVENT(bs->file, BLKDBG_REFBLOCK_LOAD);
> -    ret = qcow2_cache_get(bs, s->refcount_block_cache, refcount_block_offset,
> -        refcount_block);
> +    ret = block_cache_get(bs, s->refcount_block_cache, refcount_block_offset,
> +        refcount_block, BLOCK_TABLE_REF, s->cluster_size);
> 
>      return ret;
>  }
> @@ -98,8 +99,8 @@ static int get_refcount(BlockDriverState *bs, int64_t cluster_index)
>      if (!refcount_block_offset)
>          return 0;
> 
> -    ret = qcow2_cache_get(bs, s->refcount_block_cache, refcount_block_offset,
> -        (void**) &refcount_block);
> +    ret = block_cache_get(bs, s->refcount_block_cache, refcount_block_offset,
> +        (void **) &refcount_block, BLOCK_TABLE_REF, s->cluster_size);
>      if (ret < 0) {
>          return ret;
>      }
> @@ -108,8 +109,8 @@ static int get_refcount(BlockDriverState *bs, int64_t 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);
> +    ret = block_cache_put(bs, s->refcount_block_cache,
> +        (void **) &refcount_block, BLOCK_TABLE_REF);
>      if (ret < 0) {
>          return ret;
>      }
> @@ -201,7 +202,8 @@ static int alloc_refcount_block(BlockDriverState *bs,
>      *refcount_block = NULL;
> 
>      /* We write to the refcount table, so we might depend on L2 tables */
> -    qcow2_cache_flush(bs, s->l2_table_cache);
> +    block_cache_flush(bs, s->l2_table_cache,
> +        BLOCK_TABLE_L2, s->cluster_size);
> 
>      /* Allocate the refcount block itself and mark it as used */
>      int64_t new_block = alloc_clusters_noref(bs, s->cluster_size);
> @@ -217,8 +219,8 @@ static int alloc_refcount_block(BlockDriverState *bs,
> 
>      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);
> +        ret = block_cache_get_empty(bs, s->refcount_block_cache, new_block,
> +            (void **) refcount_block, BLOCK_TABLE_REF, s->cluster_size);
>          if (ret < 0) {
>              goto fail_block;
>          }
> @@ -241,8 +243,8 @@ static int alloc_refcount_block(BlockDriverState *bs,
> 
>          /* 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);
> +        ret = block_cache_get_empty(bs, s->refcount_block_cache, new_block,
> +            (void **) refcount_block, BLOCK_TABLE_REF, s->cluster_size);
>          if (ret < 0) {
>              goto fail_block;
>          }
> @@ -252,8 +254,9 @@ static int alloc_refcount_block(BlockDriverState *bs,
> 
>      /* 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);
> +    block_cache_entry_mark_dirty(s->refcount_block_cache, *refcount_block);
> +    ret = block_cache_flush(bs, s->refcount_block_cache,
> +        BLOCK_TABLE_REF, s->cluster_size);
>      if (ret < 0) {
>          goto fail_block;
>      }
> @@ -273,7 +276,8 @@ static int alloc_refcount_block(BlockDriverState *bs,
>          return 0;
>      }
> 
> -    ret = qcow2_cache_put(bs, s->refcount_block_cache, (void**) refcount_block);
> +    ret = block_cache_put(bs, s->refcount_block_cache,
> +        (void **) refcount_block, BLOCK_TABLE_REF);
>      if (ret < 0) {
>          goto fail_block;
>      }
> @@ -406,7 +410,8 @@ fail_table:
>      g_free(new_table);
>  fail_block:
>      if (*refcount_block != NULL) {
> -        qcow2_cache_put(bs, s->refcount_block_cache, (void**) refcount_block);
> +        block_cache_put(bs, s->refcount_block_cache,
