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[PATCH] ext4: add a new spinlock i_raw_lock to protect the ext4's raw in

To: xfs@xxxxxxxxxxx
Subject: [PATCH] ext4: add a new spinlock i_raw_lock to protect the ext4's raw inode
From: Theodore Ts'o <tytso@xxxxxxx>
Date: Sat, 12 Apr 2014 18:55:14 -0400
Cc: Ext4 Developers List <linux-ext4@xxxxxxxxxxxxxxx>, Theodore Ts'o <tytso@xxxxxxx>
Delivered-to: xfs@xxxxxxxxxxx
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To avoid potential data races, use a spinlock which protects the raw
(on-disk) inode.

Signed-off-by: "Theodore Ts'o" <tytso@xxxxxxx>
---
 fs/ext4/ext4.h  | 2 ++
 fs/ext4/inode.c | 5 ++++-
 fs/ext4/super.c | 1 +
 3 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 86c2cda..1d08a1b 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -875,6 +875,8 @@ struct ext4_inode_info {
        struct inode vfs_inode;
        struct jbd2_inode *jinode;
 
+       spinlock_t i_raw_lock;  /* protects updates to the raw inode */
+
        /*
         * File creation time. Its function is same as that of
         * struct timespec i_{a,c,m}time in the generic inode.
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 2eb5fad..1ee8ff6 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -4311,7 +4311,9 @@ static int ext4_do_update_inode(handle_t *handle,
        uid_t i_uid;
        gid_t i_gid;
 
-       /* For fields not not tracking in the in-memory inode,
+       spin_lock(&ei->i_raw_lock);
+
+       /* For fields not tracked in the in-memory inode,
         * initialise them to zero for new inodes. */
        if (ext4_test_inode_state(inode, EXT4_STATE_NEW))
                memset(raw_inode, 0, EXT4_SB(inode->i_sb)->s_inode_size);
@@ -4419,6 +4421,7 @@ static int ext4_do_update_inode(handle_t *handle,
 
        ext4_update_inode_fsync_trans(handle, inode, need_datasync);
 out_brelse:
+       spin_unlock(&ei->i_raw_lock);
        brelse(bh);
        ext4_std_error(inode->i_sb, err);
        return err;
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index c4895c1..1f8cb18 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -879,6 +879,7 @@ static struct inode *ext4_alloc_inode(struct super_block 
*sb)
                return NULL;
 
        ei->vfs_inode.i_version = 1;
+       spin_lock_init(&ei->i_raw_lock);
        INIT_LIST_HEAD(&ei->i_prealloc_list);
        spin_lock_init(&ei->i_prealloc_lock);
        ext4_es_init_tree(&ei->i_es_tree);
-- 
1.9.0

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