[PATCH 0/3] Adding offset keeping option when mapping data via SWIOTLB.*

Jianxiong Gao
2021-01-28T00:41:28Z

NVMe driver and other applications may depend on the data offset
to operate correctly. Currently when unaligned data is mapped via
SWIOTLB, the data is mapped as slab aligned with the SWIOTLB. This
patch adds an option to make sure the mapped data preserves its
offset of the orginal addrss.

Without the patch when creating xfs formatted disk on NVMe backends,
with swiotlb=force in kernel boot option, creates the following error:
meta-data=/dev/nvme2n1 isize=512 agcount=4, agsize=131072 blks
= sectsz=512 attr=2, projid32bit=1
= crc=1 finobt=1, sparse=0, rmapbt=0, refl
ink=0
data = bsize=4096 blocks=524288, imaxpct=25
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0 ftype=1
log =internal log bsize=4096 blocks=2560, version=2
= sectsz=512 sunit=0 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
mkfs.xfs: pwrite failed: Input/output error

Jianxiong Gao (3):
Adding page_offset_mask to device_dma_parameters
Add swiotlb offset preserving mapping when
dma_dma_parameters->page_offset_mask is non zero.
Adding device_dma_parameters->offset_preserve_mask to NVMe driver.

drivers/nvme/host/pci.c | 4 ++++
include/linux/device.h | 1 +
include/linux/dma-mapping.h | 17 +++++++++++++++++
kernel/dma/swiotlb.c | 16 +++++++++++++++-
4 files changed, 37 insertions(+), 1 deletion(-)

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2.27.0