We need some more space to store overlay inode data in memory,
so allocate overlay inodes from a slab of struct ovl_inode.
The ovl_inode struct includes a mutex that is going to be used
for synchronizing copy up of lower hardlinks.
Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
---
fs/overlayfs/ovl_entry.h | 12 ++++++++++
fs/overlayfs/super.c | 62 ++++++++++++++++++++++++++++++++++++++++++++++--
2 files changed, 72 insertions(+), 2 deletions(-)
diff --git a/fs/overlayfs/ovl_entry.h b/fs/overlayfs/ovl_entry.h
index 6de8725cc38a..6c36fa70abe4 100644
--- a/fs/overlayfs/ovl_entry.h
+++ b/fs/overlayfs/ovl_entry.h
@@ -65,3 +65,15 @@ static inline struct dentry *ovl_upperdentry_dereference(struct ovl_entry *oe)
{
return lockless_dereference(oe->__upperdentry);
}
+
+struct ovl_inode {
+ /* keep this first */
+ struct inode vfs_inode;
+ /* synchronize copy up and more */
+ struct mutex oi_lock;
+};
+
+static inline struct ovl_inode *OVL_I(struct inode *inode)
+{
+ return (struct ovl_inode *) inode;
+}
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index b3ac406654bd..d32ae4c00f9c 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -170,6 +170,34 @@ static const struct dentry_operations ovl_reval_dentry_operations = {
.d_weak_revalidate = ovl_dentry_weak_revalidate,
};
+static struct kmem_cache *ovl_inode_cachep;
+
+static struct inode *ovl_alloc_inode(struct super_block *sb)
+{
+ struct inode *inode;
+
+ inode = kmem_cache_alloc(ovl_inode_cachep, GFP_KERNEL);
+ if (!inode)
+ return NULL;
+
+ mutex_init(&OVL_I(inode)->oi_lock);
+
+ return inode;
+}
+
+static void ovl_i_callback(struct rcu_head *head)
+{
+ struct inode *inode = container_of(head, struct inode, i_rcu);
+
+ kmem_cache_free(ovl_inode_cachep, inode);
+}
+
+static void ovl_destroy_inode(struct inode *inode)
+{
+ mutex_destroy(&OVL_I(inode)->oi_lock);
+ call_rcu(&inode->i_rcu, ovl_i_callback);
+}
+
/* Get exclusive ownership on upper/work dir among overlay mounts */
static bool ovl_dir_lock(struct dentry *dentry)
{
@@ -294,12 +322,14 @@ static int ovl_remount(struct super_block *sb, int *flags, char *data)
}
static const struct super_operations ovl_super_operations = {
+ .alloc_inode = ovl_alloc_inode,
+ .destroy_inode = ovl_destroy_inode,
+ .drop_inode = generic_delete_inode,
.put_super = ovl_put_super,
.sync_fs = ovl_sync_fs,
.statfs = ovl_statfs,
.show_options = ovl_show_options,
.remount_fs = ovl_remount,
- .drop_inode = generic_delete_inode,
};
enum {
@@ -1171,14 +1201,42 @@ static struct file_system_type ovl_fs_type = {
};
MODULE_ALIAS_FS("overlay");
+static void ovl_inode_init_once(void *foo)
+{
+ struct inode *inode = foo;
+
+ inode_init_once(inode);
+}
+
static int __init ovl_init(void)
{
- return register_filesystem(&ovl_fs_type);
+ int err;
+
+ ovl_inode_cachep = kmem_cache_create("ovl_inode",
+ sizeof(struct ovl_inode), 0,
+ SLAB_HWCACHE_ALIGN|SLAB_ACCOUNT,
+ ovl_inode_init_once);
+ if (ovl_inode_cachep == NULL)
+ return -ENOMEM;
+
+ err = register_filesystem(&ovl_fs_type);
+ if (err)
+ kmem_cache_destroy(ovl_inode_cachep);
+
+ return err;
}
static void __exit ovl_exit(void)
{
unregister_filesystem(&ovl_fs_type);
+
+ /*
+ * Make sure all delayed rcu free inodes are flushed before we
+ * destroy cache.
+ */
+ rcu_barrier();
+ kmem_cache_destroy(ovl_inode_cachep);
+
}
module_init(ovl_init);
--
2.7.4
--
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