From 1987530fe0fbe00970d572cd2eda5a149aac3333 Mon Sep 17 00:00:00 2001 From: aliguori Date: Thu, 22 Jan 2009 18:57:34 +0000 Subject: [PATCH] qcow2 format: keep 'num_free_bytes', and show it upon 'info blockstats' (Uri Lublin) '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 Signed-off-by: Anthony Liguori git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@6407 c046a42c-6fe2-441c-8c8c-71466251a162 --- 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 a3fcfa0..50ec589 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 4334071..e1927dd 100644 --- a/block.h +++ b/block.h @@ -27,6 +27,7 @@ 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 { -- 1.7.9.5