Christian Brauner <brauner@xxxxxxxxxx> writes: > On Tue, 21 May 2024 19:49:38 +0800, Xu Yang wrote: >> Add mapping_max_folio_size() to get the maximum folio size for this >> pagecache mapping. >> >> > > Applied to the vfs.fixes branch of the vfs/vfs.git tree. > Patches in the vfs.fixes branch should appear in linux-next soon. > > Please report any outstanding bugs that were missed during review in a > new review to the original patch series allowing us to drop it. > > It's encouraged to provide Acked-bys and Reviewed-bys even though the > patch has now been applied. If possible patch trailers will be updated. iomap_write_iter() prefaults in userspace buffer chunk bytes (order MAX_PAGECACHE_ORDER) at a time. However, the iomap_write_begin() function only handles writes for PAGE_SIZE bytes at a time for mappings which does not support large folios. Hence, this causes unnecessary loops of prefaults in iomap_write_iter() -> fault_in_iov_iter_readable(), causing performance hits for block device mappings. This patch fixes iomap_write_iter() to prefault in PAGE_SIZE chunk bytes. I guess this change will then go back to v6.6 when large folios got added to iomap. Looks good to me. Please feel free add - Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@xxxxxxxxx> > > Note that commit hashes shown below are subject to change due to rebase, > trailer updates or similar. If in doubt, please check the listed branch. > > tree: https://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs.git > branch: vfs.fixes > > [1/2] filemap: add helper mapping_max_folio_size() > https://git.kernel.org/vfs/vfs/c/0c31d63eebdd > [2/2] iomap: fault in smaller chunks for non-large folio mappings > https://git.kernel.org/vfs/vfs/c/63ba6f07d115
