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[Qemu-block] [PATCH 2/3] vvfat: React to bdrv_is_allocated() errors
From: |
Eric Blake |
Subject: |
[Qemu-block] [PATCH 2/3] vvfat: React to bdrv_is_allocated() errors |
Date: |
Wed, 8 Mar 2017 15:34:28 -0600 |
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 <address@hidden>
---
block/vvfat.c | 22 +++++++++++++++++++---
1 file changed, 19 insertions(+), 3 deletions(-)
diff --git a/block/vvfat.c b/block/vvfat.c
index aa61c32..af5153d 100644
--- a/block/vvfat.c
+++ b/block/vvfat.c
@@ -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) {
--
2.9.3