Patch "nfsd: simplify the delayed disposal list code" 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: simplify the delayed disposal list code

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-simplify-the-delayed-disposal-list-code.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 4ecb6d6c3eca27b8bc257d8c46b01ee1b2f8e7c7
Author: Jeff Layton <jlayton@xxxxxxxxxx>
Date:   Fri Apr 14 17:31:44 2023 -0400

    nfsd: simplify the delayed disposal list code
    
    [ Upstream commit 92e4a6733f922f0fef1d0995f7b2d0eaff86c7ea ]
    
    When queueing a dispose list to the appropriate "freeme" lists, it
    pointlessly queues the objects one at a time to an intermediate list.
    
    Remove a few helpers and just open code a list_move to make it more
    clear and efficient. Better document the resulting functions with
    kerneldoc comments.
    
    Signed-off-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 52e67ec267965..6b8706f23eaf0 100644
--- a/fs/nfsd/filecache.c
+++ b/fs/nfsd/filecache.c
@@ -401,49 +401,26 @@ nfsd_file_dispose_list(struct list_head *dispose)
 	}
 }
 
-static void
-nfsd_file_list_remove_disposal(struct list_head *dst,
-		struct nfsd_fcache_disposal *l)
-{
-	spin_lock(&l->lock);
-	list_splice_init(&l->freeme, dst);
-	spin_unlock(&l->lock);
-}
-
-static void
-nfsd_file_list_add_disposal(struct list_head *files, struct net *net)
-{
-	struct nfsd_net *nn = net_generic(net, nfsd_net_id);
-	struct nfsd_fcache_disposal *l = nn->fcache_disposal;
-
-	spin_lock(&l->lock);
-	list_splice_tail_init(files, &l->freeme);
-	spin_unlock(&l->lock);
-	queue_work(nfsd_filecache_wq, &l->work);
-}
-
-static void
-nfsd_file_list_add_pernet(struct list_head *dst, struct list_head *src,
-		struct net *net)
-{
-	struct nfsd_file *nf, *tmp;
-
-	list_for_each_entry_safe(nf, tmp, src, nf_lru) {
-		if (nf->nf_net == net)
-			list_move_tail(&nf->nf_lru, dst);
-	}
-}
-
+/**
+ * nfsd_file_dispose_list_delayed - move list of dead files to net's freeme list
+ * @dispose: list of nfsd_files to be disposed
+ *
+ * Transfers each file to the "freeme" list for its nfsd_net, to eventually
+ * be disposed of by the per-net garbage collector.
+ */
 static void
 nfsd_file_dispose_list_delayed(struct list_head *dispose)
 {
-	LIST_HEAD(list);
-	struct nfsd_file *nf;
-
 	while(!list_empty(dispose)) {
-		nf = list_first_entry(dispose, struct nfsd_file, nf_lru);
-		nfsd_file_list_add_pernet(&list, dispose, nf->nf_net);
-		nfsd_file_list_add_disposal(&list, nf->nf_net);
+		struct nfsd_file *nf = list_first_entry(dispose,
+						struct nfsd_file, nf_lru);
+		struct nfsd_net *nn = net_generic(nf->nf_net, nfsd_net_id);
+		struct nfsd_fcache_disposal *l = nn->fcache_disposal;
+
+		spin_lock(&l->lock);
+		list_move_tail(&nf->nf_lru, &l->freeme);
+		spin_unlock(&l->lock);
+		queue_work(nfsd_filecache_wq, &l->work);
 	}
 }
 
@@ -664,8 +641,8 @@ nfsd_file_close_inode_sync(struct inode *inode)
  * nfsd_file_delayed_close - close unused nfsd_files
  * @work: dummy
  *
- * Walk the LRU list and destroy any entries that have not been used since
- * the last scan.
+ * Scrape the freeme list for this nfsd_net, and then dispose of them
+ * all.
  */
 static void
 nfsd_file_delayed_close(struct work_struct *work)
@@ -674,7 +651,10 @@ nfsd_file_delayed_close(struct work_struct *work)
 	struct nfsd_fcache_disposal *l = container_of(work,
 			struct nfsd_fcache_disposal, work);
 
-	nfsd_file_list_remove_disposal(&head, l);
+	spin_lock(&l->lock);
+	list_splice_init(&l->freeme, &head);
+	spin_unlock(&l->lock);
+
 	nfsd_file_dispose_list(&head);
 }