From: Andreas Dilger Subject: [PATCH] mke2fs: fix flexbg check to allow small filesystems Date: Wed, 30 Jul 2014 02:30:22 -0600 Message-ID: <1406709022-28957-1-git-send-email-adilger@dilger.ca> Cc: linux-ext4@vger.kernel.org, Andreas Dilger , Andreas Dilger To: tytso@mit.edu Return-path: Received: from smtp-out-02.shaw.ca ([64.59.136.138]:49224 "EHLO smtp-out-02.shaw.ca" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750894AbaG3Ij7 (ORCPT ); Wed, 30 Jul 2014 04:39:59 -0400 Sender: linux-ext4-owner@vger.kernel.org List-ID: Fix the flexbg check added in d988201ef9c so that it allows common small filesystem configurations to succeed instead of reporting a cryptic error message and failing due to a bad flex_bg layout: mke2fs -O flex_bg -b 4096 -I 1024 -F /tmp/tt 79106 mke2fs 1.42.11 (09-Jul-2014) /tmp/tt: Invalid argument passed to ext2 library while setting up superblock This check in ext2fs_initialize() was added to prevent the metadata from being allocated beyond the end of the filesystem, but it is also causing a wide range of failures for small filesystems. Fix this by shrinking the flex_bg factor by half repeatedly until it would be expected to fit into the current filesystem size, rather than return an error as previously done. Ideally it would only try a smaller flex_bg factor if the default value was being used, and had not been specified on the command line, but it isn't possible to see if this is the case in ext2fs_initialize() or not. Signed-off-by: Andreas Dilger --- lib/ext2fs/initialize.c | 13 +++++++------ 1 files changed, 7 insertions(+), 6 deletions(-) diff --git a/lib/ext2fs/initialize.c b/lib/ext2fs/initialize.c index de358fd..d58a664 100644 --- a/lib/ext2fs/initialize.c +++ b/lib/ext2fs/initialize.c @@ -91,7 +91,7 @@ errcode_t ext2fs_initialize(const char *name, int flags, unsigned int rem; unsigned int overhead = 0; unsigned int ipg; - unsigned int flexbg_size; + unsigned int flexbg_factor; dgrp_t i; blk64_t free_blocks; blk64_t flexbg_overhead; @@ -428,18 +428,19 @@ ipg_retry: * This is a simple check, so that the backup superblock and * other feature related blocks are not considered. */ - flexbg_size = 1 << fs->super->s_log_groups_per_flex; +flex_retry: + flexbg_factor = 1 << super->s_log_groups_per_flex; flexbg_overhead = super->s_first_data_block + 1 + fs->desc_blocks + super->s_reserved_gdt_blocks + - (__u64)flexbg_size * (2 + fs->inode_blocks_per_group); + (__u64)flexbg_factor * (2 + fs->inode_blocks_per_group); /* * Disallow creating ext4 which breaks flex_bg metadata layout * obviously. */ - if (flexbg_overhead > ext2fs_blocks_count(fs->super)) { - retval = EXT2_ET_INVALID_ARGUMENT; - goto cleanup; + if (flexbg_overhead > ext2fs_blocks_count(super)) { + super->s_log_groups_per_flex -= 1; + goto flex_retry; } /* -- 1.7.3.4