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authorMiklos Szeredi <mszeredi@suse.cz>2011-10-28 14:13:30 +0200
committerChristoph Hellwig <hch@serles.lst.de>2011-11-02 12:53:43 +0100
commita78ef704a8dd430225955f0709b22d4a6ba21deb (patch)
treeebd8f8a5a257077912b7cc38ecfdab43e1d7d73d
parentbfe8684869601dacfcb2cd69ef8cfd9045f62170 (diff)
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: Miklos Szeredi <mszeredi@suse.cz> Tested-by: Toshiyuki Okajima <toshi.okajima@jp.fujitsu.com> Signed-off-by: Christoph Hellwig <hch@lst.de>
-rw-r--r--fs/inode.c2
-rw-r--r--include/linux/fs.h20
2 files changed, 16 insertions, 6 deletions
diff --git a/fs/inode.c b/fs/inode.c
index ecbb68dc7e2..ee4e66b998f 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -142,7 +142,7 @@ int inode_init_always(struct super_block *sb, struct inode *inode)
atomic_set(&inode->i_count, 1);
inode->i_op = &empty_iops;
inode->i_fop = &empty_fops;
- inode->i_nlink = 1;
+ inode->__i_nlink = 1;
inode->i_opflags = 0;
inode->i_uid = 0;
inode->i_gid = 0;
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 48c1f5fc741..23467d768ca 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -768,7 +768,17 @@ struct inode {
/* Stat data, not accessed from path walking */
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;
loff_t i_size;
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)
{
- 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)
{
- inode->i_nlink++;
+ inode->__i_nlink++;
}
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)
{
- 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)
{
- inode->i_nlink = 0;
+ inode->__i_nlink = 0;
}
static inline void inode_dec_link_count(struct inode *inode)