From: Dave Kleikamp <dave.kleikamp@oracle.com>
Date: Fri, 29 May 2015 18:16:31 +0000 (-0500)
Subject: nfs: don't dirty kernel pages read by direct-io
X-Git-Tag: v4.1.12-92~320^2~5
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=1f23106b3951f644f939d81bb488d53976026ee2;p=users%2Fjedix%2Flinux-maple.git

nfs: don't dirty kernel pages read by direct-io

Replicate the logic in the commit:
fd/direct-io: introduce should_dirty for kernel aio

Signed-off-by: Dave Kleikamp <dave.kleikamp@oracle.com>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@oracle.com>
---

diff --git a/fs/nfs/direct.c b/fs/nfs/direct.c
index 38678d9a5cc4..8beeaf06e360 100644
--- a/fs/nfs/direct.c
+++ b/fs/nfs/direct.c
@@ -97,8 +97,11 @@ struct nfs_direct_req {
 	struct pnfs_ds_commit_info ds_cinfo;	/* Storage for cinfo */
 	struct work_struct	work;
 	int			flags;
+	/* for write */
 #define NFS_ODIRECT_DO_COMMIT		(1)	/* an unstable reply was received */
 #define NFS_ODIRECT_RESCHED_WRITES	(2)	/* write verification failed */
+	/* for read */
+#define NFS_ODIRECT_SHOULD_DIRTY	(3)	/* dirty user-space page after read */
 	struct nfs_writeverf	verf;		/* unstable write verifier */
 };
 
@@ -426,7 +429,8 @@ static void nfs_direct_read_completion(struct nfs_pgio_header *hdr)
 		struct nfs_page *req = nfs_list_entry(hdr->pages.next);
 		struct page *page = req->wb_page;
 
-		if (!PageCompound(page) && bytes < hdr->good_bytes)
+		if (!PageCompound(page) && bytes < hdr->good_bytes &&
+		    (dreq->flags == NFS_ODIRECT_SHOULD_DIRTY))
 			set_page_dirty(page);
 		bytes += req->wb_bytes;
 		nfs_list_remove_request(req);
@@ -608,6 +612,11 @@ ssize_t nfs_file_direct_read(struct kiocb *iocb, struct iov_iter *iter,
 	if (!is_sync_kiocb(iocb))
 		dreq->iocb = iocb;
 
+	if (iter_is_iovec(iter))
+		dreq->flags = NFS_ODIRECT_SHOULD_DIRTY;
+	else
+		dreq->flags = 0;
+
 	NFS_I(inode)->read_io += count;
 	result = nfs_direct_read_schedule_iovec(dreq, iter, pos);