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kvm tools, qcow: Add support for growing refcount blocks

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This patch enables allocating new refcount blocks and so then kvm tools
could expand qcow2 image much larger.

Signed-off-by: Lan Tianyu <tianyu.lan@intel.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
This commit is contained in:
Lan Tianyu
2011-12-15 21:40:44 +08:00
committed by Will Deacon
parent f9b8c3a634
commit 2d2179c1d1
1 changed files with 94 additions and 17 deletions
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disk/qcow.c
+94 -17
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@@ -12,14 +12,20 @@
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#ifdef CONFIG_HAS_ZLIB
#include <zlib.h>
#endif
#include <linux/err.h>
#include <linux/byteorder.h>
#include <linux/kernel.h>
#include <linux/types.h>
static int update_cluster_refcount(struct qcow *q, u64 clust_idx, u16 append);
static int qcow_write_refcount_table(struct qcow *q);
static u64 qcow_alloc_clusters(struct qcow *q, u64 size, int update_ref);
static void qcow_free_clusters(struct qcow *q, u64 clust_start, u64 size);
static inline int qcow_pwrite_sync(int fd,
void *buf, size_t count, off_t offset)
@@ -657,6 +663,58 @@ static struct qcow_refcount_block *refcount_block_search(struct qcow *q, u64 off
return rfb;
}
static struct qcow_refcount_block *qcow_grow_refcount_block(struct qcow *q,
u64 clust_idx)
{
struct qcow_header *header = q->header;
struct qcow_refcount_table *rft = &q->refcount_table;
struct qcow_refcount_block *rfb;
u64 new_block_offset;
u64 rft_idx;
rft_idx = clust_idx >> (header->cluster_bits -
QCOW_REFCOUNT_BLOCK_SHIFT);
if (rft_idx >= rft->rf_size) {
pr_warning("Don't support grow refcount block table");
return NULL;
}
new_block_offset = qcow_alloc_clusters(q, q->cluster_size, 0);
if (new_block_offset < 0)
return NULL;
rfb = new_refcount_block(q, new_block_offset);
if (!rfb)
return NULL;
memset(rfb->entries, 0x00, q->cluster_size);
rfb->dirty = 1;
/* write refcount block */
if (write_refcount_block(q, rfb) < 0)
goto free_rfb;
if (cache_refcount_block(q, rfb) < 0)
goto free_rfb;
rft->rf_table[rft_idx] = cpu_to_be64(new_block_offset);
if (update_cluster_refcount(q, new_block_offset >>
header->cluster_bits, 1) < 0)
goto recover_rft;
if (qcow_write_refcount_table(q) < 0)
goto recover_rft;
return rfb;
recover_rft:
rft->rf_table[rft_idx] = 0;
free_rfb:
free(rfb);
return NULL;
}
static struct qcow_refcount_block *qcow_read_refcount_block(struct qcow *q, u64 clust_idx)
{
struct qcow_header *header = q->header;
@@ -667,14 +725,11 @@ static struct qcow_refcount_block *qcow_read_refcount_block(struct qcow *q, u64
rft_idx = clust_idx >> (header->cluster_bits - QCOW_REFCOUNT_BLOCK_SHIFT);
if (rft_idx >= rft->rf_size)
return NULL;
return ERR_PTR(-ENOSPC);
rfb_offset = be64_to_cpu(rft->rf_table[rft_idx]);
if (!rfb_offset) {
pr_warning("Don't support to grow refcount table");
return NULL;
}
if (!rfb_offset)
return ERR_PTR(-ENOSPC);
rfb = refcount_block_search(q, rfb_offset);
if (rfb)
@@ -705,7 +760,9 @@ static u16 qcow_get_refcount(struct qcow *q, u64 clust_idx)
u64 rfb_idx;
rfb = qcow_read_refcount_block(q, clust_idx);
if (!rfb) {
if (PTR_ERR(rfb) == -ENOSPC)
return 0;
else if (IS_ERR_OR_NULL(rfb)) {
pr_warning("Error while reading refcount table");
return -1;
}
@@ -729,7 +786,13 @@ static int update_cluster_refcount(struct qcow *q, u64 clust_idx, u16 append)
u64 rfb_idx;
rfb = qcow_read_refcount_block(q, clust_idx);
if (!rfb) {
if (PTR_ERR(rfb) == -ENOSPC) {
rfb = qcow_grow_refcount_block(q, clust_idx);
if (!rfb) {
pr_warning("error while growing refcount table");
return -1;
}
} else if (IS_ERR_OR_NULL(rfb)) {
pr_warning("error while reading refcount table");
return -1;
}
@@ -774,11 +837,11 @@ static void qcow_free_clusters(struct qcow *q, u64 clust_start, u64 size)
* can satisfy the size. free_clust_idx is initialized to zero and
* Record last position.
*/
static u64 qcow_alloc_clusters(struct qcow *q, u64 size)
static u64 qcow_alloc_clusters(struct qcow *q, u64 size, int update_ref)
{
struct qcow_header *header = q->header;
u16 clust_refcount;
u32 clust_idx, i;
u32 clust_idx = 0, i;
u64 clust_num;
clust_num = (size + (q->cluster_size - 1)) >> header->cluster_bits;
@@ -793,12 +856,15 @@ again:
goto again;
}
for (i = 0; i < clust_num; i++)
if (update_cluster_refcount(q,
q->free_clust_idx - clust_num + i, 1))
return -1;
clust_idx++;
return (q->free_clust_idx - clust_num) << header->cluster_bits;
if (update_ref)
for (i = 0; i < clust_num; i++)
if (update_cluster_refcount(q,
clust_idx - clust_num + i, 1))
return -1;
return (clust_idx - clust_num) << header->cluster_bits;
}
static int qcow_write_l1_table(struct qcow *q)
@@ -848,7 +914,9 @@ static int get_cluster_table(struct qcow *q, u64 offset,
if (!l2t)
goto error;
} else {
l2t_new_offset = qcow_alloc_clusters(q, l2t_size*sizeof(u64));
l2t_new_offset = qcow_alloc_clusters(q,
l2t_size*sizeof(u64), 1);
if (l2t_new_offset < 0)
goto error;
@@ -937,7 +1005,7 @@ static ssize_t qcow_write_cluster(struct qcow *q, u64 offset,
clust_start &= QCOW2_OFFSET_MASK;
if (!(clust_flags & QCOW2_OFLAG_COPIED)) {
clust_new_start = qcow_alloc_clusters(q, q->cluster_size);
clust_new_start = qcow_alloc_clusters(q, q->cluster_size, 1);
if (clust_new_start < 0) {
pr_warning("Cluster alloc error");
goto error;
@@ -1143,6 +1211,15 @@ static int qcow_read_refcount_table(struct qcow *q)
return pread_in_full(q->fd, rft->rf_table, sizeof(u64) * rft->rf_size, header->refcount_table_offset);
}
static int qcow_write_refcount_table(struct qcow *q)
{
struct qcow_header *header = q->header;
struct qcow_refcount_table *rft = &q->refcount_table;
return qcow_pwrite_sync(q->fd, rft->rf_table,
rft->rf_size * sizeof(u64), header->refcount_table_offset);
}
static int qcow_read_l1_table(struct qcow *q)
{
struct qcow_header *header = q->header;