Commit 6b8a9433 authored by Trond Myklebust's avatar Trond Myklebust Committed by Chuck Lever
Browse files

nfsd: Fix a write performance regression 



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: default avatarJan Kara <jack@suse.cz>
Fixes: b6669305 ("nfsd: Reduce the number of calls to nfsd_file_gc()")
Signed-off-by: default avatarTrond Myklebust <trond.myklebust@hammerspace.com>
Link: https://lore.kernel.org/all/20220330103457.r4xrhy2d6nhtouzk@quack3.lan


Signed-off-by: default avatarChuck Lever <chuck.lever@oracle.com>
parent 5f7b839d

fs/nfsd/filecache.c

+15 −3
Original line number Diff line number Diff line
@@ -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;

	if (!is_hashed) {

		nfsd_file_flush(nf);

		nfsd_file_put_noref(nf);

	} else {

		nfsd_file_put_noref(nf);

	if (is_hashed)

		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))