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be8fcd4a82
sas_host_setup() unconditionally sets shost->opt_sectors from
dma_opt_mapping_size().
When the IOMMU is disabled or in passthrough mode and no DMA ops provide
an opt_mapping_size callback, dma_opt_mapping_size() returns
min(dma_max_mapping_size(), SIZE_MAX) which equals
dma_max_mapping_size() — a hard upper bound, not an optimization hint.
On a Dell PowerEdge R750 with mpt3sas (Broadcom SAS3816, FW 33.15.00.00)
and intel_iommu=off the following values are observed:
dma_opt_mapping_size() = dma_max_mapping_size() (no real hint)
shost->max_sectors = 32767
opt_sectors = min(32767, huge >> 9) = 32767
optimal_io_size = 32767 << 9 = 16776704
→ round_down(16776704, 4096) = 16773120
The SAS disk (SAMSUNG MZILT800HBHQ0D3) does not report an Optimal
Transfer Length in VPD page B0, so sdkp->opt_xfer_blocks remains 0.
sd_revalidate_disk() then uses min_not_zero(0, opt_sectors) =
opt_sectors, propagating the bogus value into the block device's
optimal_io_size (visible as OPT-IO = 16773120 in lsblk --topology).
mkfs.xfs picks up optimal_io_size and minimum_io_size and computes:
swidth = 16773120 / 4096 = 4095
sunit = 8192 / 4096 = 2
Since 4095 % 2 != 0, XFS rejects the geometry:
SB stripe unit sanity check failed
This makes it impossible to create XFS filesystems (e.g. for
/var/lib/docker) during system bootstrap.
Fix this by introducing a sas_dma_setup_opt_sectors() helper that sets
opt_sectors only when dma_opt_mapping_size() is strictly less than
dma_max_mapping_size(), indicating a genuine DMA optimization
constraint.
The helper computes min(opt_sectors, max_sectors) first, then rounds
down to a power of two so that filesystem geometry calculations always
produce clean results.
When the two DMA values are equal, no backend provided a real hint, so
opt_sectors stays at 0 ("no preference").
[mkp: implemented hch's suggestion]
Fixes:
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|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| io_uring | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| rust | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .clippy.toml | ||
| .cocciconfig | ||
| .editorconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| .pylintrc | ||
| .rustfmt.toml | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
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