This patchset converts NFS with fscache non-direct READ IO paths to use the netfs API with a non-invasive approach. The existing NFS pgio layer does not need extensive changes, and is the best way so far I've found to address Trond's concerns about modifying the IO path [1] as well as only enabling netfs when fscache is configured and enabled [2]. I have not yet attempted performance comparisions to address Chuck Lever's concern [3], though this is probably less of a concern now, since netfs is not used unless fscache is configured and enabled.
The main patch to be reviewed is patch #3 which converts nfs_read_folio and nfs_readahead. Changes since v2 (all PATCH 3) - Fix Aug 28 kernel test robot <l...@intel.com> compile warning due to unusued 'inode' variable by removing dprintk (can bring back as a trace event if needed) - Rename nfs_issue_read to nfs_netfs_issue_read - Rename nfs_begin_cache_operation to nfs_netfs_begin_cache_operation - Add nfs_netfs_read_completion and move logic from read.c into fscache.c - Add nfs_netfs_read_initiate and nfs_netfs_read_done to handle netfs IO accounting updates (resolves prior hang with BAD_STATEID errors), moving logic out of pagelist.c The patches are fairly stable as evidenced with xfstests generic with various servers: hammerspace w/NFS4.2+fscache, NetApp(ontap9) NFSv4.1+fscache, and RHEL8 NFSv3+fscache. The known issues are as follows: 1. Unit test setting rsize < readahead does not properly read from fscache but re-reads data from the NFS server * This will be fixed once another linux-cachefs [4] patch to resolve "Stop read optimisation when folio removed from pagecache" 2. "Cache volume key already in use" after xfstest runs * xfstests (hammerspace with vers=4.2,fsc) shows the following on the console after some tests: "NFS: Cache volume key already in use (nfs,4.1,2,c50,cfe0100a,3,,,8000,100000,100000,bb8,ea60,7530,ea60,1)" * This may be fixed with another patch [4] that is in progress 3. Hang (RESOLVED) 4. Data corruption seen with unit test where rsize < readahead * Seen with vanilla 6.0-rc2 (did not occur on 5.19); likely unrelated to this patchset mount -o vers=4.2,fsc,rsize=8192 127.0.0.1:/export /mnt dd if=/dev/urandom of=/tmp/integrity-rsize-file1.bin bs=16k count=1 ./nfs-readahead.sh set /mnt 16384 dd if=/tmp/integrity-rsize-file1.bin of=/mnt/integrity-rsize-file1.bin bs=16k count=1 echo 3 > /proc/sys/vm/drop_caches md5sum /mnt/integrity-rsize-file1.bin /tmp/integrity-rsize-file1.bin md5sums don't match, MD5_NFS = 00eaf1a5bc1b3dfd54711db551619afa != MD5_LOCAL = e8d835c83ba1f1264869dc40673fa20c The patchset is based on 6.0-rc3 and has been pushed to github at: https://github.com/DaveWysochanskiRH/kernel/commits/nfs-fscache-netfs [1] https://lore.kernel.org/linux-nfs/9cfd5bc3cfc6abc2d3316b0387222e708d67f595.ca...@hammerspace.com/ [2] https://lore.kernel.org/linux-nfs/da9200f1bded9b8b078a7aef227fd6b92eb028fb.ca...@hammerspace.com/ [3] https://marc.info/?l=linux-nfs&m=160597917525083&w=4 [4] https://www.mail-archive.com/linux-cachefs@redhat.com/msg03043.html [5] https://marc.info/?l=linux-nfs&m=165962662200679&w=4 Dave Wysochanski (3): NFS: Rename readpage_async_filler to nfs_pageio_add_page NFS: Add support for netfs in struct nfs_inode and Kconfig NFS: Convert nfs_read_folio and nfs_readahead to netfs APIs fs/nfs/Kconfig | 1 + fs/nfs/delegation.c | 2 +- fs/nfs/dir.c | 2 +- fs/nfs/fscache.c | 191 ++++++++++++++++++--------------------- fs/nfs/fscache.h | 77 ++++++++-------- fs/nfs/inode.c | 8 +- fs/nfs/internal.h | 10 +- fs/nfs/pagelist.c | 14 +++ fs/nfs/pnfs.c | 12 +-- fs/nfs/read.c | 117 ++++++++---------------- fs/nfs/write.c | 2 +- include/linux/nfs_fs.h | 19 +--- include/linux/nfs_page.h | 1 + include/linux/nfs_xdr.h | 1 + 14 files changed, 210 insertions(+), 247 deletions(-) -- 2.31.1 -- Linux-cachefs mailing list Linux-cachefs@redhat.com https://listman.redhat.com/mailman/listinfo/linux-cachefs
