[PATCH RFC 1/1] NFS: Allow nfs_updatepage to extend a write to cover a full page when we have a lock that covers the entire file

[Scott Mayhew <smayhew@redhat.com>]

Currently nfs_updatepage allows a write to be extended to cover a full
page only if we don't have a byte range lock on the file... but if we've
got the whole file locked, then we should be allowed to extend the
write.

Signed-off-by: Scott Mayhew <smayhew@redhat.com>
---
 fs/nfs/write.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index a2c7c28..f35fb4f 100644
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -908,13 +908,16 @@ int nfs_updatepage(struct file *file, struct page *page,
 		file->f_path.dentry->d_name.name, count,
 		(long long)(page_file_offset(page) + offset));
 
-	/* If we're not using byte range locks, and we know the page
+	/* If we're not using byte range locks (or if the range of the
+	 * lock covers the entire file), and we know the page
 	 * is up to date, it may be more efficient to extend the write
 	 * to cover the entire page in order to avoid fragmentation
 	 * inefficiencies.
 	 */
 	if (nfs_write_pageuptodate(page, inode) &&
-			inode->i_flock == NULL &&
+			(inode->i_flock == NULL ||
+			(inode->i_flock->fl_start == 0 &&
+			inode->i_flock->fl_end == OFFSET_MAX)) &&
 			!(file->f_flags & O_DSYNC)) {
 		count = max(count + offset, nfs_page_length(page));
 		offset = 0;
-- 
1.7.11.7