[PATCH] fs/namei.c: Hard link and rename should check same device instead of same mount

[Jordi Pujol Palomer <jordipujolp@gmail.com>]

[-- Attachment #1: Type: text/plain, Size: 395 bytes --]

Hello,

Working on a Linux system that bind mounts some
directories, have found frequent errors when moving files between
directories that belong to different mount points but are on the same
device.

The two attached patches solve these problems on a local filesystem.
Maybe we must test it on different configurations.

Thanks,

Jordi Pujol i Palomer
Enginyer Tècnic Industrial

[-- Attachment #2: fs-hard-link-check-same-device-instead-of-same-mount.patch --]
[-- Type: text/x-patch, Size: 503 bytes --]

Signed-off-by: Jordi Pujol Palomer <jordipujolp@gmail.com>
---
Subject: fs: Hard link must check same device instead of same mount
Date: Wed, 16 Mar 2016 09:12:21 +0100
--- linux-4.5.0-a/fs/namei.c
+++ linux-4.5.0-b/fs/namei.c	2016-03-15 22:15:03.275460823 +0100
@@ -4163,7 +4163,7 @@ retry:
 		goto out;
 
 	error = -EXDEV;
-	if (old_path.mnt != new_path.mnt)
+	if (old_path.dentry->d_sb->s_dev != new_path.dentry->d_sb->s_dev)
 		goto out_dput;
 	error = may_linkat(&old_path);
 	if (unlikely(error))

[-- Attachment #3: fs-rename-check-same-device-instead-of-same-mount.patch --]
[-- Type: text/x-patch, Size: 452 bytes --]

Signed-off-by: Jordi Pujol Palomer <jordipujolp@gmail.com>
---
Subject: fs: Rename must check same device instead of same mount
Date: Wed, 16 Mar 2016 09:12:21 +0100
--- linux-4.5.0-a/fs/namei.c
+++ linux-4.5.0-b/fs/namei.c	2016-03-15 22:15:03.275460823 +0100
@@ -4424,7 +4424,7 @@ retry:
 	}
 
 	error = -EXDEV;
-	if (old_path.mnt != new_path.mnt)
+	if (old_path.dentry->d_sb->s_dev != new_path.dentry->d_sb->s_dev)
 		goto exit2;
 
 	error = -EBUSY;