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Re: [Qemu-devel] [PATCH 2/4] qcow: Check failure of bdrv_getlength() and
From: |
Kevin Wolf |
Subject: |
Re: [Qemu-devel] [PATCH 2/4] qcow: Check failure of bdrv_getlength() and bdrv_truncate() |
Date: |
Tue, 8 Aug 2017 10:28:54 +0200 |
User-agent: |
Mutt/1.8.3 (2017-05-23) |
Am 07.08.2017 um 22:30 hat Eric Blake geschrieben:
> This also requires changing the return type of get_cluster_offset()
> and adjusting all callers.
>
> Use osdep.h macros instead of open-coded rounding while in the
> area.
>
> Reported-by: Markus Armbruster <address@hidden>
> Signed-off-by: Eric Blake <address@hidden>
> ---
> block/qcow.c | 64
> ++++++++++++++++++++++++++++++++++++++++++------------------
> 1 file changed, 45 insertions(+), 19 deletions(-)
>
> diff --git a/block/qcow.c b/block/qcow.c
> index c08cdc4a7b..937023d447 100644
> --- a/block/qcow.c
> +++ b/block/qcow.c
> @@ -347,16 +347,17 @@ static int qcow_reopen_prepare(BDRVReopenState *state,
> * 'compressed_size'. 'compressed_size' must be > 0 and <
> * cluster_size
> *
> - * return 0 if not allocated.
> + * return 0 if not allocated, -errno on failure.
> */
> -static uint64_t get_cluster_offset(BlockDriverState *bs,
> - uint64_t offset, int allocate,
> - int compressed_size,
> - int n_start, int n_end)
> +static int64_t get_cluster_offset(BlockDriverState *bs,
> + uint64_t offset, int allocate,
> + int compressed_size,
> + int n_start, int n_end)
qcow2 ended up with this prototype:
int qcow2_get_cluster_offset(BlockDriverState *bs, uint64_t offset,
unsigned int *bytes, uint64_t *cluster_offset)
Separating a full uin64_t offset by-reference parameter and an 0/-errno
status return code feels a little cleaner to me.
And in fact, it's not only cleaner, but bit 63 is QCOW_OFLAG_COMPRESSED,
so this patch breaks compressed images.
> {
> BDRVQcowState *s = bs->opaque;
> int min_index, i, j, l1_index, l2_index;
> - uint64_t l2_offset, *l2_table, cluster_offset, tmp;
> + int64_t l2_offset, cluster_offset;
> + uint64_t *l2_table, tmp;
> uint32_t min_count;
> int new_l2_table;
>
> @@ -368,8 +369,11 @@ static uint64_t get_cluster_offset(BlockDriverState *bs,
> return 0;
> /* allocate a new l2 entry */
> l2_offset = bdrv_getlength(bs->file->bs);
> + if (l2_offset < 0) {
> + return l2_offset;
> + }
> /* round to cluster size */
> - l2_offset = (l2_offset + s->cluster_size - 1) & ~(s->cluster_size -
> 1);
> + l2_offset = QEMU_ALIGN_UP(l2_offset, s->cluster_size);
> /* update the L1 entry */
> s->l1_table[l1_index] = l2_offset;
> tmp = cpu_to_be64(l2_offset);
> @@ -430,8 +434,10 @@ static uint64_t get_cluster_offset(BlockDriverState *bs,
> if (decompress_cluster(bs, cluster_offset) < 0)
> return 0;
> cluster_offset = bdrv_getlength(bs->file->bs);
> - cluster_offset = (cluster_offset + s->cluster_size - 1) &
> - ~(s->cluster_size - 1);
> + if (cluster_offset < 0) {
> + return cluster_offset;
> + }
> + cluster_offset = QEMU_ALIGN_UP(cluster_offset, s->cluster_size);
> /* write the cluster content */
> if (bdrv_pwrite(bs->file, cluster_offset, s->cluster_cache,
> s->cluster_size) !=
> @@ -439,12 +445,19 @@ static uint64_t get_cluster_offset(BlockDriverState *bs,
> return -1;
> } else {
> cluster_offset = bdrv_getlength(bs->file->bs);
> + if (cluster_offset < 0) {
> + return cluster_offset;
> + }
> if (allocate == 1) {
> + int ret;
> +
> /* round to cluster size */
> - cluster_offset = (cluster_offset + s->cluster_size - 1) &
> - ~(s->cluster_size - 1);
> - bdrv_truncate(bs->file, cluster_offset + s->cluster_size,
> - PREALLOC_MODE_OFF, NULL);
> + cluster_offset = QEMU_ALIGN_UP(cluster_offset,
> s->cluster_size);
> + ret = bdrv_truncate(bs->file, cluster_offset +
> s->cluster_size,
> + PREALLOC_MODE_OFF, NULL);
> + if (ret < 0) {
> + return ret;
> + }
> /* if encrypted, we must initialize the cluster
> content which won't be written */
> if (bs->encrypted &&
> @@ -491,11 +504,14 @@ static int64_t coroutine_fn
> qcow_co_get_block_status(BlockDriverState *bs,
> {
> BDRVQcowState *s = bs->opaque;
> int index_in_cluster, n;
> - uint64_t cluster_offset;
> + int64_t cluster_offset;
>
> qemu_co_mutex_lock(&s->lock);
> cluster_offset = get_cluster_offset(bs, sector_num << 9, 0, 0, 0, 0);
> qemu_co_mutex_unlock(&s->lock);
> + if (cluster_offset < 0) {
> + return cluster_offset;
> + }
> index_in_cluster = sector_num & (s->cluster_sectors - 1);
> n = s->cluster_sectors - index_in_cluster;
> if (n > nb_sectors)
> @@ -567,7 +583,7 @@ static coroutine_fn int qcow_co_readv(BlockDriverState
> *bs, int64_t sector_num,
> BDRVQcowState *s = bs->opaque;
> int index_in_cluster;
> int ret = 0, n;
> - uint64_t cluster_offset;
> + int64_t cluster_offset;
> struct iovec hd_iov;
> QEMUIOVector hd_qiov;
> uint8_t *buf;
> @@ -588,8 +604,10 @@ static coroutine_fn int qcow_co_readv(BlockDriverState
> *bs, int64_t sector_num,
>
> while (nb_sectors != 0) {
> /* prepare next request */
> - cluster_offset = get_cluster_offset(bs, sector_num << 9,
> - 0, 0, 0, 0);
> + cluster_offset = get_cluster_offset(bs, sector_num << 9, 0, 0, 0, 0);
> + if (cluster_offset < 0) {
> + return cluster_offset;
> + }
Oops, we're still holding s->lock. Combined with the bug that compressed
clusters are treated as errors now, this makes compressed images result
in an assertion failure:
qemu-system-x86_64: util/qemu-coroutine.c:138: qemu_aio_coroutine_enter:
Assertion `!co->locks_held' failed.
> index_in_cluster = sector_num & (s->cluster_sectors - 1);
> n = s->cluster_sectors - index_in_cluster;
> if (n > nb_sectors) {
Kevin
- Re: [Qemu-devel] [Qemu-block] [PATCH 1/4] vpc: Check failure of bdrv_getlength(), (continued)