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 attempted performance comparisions to address Chuck Lever's concern [3] because we are not converting the non-fscache enabled NFS IO paths to netfs. The main patch to be reviewed is patch #3 which converts nfs_read_folio and nfs_readahead. Changes since v3 - PATCH2: Improve #ifdef readability; use VFS_I #define (Jeff Layton) - PATCH3: Fix Aug 30 kernel test robot <lkp@xxxxxxxxx> compile warning due to unusued 'sreq' variables in fscache.c (test build with W=1) - PATCH3: Simplify nfs_netfs_init_request (Jeff Layton, Matt Wilcox) The patches are fairly stable as evidenced with xfstests generic with various servers: hammerspace w/NFS4.2+fscache, NetApp(ontap9) NFSv4.1+fscache (other tests in progress) The known issues are as follows: No major issues outstanding - the data corruption is unrelated to this patchset. 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 with 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. (RESOLVED) Hang 4. (DEFERRED/UNRELATED) Data corruption seen with unit test where rsize < readahead * Confirmed unrelated to this patchset * Seen with vanilla 6.0-rc2 (did not occur on 5.19) * Not 100% reproducible (maybe 75% of the time) * NFS protocol version doesn't matter * First page is always fine, next 3 pages are not * Garbage data is coming over the wire from the NFS server because the NFS server file is garbage (the dd of the file from /tmp to NFS /mnt corrupts it). 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 5. generic/127 triggers "Subreq overread" warning * just hit one time; did not stop test [ 4196.864176] run fstests generic/127 at 2022-08-31 17:29:38 [ 5608.997945] ------------[ cut here ]------------ [ 5609.000476] Subreq overread: R1c85d[0] 73728 > 70073 - 0 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.camel@xxxxxxxxxxxxxxx/ [2] https://lore.kernel.org/linux-nfs/da9200f1bded9b8b078a7aef227fd6b92eb028fb.camel@xxxxxxxxxxxxxxx/ [3] https://marc.info/?l=linux-nfs&m=160597917525083&w=4 [4] https://www.mail-archive.com/linux-cachefs@xxxxxxxxxx/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
