pnfs: Use byte-range for layoutget

Add offset and count parameters to pnfs_update_layout and use them to get
the layout in the pageio path.

Order cache layout segments in the following order:
* offset (ascending)
* length (descending)
* iomode (RW before READ)

Test byte range against the layout segment in use in pnfs_{read,write}_pg_test
so not to coalesce pages not using the same layout segment.

[fix lseg ordering]
[clean up pnfs_find_lseg lseg arg]
[remove unnecessary FIXME]
[fix ordering in pnfs_insert_layout]
[clean up pnfs_insert_layout]
Signed-off-by: Benny Halevy <bhalevy@panasas.com>

1 files changed, 6 insertions, 2 deletions

diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index 49c715b4ac92..7edb72f27c22 100644
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -939,7 +939,9 @@ static int nfs_flush_multi(struct nfs_pageio_descriptor *desc)
         atomic_set(&req->wb_complete, requests);
 
         BUG_ON(desc->pg_lseg);
-        lseg = pnfs_update_layout(desc->pg_inode, req->wb_context, IOMODE_RW, GFP_NOFS);
+        lseg = pnfs_update_layout(desc->pg_inode, req->wb_context,
+                                  req_offset(req), desc->pg_count,
+                                  IOMODE_RW, GFP_NOFS);
         ClearPageError(page);
         offset = 0;
         nbytes = desc->pg_count;
@@ -1013,7 +1015,9 @@ static int nfs_flush_one(struct nfs_pageio_descriptor *desc)
         }
         req = nfs_list_entry(data->pages.next);
         if ((!lseg) && list_is_singular(&data->pages))
-                lseg = pnfs_update_layout(desc->pg_inode, req->wb_context, IOMODE_RW, GFP_NOFS);
+                lseg = pnfs_update_layout(desc->pg_inode, req->wb_context,
+                                          req_offset(req), desc->pg_count,
+                                          IOMODE_RW, GFP_NOFS);
 
         if ((desc->pg_ioflags & FLUSH_COND_STABLE) &&
             (desc->pg_moreio || NFS_I(desc->pg_inode)->ncommit))