diff options
| -rw-r--r-- | block/qcow2.c | 47 |
1 files changed, 36 insertions, 11 deletions
diff --git a/block/qcow2.c b/block/qcow2.c index 52731ab..7a35f97 100644 --- a/block/qcow2.c +++ b/block/qcow2.c @@ -1783,7 +1783,7 @@ static int preallocate(BlockDriverState *bs) static int qcow2_create2(const char *filename, int64_t total_size, const char *backing_file, const char *backing_format, int flags, size_t cluster_size, PreallocMode prealloc, - QemuOpts *opts, int version, + QemuOpts *opts, int version, int refcount_order, Error **errp) { /* Calculate cluster_bits */ @@ -1816,9 +1816,21 @@ static int qcow2_create2(const char *filename, int64_t total_size, int ret; if (prealloc == PREALLOC_MODE_FULL || prealloc == PREALLOC_MODE_FALLOC) { + /* Note: The following calculation does not need to be exact; if it is a + * bit off, either some bytes will be "leaked" (which is fine) or we + * will need to increase the file size by some bytes (which is fine, + * too, as long as the bulk is allocated here). Therefore, using + * floating point arithmetic is fine. */ int64_t meta_size = 0; uint64_t nreftablee, nrefblocke, nl1e, nl2e; int64_t aligned_total_size = align_offset(total_size, cluster_size); + int refblock_bits, refblock_size; + /* refcount entry size in bytes */ + double rces = (1 << refcount_order) / 8.; + + /* see qcow2_open() */ + refblock_bits = cluster_bits - (refcount_order - 3); + refblock_size = 1 << refblock_bits; /* header: 1 cluster */ meta_size += cluster_size; @@ -1843,20 +1855,20 @@ static int qcow2_create2(const char *filename, int64_t total_size, * c = cluster size * y1 = number of refcount blocks entries * y2 = meta size including everything + * rces = refcount entry size in bytes * then, * y1 = (y2 + a)/c - * y2 = y1 * sizeof(u16) + y1 * sizeof(u16) * sizeof(u64) / c + m + * y2 = y1 * rces + y1 * rces * sizeof(u64) / c + m * we can get y1: - * y1 = (a + m) / (c - sizeof(u16) - sizeof(u16) * sizeof(u64) / c) + * y1 = (a + m) / (c - rces - rces * sizeof(u64) / c) */ - nrefblocke = (aligned_total_size + meta_size + cluster_size) / - (cluster_size - sizeof(uint16_t) - - 1.0 * sizeof(uint16_t) * sizeof(uint64_t) / cluster_size); - nrefblocke = align_offset(nrefblocke, cluster_size / sizeof(uint16_t)); - meta_size += nrefblocke * sizeof(uint16_t); + nrefblocke = (aligned_total_size + meta_size + cluster_size) + / (cluster_size - rces - rces * sizeof(uint64_t) + / cluster_size); + meta_size += DIV_ROUND_UP(nrefblocke, refblock_size) * cluster_size; /* total size of refcount tables */ - nreftablee = nrefblocke * sizeof(uint16_t) / cluster_size; + nreftablee = nrefblocke / refblock_size; nreftablee = align_offset(nreftablee, cluster_size / sizeof(uint64_t)); meta_size += nreftablee * sizeof(uint64_t); @@ -1892,7 +1904,7 @@ static int qcow2_create2(const char *filename, int64_t total_size, .l1_size = cpu_to_be32(0), .refcount_table_offset = cpu_to_be64(cluster_size), .refcount_table_clusters = cpu_to_be32(1), - .refcount_order = cpu_to_be32(4), + .refcount_order = cpu_to_be32(refcount_order), .header_length = cpu_to_be32(sizeof(*header)), }; @@ -2011,6 +2023,8 @@ static int qcow2_create(const char *filename, QemuOpts *opts, Error **errp) size_t cluster_size = DEFAULT_CLUSTER_SIZE; PreallocMode prealloc; int version = 3; + uint64_t refcount_bits = 16; + int refcount_order; Error *local_err = NULL; int ret; @@ -2065,8 +2079,19 @@ static int qcow2_create(const char *filename, QemuOpts *opts, Error **errp) goto finish; } + if (version < 3 && refcount_bits != 16) { + error_setg(errp, "Different refcount widths than 16 bits require " + "compatibility level 1.1 or above (use compat=1.1 or " + "greater)"); + ret = -EINVAL; + goto finish; + } + + refcount_order = ffs(refcount_bits) - 1; + ret = qcow2_create2(filename, size, backing_file, backing_fmt, flags, - cluster_size, prealloc, opts, version, &local_err); + cluster_size, prealloc, opts, version, refcount_order, + &local_err); if (local_err) { error_propagate(errp, local_err); } |