From: Kyungchan Koh Subject: [PATCH] fs: ext4: inode->i_generation not assigned 0. Date: Wed, 28 Jun 2017 15:06:42 -0700 Message-ID: Mime-Version: 1.0 Content-Type: text/plain Cc: To: , , , Return-path: Received: from mx0b-00082601.pphosted.com ([67.231.153.30]:38780 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751518AbdF1WGp (ORCPT ); Wed, 28 Jun 2017 18:06:45 -0400 Received: from pps.filterd (m0001303.ppops.net [127.0.0.1]) by m0001303.ppops.net (8.16.0.20/8.16.0.20) with SMTP id v5SM3FBO004055 for ; Wed, 28 Jun 2017 15:06:45 -0700 Received: from mail.thefacebook.com ([199.201.64.23]) by m0001303.ppops.net with ESMTP id 2bbxkhuue7-1 (version=TLSv1 cipher=ECDHE-RSA-AES256-SHA bits=256 verify=NOT) for ; Wed, 28 Jun 2017 15:06:45 -0700 Received: from facebook.com (2401:db00:21:6029:face:0:5:0) by mx-out.facebook.com (10.212.232.59) with ESMTP id 119c56b85c4e11e794a60002c991e86a-a5b3e8f0 for ; Wed, 28 Jun 2017 15:06:43 -0700 Sender: linux-ext4-owner@vger.kernel.org List-ID: In fs/ext4/super.c, the function ext4_nfs_get_inode takes as input "generation" that can be used to specify the generation of the inode to be returned. When 0 is given as input, then inodes of any generation can be returned. Therefore, generation 0 is a special case that should be avoided when assigning generation to inodes. A new inline function, ext4_inode_set_gen, will take care of the problem. Now, inodes cannot have a generation of 0, so this patch fixes the issue. Signed-off-by: Kyungchan Koh --- fs/ext4/ext4.h | 8 ++++++++ fs/ext4/ialloc.c | 2 +- fs/ext4/ioctl.c | 4 ++-- 3 files changed, 11 insertions(+), 3 deletions(-) diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h index 3219154..74c6677 100644 --- a/fs/ext4/ext4.h +++ b/fs/ext4/ext4.h @@ -1549,6 +1549,14 @@ static inline int ext4_valid_inum(struct super_block *sb, unsigned long ino) ino <= le32_to_cpu(EXT4_SB(sb)->s_es->s_inodes_count)); } +static inline void ext4_inode_set_gen(struct inode *inode, + struct ext4_sb_info *sbi) +{ + inode->i_generation = sbi->s_next_generation++; + if (!inode->i_generation) + inode->i_generation = sbi->s_next_generation++; +} + /* * Inode dynamic state flags */ diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c index 98ac2f1..d33f6f0 100644 --- a/fs/ext4/ialloc.c +++ b/fs/ext4/ialloc.c @@ -1072,7 +1072,7 @@ struct inode *__ext4_new_inode(handle_t *handle, struct inode *dir, goto out; } spin_lock(&sbi->s_next_gen_lock); - inode->i_generation = sbi->s_next_generation++; + ext4_inode_set_gen(inode, sbi); spin_unlock(&sbi->s_next_gen_lock); /* Precompute checksum seed for inode metadata */ diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c index 0c21e22..d52a467 100644 --- a/fs/ext4/ioctl.c +++ b/fs/ext4/ioctl.c @@ -160,8 +160,8 @@ static long swap_inode_boot_loader(struct super_block *sb, inode->i_ctime = inode_bl->i_ctime = current_time(inode); spin_lock(&sbi->s_next_gen_lock); - inode->i_generation = sbi->s_next_generation++; - inode_bl->i_generation = sbi->s_next_generation++; + ext4_inode_set_gen(inode, sbi); + ext4_inode_set_gen(inode_bl, sbi); spin_unlock(&sbi->s_next_gen_lock); ext4_discard_preallocations(inode); -- 2.9.3