9p: soften invalidation in loose_mode

Loose mode in 9p utilizes the page cache without respecting coherency with
the server.  Any writes previously invaldiated the entire mapping for a file.
This patch softens the behavior to only invalidate the region of the actual
write.

Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>

1 files changed, 4 insertions, 2 deletions

diff --git a/fs/9p/vfs_file.c b/fs/9p/vfs_file.c
index 716691689fd5..ba4b1caa9c43 100644
--- a/fs/9p/vfs_file.c
+++ b/fs/9p/vfs_file.c
@@ -162,15 +162,17 @@ v9fs_file_write(struct file *filp, const char __user * data,
 
         fid = filp->private_data;
         ret = p9_client_uwrite(fid, data, *offset, count);
-        if (ret > 0)
+        if (ret > 0) {
+                invalidate_inode_pages2_range(inode->i_mapping, *offset,
+                                                                *offset+ret);
                 *offset += ret;
+        }
 
         if (*offset > inode->i_size) {
                 inode->i_size = *offset;
                 inode->i_blocks = (inode->i_size + 512 - 1) >> 9;
         }
 
-        invalidate_inode_pages2(inode->i_mapping);
         return ret;
 }