This is a note to let you know that I've just added the patch titled nfsd: Fix a write performance regression to the 5.17-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: nfsd-fix-a-write-performance-regression.patch and it can be found in the queue-5.17 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 8e75ece84844b5994d79e1abfa71f97dfe213174 Author: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx> Date: Thu Mar 31 09:54:01 2022 -0400 nfsd: Fix a write performance regression [ Upstream commit 6b8a94332ee4f7d9a8ae0cbac7609f79c212f06c ] The call to filemap_flush() in nfsd_file_put() is there to ensure that we clear out any writes belonging to a NFSv3 client relatively quickly and avoid situations where the file can't be evicted by the garbage collector. It also ensures that we detect write errors quickly. The problem is this causes a regression in performance for some workloads. So try to improve matters by deferring writeback until we're ready to close the file, and need to detect errors so that we can force the client to resend. Tested-by: Jan Kara <jack@xxxxxxx> Fixes: b6669305d35a ("nfsd: Reduce the number of calls to nfsd_file_gc()") Signed-off-by: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx> Link: https://lore.kernel.org/all/20220330103457.r4xrhy2d6nhtouzk@xxxxxxxxxx Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/fs/nfsd/filecache.c b/fs/nfsd/filecache.c index cc2831cec669..496f7b3f7523 100644 --- a/fs/nfsd/filecache.c +++ b/fs/nfsd/filecache.c @@ -235,6 +235,13 @@ nfsd_file_check_write_error(struct nfsd_file *nf) return filemap_check_wb_err(file->f_mapping, READ_ONCE(file->f_wb_err)); } +static void +nfsd_file_flush(struct nfsd_file *nf) +{ + if (nf->nf_file && vfs_fsync(nf->nf_file, 1) != 0) + nfsd_reset_write_verifier(net_generic(nf->nf_net, nfsd_net_id)); +} + static void nfsd_file_do_unhash(struct nfsd_file *nf) { @@ -302,11 +309,14 @@ nfsd_file_put(struct nfsd_file *nf) return; } - filemap_flush(nf->nf_file->f_mapping); is_hashed = test_bit(NFSD_FILE_HASHED, &nf->nf_flags) != 0; - nfsd_file_put_noref(nf); - if (is_hashed) + if (!is_hashed) { + nfsd_file_flush(nf); + nfsd_file_put_noref(nf); + } else { + nfsd_file_put_noref(nf); nfsd_file_schedule_laundrette(); + } if (atomic_long_read(&nfsd_filecache_count) >= NFSD_FILE_LRU_LIMIT) nfsd_file_gc(); } @@ -327,6 +337,7 @@ nfsd_file_dispose_list(struct list_head *dispose) while(!list_empty(dispose)) { nf = list_first_entry(dispose, struct nfsd_file, nf_lru); list_del(&nf->nf_lru); + nfsd_file_flush(nf); nfsd_file_put_noref(nf); } } @@ -340,6 +351,7 @@ nfsd_file_dispose_list_sync(struct list_head *dispose) while(!list_empty(dispose)) { nf = list_first_entry(dispose, struct nfsd_file, nf_lru); list_del(&nf->nf_lru); + nfsd_file_flush(nf); if (!refcount_dec_and_test(&nf->nf_ref)) continue; if (nfsd_file_free(nf))