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cloop: use qemu block API 

Use bdrv_pwrite to access the backing device instead of pread, and
convert the driver to implementing the bdrv_open method which gives
it an already opened BlockDriverState for the underlying device.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Christoph Hellwig 2010-05-04 12:44:52 +02:00 committed by Kevin Wolf
parent c94304be3f
commit 20be49e47e
1 changed files with 12 additions and 14 deletions
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26
block/cloop.c
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@ -27,7 +27,6 @@
#include <zlib.h>
typedef struct BDRVCloopState {
int fd;
uint32_t block_size;
uint32_t n_blocks;
uint64_t* offsets;
@ -51,23 +50,20 @@ static int cloop_probe(const uint8_t *buf, int buf_size, const char *filename)
return 0;
}
static int cloop_open(BlockDriverState *bs, const char *filename, int flags)
static int cloop_open(BlockDriverState *bs, int flags)
{
BDRVCloopState *s = bs->opaque;
uint32_t offsets_size,max_compressed_block_size=1,i;
s->fd = open(filename, O_RDONLY | O_BINARY);
if (s->fd < 0)
return -errno;
bs->read_only = 1;
/* read header */
if (pread(s->fd, &s->block_size, 4, 128) < 4) {
if (bdrv_pread(bs->file, 128, &s->block_size, 4) < 4) {
goto cloop_close;
}
s->block_size = be32_to_cpu(s->block_size);
if (pread(s->fd, &s->n_blocks, 4, 128 + 4) < 4) {
if (bdrv_pread(bs->file, 128 + 4, &s->n_blocks, 4) < 4) {
goto cloop_close;
}
s->n_blocks = be32_to_cpu(s->n_blocks);
@ -75,7 +71,8 @@ static int cloop_open(BlockDriverState *bs, const char *filename, int flags)
/* read offsets */
offsets_size = s->n_blocks * sizeof(uint64_t);
s->offsets = qemu_malloc(offsets_size);
if (pread(s->fd, s->offsets, offsets_size, 128 + 4 + 4) < offsets_size) {
if (bdrv_pread(bs->file, 128 + 4 + 4, s->offsets, offsets_size) <
offsets_size) {
goto cloop_close;
}
for(i=0;i<s->n_blocks;i++) {
@ -99,17 +96,19 @@ static int cloop_open(BlockDriverState *bs, const char *filename, int flags)
return 0;
cloop_close:
close(s->fd);
return -1;
}
static inline int cloop_read_block(BDRVCloopState *s,int block_num)
static inline int cloop_read_block(BlockDriverState *bs, int block_num)
{
BDRVCloopState *s = bs->opaque;
if(s->current_block != block_num) {
int ret;
uint32_t bytes = s->offsets[block_num+1]-s->offsets[block_num];
ret = pread(s->fd, s->compressed_block, bytes, s->offsets[block_num]);
ret = bdrv_pread(bs->file, s->offsets[block_num], s->compressed_block,
bytes);
if (ret != bytes)
return -1;
@ -138,7 +137,7 @@ static int cloop_read(BlockDriverState *bs, int64_t sector_num,
for(i=0;i<nb_sectors;i++) {
uint32_t sector_offset_in_block=((sector_num+i)%s->sectors_per_block),
block_num=(sector_num+i)/s->sectors_per_block;
if(cloop_read_block(s, block_num) != 0)
if(cloop_read_block(bs, block_num) != 0)
return -1;
memcpy(buf+i*512,s->uncompressed_block+sector_offset_in_block*512,512);
}
@ -148,7 +147,6 @@ static int cloop_read(BlockDriverState *bs, int64_t sector_num,
static void cloop_close(BlockDriverState *bs)
{
BDRVCloopState *s = bs->opaque;
close(s->fd);
if(s->n_blocks>0)
free(s->offsets);
free(s->compressed_block);
@ -160,7 +158,7 @@ static BlockDriver bdrv_cloop = {
.format_name = "cloop",
.instance_size = sizeof(BDRVCloopState),
.bdrv_probe = cloop_probe,
.bdrv_file_open = cloop_open,
.bdrv_open = cloop_open,
.bdrv_read = cloop_read,
.bdrv_close = cloop_close,
};