--- zzzz-none-000/linux-3.10.107/fs/fat/namei_vfat.c	2017-06-27 09:49:32.000000000 +0000
+++ scorpion-7490-727/linux-3.10.107/fs/fat/namei_vfat.c	2021-02-04 17:41:59.000000000 +0000
@@ -16,10 +16,8 @@
  */
 
 #include <linux/module.h>
-#include <linux/jiffies.h>
 #include <linux/ctype.h>
 #include <linux/slab.h>
-#include <linux/buffer_head.h>
 #include <linux/namei.h>
 #include "fat.h"
 
@@ -35,7 +33,7 @@
 {
 	int ret = 1;
 	spin_lock(&dentry->d_lock);
-	if (dentry->d_time != dentry->d_parent->d_inode->i_version)
+	if (dentry->d_time != d_inode(dentry->d_parent)->i_version)
 		ret = 0;
 	spin_unlock(&dentry->d_lock);
 	return ret;
@@ -47,7 +45,7 @@
 		return -ECHILD;
 
 	/* This is not negative dentry. Always valid. */
-	if (dentry->d_inode)
+	if (d_really_is_positive(dentry))
 		return 1;
 	return vfat_revalidate_shortname(dentry);
 }
@@ -67,7 +65,7 @@
 	 * positive dentry isn't good idea. So it's unsupported like
 	 * rename("filename", "FILENAME") for now.
 	 */
-	if (dentry->d_inode)
+	if (d_really_is_positive(dentry))
 		return 1;
 
 	/*
@@ -107,8 +105,7 @@
  * that the existing dentry can be used. The vfat fs routines will
  * return ENOENT or EINVAL as appropriate.
  */
-static int vfat_hash(const struct dentry *dentry, const struct inode *inode,
-		struct qstr *qstr)
+static int vfat_hash(const struct dentry *dentry, struct qstr *qstr)
 {
 	qstr->hash = full_name_hash(qstr->name, vfat_striptail_len(qstr));
 	return 0;
@@ -120,8 +117,7 @@
  * that the existing dentry can be used. The vfat fs routines will
  * return ENOENT or EINVAL as appropriate.
  */
-static int vfat_hashi(const struct dentry *dentry, const struct inode *inode,
-		struct qstr *qstr)
+static int vfat_hashi(const struct dentry *dentry, struct qstr *qstr)
 {
 	struct nls_table *t = MSDOS_SB(dentry->d_sb)->nls_io;
 	const unsigned char *name;
@@ -142,8 +138,7 @@
 /*
  * Case insensitive compare of two vfat names.
  */
-static int vfat_cmpi(const struct dentry *parent, const struct inode *pinode,
-		const struct dentry *dentry, const struct inode *inode,
+static int vfat_cmpi(const struct dentry *parent, const struct dentry *dentry,
 		unsigned int len, const char *str, const struct qstr *name)
 {
 	struct nls_table *t = MSDOS_SB(parent->d_sb)->nls_io;
@@ -162,8 +157,7 @@
 /*
  * Case sensitive compare of two vfat names.
  */
-static int vfat_cmp(const struct dentry *parent, const struct inode *pinode,
-		const struct dentry *dentry, const struct inode *inode,
+static int vfat_cmp(const struct dentry *parent, const struct dentry *dentry,
 		unsigned int len, const char *str, const struct qstr *name)
 {
 	unsigned int alen, blen;
@@ -740,7 +734,12 @@
 	}
 
 	alias = d_find_alias(inode);
-	if (alias && !vfat_d_anon_disconn(alias)) {
+	/*
+	 * Checking "alias->d_parent == dentry->d_parent" to make sure
+	 * FS is not corrupted (especially double linked dir).
+	 */
+	if (alias && alias->d_parent == dentry->d_parent &&
+	    !vfat_d_anon_disconn(alias)) {
 		/*
 		 * This inode has non anonymous-DCACHE_DISCONNECTED
 		 * dentry. This means, the user did ->lookup() by an
@@ -759,12 +758,9 @@
 
 out:
 	mutex_unlock(&MSDOS_SB(sb)->s_lock);
-	dentry->d_time = dentry->d_parent->d_inode->i_version;
-	dentry = d_splice_alias(inode, dentry);
-	if (dentry)
-		dentry->d_time = dentry->d_parent->d_inode->i_version;
-	return dentry;
-
+	if (!inode)
+		dentry->d_time = dir->i_version;
+	return d_splice_alias(inode, dentry);
 error:
 	mutex_unlock(&MSDOS_SB(sb)->s_lock);
 	return ERR_PTR(err);
@@ -797,7 +793,6 @@
 	inode->i_mtime = inode->i_atime = inode->i_ctime = ts;
 	/* timestamp is already written, so mark_inode_dirty() is unneeded. */
 
-	dentry->d_time = dentry->d_parent->d_inode->i_version;
 	d_instantiate(dentry, inode);
 out:
 	mutex_unlock(&MSDOS_SB(sb)->s_lock);
@@ -806,7 +801,7 @@
 
 static int vfat_rmdir(struct inode *dir, struct dentry *dentry)
 {
-	struct inode *inode = dentry->d_inode;
+	struct inode *inode = d_inode(dentry);
 	struct super_block *sb = dir->i_sb;
 	struct fat_slot_info sinfo;
 	int err;
@@ -828,6 +823,7 @@
 	clear_nlink(inode);
 	inode->i_mtime = inode->i_atime = CURRENT_TIME_SEC;
 	fat_detach(inode);
+	dentry->d_time = dir->i_version;
 out:
 	mutex_unlock(&MSDOS_SB(sb)->s_lock);
 
@@ -836,7 +832,7 @@
 
 static int vfat_unlink(struct inode *dir, struct dentry *dentry)
 {
-	struct inode *inode = dentry->d_inode;
+	struct inode *inode = d_inode(dentry);
 	struct super_block *sb = dir->i_sb;
 	struct fat_slot_info sinfo;
 	int err;
@@ -853,6 +849,7 @@
 	clear_nlink(inode);
 	inode->i_mtime = inode->i_atime = CURRENT_TIME_SEC;
 	fat_detach(inode);
+	dentry->d_time = dir->i_version;
 out:
 	mutex_unlock(&MSDOS_SB(sb)->s_lock);
 
@@ -893,7 +890,6 @@
 	inode->i_mtime = inode->i_atime = inode->i_ctime = ts;
 	/* timestamp is already written, so mark_inode_dirty() is unneeded. */
 
-	dentry->d_time = dentry->d_parent->d_inode->i_version;
 	d_instantiate(dentry, inode);
 
 	mutex_unlock(&MSDOS_SB(sb)->s_lock);
@@ -919,8 +915,8 @@
 	struct super_block *sb = old_dir->i_sb;
 
 	old_sinfo.bh = sinfo.bh = dotdot_bh = NULL;
-	old_inode = old_dentry->d_inode;
-	new_inode = new_dentry->d_inode;
+	old_inode = d_inode(old_dentry);
+	new_inode = d_inode(new_dentry);
 	mutex_lock(&MSDOS_SB(sb)->s_lock);
 	err = vfat_find(old_dir, &old_dentry->d_name, &old_sinfo);
 	if (err)