Hi all, This is the alternative flushing solution to the iomap zero range problem with dirty pagecache over unwritten mappings. This is done in two steps. Patch 1 lifts the XFS workaround into iomap, flushing the range unconditionally and providing an easily backportable fix for stable kernels. Patch 2 buries the flush further down into iomap, making it conditional on the combined presence of dirty cache and unwritten mappings in the target range. This may be reasonable backportable as well, but is only required if performance is a concern. I still have to look into the improved revalidation approach discussed in the RFC thread, but given that requires validation support and this is intended to be a generic fallback, I wanted to get this nailed down first. fstests coverage for this problem is posted here [1]. Thoughts, reviews, flames appreciated. Brian v1: - Alternative approach, flush instead of revalidate. rfc: https://lore.kernel.org/linux-fsdevel/20240718130212.23905-1-bfoster@xxxxxxxxxx/ [1] https://lore.kernel.org/fstests/20240822144422.188462-1-bfoster@xxxxxxxxxx/ Brian Foster (2): iomap: fix handling of dirty folios over unwritten extents iomap: make zero range flush conditional on unwritten mappings fs/iomap/buffered-io.c | 52 ++++++++++++++++++++++++++++++++++++++---- fs/xfs/xfs_iops.c | 10 -------- 2 files changed, 48 insertions(+), 14 deletions(-) -- 2.45.0
