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: Linus Torvalds <[email protected]>
Signed-off-by: Al Viro <[email protected]>

Documentation/filesystems/Locking

@@ -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

@@ -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

@@ -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

@@ -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

@@ -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))

fs/dcache.c

@@ -1723,7 +1723,7 @@ EXPORT_SYMBOL(d_add_ci);
  * Do the slow-case of the dentry name compare.
  *
  * Unlike the dentry_cmp() function, we need to atomically
- * load the name, length and inode information, so that the
+ * load the name and length information, so that the
  * filesystem can rely on them, and can use the 'name' and
  * 'len' information without worrying about walking off the
  * end of memory etc.
@@ -1741,22 +1741,18 @@ enum slow_d_compare {
 
 static noinline enum slow_d_compare slow_dentry_cmp(
 		const struct dentry *parent,
-		struct inode *inode,
 		struct dentry *dentry,
 		unsigned int seq,
 		const struct qstr *name)
 {
 	int tlen = dentry->d_name.len;
 	const char *tname = dentry->d_name.name;
-	struct inode *i = dentry->d_inode;
 
 	if (read_seqcount_retry(&dentry->d_seq, seq)) {
 		cpu_relax();
 		return D_COMP_SEQRETRY;
 	}
-	if (parent->d_op->d_compare(parent, inode,
-				dentry, i,
-				tlen, tname, name))
+	if (parent->d_op->d_compare(parent, dentry, tlen, tname, name))
 		return D_COMP_NOMATCH;
 	return D_COMP_OK;
 }
@@ -1766,7 +1762,6 @@ static noinline enum slow_d_compare slow_dentry_cmp(
  * @parent: parent dentry
  * @name: qstr of name we wish to find
  * @seqp: returns d_seq value at the point where the dentry was found
- * @inode: returns dentry->d_inode when the inode was found valid.
  * Returns: dentry, or NULL
  *
  * __d_lookup_rcu is the dcache lookup function for rcu-walk name
@@ -1793,7 +1788,7 @@ static noinline enum slow_d_compare slow_dentry_cmp(
  */
 struct dentry *__d_lookup_rcu(const struct dentry *parent,
 				const struct qstr *name,
-				unsigned *seqp, struct inode *inode)
+				unsigned *seqp)
 {
 	u64 hashlen = name->hash_len;
 	const unsigned char *str = name->name;
@@ -1827,11 +1822,10 @@ struct dentry *__d_lookup_rcu(const struct dentry *parent,
 seqretry:
 		/*
 		 * The dentry sequence count protects us from concurrent
-		 * renames, and thus protects inode, parent and name fields.
+		 * renames, and thus protects parent and name fields.
 		 *
 		 * The caller must perform a seqcount check in order
-		 * to do anything useful with the returned dentry,
-		 * including using the 'd_inode' pointer.
+		 * to do anything useful with the returned dentry.
 		 *
 		 * NOTE! We do a "raw" seqcount_begin here. That means that
 		 * we don't wait for the sequence count to stabilize if it
@@ -1845,12 +1839,12 @@ struct dentry *__d_lookup_rcu(const struct dentry *parent,
 			continue;
 		if (d_unhashed(dentry))
 			continue;
-		*seqp = seq;
 
 		if (unlikely(parent->d_flags & DCACHE_OP_COMPARE)) {
 			if (dentry->d_name.hash != hashlen_hash(hashlen))
 				continue;
-			switch (slow_dentry_cmp(parent, inode, dentry, seq, name)) {
+			*seqp = seq;
+			switch (slow_dentry_cmp(parent, dentry, seq, name)) {
 			case D_COMP_OK:
 				return dentry;
 			case D_COMP_NOMATCH:
@@ -1862,6 +1856,7 @@ struct dentry *__d_lookup_rcu(const struct dentry *parent,
 
 		if (dentry->d_name.hash_len != hashlen)
 			continue;
+		*seqp = seq;
 		if (!dentry_cmp(dentry, str, hashlen_len(hashlen)))
 			return dentry;
 	}
@@ -1959,9 +1954,7 @@ struct dentry *__d_lookup(const struct dentry *parent, const struct qstr *name)
 		if (parent->d_flags & DCACHE_OP_COMPARE) {
 			int tlen = dentry->d_name.len;
 			const char *tname = dentry->d_name.name;
-			if (parent->d_op->d_compare(parent, parent->d_inode,
-						dentry, dentry->d_inode,
-						tlen, tname, name))
+			if (parent->d_op->d_compare(parent, dentry, tlen, tname, name))
 				goto next;
 		} else {
 			if (dentry->d_name.len != len)
@@ -1998,7 +1991,7 @@ struct dentry *d_hash_and_lookup(struct dentry *dir, struct qstr *name)
 	 */
 	name->hash = full_name_hash(name->name, name->len);
 	if (dir->d_flags & DCACHE_OP_HASH) {
-		int err = dir->d_op->d_hash(dir, dir->d_inode, name);
+		int err = dir->d_op->d_hash(dir, name);
 		if (unlikely(err < 0))
 			return ERR_PTR(err);
 	}

