[GFS2] Fix problems relating to execution of files on GFS2

This patch fixes a couple of problems which affected the execution of files
on GFS2. The first is that there was a corner case where inodes were not
always uptodate at the point at which permissions checks were being carried
out, this was resulting in refusal of execute permission, but only on the
first lookup, subsequent requests worked correctly. The second was a problem
relating to incorrect updating of file sizes which was introduced with the
write_begin/end code for GFS2 a little while back.
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
Cc: Abhijith Das <adas@redhat.com>

fs/gfs2/ops_address.c

@@ -848,15 +848,12 @@ static int gfs2_write_end(struct file *file, struct address_space *mapping,
 
 	ret = generic_write_end(file, mapping, pos, len, copied, page, fsdata);
 
-	if (likely(ret >= 0)) {
-		copied = ret;
-		if  ((pos + copied) > inode->i_size) {
+	if (likely(ret >= 0) && (inode->i_size > ip->i_di.di_size)) {
 		di = (struct gfs2_dinode *)dibh->b_data;
 		ip->i_di.di_size = inode->i_size;
 		di->di_size = cpu_to_be64(inode->i_size);
 		mark_inode_dirty(inode);
 	}
-	}
 
 	if (inode == sdp->sd_rindex)
 		adjust_fs_space(inode);

fs/gfs2/ops_inode.c

@@ -113,8 +113,18 @@ static struct dentry *gfs2_lookup(struct inode *dir, struct dentry *dentry,
 	if (inode && IS_ERR(inode))
 		return ERR_PTR(PTR_ERR(inode));
 
-	if (inode)
+	if (inode) {
+		struct gfs2_glock *gl = GFS2_I(inode)->i_gl;
+		struct gfs2_holder gh;
+		int error;
+		error = gfs2_glock_nq_init(gl, LM_ST_SHARED, LM_FLAG_ANY, &gh);
+		if (error) {
+			iput(inode);
+			return ERR_PTR(error);
+		}
+		gfs2_glock_dq_uninit(&gh);
 		return d_splice_alias(inode, dentry);
+	}
 	d_add(dentry, inode);
 
 	return NULL;