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@xxxxxxxxx>
---
tools/kvm/disk/qcow.c | 111 +++++++++++++++++++++++++++++++++++++++++-------
1 files changed, 94 insertions(+), 17 deletions(-)
diff --git a/tools/kvm/disk/qcow.c b/tools/kvm/disk/qcow.c
index e139fa5..b2dae66 100644
--- a/tools/kvm/disk/qcow.c
+++ b/tools/kvm/disk/qcow.c
@@ -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++;
+
+ if (update_ref)
+ for (i = 0; i < clust_num; i++)
+ if (update_cluster_refcount(q,
+ clust_idx - clust_num + i, 1))
+ return -1;
- return (q->free_clust_idx - clust_num) << header->cluster_bits;
+ 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;
--
1.7.6.rc2.8.g28eb
--
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