NFS: prepare coalesce testing for directio

The coalesce code made assumptions that will no longer be true once
non-page aligned io occurs.  This introduces no change in
current behavior, but allows for more general situations to come.

Signed-off-by: Fred Isaman <iisaman@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

3 files changed, 22 insertions, 2 deletions

diff --git a/fs/nfs/nfs4filelayout.c b/fs/nfs/nfs4filelayout.c
index 02d8170ce0f3..e40523f2fe26 100644
--- a/fs/nfs/nfs4filelayout.c
+++ b/fs/nfs/nfs4filelayout.c
@@ -796,6 +796,16 @@ filelayout_pg_init_read(struct nfs_pageio_descriptor *pgio,
 {
         BUG_ON(pgio->pg_lseg != NULL);
 
+        if (req->wb_offset != req->wb_pgbase) {
+                /*
+                 * Handling unaligned pages is difficult, because have to
+                 * somehow split a req in two in certain cases in the
+                 * pg.test code.  Avoid this by just not using pnfs
+                 * in this case.
+                 */
+                nfs_pageio_reset_read_mds(pgio);
+                return;
+        }
         pgio->pg_lseg = pnfs_update_layout(pgio->pg_inode,
                                            req->wb_context,
                                            0,
@@ -815,6 +825,8 @@ filelayout_pg_init_write(struct nfs_pageio_descriptor *pgio,
 
         BUG_ON(pgio->pg_lseg != NULL);
 
+        if (req->wb_offset != req->wb_pgbase)
+                goto out_mds;
         pgio->pg_lseg = pnfs_update_layout(pgio->pg_inode,
                                            req->wb_context,
                                            0,
diff --git a/fs/nfs/pagelist.c b/fs/nfs/pagelist.c
index 5d01a1651084..638ca7f5a1e4 100644
--- a/fs/nfs/pagelist.c
+++ b/fs/nfs/pagelist.c
@@ -280,12 +280,12 @@ static bool nfs_can_coalesce_requests(struct nfs_page *prev,
                 return false;
         if (req->wb_context->state != prev->wb_context->state)
                 return false;
-        if (req->wb_index != (prev->wb_index + 1))
-                return false;
         if (req->wb_pgbase != 0)
                 return false;
         if (prev->wb_pgbase + prev->wb_bytes != PAGE_CACHE_SIZE)
                 return false;
+        if (req_offset(req) != req_offset(prev) + prev->wb_bytes)
+                return false;
         return pgio->pg_ops->pg_test(pgio, prev, req);
 }
 
diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
index b3a0c01718af..4da05e469be5 100644
--- a/fs/nfs/pnfs.c
+++ b/fs/nfs/pnfs.c
@@ -1082,6 +1082,10 @@ pnfs_generic_pg_init_read(struct nfs_pageio_descriptor *pgio, struct nfs_page *r
 {
         BUG_ON(pgio->pg_lseg != NULL);
 
+        if (req->wb_offset != req->wb_pgbase) {
+                nfs_pageio_reset_read_mds(pgio);
+                return;
+        }
         pgio->pg_lseg = pnfs_update_layout(pgio->pg_inode,
                                            req->wb_context,
                                            req_offset(req),
@@ -1100,6 +1104,10 @@ pnfs_generic_pg_init_write(struct nfs_pageio_descriptor *pgio, struct nfs_page *
 {
         BUG_ON(pgio->pg_lseg != NULL);
 
+        if (req->wb_offset != req->wb_pgbase) {
+                nfs_pageio_reset_write_mds(pgio);
+                return;
+        }
         pgio->pg_lseg = pnfs_update_layout(pgio->pg_inode,
                                            req->wb_context,
                                            req_offset(req),