[3/5] pstore: add subdirs for multi-backends

diff --git a/fs/pstore/inode.c b/fs/pstore/inode.c
index 312e7d55b95f..0f6d888a3b06 100644
--- a/fs/pstore/inode.c
+++ b/fs/pstore/inode.c
@@ -288,9 +288,14 @@  static const struct super_operations pstore_ops = {
 	.show_options	= pstore_show_options,
 };
 
-static struct dentry *psinfo_lock_root(struct pstore_info *psinfo)
+static struct dentry *psinfo_lock(struct pstore_info *psinfo)
 {
-	struct dentry *root;
+	struct dentry *dentry;
+	struct qstr qname;
+
+	qname.name = psinfo->name;
+	qname.len  = strlen(psinfo->name);
+	qname.hash = full_name_hash(pstore_sb->s_root, qname.name, qname.len);
 
 	mutex_lock(&pstore_sb_lock);
 	/*
@@ -302,11 +307,16 @@  static struct dentry *psinfo_lock_root(struct pstore_info *psinfo)
 		return NULL;
 	}
 
-	root = pstore_sb->s_root;
-	inode_lock(d_inode(root));
+	dentry = d_lookup(pstore_sb->s_root, &qname);
+	if (!dentry) {
+		mutex_unlock(&pstore_sb_lock);
+		return NULL;
+	}
+
+	inode_lock(d_inode(dentry));
 	mutex_unlock(&pstore_sb_lock);
 
-	return root;
+	return dentry;
 }
 
 int pstore_put_backend_records(struct pstore_info *psi)
@@ -315,7 +325,7 @@  int pstore_put_backend_records(struct pstore_info *psi)
 	struct dentry *root;
 	int rc = 0;
 
-	root = psinfo_lock_root(psi);
+	root = psinfo_lock(psi);
 	if (!root)
 		return 0;
 
@@ -416,14 +426,60 @@  int pstore_mkfile(struct dentry *root, struct pstore_record *record)
  */
 void pstore_get_records(struct pstore_info *psi, int pos, int quiet)
 {
+	struct dentry *dentry;
+
+	dentry = psinfo_lock(psi);
+	if (!dentry)
+		return;
+
+	pstore_get_backend_records(psi, dentry, quiet, pos);
+	inode_unlock(d_inode(dentry));
+}
+
+void pstore_mksubdir(struct pstore_info *psi)
+{
+	struct dentry *dentry;
+	struct inode *inode;
 	struct dentry *root;
+	struct qstr qname;
 
-	root = psinfo_lock_root(psi);
-	if (!root)
+	if (!psi || !pstore_sb)
+		return;
+
+	root = pstore_sb->s_root;
+	qname.name = psi->name;
+	qname.len = strlen(psi->name);
+	qname.hash = full_name_hash(root, qname.name, qname.len);
+	dentry = d_lookup(root, &qname);
+
+	/* Skip if subdir is already present in the filesystem. */
+	if (dentry)
 		return;
 
-	pstore_get_backend_records(psi, root, quiet, pos);
+	inode_lock(d_inode(root));
+
+	dentry = d_alloc_name(root, psi->name);
+	if (!dentry)
+		goto fail;
+
+	inode = pstore_get_inode(pstore_sb);
+	if (!inode) {
+		dput(dentry);
+		dentry = ERR_PTR(-ENOMEM);
+		goto fail;
+	}
+	inode->i_mode = S_IFDIR | 0750;
+	inode->i_op = &pstore_dir_inode_operations;
+	inode->i_fop = &simple_dir_operations;
+
+	inc_nlink(inode);
+	inc_nlink(d_inode(root));
+
+	d_add(dentry, inode);
+
+fail:
 	inode_unlock(d_inode(root));
+	return;
 }
 
 static int pstore_fill_super(struct super_block *sb, void *data, int silent)
@@ -456,10 +512,14 @@  static int pstore_fill_super(struct super_block *sb, void *data, int silent)
 	mutex_unlock(&pstore_sb_lock);
 
 	rcu_read_lock();
-	list_for_each_entry_rcu(entry, &psback->list_entry, list)
+	list_for_each_entry_rcu(entry, &psback->list_entry, list) {
+		pstore_mksubdir(entry->psi);
 		pstore_get_records(entry->psi, entry->index, 0);
+	}
 	rcu_read_unlock();
 
+	psback->fs_ready = true;
+
 	return 0;
 }
 
diff --git a/fs/pstore/internal.h b/fs/pstore/internal.h
index 7465b5baf002..20449ca940bb 100644
--- a/fs/pstore/internal.h
+++ b/fs/pstore/internal.h
@@ -44,6 +44,7 @@  static inline void pstore_unregister_tty(void) {}
 extern struct pstore_backends *psback;
 
 extern void	pstore_set_kmsg_bytes(int);
+extern void	pstore_mksubdir(struct pstore_info *psi);
 extern void	pstore_get_records(struct pstore_info *psi, int pos,
 						int quiet);
 extern void	pstore_get_backend_records(struct pstore_info *psi,
diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
index 34fb21e6ff4f..d576ee48527c 100644
--- a/fs/pstore/platform.c
+++ b/fs/pstore/platform.c
@@ -652,7 +652,10 @@  int pstore_register(struct pstore_info *psi)
 	if (psi->flags & PSTORE_FLAGS_DMESG && !psback->front_cnt[PSTORE_TYPE_DMESG])
 		allocate_buf_for_compression(psi, newpsi->index);
 
-	pstore_get_records(psi, newpsi->index, 0);
+	if (psback->fs_ready) {
+		pstore_mksubdir(psi);
+		pstore_get_records(psi, newpsi->index, 0);
+	}
 
 	list_add_rcu(&newpsi->list, &psback->list_entry);
 
diff --git a/include/linux/pstore.h b/include/linux/pstore.h
index ede60617d778..306597545f2d 100644
--- a/include/linux/pstore.h
+++ b/include/linux/pstore.h
@@ -220,6 +220,7 @@  struct pstore_info_list {
  * @list_entry:	entry of pstore backend driver information list
  * @front_cnt:	count of each enabled frontend
  * @flag:	bitmap of enabled pstore backend
+ * @fs_ready:	whether the pstore filesystem is ready
  *
  */
 
@@ -227,6 +228,7 @@  struct pstore_backends {
 	struct list_head list_entry;
 	int front_cnt[PSTORE_TYPE_MAX];
 	u16 flag;
+	bool fs_ready;
 };
 
 /* Supported frontends */