[PATCH 2/9] kvm tools, qcow: Use 'struct qcow_l2_table' instead of untyped array

Pekka Enberg
2011-07-09T13:03:01Z

This patch converts disk/qcow.c to use 'struct qcow_l2_table' for tracking
dirty L2 tables later on in this series.

Cc: Asias He <asias.hejun@gmail.com>
Cc: Cyrill Gorcunov <gorcunov@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Prasad Joshi <prasadjoshi124@gmail.com>
Cc: Sasha Levin <levinsasha928@gmail.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
---
tools/kvm/disk/qcow.c | 80 ++++++++++++++++++++++---------------------------
1 files changed, 36 insertions(+), 44 deletions(-)

diff --git a/tools/kvm/disk/qcow.c b/tools/kvm/disk/qcow.c
index a346c3d..a1f6ef3 100644
--- a/tools/kvm/disk/qcow.c
+++ b/tools/kvm/disk/qcow.c
@@ -121,21 +121,18 @@ error:
return -1;
}

-static int search_table(struct qcow *q, u64 **table, u64 offset)
+static struct qcow_l2_table *search_table(struct qcow *q, u64 offset)
{
- struct qcow_l2_table *c;
-
- *table = NULL;
+ struct qcow_l2_table *l2t;

- c = search(&q->root, offset);
- if (!c)
- return -1;
+ l2t = search(&q->root, offset);
+ if (!l2t)
+ return NULL;

/* Update the LRU state, by moving the searched node to list tail */
- list_move_tail(&c->list, &q->lru_list);
+ list_move_tail(&l2t->list, &q->lru_list);

- *table = c->table;
- return 0;
+ return l2t;
}

/* Allocates a new node for caching L2 table */
@@ -180,62 +177,57 @@ static inline u64 get_cluster_offset(struct qcow *q, u64 offset)
return offset & ((1 << header->cluster_bits)-1);
}

-static int qcow_read_l2_table(struct qcow *q, u64 **table, u64 offset)
+static struct qcow_l2_table *qcow_read_l2_table(struct qcow *q, u64 offset)
{
struct qcow_header *header = q->header;
- struct qcow_l2_table *c;
+ struct qcow_l2_table *l2t;
u64 size;
u64 i;
- u64 *t;

- c = NULL;
- *table = NULL;
- size = 1 << header->l2_bits;
+ size = 1 << header->l2_bits;

/* search an entry for offset in cache */
- if (search_table(q, table, offset) >= 0)
- return 0;
+ l2t = search_table(q, offset);
+ if (l2t)
+ return l2t;

/* allocate new node for caching l2 table */
- c = new_cache_table(q, offset);
- if (!c)
+ l2t = new_cache_table(q, offset);
+ if (!l2t)
goto error;
- t = c->table;

/* table not cached: read from the disk */
- if (pread_in_full(q->fd, t, size * sizeof(u64), offset) < 0)
+ if (pread_in_full(q->fd, l2t->table, size * sizeof(u64), offset) < 0)
goto error;

/* cache the table */
- if (cache_table(q, c) < 0)
+ if (cache_table(q, l2t) < 0)
goto error;

/* change cached table to CPU's byte-order */
for (i = 0; i < size; i++)
- be64_to_cpus(&t[i]);
+ be64_to_cpus(&l2t->table[i]);

- *table = t;
- return 0;
+ return l2t;
error:
- free(c);
- return -1;
+ free(l2t);
+ return NULL;
}

static ssize_t qcow_read_cluster(struct qcow *q, u64 offset, void *dst, u32 dst_len)
{
struct qcow_header *header = q->header;
struct qcow_table *table = &q->table;
+ struct qcow_l2_table *l2_table;
u64 l2_table_offset;
u64 l2_table_size;
u64 cluster_size;
u64 clust_offset;
u64 clust_start;
size_t length;
- u64 *l2_table;
u64 l1_idx;
u64 l2_idx;

