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From:   trondmy@kernel.org
To:     Anna Schumaker <anna.schumaker@netapp.com>
Cc:     linux-nfs@vger.kernel.org
Subject: [PATCH] NFS: Don't overfill uncached readdir pages
Date:   Tue, 18 Jan 2022 19:25:42 -0500
Message-Id: <20220119002542.245587-1-trondmy@kernel.org>
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From: Trond Myklebust <trond.myklebust@hammerspace.com>

If we're doing an uncached read of the directory, then we ideally want
to read only the exact set of entries that will fit in the buffer
supplied by the getdents() system call. So unlike the case where we're
reading into the page cache, let's send only one READDIR call, before
trying to fill up the buffer.

Fixes: 35df59d3ef69 ("NFS: Reduce number of RPC calls when doing uncached readdir")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
---
 fs/nfs/dir.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index 24ce5652d9be..cbf1a304ca18 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -866,7 +866,8 @@ static int nfs_readdir_xdr_to_array(struct nfs_readdir_descriptor *desc,
 
 		status = nfs_readdir_page_filler(desc, entry, pages, pglen,
 						 arrays, narrays);
-	} while (!status && nfs_readdir_page_needs_filling(page));
+	} while (!status && nfs_readdir_page_needs_filling(page) &&
+		 page_mapping(page));
 
 	nfs_readdir_free_pages(pages, array_size);
 out:
-- 
2.34.1