Commit da53be12 authored by Linus Torvalds's avatar Linus Torvalds Committed by Al Viro
Browse files

Don't pass inode to ->d_hash() and ->d_compare() 



Instances either don't look at it at all (the majority of cases) or
only want it to find the superblock (which can be had as dentry->d_sb).
A few cases that want more are actually safe with dentry->d_inode -
the only precaution needed is the check that it hadn't been replaced with
NULL by rmdir() or by overwriting rename(), which case should be simply
treated as cache miss.

Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 642b704c

Documentation/filesystems/Locking

+2 −4
Original line number Diff line number Diff line
@@ -11,10 +11,8 @@ be able to use diff(1). 
prototypes:

	int (*d_revalidate)(struct dentry *, unsigned int);

	int (*d_weak_revalidate)(struct dentry *, unsigned int);

	int (*d_hash)(const struct dentry *, const struct inode *,

			struct qstr *);

	int (*d_compare)(const struct dentry *, const struct inode *,

			const struct dentry *, const struct inode *,

	int (*d_hash)(const struct dentry *, struct qstr *);

	int (*d_compare)(const struct dentry *, const struct dentry *,

			unsigned int, const char *, const struct qstr *);

	int (*d_delete)(struct dentry *);

	void (*d_release)(struct dentry *);

Documentation/filesystems/vfs.txt

+8 −11
Original line number Diff line number Diff line
@@ -901,10 +901,8 @@ defined: 
struct dentry_operations {

	int (*d_revalidate)(struct dentry *, unsigned int);

	int (*d_weak_revalidate)(struct dentry *, unsigned int);

	int (*d_hash)(const struct dentry *, const struct inode *,

			struct qstr *);

	int (*d_compare)(const struct dentry *, const struct inode *,

			const struct dentry *, const struct inode *,

	int (*d_hash)(const struct dentry *, struct qstr *);

	int (*d_compare)(const struct dentry *, const struct dentry *,

			unsigned int, const char *, const struct qstr *);

	int (*d_delete)(const struct dentry *);

	void (*d_release)(struct dentry *);
@@ -949,25 +947,24 @@ struct dentry_operations { 


  d_hash: called when the VFS adds a dentry to the hash table. The first

	dentry passed to d_hash is the parent directory that the name is

	to be hashed into. The inode is the dentry's inode.

	to be hashed into.



	Same locking and synchronisation rules as d_compare regarding

	what is safe to dereference etc.



  d_compare: called to compare a dentry name with a given name. The first

	dentry is the parent of the dentry to be compared, the second is

	the parent's inode, then the dentry and inode (may be NULL) of the

	child dentry. len and name string are properties of the dentry to be

	compared. qstr is the name to compare it with.

	the child dentry. len and name string are properties of the dentry

	to be compared. qstr is the name to compare it with.



	Must be constant and idempotent, and should not take locks if

	possible, and should not or store into the dentry or inodes.

	Should not dereference pointers outside the dentry or inodes without

	possible, and should not or store into the dentry.

	Should not dereference pointers outside the dentry without

	lots of care (eg.  d_parent, d_inode, d_name should not be used).



	However, our vfsmount is pinned, and RCU held, so the dentries and

	inodes won't disappear, neither will our sb or filesystem module.

	->i_sb and ->d_sb may be used.

	->d_sb may be used.



	It is a tricky calling convention because it needs to be called under

	"rcu-walk", ie. without any locks or references on things.

fs/adfs/dir.c

+2 −4
Original line number Diff line number Diff line
@@ -191,8 +191,7 @@ const struct file_operations adfs_dir_operations = { 
};



static int

adfs_hash(const struct dentry *parent, const struct inode *inode,

		struct qstr *qstr)

adfs_hash(const struct dentry *parent, struct qstr *qstr)

{

	const unsigned int name_len = ADFS_SB(parent->d_sb)->s_namelen;

	const unsigned char *name;
@@ -228,8 +227,7 @@ adfs_hash(const struct dentry *parent, const struct inode *inode, 
 * requirements of the underlying filesystem.

