Skip to contentSkip to conversation

Patch "overlayfs: Make f_path always point to the overlay and f_inode to the underlay" has been added to the 4.1-stable tree

PATCH [email protected] 1 participant 1 message Oct 18, 2015

Subsystems (3)
Stable branch VFS Overlay filesystem
lore
Share & tools
lore

[email protected]

author maintainer Applied
#0 lore raw

This is a note to let you know that I've just added the patch titled

overlayfs: Make f_path always point to the overlay and f_inode to the underlay

to the 4.1-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
overlayfs-make-f_path-always-point-to-the-overlay-and-f_inode-to-the-underlay.patch
and it can be found in the queue-4.1 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

Quoted 1 line

From 4bacc9c9234c7c8eec44f5ed4e960d9f96fa0f01 Mon Sep 17 00:00:00 2001

From: David Howells <[email protected]>
Date: Thu, 18 Jun 2015 14:32:31 +0100
Subject: overlayfs: Make f_path always point to the overlay and f_inode to the underlay

From: David Howells <[email protected]>

commit 4bacc9c9234c7c8eec44f5ed4e960d9f96fa0f01 upstream.

Make file->f_path always point to the overlay dentry so that the path in /proc/pid/fd is correct and to ensure that label-based LSMs have access to the overlay as well as the underlay (path-based LSMs probably don't need it).

Using my union testsuite to set things up, before the patch I see:

	[root@andromeda union-testsuite]# bash 5</mnt/a/foo107
	[root@andromeda union-testsuite]# ls -l /proc/$$/fd/
	...
	lr-x------. 1 root root 64 Jun  5 14:38 5 -> /a/foo107
	[root@andromeda union-testsuite]# stat /mnt/a/foo107
	...
	Device: 23h/35d Inode: 13381       Links: 1
	...
	[root@andromeda union-testsuite]# stat -L /proc/$$/fd/5
	...
	Device: 23h/35d Inode: 13381       Links: 1
	...

After the patch:

	[root@andromeda union-testsuite]# bash 5</mnt/a/foo107
	[root@andromeda union-testsuite]# ls -l /proc/$$/fd/
	...
	lr-x------. 1 root root 64 Jun  5 14:22 5 -> /mnt/a/foo107
	[root@andromeda union-testsuite]# stat /mnt/a/foo107
	...
	Device: 23h/35d Inode: 40346       Links: 1
	...
	[root@andromeda union-testsuite]# stat -L /proc/$$/fd/5
	...
	Device: 23h/35d Inode: 40346       Links: 1
	...

Note the change in where /proc/$$/fd/5 points to in the ls command. It was pointing to /a/foo107 (which doesn't exist) and now points to /mnt/a/foo107 (which is correct).

The inode accessed, however, is the lower layer. The union layer is on device 25h/37d and the upper layer on 24h/36d.

Signed-off-by David Howells <[email protected]>
Signed-off-by Al Viro <[email protected]>
Cc "Kamata, Munehisa" <[email protected]>
Signed-off-by Greg Kroah-Hartman <[email protected]>
---
 fs/dcache.c              |    5 +++-
 fs/internal.h            |    1 
 fs/open.c                |   49 ++++++++++++++++++++++++-----------------------
 fs/overlayfs/inode.c     |   14 +++++--------
 fs/overlayfs/overlayfs.h |    1 
 fs/overlayfs/super.c     |    1 
 include/linux/dcache.h   |    2 +
 include/linux/fs.h       |    2 -
 8 files changed, 41 insertions(+), 34 deletions(-)
fs/dcache.c +4 -1
@@ -1676,7 +1676,8 @@ void d_set_d_op(struct dentry *dentry, c
 				DCACHE_OP_COMPARE	|
 				DCACHE_OP_REVALIDATE	|
 				DCACHE_OP_WEAK_REVALIDATE	|
-				DCACHE_OP_DELETE ));
+				DCACHE_OP_DELETE	|
+				DCACHE_OP_SELECT_INODE));
 	dentry->d_op = op;
 	if (!op)
 		return;

@@ -1692,6 +1693,8 @@ void d_set_d_op(struct dentry *dentry, c
 		dentry->d_flags |= DCACHE_OP_DELETE;
 	if (op->d_prune)
 		dentry->d_flags |= DCACHE_OP_PRUNE;
+	if (op->d_select_inode)
+		dentry->d_flags |= DCACHE_OP_SELECT_INODE;
 
 }
 EXPORT_SYMBOL(d_set_d_op);
fs/internal.h +1 -0
@@ -107,6 +107,7 @@ extern struct file *do_file_open_root(st
 extern long do_handle_open(int mountdirfd,
 			   struct file_handle __user *ufh, int open_flag);
 extern int open_check_o_direct(struct file *f);
+extern int vfs_open(const struct path *, struct file *, const struct cred *);
 
