Unverified Commit 822c1159 authored by Christian Brauner's avatar Christian Brauner
Browse files

Merge patch series "CONFIG_DEBUG_VFS at last" 

Mateusz Guzik <mjguzik@gmail.com> says:

This adds a super basic version just to get the mechanism going, along
with sample usage.

The macro set is incomplete (e.g., lack of locking macros) and
dump_inode routine fails to dump any state yet, to be implemented(tm).

I think despite the primitive state this is complete enough to start
sprinkling asserts as necessary.

* patches from https://lore.kernel.org/r/20250209185523.745956-1-mjguzik@gmail.com:
  vfs: use the new debug macros in inode_set_cached_link()
  vfs: catch invalid modes in may_open()
  vfs: add initial support for CONFIG_DEBUG_VFS

Link: https://lore.kernel.org/r/20250209185523.745956-1-mjguzik@gmail.com


Signed-off-by: default avatarChristian Brauner <brauner@kernel.org>
parents 2014c95a 3eb7e951

fs/inode.c

+15 −0
Original line number Diff line number Diff line
@@ -2953,3 +2953,18 @@ umode_t mode_strip_sgid(struct mnt_idmap *idmap, 
	return mode & ~S_ISGID;

}

EXPORT_SYMBOL(mode_strip_sgid);



#ifdef CONFIG_DEBUG_VFS

/*

 * Dump an inode.

 *

 * TODO: add a proper inode dumping routine, this is a stub to get debug off the

 * ground.

 */

void dump_inode(struct inode *inode, const char *reason)

{

       pr_warn("%s encountered for inode %px", reason, inode);

}



EXPORT_SYMBOL(dump_inode);

#endif

fs/namei.c

+2 −0
Original line number Diff line number Diff line
@@ -3415,6 +3415,8 @@ static int may_open(struct mnt_idmap *idmap, const struct path *path, 
		if ((acc_mode & MAY_EXEC) && path_noexec(path))

			return -EACCES;

		break;

	default:

		VFS_BUG_ON_INODE(1, inode);

	}



	error = inode_permission(idmap, inode, MAY_OPEN | acc_mode);

include/linux/fs.h

+3 −0
Original line number Diff line number Diff line
@@ -2,6 +2,7 @@ 
#ifndef _LINUX_FS_H

#define _LINUX_FS_H



#include <linux/vfsdebug.h>

#include <linux/linkage.h>

#include <linux/wait_bit.h>

#include <linux/kdev_t.h>
@@ -791,6 +792,8 @@ struct inode { 


static inline void inode_set_cached_link(struct inode *inode, char *link, int linklen)

{

	VFS_WARN_ON_INODE(strlen(link) != linklen, inode);

	VFS_WARN_ON_INODE(inode->i_opflags & IOP_CACHED_LINK, inode);

	inode->i_link = link;

	inode->i_linklen = linklen;

	inode->i_opflags |= IOP_CACHED_LINK;

include/linux/vfsdebug.h

0 → 100644
+45 −0
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0 */

#ifndef LINUX_VFS_DEBUG_H

#define LINUX_VFS_DEBUG_H 1



#include <linux/bug.h>



struct inode;



#ifdef CONFIG_DEBUG_VFS

void dump_inode(struct inode *inode, const char *reason);



#define VFS_BUG_ON(cond) BUG_ON(cond)

#define VFS_WARN_ON(cond) (void)WARN_ON(cond)

#define VFS_WARN_ON_ONCE(cond) (void)WARN_ON_ONCE(cond)

#define VFS_WARN_ONCE(cond, format...) (void)WARN_ONCE(cond, format)

#define VFS_WARN(cond, format...) (void)WARN(cond, format)



#define VFS_BUG_ON_INODE(cond, inode)		({			\

	if (unlikely(!!(cond))) {					\

		dump_inode(inode, "VFS_BUG_ON_INODE(" #cond")");\

		BUG_ON(1);						\

	}								\

})



#define VFS_WARN_ON_INODE(cond, inode)		({			\

	int __ret_warn = !!(cond);					\

									\

	if (unlikely(__ret_warn)) {					\

		dump_inode(inode, "VFS_WARN_ON_INODE(" #cond")");\

		WARN_ON(1);						\

	}								\

	unlikely(__ret_warn);						\

})

#else

#define VFS_BUG_ON(cond) BUILD_BUG_ON_INVALID(cond)

#define VFS_WARN_ON(cond) BUILD_BUG_ON_INVALID(cond)

#define VFS_WARN_ON_ONCE(cond) BUILD_BUG_ON_INVALID(cond)

#define VFS_WARN_ONCE(cond, format...) BUILD_BUG_ON_INVALID(cond)

#define VFS_WARN(cond, format...) BUILD_BUG_ON_INVALID(cond)



#define VFS_BUG_ON_INODE(cond, inode) VFS_BUG_ON(cond)

#define VFS_WARN_ON_INODE(cond, inode)  BUILD_BUG_ON_INVALID(cond)

#endif /* CONFIG_DEBUG_VFS */



#endif

lib/Kconfig.debug

+9 −0
Original line number Diff line number Diff line
@@ -808,6 +808,15 @@ config ARCH_HAS_DEBUG_VM_PGTABLE 
	  An architecture should select this when it can successfully

	  build and run DEBUG_VM_PGTABLE.



config DEBUG_VFS

	bool "Debug VFS"

	depends on DEBUG_KERNEL

	help

	  Enable this to turn on extended checks in the VFS layer that may impact

	  performance.



	  If unsure, say N.



config DEBUG_VM_IRQSOFF

	def_bool DEBUG_VM && !PREEMPT_RT