On Wed, Jun 25, 2025 at 07:51:56PM +0800, Baokun Li wrote: > On 2025/6/25 19:13, Pankaj Raghav (Samsung) wrote: > > Thanks for the reply, Ted. > > > > On Mon, Jun 23, 2025 at 10:17:53AM -0400, Theodore Ts'o wrote: > > > If you want to review and test the ext4/iomap changes, that would be > > > great. Be aware, though, that there are some features of ext4 > > > (example: data journalling, fscrypt, fsverity, etc.) that the current > > > iomap buffered I/O code may not support today. The alternatives are > > > to keep the existing ext4 code paths for those file system features, > > > or to try to add that functionality into iomap. There are of course > > > tradeoffs to both alternatives; one might result in more code that we > > > have to maintain; the other might require a lot more work. > > > > > > It _might_ be less effort to add LBS support to native ext4 code. I > > > think the main thing is to make sure that we always we use a large > > > folio and not fall back to a sub-blocksize set of pages. So again, > > > it's all about tradeoffs and what you consider to be the highest > > > priority. > > @Baokun are your LBS patches based on the native ext4 code or on top of > > Zhang's iomap patches. > Now that mainline ext4 supports buffer head large folios, we'll first > focus on LBS support based on buffer heads. The main work involves adapting > ext4's internal logic (e.g., block allocation, read/write operations, > defragmentation) and clean up the process related to buffer head. Makes sense. When we added the LBS support to XFS, the changes in XFS itself was very minimal. But I can imagine there is a bit more work and testing involved in adding LBS support to EXT4 with buffer heads. > This doesn't conflict with iomap buffer write support. The iomap framework > already supports LBS (as xfs is already using it), so once ext4's internal > logic is adapted, Zhang Yi's iomap buffer write patches should also support > LBS upon their merge. Yes. iomap has all the logic to handle LBS. Thanks for the clarification. Looking forward to the patches. -- Pankaj Raghav
