Guys, While Andrew discovered a bug with non atomic d_move usage in rename patch (http://marc.info/?l=linux-fsdevel&m=147584842303074&w=2), i make a patch which solve a problem. May you review it? Before LRU lookup landing cwd vs d_move race was resolved via dcache_lock, but now, dentry may move into invalid state while rehashed due non atomic dentry->d_hash changes. Patch tries to solve it problem and Andrew reproducer run a hours now without error. Reported-by: Andrew Perepechko <anserper@xxxxxxxxx> Signed-off-by: Alexey Lyashkov <alexey.lyashkov@xxxxxxxxx> diff --git a/fs/dcache.c b/fs/dcache.c index 5c7cc95..86a65d2 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -438,7 +438,7 @@ static void dentry_lru_add(struct dentry *dentry) */ void __d_drop(struct dentry *dentry) { - if (!d_unhashed(dentry)) { + if (!hlist_bl_unhashed(&dentry->d_hash)) { struct hlist_bl_head *b; /* * Hashed dentries are normally on the dentry hashtable, @@ -2342,7 +2342,8 @@ EXPORT_SYMBOL(d_delete); static void __d_rehash(struct dentry *entry) { struct hlist_bl_head *b = d_hash(entry->d_name.hash); - BUG_ON(!d_unhashed(entry)); + + BUG_ON(!hlist_bl_unhashed(&entry->d_hash)); hlist_bl_lock(b); hlist_bl_add_head_rcu(&entry->d_hash, b); hlist_bl_unlock(b); diff --git a/include/linux/dcache.h b/include/linux/dcache.h index 5beed7b..83ba074 100644 --- a/include/linux/dcache.h +++ b/include/linux/dcache.h @@ -330,7 +330,15 @@ extern struct dentry *dget_parent(struct dentry *dentry); static inline int d_unhashed(const struct dentry *dentry) { - return hlist_bl_unhashed(&dentry->d_hash); + int ret; + unsigned int seq; + + do { + seq = read_seqcount_begin(&dentry->d_seq); + ret = hlist_bl_unhashed(&dentry->d_hash); + } while (read_seqcount_retry(&dentry->d_seq, seq)); + + return ret; } static inline int d_unlinked(const struct dentry *dentry) Alexey Lyashkov alexey.lyashkov@xxxxxxxxx -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