 */

static int

adfs_compare(const struct dentry *parent, const struct inode *pinode,

		const struct dentry *dentry, const struct inode *inode,

adfs_compare(const struct dentry *parent, const struct dentry *dentry,

		unsigned int len, const char *str, const struct qstr *name)

{

	int i;

fs/affs/namei.c

+8 −18
Original line number Diff line number Diff line
@@ -13,18 +13,12 @@ 
typedef int (*toupper_t)(int);



static int	 affs_toupper(int ch);

static int	 affs_hash_dentry(const struct dentry *,

		const struct inode *, struct qstr *);

static int       affs_compare_dentry(const struct dentry *parent,

		const struct inode *pinode,

		const struct dentry *dentry, const struct inode *inode,

static int	 affs_hash_dentry(const struct dentry *, struct qstr *);

static int       affs_compare_dentry(const struct dentry *parent, const struct dentry *dentry,

		unsigned int len, const char *str, const struct qstr *name);

static int	 affs_intl_toupper(int ch);

static int	 affs_intl_hash_dentry(const struct dentry *,

		const struct inode *, struct qstr *);

static int       affs_intl_compare_dentry(const struct dentry *parent,

		const struct inode *pinode,

		const struct dentry *dentry, const struct inode *inode,

static int	 affs_intl_hash_dentry(const struct dentry *, struct qstr *);

static int       affs_intl_compare_dentry(const struct dentry *parent, const struct dentry *dentry,

		unsigned int len, const char *str, const struct qstr *name);



const struct dentry_operations affs_dentry_operations = {
@@ -86,14 +80,12 @@ __affs_hash_dentry(struct qstr *qstr, toupper_t toupper) 
}



static int

affs_hash_dentry(const struct dentry *dentry, const struct inode *inode,

		struct qstr *qstr)

affs_hash_dentry(const struct dentry *dentry, struct qstr *qstr)

{

	return __affs_hash_dentry(qstr, affs_toupper);

}

static int

affs_intl_hash_dentry(const struct dentry *dentry, const struct inode *inode,

		struct qstr *qstr)

affs_intl_hash_dentry(const struct dentry *dentry, struct qstr *qstr)

{

	return __affs_hash_dentry(qstr, affs_intl_toupper);

}
@@ -131,15 +123,13 @@ static inline int __affs_compare_dentry(unsigned int len, 
}



static int

affs_compare_dentry(const struct dentry *parent, const struct inode *pinode,

		const struct dentry *dentry, const struct inode *inode,

affs_compare_dentry(const struct dentry *parent, const struct dentry *dentry,

		unsigned int len, const char *str, const struct qstr *name)

{

	return __affs_compare_dentry(len, str, name, affs_toupper);

}

static int

affs_intl_compare_dentry(const struct dentry *parent,const struct inode *pinode,

		const struct dentry *dentry, const struct inode *inode,

affs_intl_compare_dentry(const struct dentry *parent, const struct dentry *dentry,

		unsigned int len, const char *str, const struct qstr *name)

{

	return __affs_compare_dentry(len, str, name, affs_intl_toupper);

fs/cifs/dir.c

+3 −6
Original line number Diff line number Diff line
@@ -822,8 +822,7 @@ const struct dentry_operations cifs_dentry_ops = { 
/* d_delete:       cifs_d_delete,      */ /* not needed except for debugging */

};



static int cifs_ci_hash(const struct dentry *dentry, const struct inode *inode,

		struct qstr *q)

static int cifs_ci_hash(const struct dentry *dentry, struct qstr *q)

{

	struct nls_table *codepage = CIFS_SB(dentry->d_sb)->local_nls;

	unsigned long hash;
@@ -838,12 +837,10 @@ static int cifs_ci_hash(const struct dentry *dentry, const struct inode *inode, 
	return 0;

}



static int cifs_ci_compare(const struct dentry *parent,

		const struct inode *pinode,

		const struct dentry *dentry, const struct inode *inode,

static int cifs_ci_compare(const struct dentry *parent, const struct dentry *dentry,

		unsigned int len, const char *str, const struct qstr *name)

{

	struct nls_table *codepage = CIFS_SB(pinode->i_sb)->local_nls;

	struct nls_table *codepage = CIFS_SB(parent->d_sb)->local_nls;



	if ((name->len == len) &&

	    (nls_strnicmp(codepage, name->name, str, len) == 0))

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