On Oct 28, 2022, at 2:57 PM, Jeff Layton [off-list ref] wrote:

When a GC entry gets added to the LRU, kick off SYNC_NONE writeback
so that we can be ready to close it when the time comes. This should
help minimize delays when freeing objects reaped from the LRU.

Signed-off-by: Jeff Layton <jlayton@kernel.org>
---
fs/nfsd/filecache.c | 23 +++++++++++++++++++++--
1 file changed, 21 insertions(+), 2 deletions(-)

diff --git a/fs/nfsd/filecache.c b/fs/nfsd/filecache.c
index 47cdc6129a7b..c43b6cff03e2 100644
--- a/fs/nfsd/filecache.c
+++ b/fs/nfsd/filecache.c

@@ -325,6 +325,20 @@ nfsd_file_fsync(struct nfsd_file *nf)

		nfsd_reset_write_verifier(net_generic(nf->nf_net, nfsd_net_id));
}

+static void
+nfsd_file_flush(struct nfsd_file *nf)
+{
+	struct file *file = nf->nf_file;
+	struct address_space *mapping;
+
+	if (!file || !(file->f_mode & FMODE_WRITE))
+		return;
+
+	mapping = file->f_mapping;
+	if (mapping_tagged(mapping, PAGECACHE_TAG_DIRTY))
+		filemap_flush(mapping);
+}
+
static int
nfsd_file_check_write_error(struct nfsd_file *nf)
{

@@ -484,9 +498,14 @@ nfsd_file_put(struct nfsd_file *nf)

		/* Try to add it to the LRU.  If that fails, decrement. */
		if (nfsd_file_lru_add(nf)) {
-			/* If it's still hashed, we're done */
-			if (test_bit(NFSD_FILE_HASHED, &nf->nf_flags))
+			/*
+			 * If it's still hashed, we can just return now,
+			 * after kicking off SYNC_NONE writeback.
+			 */
+			if (test_bit(NFSD_FILE_HASHED, &nf->nf_flags)) {
+				nfsd_file_flush(nf);
				return;
+			}