On 2/17/20 10:45 AM, Matthew Wilcox wrote: > From: "Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx> > > This series adds a readahead address_space operation to eventually > replace the readpages operation. The key difference is that > pages are added to the page cache as they are allocated (and > then looked up by the filesystem) instead of passing them on a > list to the readpages operation and having the filesystem add > them to the page cache. It's a net reduction in code for each > implementation, more efficient than walking a list, and solves > the direct-write vs buffered-read problem reported by yu kuai at > https://lore.kernel.org/linux-fsdevel/20200116063601.39201-1-yukuai3@xxxxxxxxxx/ > > The only unconverted filesystems are those which use fscache. > Their conversion is pending Dave Howells' rewrite which will make the > conversion substantially easier. Hi Matthew, I see that Dave Chinner is reviewing this series, but I'm trying out his recent advice about code reviews [1], and so I'm not going to read his comments first. So you may see some duplication or contradictions this time around. [1] Somewhere in this thread, "[LSF/MM/BPF TOPIC] FS Maintainers Don't Scale": https://lore.kernel.org/r/20200131052520.GC6869@magnolia thanks, -- John Hubbard NVIDIA > > v6: > - Name the private members of readahead_control with a leading underscore > (suggested by Christoph Hellwig) > - Fix whitespace in rst file > - Remove misleading comment in btrfs patch > - Add readahead_next() API and use it in iomap > - Add iomap_readahead kerneldoc. > - Fix the mpage_readahead kerneldoc > - Make various readahead functions return void > - Keep readahead_index() and readahead_offset() pointing to the start of > this batch through the body. No current user requires this, but it's > less surprising. > - Add kerneldoc for page_cache_readahead_limit > - Make page_idx an unsigned long, and rename it to just 'i' > - Get rid of page_offset local variable > - Add patch to call memalloc_nofs_save() before allocating pages (suggested > by Michal Hocko) > - Resplit a lot of patches for more logical progression and easier review > (suggested by John Hubbard) > - Added sign-offs where received, and I deemed still relevant > > v5 switched to passing a readahead_control struct (mirroring the > writepages_control struct passed to writepages). This has a number of > advantages: > - It fixes a number of bugs in various implementations, eg forgetting to > increment 'start', an off-by-one error in 'nr_pages' or treating 'start' > as a byte offset instead of a page offset. > - It allows us to change the arguments without changing all the > implementations of ->readahead which just call mpage_readahead() or > iomap_readahead() > - Figuring out which pages haven't been attempted by the implementation > is more natural this way. > - There's less code in each implementation. > > Matthew Wilcox (Oracle) (19): > mm: Return void from various readahead functions > mm: Ignore return value of ->readpages > mm: Use readahead_control to pass arguments > mm: Rearrange readahead loop > mm: Remove 'page_offset' from readahead loop > mm: rename readahead loop variable to 'i' > mm: Put readahead pages in cache earlier > mm: Add readahead address space operation > mm: Add page_cache_readahead_limit > fs: Convert mpage_readpages to mpage_readahead > btrfs: Convert from readpages to readahead > erofs: Convert uncompressed files from readpages to readahead > erofs: Convert compressed files from readpages to readahead > ext4: Convert from readpages to readahead > f2fs: Convert from readpages to readahead > fuse: Convert from readpages to readahead > iomap: Restructure iomap_readpages_actor > iomap: Convert from readpages to readahead > mm: Use memalloc_nofs_save in readahead path > > Documentation/filesystems/locking.rst | 6 +- > Documentation/filesystems/vfs.rst | 13 ++ > drivers/staging/exfat/exfat_super.c | 7 +- > fs/block_dev.c | 7 +- > fs/btrfs/extent_io.c | 46 ++----- > fs/btrfs/extent_io.h | 3 +- > fs/btrfs/inode.c | 16 +-- > fs/erofs/data.c | 39 ++---- > fs/erofs/zdata.c | 29 ++-- > fs/ext2/inode.c | 10 +- > fs/ext4/ext4.h | 3 +- > fs/ext4/inode.c | 23 ++-- > fs/ext4/readpage.c | 22 ++- > fs/ext4/verity.c | 35 +---- > fs/f2fs/data.c | 50 +++---- > fs/f2fs/f2fs.h | 5 +- > fs/f2fs/verity.c | 35 +---- > fs/fat/inode.c | 7 +- > fs/fuse/file.c | 46 +++---- > fs/gfs2/aops.c | 23 ++-- > fs/hpfs/file.c | 7 +- > fs/iomap/buffered-io.c | 118 +++++++---------- > fs/iomap/trace.h | 2 +- > fs/isofs/inode.c | 7 +- > fs/jfs/inode.c | 7 +- > fs/mpage.c | 38 ++---- > fs/nilfs2/inode.c | 15 +-- > fs/ocfs2/aops.c | 34 ++--- > fs/omfs/file.c | 7 +- > fs/qnx6/inode.c | 7 +- > fs/reiserfs/inode.c | 8 +- > fs/udf/inode.c | 7 +- > fs/xfs/xfs_aops.c | 13 +- > fs/zonefs/super.c | 7 +- > include/linux/fs.h | 2 + > include/linux/iomap.h | 3 +- > include/linux/mpage.h | 4 +- > include/linux/pagemap.h | 90 +++++++++++++ > include/trace/events/erofs.h | 6 +- > include/trace/events/f2fs.h | 6 +- > mm/internal.h | 8 +- > mm/migrate.c | 2 +- > mm/readahead.c | 184 +++++++++++++++++--------- > 43 files changed, 474 insertions(+), 533 deletions(-) > > > base-commit: 11a48a5a18c63fd7621bb050228cebf13566e4d8 >
