This patchset converts NFS non-direct READ IO paths to unconditionally 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 avoid Trond's earlier objection [1]. I have not yet attempted performance comparisions to address Chuck Lever's concern [2]. The main patch to be reviewed is patch #3 which converts nfs_read_folio and nfs_readahead. I do not really like this patchset but so far this is what I was able to come up with the move things forward. I think it is awkward and still needs work, has some issues (below) though it is fairly stable by running xfstests generic with various servers. 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 [3] 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. Occasional process IO hangs in read paths * May be due to out-of-order RPC replies or something unique to NetApp triggering a bug in the conversion patch * xfstests (Example: generic/075 with netapp ontap9 vers=4.1) * Sample backtrace #2 [ffff888104967990] io_schedule at ffffffffbc46969d #3 [ffff8881049679b0] folio_wait_bit_common at ffffffffbb40214b #4 [ffff888104967ad0] filemap_get_pages at ffffffffbb40688c #5 [ffff888104967c00] filemap_read at ffffffffbb406a61 #6 [ffff888104967d80] nfs_file_read at ffffffffc0e0f415 [nfs] #7 [ffff888104967db0] vfs_read at ffffffffbb5681a5 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-rc2 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://marc.info/?l=linux-nfs&m=160597917525083&w=4 [3] https://www.mail-archive.com/linux-cachefs@xxxxxxxxxx/msg03043.html [4] 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
