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[Qemu-devel] [PATCH 4/5 v2] qcow2 format: keep 'num_free_bytes', and sho
From: |
Uri Lublin |
Subject: |
[Qemu-devel] [PATCH 4/5 v2] qcow2 format: keep 'num_free_bytes', and show it upon 'info blockstats' |
Date: |
Thu, 22 Jan 2009 12:43:54 +0200 |
'num_free_bytes' is the number of non-allocated bytes below highest-allocation.
It's useful, together with the highest-allocation, to figure out how
fragmented the image is, and how likely it will run out-of-space soon.
For example when the highest allocation is high (almost end-of-disk), but
many bytes (clusters) are free, and can be re-allocated when neeeded, than
we know it's probably not going to reach end-of-disk-space soon.
Added bookkeeping to block-qcow2.c
Export it using BlockDeviceInfo
Show it upon 'info blockstats' if BlockDeviceInfo exists
Signed-off-by: Uri Lublin <address@hidden>
---
block-qcow2.c | 36 ++++++++++++++++++++++++++++--------
block.c | 5 +++--
block.h | 1 +
3 files changed, 32 insertions(+), 10 deletions(-)
diff --git a/block-qcow2.c b/block-qcow2.c
index 7c00ee8..8a5b621 100644
--- a/block-qcow2.c
+++ b/block-qcow2.c
@@ -145,6 +145,7 @@ typedef struct BDRVQcowState {
AES_KEY aes_decrypt_key;
int64_t highest_alloc; /* highest cluester allocated (in clusters) */
+ int64_t nc_free; /* num of free clusters below highest_alloc */
uint64_t snapshots_offset;
int snapshots_size;
@@ -173,7 +174,7 @@ static void free_clusters(BlockDriverState *bs,
#ifdef DEBUG_ALLOC
static void check_refcounts(BlockDriverState *bs);
#endif
-static void scan_refcount(BlockDriverState *bs, int64_t *high);
+static void scan_refcount(BlockDriverState *bs, int64_t *high, int64_t *free);
static int qcow_probe(const uint8_t *buf, int buf_size, const char *filename)
@@ -283,7 +284,7 @@ static int qcow_open(BlockDriverState *bs, const char
*filename, int flags)
if (refcount_init(bs) < 0)
goto fail;
- scan_refcount(bs, &s->highest_alloc);
+ scan_refcount(bs, &s->highest_alloc, &s->nc_free);
/* read the backing file name */
if (header.backing_file_offset != 0) {
@@ -1672,6 +1673,7 @@ static int qcow_get_info(BlockDriverState *bs,
BlockDriverInfo *bdi)
bdi->vm_state_offset = (int64_t)s->l1_vm_state_index <<
(s->cluster_bits + s->l2_bits);
bdi->highest_alloc = s->highest_alloc << s->cluster_bits;
+ bdi->num_free_bytes = s->nc_free << s->cluster_bits;
return 0;
}
@@ -2214,25 +2216,35 @@ static int load_refcount_block(BlockDriverState *bs,
return 0;
}
-static void scan_refcount(BlockDriverState *bs, int64_t *high)
+static void scan_refcount(BlockDriverState *bs, int64_t *high, int64_t *free)
{
BDRVQcowState *s = bs->opaque;
- int64_t refcnt_index, cluster_index, cluster_end, h = 0;
+ int64_t refcnt_index, cluster_index, cluster_end, h = 0, f = 0;
+ int64_t tail = 0; /* do not count last consecutive free entries */
for (refcnt_index=0; refcnt_index < s->refcount_table_size;
refcnt_index++){
if (s->refcount_table[refcnt_index] == 0) {
+ f += 1 << (s->cluster_bits - REFCOUNT_SHIFT);
+ tail += 1 << (s->cluster_bits - REFCOUNT_SHIFT);
continue;
}
cluster_index = refcnt_index << (s->cluster_bits - REFCOUNT_SHIFT);
cluster_end = (refcnt_index + 1) << (s->cluster_bits - REFCOUNT_SHIFT);
for ( ; cluster_index < cluster_end; cluster_index++) {
- if (get_refcount(bs, cluster_index) == 0)
- /* do nothing -- reserved for free counting */;
- else
+ if (get_refcount(bs, cluster_index) == 0) {
+ f++;
+ tail++;
+ }
+ else {
h = cluster_index;
+ tail = 0;
+ }
}
}
+ f -= tail;
+ if (free)
+ *free = f;
if (high)
*high = (h+1);
}
@@ -2278,8 +2290,10 @@ retry:
(s->free_cluster_index - nb_clusters) << s->cluster_bits);
#endif
- if (s->highest_alloc < s->free_cluster_index)
+ if (s->highest_alloc < s->free_cluster_index) {
+ s->nc_free += (s->free_cluster_index - s->highest_alloc);
s->highest_alloc = s->free_cluster_index;
+ }
return (s->free_cluster_index - nb_clusters) << s->cluster_bits;
}
@@ -2456,6 +2470,12 @@ static int update_cluster_refcount(BlockDriverState *bs,
block_index = cluster_index &
((1 << (s->cluster_bits - REFCOUNT_SHIFT)) - 1);
refcount = be16_to_cpu(s->refcount_block_cache[block_index]);
+
+ if (refcount == 1 && addend == -1)
+ s->nc_free += 1;
+ else if (refcount == 0 && addend == 1)
+ s->nc_free -= 1;
+
refcount += addend;
if (refcount < 0 || refcount > 0xffff)
return -EINVAL;
diff --git a/block.c b/block.c
index 0058531..589c67a 100644
--- a/block.c
+++ b/block.c
@@ -1090,8 +1090,9 @@ void bdrv_info_stats (void)
bs->rd_bytes, bs->wr_bytes,
bs->rd_ops, bs->wr_ops);
if (bdrv_get_info(bs, &bdi) == 0)
- term_printf(" high=%" PRIu64,
- bdi.highest_alloc);
+ term_printf(" high=%" PRId64
+ " bytes_free=%" PRId64,
+ bdi.highest_alloc, bdi.num_free_bytes);
term_printf("\n");
}
}
diff --git a/block.h b/block.h
index 9c64af3..dca17db 100644
--- a/block.h
+++ b/block.h
@@ -26,6 +26,7 @@ typedef struct BlockDriverInfo {
/* offset at which the VM state can be saved (0 if not possible) */
int64_t vm_state_offset;
int64_t highest_alloc; /* highest allocated block offset (in bytes) */
+ int64_t num_free_bytes; /* below highest_alloc */
} BlockDriverInfo;
typedef struct QEMUSnapshotInfo {
--
1.6.0.6
Re: [Qemu-devel] [PATCH 0/5 v2] qcow2 info: show highest-allocation and num-free-bytes, Anthony Liguori, 2009/01/22