check ATTR_SIZE contraints in inode_change_ok

Make sure we check the truncate constraints early on in ->setattr by adding
those checks to inode_change_ok.  Also clean up and document inode_change_ok
to make this obvious.

As a fallout we don't have to call inode_newsize_ok from simple_setsize and
simplify it down to a truncate_setsize which doesn't return an error.  This
simplifies a lot of setattr implementations and means we use truncate_setsize
almost everywhere.  Get rid of fat_setsize now that it's trivial and mark
ext2_setsize static to make the calling convention obvious.

Keep the inode_newsize_ok in vmtruncate for now as all callers need an
audit for its removal anyway.

Note: setattr code in ecryptfs doesn't call inode_change_ok at all and
needs a deeper audit, but that is left for later.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 2 insertions, 3 deletions

diff --git a/mm/shmem.c b/mm/shmem.c
index 0a43505..33222ba 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -805,11 +805,10 @@ static int shmem_notify_change(struct dentry *dentry, struct iattr *attr)
 			}
 		}
 
-		error = simple_setsize(inode, newsize);
+		/* XXX(truncate): truncate_setsize should be called last */
+		truncate_setsize(inode, newsize);
 		if (page)
 			page_cache_release(page);
-		if (error)
-			return error;
 		shmem_truncate_range(inode, newsize, (loff_t)-1);
 	}