From: Theodore Ts'o Subject: [PATCH 4/5] ext4: Replace lock/unlock_super() with an explicit lock for the orphan list Date: Sat, 25 Apr 2009 23:49:24 -0400 Message-ID: <1240717765-16572-5-git-send-email-tytso@mit.edu> References: <1240717765-16572-1-git-send-email-tytso@mit.edu> <1240717765-16572-2-git-send-email-tytso@mit.edu> <1240717765-16572-3-git-send-email-tytso@mit.edu> <1240717765-16572-4-git-send-email-tytso@mit.edu> Cc: Linux Kernel Developers List , Christoph Hellwig , Al Viro , Theodore Ts'o To: Ext4 Developers List Return-path: Received: from THUNK.ORG ([69.25.196.29]:60013 "EHLO thunker.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752839AbZDZDtc (ORCPT ); Sat, 25 Apr 2009 23:49:32 -0400 In-Reply-To: <1240717765-16572-4-git-send-email-tytso@mit.edu> Sender: linux-ext4-owner@vger.kernel.org List-ID: Use a separate lock to protect the orphan list, so we can stop overloading the use of lock_super(). Signed-off-by: "Theodore Ts'o" --- fs/ext4/ext4_sb.h | 1 + fs/ext4/namei.c | 20 +++++++++++--------- fs/ext4/super.c | 1 + 3 files changed, 13 insertions(+), 9 deletions(-) diff --git a/fs/ext4/ext4_sb.h b/fs/ext4/ext4_sb.h index 57b71fe..4bda2f7 100644 --- a/fs/ext4/ext4_sb.h +++ b/fs/ext4/ext4_sb.h @@ -71,6 +71,7 @@ struct ext4_sb_info { struct inode *s_journal_inode; struct journal_s *s_journal; struct list_head s_orphan; + struct mutex s_orphan_lock; unsigned long s_commit_interval; u32 s_max_batch_time; u32 s_min_batch_time; diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c index 22098e1..8018e49 100644 --- a/fs/ext4/namei.c +++ b/fs/ext4/namei.c @@ -1997,7 +1997,7 @@ int ext4_orphan_add(handle_t *handle, struct inode *inode) if (!ext4_handle_valid(handle)) return 0; - lock_super(sb); + mutex_lock(&EXT4_SB(sb)->s_orphan_lock); if (!list_empty(&EXT4_I(inode)->i_orphan)) goto out_unlock; @@ -2006,9 +2006,13 @@ int ext4_orphan_add(handle_t *handle, struct inode *inode) /* @@@ FIXME: Observation from aviro: * I think I can trigger J_ASSERT in ext4_orphan_add(). We block - * here (on lock_super()), so race with ext4_link() which might bump + * here (on s_orphan_lock), so race with ext4_link() which might bump * ->i_nlink. For, say it, character device. Not a regular file, * not a directory, not a symlink and ->i_nlink > 0. + * + * tytso, 4/25/2009: I'm not sure how that could happen; + * shouldn't the fs core protect us from these sort of + * unlink()/link() races? */ J_ASSERT((S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) || S_ISLNK(inode->i_mode)) || inode->i_nlink == 0); @@ -2045,7 +2049,7 @@ int ext4_orphan_add(handle_t *handle, struct inode *inode) jbd_debug(4, "orphan inode %lu will point to %d\n", inode->i_ino, NEXT_ORPHAN(inode)); out_unlock: - unlock_super(sb); + mutex_unlock(&EXT4_SB(sb)->s_orphan_lock); ext4_std_error(inode->i_sb, err); return err; } @@ -2066,11 +2070,9 @@ int ext4_orphan_del(handle_t *handle, struct inode *inode) if (!ext4_handle_valid(handle)) return 0; - lock_super(inode->i_sb); - if (list_empty(&ei->i_orphan)) { - unlock_super(inode->i_sb); - return 0; - } + mutex_lock(&EXT4_SB(inode->i_sb)->s_orphan_lock); + if (list_empty(&ei->i_orphan)) + goto out; ino_next = NEXT_ORPHAN(inode); prev = ei->i_orphan.prev; @@ -2120,7 +2122,7 @@ int ext4_orphan_del(handle_t *handle, struct inode *inode) out_err: ext4_std_error(inode->i_sb, err); out: - unlock_super(inode->i_sb); + mutex_unlock(&EXT4_SB(inode->i_sb)->s_orphan_lock); return err; out_brelse: diff --git a/fs/ext4/super.c b/fs/ext4/super.c index 176d43f..c23e82c 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -2623,6 +2623,7 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent) sb->dq_op = &ext4_quota_operations; #endif INIT_LIST_HEAD(&sbi->s_orphan); /* unlinked but open files */ + mutex_init(&sbi->s_orphan_lock); sb->s_root = NULL; -- 1.5.6.3