> +            (void **) refcount_block, BLOCK_TABLE_REF);
>      }
>      return ret;
>  }
> @@ -432,8 +437,8 @@ static int QEMU_WARN_UNUSED_RESULT update_refcount(BlockDriverState *bs,
>      }
> 
>      if (addend < 0) {
> -        qcow2_cache_set_dependency(bs, s->refcount_block_cache,
> -            s->l2_table_cache);
> +        block_cache_set_dependency(bs, s->refcount_block_cache, BLOCK_TABLE_REF,
> +            s->l2_table_cache, s->cluster_size);
>      }
> 
>      start = offset & ~(s->cluster_size - 1);
> @@ -449,8 +454,8 @@ static int QEMU_WARN_UNUSED_RESULT update_refcount(BlockDriverState *bs,
>          /* 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);
> +                ret = block_cache_put(bs, s->refcount_block_cache,
> +                    (void **) &refcount_block, BLOCK_TABLE_REF);
>                  if (ret < 0) {
>                      goto fail;
>                  }
> @@ -463,7 +468,7 @@ static int QEMU_WARN_UNUSED_RESULT update_refcount(BlockDriverState *bs,
>          }
>          old_table_index = table_index;
> 
> -        qcow2_cache_entry_mark_dirty(s->refcount_block_cache, refcount_block);
> +        block_cache_entry_mark_dirty(s->refcount_block_cache, refcount_block);
> 
>          /* we can update the count and save it */
>          block_index = cluster_index &
> @@ -486,8 +491,8 @@ fail:
>      /* Write last changed block to disk */
>      if (refcount_block) {
>          int wret;
> -        wret = qcow2_cache_put(bs, s->refcount_block_cache,
> -            (void**) &refcount_block);
> +        wret = block_cache_put(bs, s->refcount_block_cache,
> +            (void **) &refcount_block, BLOCK_TABLE_REF);
>          if (wret < 0) {
>              return ret < 0 ? ret : wret;
>          }
> @@ -763,8 +768,8 @@ int qcow2_update_snapshot_refcount(BlockDriverState *bs,
>              old_l2_offset = l2_offset;
>              l2_offset &= L1E_OFFSET_MASK;
> 
> -            ret = qcow2_cache_get(bs, s->l2_table_cache, l2_offset,
> -                (void**) &l2_table);
> +            ret = block_cache_get(bs, s->l2_table_cache, l2_offset,
> +                (void **) &l2_table, BLOCK_TABLE_L2, s->cluster_size);
>              if (ret < 0) {
>                  goto fail;
>              }
> @@ -811,16 +816,18 @@ int qcow2_update_snapshot_refcount(BlockDriverState *bs,
>                      }
>                      if (offset != old_offset) {
>                          if (addend > 0) {
> -                            qcow2_cache_set_dependency(bs, s->l2_table_cache,
> -                                s->refcount_block_cache);
> +                            block_cache_set_dependency(bs, s->l2_table_cache,
> +                                BLOCK_TABLE_L2, s->refcount_block_cache,
> +                                s->cluster_size);
>                          }
>                          l2_table[j] = cpu_to_be64(offset);
> -                        qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_table);
> +                        block_cache_entry_mark_dirty(s->l2_table_cache, l2_table);
>                      }
>                  }
>              }
> 
> -            ret = qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table);
> +            ret = block_cache_put(bs, s->l2_table_cache,
> +                (void **) &l2_table, BLOCK_TABLE_L2);
