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 v4 (all PATCH3) - Remove more #ifdefs, replace with stub functions (Jeff Layton)[6] - Use refcount for last RPC marker (Jeff Layton)[6] The patches are fairly stable as evidenced with xfstests generic with various servers, both with and without fscache enabled: hammerspace(pNFS flexfiles): vers=4.2,fsc; vers=4.2 NetApp(pNFS filelayout): vers=4.1,fsc; vers=4.0,fsc RHEL8: vers=3,fsc; vers=3 No major issues outstanding. Even the previous issue with the "Subreq overread" was not reproducible with this set. 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" * Daire Byrne also verified the patch fixes his issue as well 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 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 [6] https://marc.info/?l=linux-nfs&m=166204800323762&w=4 Dave Wysochanski (3): NFS: Rename readpage_async_filler to nfs_pageio_add_page NFS: Configure support for netfs when NFS fscache is configured NFS: Convert buffered read paths to use netfs when fscache is enabled fs/nfs/Kconfig | 1 + fs/nfs/delegation.c | 2 +- fs/nfs/dir.c | 2 +- fs/nfs/fscache.c | 256 ++++++++++++++++++++++++--------------- fs/nfs/fscache.h | 102 ++++++++++------ fs/nfs/inode.c | 8 +- fs/nfs/internal.h | 11 +- fs/nfs/pagelist.c | 12 ++ fs/nfs/pnfs.c | 12 +- fs/nfs/read.c | 110 ++++++++--------- fs/nfs/write.c | 2 +- include/linux/nfs_fs.h | 34 ++++-- include/linux/nfs_page.h | 3 + include/linux/nfs_xdr.h | 3 + 14 files changed, 341 insertions(+), 217 deletions(-) -- 2.31.1
