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block: Handle failure for potentially large allocations

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Some code in the block layer makes potentially huge allocations. Failure
is not completely unexpected there, so avoid aborting qemu and handle
out-of-memory situations gracefully.

This patch addresses bounce buffer allocations in block.c. While at it,
convert bdrv_commit() from plain g_malloc() to qemu_try_blockalign().

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Kevin Wolf 2014-05-20 13:16:51 +02:00
parent 7d2a35cc92
commit 857d4f46c3
1 changed files with 27 additions and 7 deletions
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34
block.c
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@ -2275,7 +2275,14 @@ int bdrv_commit(BlockDriverState *bs)
}
total_sectors = length >> BDRV_SECTOR_BITS;
buf = g_malloc(COMMIT_BUF_SECTORS * BDRV_SECTOR_SIZE);
/* qemu_try_blockalign() for bs will choose an alignment that works for
* bs->backing_hd as well, so no need to compare the alignment manually. */
buf = qemu_try_blockalign(bs, COMMIT_BUF_SECTORS * BDRV_SECTOR_SIZE);
if (buf == NULL) {
ret = -ENOMEM;
goto ro_cleanup;
}
for (sector = 0; sector < total_sectors; sector += n) {
ret = bdrv_is_allocated(bs, sector, COMMIT_BUF_SECTORS, &n);
@ -2313,7 +2320,7 @@ int bdrv_commit(BlockDriverState *bs)
ret = 0;
ro_cleanup:
g_free(buf);
qemu_vfree(buf);
if (ro) {
/* ignoring error return here */
@ -2972,7 +2979,12 @@ static int coroutine_fn bdrv_co_do_copy_on_readv(BlockDriverState *bs,
cluster_sector_num, cluster_nb_sectors);
iov.iov_len = cluster_nb_sectors * BDRV_SECTOR_SIZE;
iov.iov_base = bounce_buffer = qemu_blockalign(bs, iov.iov_len);
iov.iov_base = bounce_buffer = qemu_try_blockalign(bs, iov.iov_len);
if (bounce_buffer == NULL) {
ret = -ENOMEM;
goto err;
}
qemu_iovec_init_external(&bounce_qiov, &iov, 1);
ret = drv->bdrv_co_readv(bs, cluster_sector_num, cluster_nb_sectors,
@ -3256,7 +3268,11 @@ static int coroutine_fn bdrv_co_do_write_zeroes(BlockDriverState *bs,
/* Fall back to bounce buffer if write zeroes is unsupported */
iov.iov_len = num * BDRV_SECTOR_SIZE;
if (iov.iov_base == NULL) {
iov.iov_base = qemu_blockalign(bs, num * BDRV_SECTOR_SIZE);
iov.iov_base = qemu_try_blockalign(bs, num * BDRV_SECTOR_SIZE);
if (iov.iov_base == NULL) {
ret = -ENOMEM;
goto fail;
}
memset(iov.iov_base, 0, num * BDRV_SECTOR_SIZE);
}
qemu_iovec_init_external(&qiov, &iov, 1);
@ -3276,6 +3292,7 @@ static int coroutine_fn bdrv_co_do_write_zeroes(BlockDriverState *bs,
nb_sectors -= num;
}
fail:
qemu_vfree(iov.iov_base);
return ret;
}
@ -4618,8 +4635,9 @@ static void bdrv_aio_bh_cb(void *opaque)
{
BlockDriverAIOCBSync *acb = opaque;
if (!acb->is_write)
if (!acb->is_write && acb->ret >= 0) {
qemu_iovec_from_buf(acb->qiov, 0, acb->bounce, acb->qiov->size);
}
qemu_vfree(acb->bounce);
acb->common.cb(acb->common.opaque, acb->ret);
qemu_bh_delete(acb->bh);
@ -4641,10 +4659,12 @@ static BlockDriverAIOCB *bdrv_aio_rw_vector(BlockDriverState *bs,
acb = qemu_aio_get(&bdrv_em_aiocb_info, bs, cb, opaque);
acb->is_write = is_write;
acb->qiov = qiov;
acb->bounce = qemu_blockalign(bs, qiov->size);
acb->bounce = qemu_try_blockalign(bs, qiov->size);
acb->bh = aio_bh_new(bdrv_get_aio_context(bs), bdrv_aio_bh_cb, acb);
if (is_write) {
if (acb->bounce == NULL) {
acb->ret = -ENOMEM;
} else if (is_write) {
qemu_iovec_to_buf(acb->qiov, 0, acb->bounce, qiov->size);
acb->ret = bs->drv->bdrv_write(bs, sector_num, acb->bounce, nb_sectors);
} else {