From: Eric Sandeen Subject: [PATCH 2/2] delay capable() check in ext4_has_free_blocks( Date: Fri, 24 Oct 2008 15:27:35 -0500 Message-ID: <49022FB7.9050608@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: Eric Paris To: ext4 development Return-path: Received: from mx2.redhat.com ([66.187.237.31]:43430 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754794AbYJXU1h (ORCPT ); Fri, 24 Oct 2008 16:27:37 -0400 Received: from int-mx2.corp.redhat.com (int-mx2.corp.redhat.com [172.16.27.26]) by mx2.redhat.com (8.13.8/8.13.8) with ESMTP id m9OKRb54025829 for ; Fri, 24 Oct 2008 16:27:37 -0400 Sender: linux-ext4-owner@vger.kernel.org List-ID: As reported by Eric Paris, the capable() check in ext4_has_free_blocks() sometimes causes SELinux denials. We can rearrange the logic so that we only try to use the root-reserved blocks when necessary, and even then we can move the capable() test to last, to avoid the check most of the time. Signed-off-by: Eric Sandeen -- Index: linux-2.6/fs/ext4/balloc.c =================================================================== --- linux-2.6.orig/fs/ext4/balloc.c 2008-10-24 14:43:11.103063953 -0500 +++ linux-2.6/fs/ext4/balloc.c 2008-10-24 14:43:18.082063765 -0500 @@ -596,23 +596,19 @@ void ext4_free_blocks(handle_t *handle, * * Check if filesystem has free blocks available for allocation. * Return the number of blocks avaible for allocation for this request - * On success, return nblocks + * On success, return 1, on failure, return 0. */ int ext4_has_free_blocks(struct ext4_sb_info *sbi, s64 nblocks) { - s64 free_blocks, dirty_blocks; - s64 root_blocks = 0; + s64 free_blocks, dirty_blocks, root_blocks; struct percpu_counter *fbc = &sbi->s_freeblocks_counter; struct percpu_counter *dbc = &sbi->s_dirtyblocks_counter; free_blocks = percpu_counter_read_positive(fbc); dirty_blocks = percpu_counter_read_positive(dbc); + root_blocks = ext4_r_blocks_count(sbi->s_es); - if (!capable(CAP_SYS_RESOURCE) && - sbi->s_resuid != current->fsuid && - (sbi->s_resgid == 0 || !in_group_p(sbi->s_resgid))) - root_blocks = ext4_r_blocks_count(sbi->s_es); if (free_blocks - (nblocks + root_blocks + dirty_blocks) < EXT4_FREEBLOCKS_WATERMARK) { @@ -625,13 +621,20 @@ int ext4_has_free_blocks(struct ext4_sb_ } } /* Check whether we have space after - * accounting for current dirty blocks + * accounting for current dirty blocks & root reserved blocks. */ - if (free_blocks < ((root_blocks + nblocks) + dirty_blocks)) - /* we don't have free space */ - return 0; + if (free_blocks >= ((root_blocks + nblocks) + dirty_blocks)) + return 1; - return 1; + /* Hm, nope. Are (enough) root reserved blocks available? */ + if (sbi->s_resuid == current->fsuid || + ((sbi->s_resgid != 0) && in_group_p(sbi->s_resgid)) || + capable(CAP_SYS_RESOURCE)) { + if (free_blocks >= (nblocks + dirty_blocks)) + return 1; + } + + return 0; } int ext4_claim_free_blocks(struct ext4_sb_info *sbi,