i_rcu (struct rcu_head) has two pointers but it is unioned with i_dentry
(struct hlist_head) which has only one pointer. Union i_rcu with
i_sb_list instead and thus safe one pointer in struct inode.
Signed-off-by: Jan Kara <jack@xxxxxxx>
---
Documentation/filesystems/porting | 5 -----
fs/inode.c | 3 ++-
include/linux/fs.h | 4 ++--
3 files changed, 4 insertions(+), 8 deletions(-)
diff --git a/Documentation/filesystems/porting b/Documentation/filesystems/porting
index fe2b7ae6f962..26ce6cd742c6 100644
--- a/Documentation/filesystems/porting
+++ b/Documentation/filesystems/porting
@@ -354,11 +354,6 @@ protects *all* the dcache state of a given dentry.
via rcu-walk path walk (basically, if the file can have had a path name in the
vfs namespace).
- Even though i_dentry and i_rcu share storage in a union, we will
-initialize the former in inode_init_always(), so just leave it alone in
-the callback. It used to be necessary to clean it there, but not anymore
-(starting at 3.2).
-
--
[recommended]
vfs now tries to do path walking in "rcu-walk mode", which avoids
diff --git a/fs/inode.c b/fs/inode.c
index e89be4c4c9f4..1b888eb524ca 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -183,7 +183,7 @@ int inode_init_always(struct super_block *sb, struct inode *inode)
}
inode->i_private = NULL;
inode->i_mapping = mapping;
- INIT_HLIST_HEAD(&inode->i_dentry); /* buggered by rcu freeing */
+ INIT_LIST_HEAD(&inode->i_sb_list); /* buggered by rcu freeing */
#ifdef CONFIG_FS_POSIX_ACL
inode->i_acl = inode->i_default_acl = ACL_NOT_CACHED;
#endif
@@ -258,6 +258,7 @@ static void i_callback(struct rcu_head *head)
static void destroy_inode(struct inode *inode)
{
BUG_ON(!list_empty(&inode->i_lru));
+ BUG_ON(!list_empty(&inode->i_sb_list));
__destroy_inode(inode);
if (inode->i_sb->s_op->destroy_inode)
inode->i_sb->s_op->destroy_inode(inode);
diff --git a/include/linux/fs.h b/include/linux/fs.h
index ac6e06a09980..b76720852f5f 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -579,9 +579,9 @@ struct inode {
struct hlist_node i_hash;
struct list_head i_wb_list; /* backing dev IO list */
struct list_head i_lru; /* inode LRU list */
- struct list_head i_sb_list;
+ struct hlist_head i_dentry;
union {
- struct hlist_head i_dentry;
+ struct list_head i_sb_list;
struct rcu_head i_rcu;
};
u64 i_version;
--
1.8.1.4
--
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