>              if (ret < 0) {
>                  goto fail;
>              }
> @@ -847,7 +854,8 @@ int qcow2_update_snapshot_refcount(BlockDriverState *bs,
>      ret = 0;
>  fail:
>      if (l2_table) {
> -        qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table);
> +        block_cache_put(bs, s->l2_table_cache,
> +            (void **) &l2_table, BLOCK_TABLE_L2);
>      }
> 
>      /* Update L1 only if it isn't deleted anyway (addend = -1) */
> diff --git a/block/qcow2.c b/block/qcow2.c
> index fd5e214..b89d312 100644
> --- a/block/qcow2.c
> +++ b/block/qcow2.c
> @@ -30,6 +30,7 @@
>  #include "qemu-error.h"
>  #include "qerror.h"
>  #include "trace.h"
> +#include "block-cache.h"
> 
>  /*
>    Differences with QCOW:
> @@ -415,8 +416,9 @@ static int qcow2_open(BlockDriverState *bs, int flags)
>      }
> 
>      /* alloc L2 table/refcount block cache */
> -    s->l2_table_cache = qcow2_cache_create(bs, L2_CACHE_SIZE);
> -    s->refcount_block_cache = qcow2_cache_create(bs, REFCOUNT_CACHE_SIZE);
> +    s->l2_table_cache = block_cache_create(bs, L2_CACHE_SIZE, s->cluster_size);
> +    s->refcount_block_cache =
> +        block_cache_create(bs, REFCOUNT_CACHE_SIZE, s->cluster_size);
> 
>      s->cluster_cache = g_malloc(s->cluster_size);
>      /* one more sector for decompressed data alignment */
> @@ -500,7 +502,7 @@ static int qcow2_open(BlockDriverState *bs, int flags)
>      qcow2_refcount_close(bs);
>      g_free(s->l1_table);
>      if (s->l2_table_cache) {
> -        qcow2_cache_destroy(bs, s->l2_table_cache);
> +        block_cache_destroy(bs, s->l2_table_cache, BLOCK_TABLE_L2);
>      }
>      g_free(s->cluster_cache);
>      qemu_vfree(s->cluster_data);
> @@ -860,13 +862,13 @@ static void qcow2_close(BlockDriverState *bs)
>      BDRVQcowState *s = bs->opaque;
>      g_free(s->l1_table);
> 
> -    qcow2_cache_flush(bs, s->l2_table_cache);
> -    qcow2_cache_flush(bs, s->refcount_block_cache);
> -
> +    block_cache_flush(bs, s->l2_table_cache,
> +        BLOCK_TABLE_L2, s->cluster_size);
> +    block_cache_flush(bs, s->refcount_block_cache,
> +        BLOCK_TABLE_REF, s->cluster_size);
>      qcow2_mark_clean(bs);
> -
> -    qcow2_cache_destroy(bs, s->l2_table_cache);
> -    qcow2_cache_destroy(bs, s->refcount_block_cache);
> +    block_cache_destroy(bs, s->l2_table_cache, BLOCK_TABLE_L2);
> +    block_cache_destroy(bs, s->refcount_block_cache, BLOCK_TABLE_REF);
> 
>      g_free(s->unknown_header_fields);
>      cleanup_unknown_header_ext(bs);
> @@ -1339,8 +1341,6 @@ 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++;
>      }
> @@ -1537,18 +1537,18 @@ static coroutine_fn int qcow2_co_flush_to_os(BlockDriverState *bs)
>      int ret;
> 
>      qemu_co_mutex_lock(&s->lock);
> -    ret = qcow2_cache_flush(bs, s->l2_table_cache);
> +    ret = block_cache_flush(bs, s->l2_table_cache,
> +        BLOCK_TABLE_L2, s->cluster_size);
>      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;
> -        }
> +    ret = block_cache_flush(bs, s->refcount_block_cache,
> +        BLOCK_TABLE_REF, s->cluster_size);
> +    if (ret < 0) {
> +        qemu_co_mutex_unlock(&s->lock);
> +        return ret;
>      }
>      qemu_co_mutex_unlock(&s->lock);
> 
> diff --git a/block/qcow2.h b/block/qcow2.h
> index b4eb654..cb6fd7a 100644
