NFSv4.1: coelesce across layout stripes

Add a pg_test layout driver hook which is used to avoid coelescing I/O across
layout stripes.

Signed-off-by: Andy Adamson <andros@netapp.com>
Signed-off-by: Andy Adamson <andros@citi.umich.edu>
Signed-off-by: Dean Hildebrand <dhildeb@us.ibm.com>
Signed-off-by: Fred Isaman <iisaman@citi.umich.edu>
Signed-off-by: Fred Isaman <iisaman@netapp.com>
Signed-off-by: Benny Halevy <bhalevy@panasas.com>
Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
Signed-off-by: Oleg Drokin <green@linuxhacker.ru>
Signed-off-by: Tao Guo <guotao@nrchpc.ac.cn>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 10 insertions, 2 deletions

diff --git a/fs/nfs/pagelist.c b/fs/nfs/pagelist.c
index e1164e3f9e69..9b9a65c9bb4f 100644
--- a/fs/nfs/pagelist.c
+++ b/fs/nfs/pagelist.c
@@ -226,6 +226,7 @@ void nfs_pageio_init(struct nfs_pageio_descriptor *desc,
         desc->pg_doio = doio;
         desc->pg_ioflags = io_flags;
         desc->pg_error = 0;
+        desc->pg_lseg = NULL;
 }
 
 /**
@@ -240,7 +241,8 @@ void nfs_pageio_init(struct nfs_pageio_descriptor *desc,
  * Return 'true' if this is the case, else return 'false'.
  */
 static int nfs_can_coalesce_requests(struct nfs_page *prev,
-                                     struct nfs_page *req)
+                                     struct nfs_page *req,
+                                     struct nfs_pageio_descriptor *pgio)
 {
         if (req->wb_context->cred != prev->wb_context->cred)
                 return 0;
@@ -254,6 +256,12 @@ static int nfs_can_coalesce_requests(struct nfs_page *prev,
                 return 0;
         if (prev->wb_pgbase + prev->wb_bytes != PAGE_CACHE_SIZE)
                 return 0;
+        /*
+         * Non-whole file layouts need to check that req is inside of
+         * pgio->pg_lseg.
+         */
+        if (pgio->pg_test && !pgio->pg_test(pgio, prev, req))
+                return 0;
         return 1;
 }
 
@@ -286,7 +294,7 @@ static int nfs_pageio_do_add_request(struct nfs_pageio_descriptor *desc,
                 if (newlen > desc->pg_bsize)
                         return 0;
                 prev = nfs_list_entry(desc->pg_list.prev);
-                if (!nfs_can_coalesce_requests(prev, req))
+                if (!nfs_can_coalesce_requests(prev, req, desc))
                         return 0;
         } else
                 desc->pg_base = req->wb_pgbase;