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Subject: [PATCH v3 3/3] NFSD: Batch release pages during splice read
From:   Chuck Lever <chuck.lever@oracle.com>
To:     linux-nfs@vger.kernel.org, linux-mm@kvack.org
Cc:     neilb@suse.de
Date:   Thu, 08 Jul 2021 11:26:35 -0400
Message-ID: <162575799527.2532.9850430992854215546.stgit@klimt.1015granger.net>
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References: <162575623717.2532.8517369487503961860.stgit@klimt.1015granger.net>
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Large splice reads call put_page() repeatedly. put_page() is
relatively expensive to call, so replace it with the new
svc_rqst_replace_page() helper to help amortize that cost.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
 fs/nfsd/vfs.c |    9 ++-------
 1 file changed, 2 insertions(+), 7 deletions(-)

diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index da5340dc0203..43ac23b200d2 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -849,15 +849,10 @@ nfsd_splice_actor(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
 	struct page *page = buf->page;
 
 	if (rqstp->rq_res.page_len == 0) {
-		get_page(page);
-		put_page(*rqstp->rq_next_page);
-		*(rqstp->rq_next_page++) = page;
+		svc_rqst_replace_page(rqstp, page);
 		rqstp->rq_res.page_base = buf->offset;
 	} else if (page != pp[-1]) {
-		get_page(page);
-		if (*rqstp->rq_next_page)
-			put_page(*rqstp->rq_next_page);
-		*(rqstp->rq_next_page++) = page;
+		svc_rqst_replace_page(rqstp, page);
 	}
 	rqstp->rq_res.page_len += sd->len;