[RFC 0/6] ext4: Add dma-buf read/write support

[Mengmeng Zhao <mengmeng.zhao@linux.dev>]

From: Mengmeng Zhao <zhaomengmeng@kylinos.cn>

This series add dma-buf read/write support for ext4. The dma-buf direct
I/O infrastructure allows dma-buf to be handed to file I/O as an iov_iter,
currently it only supports raw device. To better serve the GPU-NVME direct
access through normal filesystem, prior work for XFS has been discussed
at [1]. We also are interested in this field and working on it[2]. This
patchset is based on Anuj Gupta's patchset as there are common parts at
block/iomap. The base tree is:
https://github.com/anuj7781/linux-kernel/tree/anuj/fs-dmabuf-rfc-v11-desc-v2

Patches 1-5 add dma-buf guards at several common paths at block,
mm/filemap, dax and iomap. Patches 6 add dma-buf support for ext4.

[1] https://lore.kernel.org/linux-xfs/20261016091919.971295-1-anuj1072538@gmail.com/
[2] https://lore.kernel.org/all/20260908131545.105987-1-liwang@kylinos.cn/

Mengmeng Zhao (6):
  block: refuse a dma-buf bio that carries a crypto context
  mm/filemap: refuse dmabuf iterators in the generic read/write copy
    paths
  dax: refuse dmabuf iterators in dax_iomap_rw()
  iomap: refuse dmabuf iterators in iomap_file_buffered_write()
  iomap: refuse dmabuf iterators on contents-encrypted inodes
  ext4: support dma-buf registered buffers for direct I/O

 block/blk-mq.c         |  4 +++-
 fs/dax.c               |  4 ++++
 fs/ext4/file.c         | 33 +++++++++++++++++++++++++++++++++
 fs/iomap/buffered-io.c |  7 +++++++
 fs/iomap/direct-io.c   | 10 ++++++++++
 mm/filemap.c           | 22 +++++++++++++++++++++-
 6 files changed, 78 insertions(+), 2 deletions(-)

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2.43.0