-
cluster_size = 1 << header->cluster_bits;

l1_idx = get_l1_index(q, offset);
@@ -257,14 +249,15 @@ static ssize_t qcow_read_cluster(struct qcow *q, u64 offset, void *dst, u32 dst_
l2_table_size = 1 << header->l2_bits;

/* read and cache level 2 table */
- if (qcow_read_l2_table(q, &l2_table, l2_table_offset) < 0)
+ l2_table = qcow_read_l2_table(q, l2_table_offset);
+ if (!l2_table)
goto out_error;

l2_idx = get_l2_index(q, offset);
if (l2_idx >= l2_table_size)
goto out_error;

- clust_start = l2_table[l2_idx] & ~header->oflag_mask;
+ clust_start = l2_table->table[l2_idx] & ~header->oflag_mask;
if (!clust_start)
goto zero_cluster;

@@ -367,7 +360,7 @@ static ssize_t qcow_write_cluster(struct qcow *q, u64 offset, void *buf, u32 src
{
struct qcow_header *header = q->header;
struct qcow_table *table = &q->table;
- struct qcow_l2_table *c;
+ struct qcow_l2_table *l2t;
bool update_meta;
u64 clust_start;
u64 clust_off;
@@ -376,12 +369,11 @@ static ssize_t qcow_write_cluster(struct qcow *q, u64 offset, void *buf, u32 src
u64 l2t_idx;
u64 l2t_off;
u64 l2t_sz;
- u64 *l2t;
u64 f_sz;
u64 len;
u64 t;

- c = NULL;
+ l2t = NULL;
l2t_sz = 1 << header->l2_bits;
clust_sz = 1 << header->cluster_bits;

@@ -404,13 +396,13 @@ static ssize_t qcow_write_cluster(struct qcow *q, u64 offset, void *buf, u32 src
l2t_off = table->l1_table[l1t_idx] & ~header->oflag_mask;
if (l2t_off) {
/* read and cache l2 table */
- if (qcow_read_l2_table(q, &l2t, l2t_off) < 0)
+ l2t = qcow_read_l2_table(q, l2t_off);
+ if (!l2t)
goto error;
} else {
- c = new_cache_table(q, l2t_off);
- if (!c)
+ l2t = new_cache_table(q, l2t_off);
+ if (!l2t)
goto error;
- l2t = c->table;

/* Capture the state of the consistent QCOW image */
f_sz = file_size(q->fd);
@@ -418,7 +410,7 @@ static ssize_t qcow_write_cluster(struct qcow *q, u64 offset, void *buf, u32 src
goto free_cache;

/* Write the l2 table of 0's at the end of the file */
- l2t_off = qcow_write_l2_table(q, l2t);
+ l2t_off = qcow_write_l2_table(q, l2t->table);
if (!l2t_off)
goto free_cache;

@@ -433,7 +425,7 @@ static ssize_t qcow_write_cluster(struct qcow *q, u64 offset, void *buf, u32 src
goto free_cache;
}

- if (cache_table(q, c) < 0) {
+ if (cache_table(q, l2t) < 0) {
if (ftruncate(q->fd, f_sz) < 0)
goto free_cache;

@@ -449,7 +441,7 @@ static ssize_t qcow_write_cluster(struct qcow *q, u64 offset, void *buf, u32 src
if (!f_sz)
goto error;

- clust_start = l2t[l2t_idx] & ~header->oflag_mask;
+ clust_start = l2t->table[l2t_idx] & ~header->oflag_mask;
if (!clust_start) {
clust_start = ALIGN(f_sz, clust_sz);
update_meta = true;
@@ -471,13 +463,13 @@ static ssize_t qcow_write_cluster(struct qcow *q, u64 offset, void *buf, u32 src
}

/* Update the cached level2 entry */
- l2t[l2t_idx] = clust_start;
+ l2t->table[l2t_idx] = clust_start;
}

return len;

free_cache:
- free(c);
+ free(l2t);
error:
return -1;
}
--
1.7.0.4