From: Theodore Ts'o Subject: Re: [PATCH] resize2fs: move bitmaps if shrinking would orphan them Date: Thu, 20 Jun 2013 22:47:07 -0400 Message-ID: <20130621024707.GC10730@thunk.org> References: <51C0FA44.3030600@redhat.com> <51C10B41.9020103@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: ext4 development , Leonardo Menezes Vaz To: Eric Sandeen Return-path: Received: from li9-11.members.linode.com ([67.18.176.11]:59965 "EHLO imap.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965231Ab3FUCrM (ORCPT ); Thu, 20 Jun 2013 22:47:12 -0400 Content-Disposition: inline In-Reply-To: <51C10B41.9020103@redhat.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Tue, Jun 18, 2013 at 08:37:05PM -0500, Eric Sandeen wrote: > It is possible to have a flex_bg filesystem with block groups > which have inode & block bitmaps at some point well past the > start of the group. > > If an offline shrink puts the new size somewhere between > the start of the block group and the (old) location of > the bitmaps, they can be left beyond the end of the filesystem, > i.e. result in fs corruption. > > Check each remaining block group for whether its bitmaps > are beyond the end of the new filesystem, and reallocate > them in a new location if needed. > > Signed-off-by: Eric Sandeen Looks good, thanks for the patch. I made a few minor changes to fix up some extra whitespace and a minor optimization. - Ted diff --git a/resize/resize2fs.c b/resize/resize2fs.c index 28131c2..204b10a 100644 --- a/resize/resize2fs.c +++ b/resize/resize2fs.c @@ -889,7 +889,7 @@ static errcode_t blocks_to_move(ext2_resize_t rfs) * bitmaps which are beyond the end of the new filesystem. */ new_size = ext2fs_blocks_count(fs->super); - if (ext2fs_blocks_count(fs->super) < ext2fs_blocks_count(old_fs->super)) { + if (new_size < ext2fs_blocks_count(old_fs->super)) { for (g = 0; g < fs->group_desc_count; g++) { /* * ext2fs_allocate_group_table re-allocates bitmaps @@ -900,13 +900,13 @@ static errcode_t blocks_to_move(ext2_resize_t rfs) retval = ext2fs_allocate_group_table(fs, g, 0); if (retval) return retval; - } + } if (ext2fs_inode_bitmap_loc(fs, g) >= new_size) { ext2fs_inode_bitmap_loc_set(fs, g, 0); retval = ext2fs_allocate_group_table(fs, g, 0); if (retval) return retval; - } + } } }