This minimal set of patches update the NFS client to use the new readahead method and convert the fscache read paths to use the new netfs API, and are at: https://github.com/DaveWysochanskiRH/kernel/releases/tag/fscache-iter-lib-nfs-20210127 https://github.com/DaveWysochanskiRH/kernel/commit/8693c3602ce02e4038fa732bef02b2641f739e02 The patches are based on David Howells fscache-netfs-lib tree at https://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs.git/log/?h=fscache-netfs-lib The first 6 patches refactor some of the NFS read code to facilitate re-use, the next 2 patches do the conversion to the new API. Note that the last patch converts nfs_readpages to nfs_readahead. Changes since dhowells posting on Jan 25, 2021 - address feedback from Willy (Chuck's feedback in TODO list) - ensure kernel builds cleanly with each patch - readahead patch: cleanup handling of 'ret' Still TODO 1. Fix known bugs (some may disappear with uncondional netfs API) a) One oops with fscache enabled on parallel read unit test b) nfs_issue_op: takes rcu_read_lock but may calls nfs_page_alloc() with GFP_KERNEL which may sleep (dhowells noted this in a review) c) nfs_refresh_inode() takes inode->i_lock but may call __fscache_invalidate() which may sleep (found with lockdep) 2. Fixup NFS fscache stats (NFSIOS_FSCACHE_*) * Compare with netfs stats and determine if still needed 3. Cleanup dfprintks and/or convert to tracepoints 4. Further tests (see "Not tested yet") Tests run 1. Custom NFS+fscache unit tests for basic operation: PASS* * vers=3,4.0,4.1,4.2,sec=sys,server=localhost (same kernel) * one fscache enabled parallel read test that oopses due to page lock state * probably goes away if we unconditionally call netfs API 2. cthon04: PASS * test options "-b -g -s -l", fsc,vers=3,4.0,4.1,4.2,sec=sys * No failures, oopses or hangs 3. iozone tests: PASS * nofsc,fsc,vers=3,4.0,4.1,4.2,sec=sys,server=rhel7,rhel8 * No failures, oopses, or hangs 4. xfstests/generic: PASS* * no hangs or oopses; a few failures unrelated to these patches * Ran following configurations * vers=4.2,fsc,sec=sys,rhel7-server * vers=4.2,nofsc,sec=sys,rhel8-server (test still running, ok so far) * vers=4.1,nofsc,sec=sys,netapp-server(pnfs/files) * vers=4.0,fsc (test still running, ok so far) Not tested yet: * error injections (for example, connection disruptions, server errors during IO, etc) * many process mixed read/write on same file * performance