 /*
  * inode.c
fs/open.c +26 -23

83 lines not on this page · raw message

fs/overlayfs/inode.c +6 -8
@@ -336,31 +336,30 @@ static bool ovl_open_need_copy_up(int fl
 	return true;
 }
 
-static int ovl_dentry_open(struct dentry *dentry, struct file *file,
-		    const struct cred *cred)
+struct inode *ovl_d_select_inode(struct dentry *dentry, unsigned file_flags)
 {
 	int err;
 	struct path realpath;
 	enum ovl_path_type type;
 
 	type = ovl_path_real(dentry, &realpath);
-	if (ovl_open_need_copy_up(file->f_flags, type, realpath.dentry)) {
+	if (ovl_open_need_copy_up(file_flags, type, realpath.dentry)) {
 		err = ovl_want_write(dentry);
 		if (err)
-			return err;
+			return ERR_PTR(err);
 
-		if (file->f_flags & O_TRUNC)
+		if (file_flags & O_TRUNC)
 			err = ovl_copy_up_last(dentry, NULL, true);
 		else
 			err = ovl_copy_up(dentry);
 		ovl_drop_write(dentry);
 		if (err)
-			return err;
+			return ERR_PTR(err);
 
 		ovl_path_upper(dentry, &realpath);
 	}
 
-	return vfs_open(&realpath, file, cred);
+	return d_backing_inode(realpath.dentry);
 }
 
 static const struct inode_operations ovl_file_inode_operations = {

@@ -371,7 +370,6 @@ static const struct inode_operations ovl
 	.getxattr	= ovl_getxattr,
 	.listxattr	= ovl_listxattr,
 	.removexattr	= ovl_removexattr,
-	.dentry_open	= ovl_dentry_open,
 };
 
 static const struct inode_operations ovl_symlink_inode_operations = {
fs/overlayfs/overlayfs.h +1 -0
@@ -173,6 +173,7 @@ ssize_t ovl_getxattr(struct dentry *dent
 		     void *value, size_t size);
 ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size);
 int ovl_removexattr(struct dentry *dentry, const char *name);
+struct inode *ovl_d_select_inode(struct dentry *dentry, unsigned file_flags);
 
 struct inode *ovl_new_inode(struct super_block *sb, umode_t mode,
 			    struct ovl_entry *oe);
fs/overlayfs/super.c +1 -0
@@ -275,6 +275,7 @@ static void ovl_dentry_release(struct de
 
 static const struct dentry_operations ovl_dentry_operations = {
 	.d_release = ovl_dentry_release,
+	.d_select_inode = ovl_d_select_inode,
 };
 
 static struct ovl_entry *ovl_alloc_entry(unsigned int numlower)
include/linux/dcache.h +2 -0
@@ -160,6 +160,7 @@ struct dentry_operations {
 	char *(*d_dname)(struct dentry *, char *, int);
 	struct vfsmount *(*d_automount)(struct path *);
 	int (*d_manage)(struct dentry *, bool);
+	struct inode *(*d_select_inode)(struct dentry *, unsigned);
 } ____cacheline_aligned;
 
 /*

@@ -225,6 +226,7 @@ struct dentry_operations {
 
 #define DCACHE_MAY_FREE			0x00800000
 #define DCACHE_FALLTHRU			0x01000000 /* Fall through to lower layer */
+#define DCACHE_OP_SELECT_INODE		0x02000000 /* Unioned entry: dcache op selects inode */
 
 extern seqlock_t rename_lock;
include/linux/fs.h +0 -2
@@ -1641,7 +1641,6 @@ struct inode_operations {
 	int (*set_acl)(struct inode *, struct posix_acl *, int);
 
 	/* WARNING: probably going away soon, do not use! */
-	int (*dentry_open)(struct dentry *, struct file *, const struct cred *);
 } ____cacheline_aligned;
 
 ssize_t rw_copy_check_uvector(int type, const struct iovec __user * uvector,

@@ -2193,7 +2192,6 @@ extern struct file *file_open_name(struc
 extern struct file *filp_open(const char *, int, umode_t);
 extern struct file *file_open_root(struct dentry *, struct vfsmount *,
 				   const char *, int);
-extern int vfs_open(const struct path *, struct file *, const struct cred *);
 extern struct file * dentry_open(const struct path *, int, const struct cred *);
 extern int filp_close(struct file *, fl_owner_t id);

Patches currently in stable-queue which might be from [email protected] are

queue-4.1/overlay-call-ovl_drop_write-earlier-in-ovl_dentry_open.patch queue-4.1/overlayfs-make-f_path-always-point-to-the-overlay-and-f_inode-to-the-underlay.patch