| Message ID | 1395835569-21193-35-git-send-email-stefanha@redhat.com |
|---|---|
| State | New |
| Headers | show |
On 26.03.2014 13:05, Stefan Hajnoczi wrote: > It is not necessary to check errno for EINTR and the block layer does > not produce short reads. Therefore we can drop the loop that attempts > to read a compressed chunk. > > The loop is buggy because it incorrectly adds the transferred bytes > twice: > > do { > ret = bdrv_pread(...); > i += ret; > } while (ret >= 0 && ret + i < s->lengths[chunk]); > > Luckily we can drop the loop completely and perform a single > bdrv_pread(). > > Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> > Signed-off-by: Kevin Wolf <kwolf@redhat.com> > --- > block/dmg.c | 15 ++------------- > 1 file changed, 2 insertions(+), 13 deletions(-) Reviewed-by: Max Reitz <mreitz@redhat.com>
diff --git a/block/dmg.c b/block/dmg.c index f4f3e8e..1cc5426 100644 --- a/block/dmg.c +++ b/block/dmg.c @@ -298,21 +298,10 @@ static inline int dmg_read_chunk(BlockDriverState *bs, int sector_num) s->current_chunk = s->n_chunks; switch (s->types[chunk]) { case 0x80000005: { /* zlib compressed */ - int i; - /* we need to buffer, because only the chunk as whole can be * inflated. */ - i = 0; - do { - ret = bdrv_pread(bs->file, s->offsets[chunk] + i, - s->compressed_chunk + i, - s->lengths[chunk] - i); - if (ret < 0 && errno == EINTR) { - ret = 0; - } - i += ret; - } while (ret >= 0 && ret + i < s->lengths[chunk]); - + ret = bdrv_pread(bs->file, s->offsets[chunk], + s->compressed_chunk, s->lengths[chunk]); if (ret != s->lengths[chunk]) { return -1; }
It is not necessary to check errno for EINTR and the block layer does not produce short reads. Therefore we can drop the loop that attempts to read a compressed chunk. The loop is buggy because it incorrectly adds the transferred bytes twice: do { ret = bdrv_pread(...); i += ret; } while (ret >= 0 && ret + i < s->lengths[chunk]); Luckily we can drop the loop completely and perform a single bdrv_pread(). Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com> --- block/dmg.c | 15 ++------------- 1 file changed, 2 insertions(+), 13 deletions(-)