[LU-17916] Enable folio allocation support on the buffed io read/write path (BIO)

• Type: Improvement
• Resolution: Unresolved
• Priority: Minor
• Fix Version/s: Lustre 2.17.0
• Severity: 3
• Assignee: Shaun Tancheff
• Reporter: Shaun Tancheff

Description

When support for folios are added to generic_perform_write() we can enable folio based allocations without re-writing the lustre i/o path to use iomap:

https://www.spinics.net/lists/linux-nfs/msg104002.html
Updated patch:
https://lore.kernel.org/linux-fsdevel/[e-mail]/
Depends on (landed for v6.9):
https://patchwork.kernel.org/project/linux-fsdevel/patch/[e-mail]/

This is tested for NFS
https://www.spinics.net/lists/linux-nfs/msg104003.html

suggesting this alone is enough for a 2x improvement in buffered i/o.

Update lustre to use the folio allocation ie: __filemap_get_folio() instead of the grab_cache_page* family.

Provide a __filemap_get_folio() implementation for compatibility with older kernels.

Assuming no large regressions this should be available in kernel v6.11:
Linux kernel commit: v6.10-rc7-2-g9aac777aaf945
filemap: Convert generic_perform_write() to support large folios