[LU-6220] push ext4/ldiskfs patches upstream if possible

• Type: Improvement
• Status: Open
• Priority: Minor
• Resolution: Unresolved
• Affects Version/s: Lustre 2.8.0
• Fix Version/s: Upstream
• Assignee: Yang Sheng
• Reporter: Andreas Dilger

Description

There are a number of ldiskfs patches that we could potentially push upstream, possibly with some cleanups. All patches should be run through checkpatch.pl first.

• ext4-print-inum-in-htree-warning.patch: could be pushed upstream after moving string to the next line so it fits inside 80 columns
• ext4-disable-mb-cache.patch: I was involved in some discussion upstream about removing the mbcache (http://lwn.net/Articles/564802/), but that patch was never accepted upstream. We could try pushing this patch again, since it is fairly simple, and it wouldn't be very incompatible with the other mbcache speedup patch if that was ever landed.
• ext4-inode-version.patch: It might be possible to submit a patch upstream that moves dir->i_version++ into ext4_mark_iloc_dirty() like if (IS_I_VERSION(inode) || S_ISDIR(dir)). Then, we can add a mount flag or patch that makes this check a no-op so we only need a very small patch. More importantly, it will reduce the size of ext4_inode_info because we don't need a separate i_fs_version and reduce the memory usage on the MDS.
• ext4-journal-path-opt.patch: I think this can be pushed upstream without any significant changes
• ext4-kill-dx-root.patch: could be submitted upstream as a cleanup with some style fixes
• ext4-max-dir-size.patch: we should print out a deprecation warning in newer kernels to mount with "-o max_dir_size_kb" instead, and then we can eventually remove it? The mount option has existed since kernel 3.6, maybe it would be better to backport support for the mount option to RHEL6 instead of maintaining this patch forever?
• ext4-large-eas.patch: this is described in LU-908

Issue Links

• is duplicated by: LU-6141 Merge ldiskfs patches into upstream ext4 linux sources
• is related to: LU-9724 update ext4-large-eas.patch to match upstream ext4 feature
• is related to: LU-12511 Prepare lustre for adoption into the linux kernel
• is related to: LU-13054 MDS kernel BUG at ldiskfs/htree_lock.c:429!
• is related to: LU-908 multi-block xattr support
• is related to: LU-6030 cleanup for ldiskfs patches