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vvfat: React to bdrv_is_allocated() errors

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If bdrv_is_allocated() fails, we should react to that failure.
For 2 of the 3 callers, reporting the error was easy.  But in
cluster_was_modified() and its lone caller
get_cluster_count_for_direntry(), it's rather invasive to update
the logic to pass the error back; so there, I went with merely
documenting the issue by changing the return type to bool (in
all likelihood, treating the cluster as modified will then
trigger a read which will also fail, and eventually get to an
error - but given the appalling number of abort() calls in this
code, I'm not making it any worse).

Signed-off-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Eric Blake 2017-03-08 15:34:28 -06:00 committed by Kevin Wolf
parent 666a9543fa
commit 6f712ee080
1 changed files with 19 additions and 3 deletions
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22
block/vvfat.c
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@ -1394,7 +1394,13 @@ static int vvfat_read(BlockDriverState *bs, int64_t sector_num,
return -1;
if (s->qcow) {
int n;
if (bdrv_is_allocated(s->qcow->bs, sector_num, nb_sectors-i, &n)) {
int ret;
ret = bdrv_is_allocated(s->qcow->bs, sector_num,
nb_sectors - i, &n);
if (ret < 0) {
return ret;
}
if (ret) {
DLOG(fprintf(stderr, "sectors %d+%d allocated\n",
(int)sector_num, n));
if (bdrv_read(s->qcow, sector_num, buf + i * 0x200, n)) {
@ -1668,7 +1674,8 @@ static inline uint32_t modified_fat_get(BDRVVVFATState* s,
}
}
static inline int cluster_was_modified(BDRVVVFATState* s, uint32_t cluster_num)
static inline bool cluster_was_modified(BDRVVVFATState *s,
uint32_t cluster_num)
{
int was_modified = 0;
int i, dummy;
@ -1683,7 +1690,13 @@ static inline int cluster_was_modified(BDRVVVFATState* s, uint32_t cluster_num)
1, &dummy);
}
return was_modified;
/*
* Note that this treats failures to learn allocation status the
* same as if an allocation has occurred. It's as safe as
* anything else, given that a failure to learn allocation status
* will probably result in more failures.
*/
return !!was_modified;
}
static const char* get_basename(const char* path)
@ -1833,6 +1846,9 @@ static uint32_t get_cluster_count_for_direntry(BDRVVVFATState* s,
int res;
res = bdrv_is_allocated(s->qcow->bs, offset + i, 1, &dummy);
if (res < 0) {
return -1;
}
if (!res) {
res = vvfat_read(s->bs, offset, s->cluster_buffer, 1);
if (res) {