Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754695AbcD0AOW (ORCPT ); Tue, 26 Apr 2016 20:14:22 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:40124 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753977AbcDZXN6 (ORCPT ); Tue, 26 Apr 2016 19:13:58 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Theodore Ts'o" Date: Wed, 27 Apr 2016 01:02:21 +0200 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 161/217] ext4: add lockdep annotations for i_data_sem In-Reply-To: X-SA-Exim-Connect-IP: 2a02:8426:ae4:c500:9cba:69ae:962d:6167 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4870 Lines: 146 3.16.35-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Theodore Ts'o commit daf647d2dd58cec59570d7698a45b98e580f2076 upstream. With the internal Quota feature, mke2fs creates empty quota inodes and quota usage tracking is enabled as soon as the file system is mounted. Since quotacheck is no longer preallocating all of the blocks in the quota inode that are likely needed to be written to, we are now seeing a lockdep false positive caused by needing to allocate a quota block from inside ext4_map_blocks(), while holding i_data_sem for a data inode. This results in this complaint: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&ei->i_data_sem); lock(&s->s_dquot.dqio_mutex); lock(&ei->i_data_sem); lock(&s->s_dquot.dqio_mutex); Google-Bug-Id: 27907753 Signed-off-by: Theodore Ts'o Signed-off-by: Ben Hutchings --- fs/ext4/ext4.h | 23 +++++++++++++++++++++++ fs/ext4/move_extent.c | 11 +++++++++-- fs/ext4/super.c | 25 +++++++++++++++++++++++-- 3 files changed, 55 insertions(+), 4 deletions(-) --- a/fs/ext4/ext4.h +++ b/fs/ext4/ext4.h @@ -850,6 +850,29 @@ do { \ #include "extents_status.h" /* + * Lock subclasses for i_data_sem in the ext4_inode_info structure. + * + * These are needed to avoid lockdep false positives when we need to + * allocate blocks to the quota inode during ext4_map_blocks(), while + * holding i_data_sem for a normal (non-quota) inode. Since we don't + * do quota tracking for the quota inode, this avoids deadlock (as + * well as infinite recursion, since it isn't turtles all the way + * down...) + * + * I_DATA_SEM_NORMAL - Used for most inodes + * I_DATA_SEM_OTHER - Used by move_inode.c for the second normal inode + * where the second inode has larger inode number + * than the first + * I_DATA_SEM_QUOTA - Used for quota inodes only + */ +enum { + I_DATA_SEM_NORMAL = 0, + I_DATA_SEM_OTHER, + I_DATA_SEM_QUOTA, +}; + + +/* * fourth extended file system inode data in memory */ struct ext4_inode_info { --- a/fs/ext4/move_extent.c +++ b/fs/ext4/move_extent.c @@ -154,10 +154,10 @@ ext4_double_down_write_data_sem(struct i { if (first < second) { down_write(&EXT4_I(first)->i_data_sem); - down_write_nested(&EXT4_I(second)->i_data_sem, SINGLE_DEPTH_NESTING); + down_write_nested(&EXT4_I(second)->i_data_sem, I_DATA_SEM_OTHER); } else { down_write(&EXT4_I(second)->i_data_sem); - down_write_nested(&EXT4_I(first)->i_data_sem, SINGLE_DEPTH_NESTING); + down_write_nested(&EXT4_I(first)->i_data_sem, I_DATA_SEM_OTHER); } } @@ -1124,6 +1124,13 @@ mext_check_arguments(struct inode *orig_ return -EINVAL; } + if (IS_NOQUOTA(orig_inode) || IS_NOQUOTA(donor_inode)) { + ext4_debug("ext4 move extent: The argument files should " + "not be quota files [ino:orig %lu, donor %lu]\n", + orig_inode->i_ino, donor_inode->i_ino); + return -EBUSY; + } + /* Ext4 move extent supports only extent based file */ if (!(ext4_test_inode_flag(orig_inode, EXT4_INODE_EXTENTS))) { ext4_debug("ext4 move extent: orig file is not extents " --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -5160,6 +5160,20 @@ static int ext4_quota_on_mount(struct su EXT4_SB(sb)->s_jquota_fmt, type); } +static void lockdep_set_quota_inode(struct inode *inode, int subclass) +{ + struct ext4_inode_info *ei = EXT4_I(inode); + + /* The first argument of lockdep_set_subclass has to be + * *exactly* the same as the argument to init_rwsem() --- in + * this case, in init_once() --- or lockdep gets unhappy + * because the name of the lock is set using the + * stringification of the argument to init_rwsem(). + */ + (void) ei; /* shut up clang warning if !CONFIG_LOCKDEP */ + lockdep_set_subclass(&ei->i_data_sem, subclass); +} + /* * Standard function to be called on quota_on */ @@ -5199,8 +5213,12 @@ static int ext4_quota_on(struct super_bl if (err) return err; } - - return dquot_quota_on(sb, type, format_id, path); + lockdep_set_quota_inode(path->dentry->d_inode, I_DATA_SEM_QUOTA); + err = dquot_quota_on(sb, type, format_id, path); + if (err) + lockdep_set_quota_inode(path->dentry->d_inode, + I_DATA_SEM_NORMAL); + return err; } static int ext4_quota_enable(struct super_block *sb, int type, int format_id, @@ -5226,8 +5244,11 @@ static int ext4_quota_enable(struct supe /* Don't account quota for quota files to avoid recursion */ qf_inode->i_flags |= S_NOQUOTA; + lockdep_set_quota_inode(qf_inode, I_DATA_SEM_QUOTA); err = dquot_enable(qf_inode, type, format_id, flags); iput(qf_inode); + if (err) + lockdep_set_quota_inode(qf_inode, I_DATA_SEM_NORMAL); return err; }