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Commit a78ef704 authored by Miklos Szeredi's avatar Miklos Szeredi Committed by Christoph Hellwig
Browse files

vfs: protect i_nlink 



Prevent direct modification of i_nlink by making it const and adding a
non-const __i_nlink alias.

Signed-off-by: default avatarMiklos Szeredi <mszeredi@suse.cz>
Tested-by: default avatarToshiyuki Okajima <toshi.okajima@jp.fujitsu.com>
Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
parent bfe86848

fs/inode.c

+1 −1
Original line number Original line Diff line number Diff line
@@ -142,7 +142,7 @@ int inode_init_always(struct super_block *sb, struct inode *inode) 
	atomic_set(&inode->i_count, 1);

	atomic_set(&inode->i_count, 1);

	inode->i_op = &empty_iops;

	inode->i_op = &empty_iops;

	inode->i_fop = &empty_fops;

	inode->i_fop = &empty_fops;

	inode->i_nlink = 1;

	inode->__i_nlink = 1;

	inode->i_opflags = 0;

	inode->i_opflags = 0;

	inode->i_uid = 0;

	inode->i_uid = 0;

	inode->i_gid = 0;

	inode->i_gid = 0;

include/linux/fs.h

+15 −5
Original line number Original line Diff line number Diff line
@@ -768,7 +768,17 @@ struct inode { 




	/* Stat data, not accessed from path walking */

	/* Stat data, not accessed from path walking */

	unsigned long		i_ino;

	unsigned long		i_ino;

	unsigned int		i_nlink;

	/*

	 * Filesystems may only read i_nlink directly.  They shall use the

	 * following functions for modification:

	 *

	 *    (set|clear|inc|drop)_nlink

	 *    inode_(inc|dec)_link_count

	 */

	union {

		const unsigned int i_nlink;

		unsigned int __i_nlink;

	};

	dev_t			i_rdev;

	dev_t			i_rdev;

	loff_t			i_size;

	loff_t			i_size;

	struct timespec		i_atime;

	struct timespec		i_atime;
@@ -1764,7 +1774,7 @@ static inline void mark_inode_dirty_sync(struct inode *inode) 
 */

 */

static inline void set_nlink(struct inode *inode, unsigned int nlink)

static inline void set_nlink(struct inode *inode, unsigned int nlink)

{

{

	inode->i_nlink = nlink;

	inode->__i_nlink = nlink;

}

}





/**

/**
@@ -1777,7 +1787,7 @@ static inline void set_nlink(struct inode *inode, unsigned int nlink) 
 */

 */

static inline void inc_nlink(struct inode *inode)

static inline void inc_nlink(struct inode *inode)

{

{

	inode->i_nlink++;

	inode->__i_nlink++;

}

}





static inline void inode_inc_link_count(struct inode *inode)

static inline void inode_inc_link_count(struct inode *inode)
@@ -1799,7 +1809,7 @@ static inline void inode_inc_link_count(struct inode *inode) 
 */

 */

static inline void drop_nlink(struct inode *inode)

static inline void drop_nlink(struct inode *inode)

{

{

	inode->i_nlink--;

	inode->__i_nlink--;

}

}





/**

/**
@@ -1812,7 +1822,7 @@ static inline void drop_nlink(struct inode *inode) 
 */

 */

static inline void clear_nlink(struct inode *inode)

static inline void clear_nlink(struct inode *inode)

{

{

	inode->i_nlink = 0;

	inode->__i_nlink = 0;

}

}





static inline void inode_dec_link_count(struct inode *inode)

static inline void inode_dec_link_count(struct inode *inode)