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block/vpc.c: Handle write failures in get_image_offset() 

Coverity (CID 1355236) points out that get_image_offset() doesn't check that
it actually succeeded in writing the updated block bitmap to the file.
Check the error return from bdrv_pwrite_sync() and propagate an error
response back up to the function which calls get_image_offset() for
a write so that it can return the error to its caller.

get_sector_offset() is only used for reads, but we move it to the
same API for consistency.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Peter Maydell 2017-07-09 22:07:17 +01:00 committed by Kevin Wolf
parent 9877860e7b
commit cfc87e00c2
1 changed files with 23 additions and 7 deletions
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30
block/vpc.c
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@ -460,17 +460,23 @@ static int vpc_reopen_prepare(BDRVReopenState *state,
/*
* Returns the absolute byte offset of the given sector in the image file.
* If the sector is not allocated, -1 is returned instead.
* If an error occurred trying to write an updated block bitmap back to
* the file, -2 is returned, and the error value is written to *err.
* This can only happen for a write operation.
*
* The parameter write must be 1 if the offset will be used for a write
* operation (the block bitmaps is updated then), 0 otherwise.
* If write is true then err must not be NULL.
*/
static inline int64_t get_image_offset(BlockDriverState *bs, uint64_t offset,
bool write)
bool write, int *err)
{
BDRVVPCState *s = bs->opaque;
uint64_t bitmap_offset, block_offset;
uint32_t pagetable_index, offset_in_block;
assert(!(write && err == NULL));
pagetable_index = offset / s->block_size;
offset_in_block = offset % s->block_size;
@ -487,10 +493,15 @@ static inline int64_t get_image_offset(BlockDriverState *bs, uint64_t offset,
correctness. */
if (write && (s->last_bitmap_offset != bitmap_offset)) {
uint8_t bitmap[s->bitmap_size];
int r;
s->last_bitmap_offset = bitmap_offset;
memset(bitmap, 0xff, s->bitmap_size);
bdrv_pwrite_sync(bs->file, bitmap_offset, bitmap, s->bitmap_size);
r = bdrv_pwrite_sync(bs->file, bitmap_offset, bitmap, s->bitmap_size);
if (r < 0) {
*err = r;
return -2;
}
}
return block_offset;
@ -561,7 +572,7 @@ static int64_t alloc_block(BlockDriverState* bs, int64_t offset)
if (ret < 0)
goto fail;
return get_image_offset(bs, offset, false);
return get_image_offset(bs, offset, false, NULL);
fail:
s->free_data_block_offset -= (s->block_size + s->bitmap_size);
@ -601,7 +612,7 @@ vpc_co_preadv(BlockDriverState *bs, uint64_t offset, uint64_t bytes,
qemu_iovec_init(&local_qiov, qiov->niov);
while (bytes > 0) {
image_offset = get_image_offset(bs, offset, false);
image_offset = get_image_offset(bs, offset, false, NULL);
n_bytes = MIN(bytes, s->block_size - (offset % s->block_size));
if (image_offset == -1) {
@ -650,7 +661,11 @@ vpc_co_pwritev(BlockDriverState *bs, uint64_t offset, uint64_t bytes,
qemu_iovec_init(&local_qiov, qiov->niov);
while (bytes > 0) {
image_offset = get_image_offset(bs, offset, true);
image_offset = get_image_offset(bs, offset, true, &ret);
if (image_offset == -2) {
/* Failed to write block bitmap: can't proceed with write */
goto fail;
}
n_bytes = MIN(bytes, s->block_size - (offset % s->block_size));
if (image_offset == -1) {
@ -702,7 +717,7 @@ static int64_t coroutine_fn vpc_co_get_block_status(BlockDriverState *bs,
qemu_co_mutex_lock(&s->lock);
offset = get_image_offset(bs, sector_num << BDRV_SECTOR_BITS, false);
offset = get_image_offset(bs, sector_num << BDRV_SECTOR_BITS, false, NULL);
start = offset;
allocated = (offset != -1);
*pnum = 0;
@ -727,7 +742,8 @@ static int64_t coroutine_fn vpc_co_get_block_status(BlockDriverState *bs,
if (nb_sectors == 0) {
break;
}
offset = get_image_offset(bs, sector_num << BDRV_SECTOR_BITS, false);
offset = get_image_offset(bs, sector_num << BDRV_SECTOR_BITS, false,
NULL);
} while (offset == -1);
qemu_co_mutex_unlock(&s->lock);