> --- a/block/qcow2.h
> +++ b/block/qcow2.h
> @@ -27,6 +27,7 @@
> 
>  #include "aes.h"
>  #include "qemu-coroutine.h"
> +#include "block-cache.h"
> 
>  //#define DEBUG_ALLOC
>  //#define DEBUG_ALLOC2
> @@ -94,8 +95,6 @@ typedef struct QCowSnapshot {
>      uint64_t vm_clock_nsec;
>  } QCowSnapshot;
> 
> -struct Qcow2Cache;
> -typedef struct Qcow2Cache Qcow2Cache;
> 
>  typedef struct Qcow2UnknownHeaderExtension {
>      uint32_t magic;
> @@ -146,8 +145,8 @@ typedef struct BDRVQcowState {
>      uint64_t l1_table_offset;
>      uint64_t *l1_table;
> 
> -    Qcow2Cache* l2_table_cache;
> -    Qcow2Cache* refcount_block_cache;
> +    BlockCache *l2_table_cache;
> +    BlockCache *refcount_block_cache;
> 
>      uint8_t *cluster_cache;
>      uint8_t *cluster_data;
> @@ -316,21 +315,4 @@ int qcow2_snapshot_load_tmp(BlockDriverState *bs, const char *snapshot_name);
> 
>  void qcow2_free_snapshots(BlockDriverState *bs);
>  int qcow2_read_snapshots(BlockDriverState *bs);
> -
> -/* qcow2-cache.c functions */
> -Qcow2Cache *qcow2_cache_create(BlockDriverState *bs, int num_tables);
> -int qcow2_cache_destroy(BlockDriverState* bs, Qcow2Cache *c);
> -
> -void qcow2_cache_entry_mark_dirty(Qcow2Cache *c, void *table);
> -int qcow2_cache_flush(BlockDriverState *bs, Qcow2Cache *c);
> -int qcow2_cache_set_dependency(BlockDriverState *bs, Qcow2Cache *c,
> -    Qcow2Cache *dependency);
> -void qcow2_cache_depends_on_flush(Qcow2Cache *c);
> -
> -int qcow2_cache_get(BlockDriverState *bs, Qcow2Cache *c, uint64_t offset,
> -    void **table);
> -int qcow2_cache_get_empty(BlockDriverState *bs, Qcow2Cache *c, uint64_t offset,
> -    void **table);
> -int qcow2_cache_put(BlockDriverState *bs, Qcow2Cache *c, void **table);
> -
>  #endif
> diff --git a/trace-events b/trace-events
> index 6b12f83..52b6438 100644
> --- a/trace-events
> +++ b/trace-events
> @@ -439,12 +439,13 @@ qcow2_l2_allocate_write_l2(void *bs, int l1_index) "bs %p l1_index %d"
>  qcow2_l2_allocate_write_l1(void *bs, int l1_index) "bs %p l1_index %d"
>  qcow2_l2_allocate_done(void *bs, int l1_index, int ret) "bs %p l1_index %d ret %d"
> 
> -qcow2_cache_get(void *co, int c, uint64_t offset, bool read_from_disk) "co %p is_l2_cache %d offset %" PRIx64 " read_from_disk %d"
> -qcow2_cache_get_replace_entry(void *co, int c, int i) "co %p is_l2_cache %d index %d"
> -qcow2_cache_get_read(void *co, int c, int i) "co %p is_l2_cache %d index %d"
> -qcow2_cache_get_done(void *co, int c, int i) "co %p is_l2_cache %d index %d"
> -qcow2_cache_flush(void *co, int c) "co %p is_l2_cache %d"
> -qcow2_cache_entry_flush(void *co, int c, int i) "co %p is_l2_cache %d index %d"
> +# block/block-cache.c
> +block_cache_get(void *co, int c, uint64_t offset, bool read_from_disk) "co %p is_l2_cache %d offset %" PRIx64 " read_from_disk %d"
> +block_cache_get_replace_entry(void *co, int c, int i) "co %p is_l2_cache %d index %d"
> +block_cache_get_read(void *co, int c, int i) "co %p is_l2_cache %d index %d"
> +block_cache_get_done(void *co, int c, int i) "co %p is_l2_cache %d index %d"
> +block_cache_flush(void *co, int c) "co %p is_l2_cache %d"
> +block_cache_entry_flush(void *co, int c, int i) "co %p is_l2_cache %d index %d"
> 
>  # block/qed-l2-cache.c
>  qed_alloc_l2_cache_entry(void *l2_cache, void *entry) "l2_cache %p entry %p"
> -- 
> 1.7.1
> 
>