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fuse: virtio_fs: clamp max_pages_limit by the transport DMA mapping size #261

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fuse: virtio_fs: clamp max_pages_limit by the transport DMA mapping size #261

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9 changes: 9 additions & 0 deletions fs/fuse/virtio_fs.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1703,6 +1703,15 @@ static int virtio_fs_get_tree(struct fs_context *fsc)
fc->max_pages_limit = min_t(unsigned int, fc->max_pages_limit,
virtqueue_size - FUSE_HEADER_OVERHEAD);

/*
* Also bound requests by the transport's maximum single DMA mapping
* size (e.g. swiotlb's 256 KiB cap) so the guest never builds a
* request whose buffer cannot be DMA-mapped.
*/
fc->max_pages_limit = min_t(unsigned int, fc->max_pages_limit,
virtio_max_dma_size(fs->vqs[VQ_REQUEST].vq->vdev)
>> PAGE_SHIFT);

fsc->s_fs_info = fm;
sb = sget_fc(fsc, virtio_fs_test_super, set_anon_super_fc);
if (fsc->s_fs_info)
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