[PATCH v2 3/3] nfsd: start non-blocking writeback after adding nfsd_file to the LRU

Jeff Layton
2022-10-27T21:52:24Z

When a GC entry gets added to the LRU, kick off SYNC_NONE writeback
so that we can be ready to close it out when the time comes.

Signed-off-by: Jeff Layton <jlayton@kernel.org>
---
fs/nfsd/filecache.c | 37 +++++++++++++++++++++++++++++++------
1 file changed, 31 insertions(+), 6 deletions(-)

diff --git a/fs/nfsd/filecache.c b/fs/nfsd/filecache.c
index d2bbded805d4..491d3d9a1870 100644
--- a/fs/nfsd/filecache.c
+++ b/fs/nfsd/filecache.c
@@ -316,7 +316,7 @@ nfsd_file_alloc(struct nfsd_file_lookup_key *key, unsigned int may)
}

static void
-nfsd_file_flush(struct nfsd_file *nf)
+nfsd_file_fsync(struct nfsd_file *nf)
{
struct file *file = nf->nf_file;

@@ -327,6 +327,22 @@ nfsd_file_flush(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;
+ unsigned long nrpages;
+
+ if (!file || !(file->f_mode & FMODE_WRITE))
+ return;
+
+ nrpages = file->f_mapping->nrpages;
+ if (nrpages) {
+ this_cpu_add(nfsd_file_pages_flushed, nrpages);
+ filemap_flush(file->f_mapping);
+ }
+}
+
static void
nfsd_file_free(struct nfsd_file *nf)
{
@@ -337,7 +353,7 @@ nfsd_file_free(struct nfsd_file *nf)
this_cpu_inc(nfsd_file_releases);
this_cpu_add(nfsd_file_total_age, age);

- nfsd_file_flush(nf);
+ nfsd_file_fsync(nf);

if (nf->nf_mark)
nfsd_file_mark_put(nf->nf_mark);
@@ -500,12 +516,21 @@ nfsd_file_put(struct nfsd_file *nf)

if (test_bit(NFSD_FILE_GC, &nf->nf_flags)) {
/*
- * If this is the last reference (nf_ref == 1), then transfer
- * it to the LRU. If the add to the LRU fails, just put it as
- * usual.
+ * If this is the last reference (nf_ref == 1), then try
+ * to transfer it to the LRU.
+ */
+ if (refcount_dec_not_one(&nf->nf_ref))
+ return;
+
+ /*
+ * If the add to the list succeeds, try to kick off SYNC_NONE
+ * writeback. If the add fails, then just fall through to
+ * decrement as usual.
*/
- if (refcount_dec_not_one(&nf->nf_ref) || nfsd_file_lru_add(nf))
+ if (nfsd_file_lru_add(nf)) {
+ nfsd_file_flush(nf);
return;
+ }
}
__nfsd_file_put(nf);
}
--
2.37.3