mirror of https://github.com/proxmox/mirror_qemu
block: limited request size in write zeroes unsupported path
If bs->bl.max_write_zeroes is large and we end up in the unsupported path we might allocate a lot of memory for the iovector and/or even generate an oversized requests. Fix this by limiting the request by the minimum of the reported maximum transfer size or 16MB (32768 sectors). Reported-by: Denis V. Lunev <den@openvz.org> Signed-off-by: Peter Lieven <pl@kamp.de> Reviewed-by: Denis V. Lunev <den@openvz.org> Message-id: 1420457389-16332-1-git-send-email-pl@kamp.de Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>master
parent
51a2219bdc
commit
095e4fa4b5
5
block.c
5
block.c
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@ -3244,6 +3244,9 @@ static int coroutine_fn bdrv_co_do_write_zeroes(BlockDriverState *bs,
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if (ret == -ENOTSUP) {
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if (ret == -ENOTSUP) {
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/* Fall back to bounce buffer if write zeroes is unsupported */
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/* Fall back to bounce buffer if write zeroes is unsupported */
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int max_xfer_len = MIN_NON_ZERO(bs->bl.max_transfer_length,
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MAX_WRITE_ZEROES_DEFAULT);
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num = MIN(num, max_xfer_len);
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iov.iov_len = num * BDRV_SECTOR_SIZE;
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iov.iov_len = num * BDRV_SECTOR_SIZE;
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if (iov.iov_base == NULL) {
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if (iov.iov_base == NULL) {
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iov.iov_base = qemu_try_blockalign(bs, num * BDRV_SECTOR_SIZE);
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iov.iov_base = qemu_try_blockalign(bs, num * BDRV_SECTOR_SIZE);
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@ -3260,7 +3263,7 @@ static int coroutine_fn bdrv_co_do_write_zeroes(BlockDriverState *bs,
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/* Keep bounce buffer around if it is big enough for all
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/* Keep bounce buffer around if it is big enough for all
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* all future requests.
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* all future requests.
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*/
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*/
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if (num < max_write_zeroes) {
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if (num < max_xfer_len) {
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qemu_vfree(iov.iov_base);
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qemu_vfree(iov.iov_base);
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iov.iov_base = NULL;
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iov.iov_base = NULL;
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}
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}
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