Patch "NFSD: Add nfsd_file_lru_dispose_list() helper" has been added to the 5.15-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    NFSD: Add nfsd_file_lru_dispose_list() helper

to the 5.15-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-add-nfsd_file_lru_dispose_list-helper.patch
and it can be found in the queue-5.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 0cee4746ee53471ad8dc55e306ba0cd0ac8fa4e5
Author: Chuck Lever <chuck.lever@xxxxxxxxxx>
Date:   Fri Jul 8 14:24:18 2022 -0400

    NFSD: Add nfsd_file_lru_dispose_list() helper
    
    [ Upstream commit 0bac5a264d9a923f5b01f3521e1519a8d0358342 ]
    
    Refactor the invariant part of nfsd_file_lru_walk_list() into a
    separate helper function.
    
    Reviewed-by: Jeff Layton <jlayton@xxxxxxxxxx>
    Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>

diff --git a/fs/nfsd/filecache.c b/fs/nfsd/filecache.c
index 0cd72c20fc12d..ffe46f3f33495 100644
--- a/fs/nfsd/filecache.c
+++ b/fs/nfsd/filecache.c
@@ -450,11 +450,31 @@ nfsd_file_lru_cb(struct list_head *item, struct list_lru_one *lru,
 	return LRU_SKIP;
 }
 
+/*
+ * Unhash items on @dispose immediately, then queue them on the
+ * disposal workqueue to finish releasing them in the background.
+ *
+ * cel: Note that between the time list_lru_shrink_walk runs and
+ * now, these items are in the hash table but marked unhashed.
+ * Why release these outside of lru_cb ? There's no lock ordering
+ * problem since lru_cb currently takes no lock.
+ */
+static void nfsd_file_gc_dispose_list(struct list_head *dispose)
+{
+	struct nfsd_file *nf;
+
+	list_for_each_entry(nf, dispose, nf_lru) {
+		spin_lock(&nfsd_file_hashtbl[nf->nf_hashval].nfb_lock);
+		nfsd_file_do_unhash(nf);
+		spin_unlock(&nfsd_file_hashtbl[nf->nf_hashval].nfb_lock);
+	}
+	nfsd_file_dispose_list_delayed(dispose);
+}
+
 static unsigned long
 nfsd_file_lru_walk_list(struct shrink_control *sc)
 {
 	LIST_HEAD(head);
-	struct nfsd_file *nf;
 	unsigned long ret;
 
 	if (sc)
@@ -464,12 +484,7 @@ nfsd_file_lru_walk_list(struct shrink_control *sc)
 		ret = list_lru_walk(&nfsd_file_lru,
 				nfsd_file_lru_cb,
 				&head, LONG_MAX);
-	list_for_each_entry(nf, &head, nf_lru) {
-		spin_lock(&nfsd_file_hashtbl[nf->nf_hashval].nfb_lock);
-		nfsd_file_do_unhash(nf);
-		spin_unlock(&nfsd_file_hashtbl[nf->nf_hashval].nfb_lock);
-	}
-	nfsd_file_dispose_list_delayed(&head);
+	nfsd_file_gc_dispose_list(&head);
 	return ret;
 }