nfs41: .init_read and .init_write can be called with valid pg_lseg

With pgio refactoring in v3.15, .init_read and .init_write can be
called with valid pgio->pg_lseg. file layout was fixed at that time
by commit c6194271f (pnfs: filelayout: support non page aligned
layouts). But the generic helper still needs to be fixed.

Cc: stable@vger.kernel.org # 3.15+
Signed-off-by: Peng Tao <tao.peng@primarydata.com>

1 files changed, 20 insertions, 21 deletions

diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
index 0fb0f1920a1f..c7be9b997f5e 100644
--- a/fs/nfs/pnfs.c
+++ b/fs/nfs/pnfs.c
@@ -1711,19 +1711,19 @@ pnfs_generic_pg_init_read(struct nfs_pageio_descriptor *pgio, struct nfs_page *r
 {
         u64 rd_size = req->wb_bytes;
 
-        WARN_ON_ONCE(pgio->pg_lseg != NULL);
-
-        if (pgio->pg_dreq == NULL)
-                rd_size = i_size_read(pgio->pg_inode) - req_offset(req);
-        else
-                rd_size = nfs_dreq_bytes_left(pgio->pg_dreq);
-
-        pgio->pg_lseg = pnfs_update_layout(pgio->pg_inode,
-                                           req->wb_context,
-                                           req_offset(req),
-                                           rd_size,
-                                           IOMODE_READ,
-                                           GFP_KERNEL);
+        if (pgio->pg_lseg == NULL) {
+                if (pgio->pg_dreq == NULL)
+                        rd_size = i_size_read(pgio->pg_inode) - req_offset(req);
+                else
+                        rd_size = nfs_dreq_bytes_left(pgio->pg_dreq);
+
+                pgio->pg_lseg = pnfs_update_layout(pgio->pg_inode,
+                                                   req->wb_context,
+                                                   req_offset(req),
+                                                   rd_size,
+                                                   IOMODE_READ,
+                                                   GFP_KERNEL);
+        }
         /* If no lseg, fall back to read through mds */
         if (pgio->pg_lseg == NULL)
                 nfs_pageio_reset_read_mds(pgio);
@@ -1735,14 +1735,13 @@ void
 pnfs_generic_pg_init_write(struct nfs_pageio_descriptor *pgio,
                            struct nfs_page *req, u64 wb_size)
 {
-        WARN_ON_ONCE(pgio->pg_lseg != NULL);
-
-        pgio->pg_lseg = pnfs_update_layout(pgio->pg_inode,
-                                           req->wb_context,
-                                           req_offset(req),
-                                           wb_size,
-                                           IOMODE_RW,
-                                           GFP_NOFS);
+        if (pgio->pg_lseg == NULL)
+                pgio->pg_lseg = pnfs_update_layout(pgio->pg_inode,
+                                                   req->wb_context,
+                                                   req_offset(req),
+                                                   wb_size,
+                                                   IOMODE_RW,
+                                                   GFP_NOFS);
         /* If no lseg, fall back to write through mds */
         if (pgio->pg_lseg == NULL)
                 nfs_pageio_reset_write_mds(pgio);