[PATCH 1/1] Prevent 3.0 from crashing if it receives a partial layout

[Fred Isaman <iisaman@netapp.com>]

This is a backport of critical parts of
commit 7c24d9489f "NFSv4.1: File layout only supports whole file layouts"

It prevents the file layout driver from (incorrectly) using
partial layouts, but ignores the part of the referenced commmit that
relies on additional machinery to change the LAYOUTGET request
based on layout driver.

Signed-off-by: Fred Isaman <iisaman@netapp.com>
---
 fs/nfs/nfs4filelayout.c |    8 ++++++++
 fs/nfs/pnfs.c           |    3 ++-
 2 files changed, 10 insertions(+), 1 deletions(-)

diff --git a/fs/nfs/nfs4filelayout.c b/fs/nfs/nfs4filelayout.c
index 614c4d2..75af812 100644
--- a/fs/nfs/nfs4filelayout.c
+++ b/fs/nfs/nfs4filelayout.c
@@ -428,6 +428,14 @@ filelayout_check_layout(struct pnfs_layout_hdr *lo,
 
 	dprintk("--> %s\n", __func__);
 
+	/* FIXME: remove this check when layout segment support is added */
+	if (lgr->range.offset != 0 ||
+	    lgr->range.length != NFS4_MAX_UINT64) {
+		dprintk("%s Only whole file layouts supported. Use MDS i/o\n",
+			__func__);
+		goto out;
+	}
+
 	if (fl->pattern_offset > lgr->range.offset) {
 		dprintk("%s pattern_offset %lld too large\n",
 				__func__, fl->pattern_offset);
diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
index a726c0a..36d2a29 100644
--- a/fs/nfs/pnfs.c
+++ b/fs/nfs/pnfs.c
@@ -980,7 +980,8 @@ pnfs_update_layout(struct inode *ino,
 		arg.offset -= pg_offset;
 		arg.length += pg_offset;
 	}
-	arg.length = PAGE_CACHE_ALIGN(arg.length);
+	if (arg.length != NFS4_MAX_UINT64)
+		arg.length = PAGE_CACHE_ALIGN(arg.length);
 
 	lseg = send_layoutget(lo, ctx, &arg, gfp_flags);
 	if (!lseg && first) {
-- 
1.7.2.1