fs/efivarfs/super.c

@@ -45,8 +45,8 @@ static struct super_block *efivarfs_sb;
  * So we need to perform a case-sensitive match on part 1 and a
  * case-insensitive match on part 2.
  */
-static int efivarfs_d_compare(const struct dentry *parent, const struct inode *pinode,
-			      const struct dentry *dentry, const struct inode *inode,
+static int efivarfs_d_compare(const struct dentry *parent,
+			      const struct dentry *dentry,
 			      unsigned int len, const char *str,
 			      const struct qstr *name)
 {
@@ -63,8 +63,7 @@ static int efivarfs_d_compare(const struct dentry *parent, const struct inode *p
 	return strncasecmp(name->name + guid, str + guid, EFI_VARIABLE_GUID_LEN);
 }
 
-static int efivarfs_d_hash(const struct dentry *dentry,
-			   const struct inode *inode, struct qstr *qstr)
+static int efivarfs_d_hash(const struct dentry *dentry, struct qstr *qstr)
 {
 	unsigned long hash = init_name_hash();
 	const unsigned char *s = qstr->name;
@@ -108,7 +107,7 @@ static struct dentry *efivarfs_alloc_dentry(struct dentry *parent, char *name)
 	q.name = name;
 	q.len = strlen(name);
 
-	err = efivarfs_d_hash(NULL, NULL, &q);
+	err = efivarfs_d_hash(NULL, &q);
 	if (err)
 		return ERR_PTR(err);
 

fs/fat/namei_msdos.c

@@ -148,8 +148,7 @@ static int msdos_find(struct inode *dir, const unsigned char *name, int len,
  * that the existing dentry can be used. The msdos fs routines will
  * return ENOENT or EINVAL as appropriate.
  */
-static int msdos_hash(const struct dentry *dentry, const struct inode *inode,
-	       struct qstr *qstr)
+static int msdos_hash(const struct dentry *dentry, struct qstr *qstr)
 {
 	struct fat_mount_options *options = &MSDOS_SB(dentry->d_sb)->options;
 	unsigned char msdos_name[MSDOS_NAME];
@@ -165,8 +164,7 @@ static int msdos_hash(const struct dentry *dentry, const struct inode *inode,
  * Compare two msdos names. If either of the names are invalid,
  * we fall back to doing the standard name comparison.
  */
-static int msdos_cmp(const struct dentry *parent, const struct inode *pinode,
-		const struct dentry *dentry, const struct inode *inode,
+static int msdos_cmp(const struct dentry *parent, const struct dentry *dentry,
 		unsigned int len, const char *str, const struct qstr *name)
 {
 	struct fat_mount_options *options = &MSDOS_SB(parent->d_sb)->options;

fs/fat/namei_vfat.c

@@ -107,8 +107,7 @@ static unsigned int vfat_striptail_len(const struct qstr *qstr)
  * that the existing dentry can be used. The vfat fs routines will
  * return ENOENT or EINVAL as appropriate.
  */
-static int vfat_hash(const struct dentry *dentry, const struct inode *inode,
-		struct qstr *qstr)
+static int vfat_hash(const struct dentry *dentry, struct qstr *qstr)
 {
 	qstr->hash = full_name_hash(qstr->name, vfat_striptail_len(qstr));
 	return 0;
@@ -120,8 +119,7 @@ static int vfat_hash(const struct dentry *dentry, const struct inode *inode,
  * that the existing dentry can be used. The vfat fs routines will
  * return ENOENT or EINVAL as appropriate.
  */
-static int vfat_hashi(const struct dentry *dentry, const struct inode *inode,
-		struct qstr *qstr)
+static int vfat_hashi(const struct dentry *dentry, struct qstr *qstr)
 {
 	struct nls_table *t = MSDOS_SB(dentry->d_sb)->nls_io;
 	const unsigned char *name;
@@ -142,8 +140,7 @@ static int vfat_hashi(const struct dentry *dentry, const struct inode *inode,
 /*
  * Case insensitive compare of two vfat names.
  */
-static int vfat_cmpi(const struct dentry *parent, const struct inode *pinode,
-		const struct dentry *dentry, const struct inode *inode,
+static int vfat_cmpi(const struct dentry *parent, const struct dentry *dentry,
 		unsigned int len, const char *str, const struct qstr *name)
 {
 	struct nls_table *t = MSDOS_SB(parent->d_sb)->nls_io;
@@ -162,8 +159,7 @@ static int vfat_cmpi(const struct dentry *parent, const struct inode *pinode,
 /*
  * Case sensitive compare of two vfat names.
  */
-static int vfat_cmp(const struct dentry *parent, const struct inode *pinode,
-		const struct dentry *dentry, const struct inode *inode,
+static int vfat_cmp(const struct dentry *parent, const struct dentry *dentry,
 		unsigned int len, const char *str, const struct qstr *name)
 {
 	unsigned int alen, blen;

fs/gfs2/dentry.c

@@ -109,8 +109,7 @@ static int gfs2_drevalidate(struct dentry *dentry, unsigned int flags)
 	return 0;
 }
 
-static int gfs2_dhash(const struct dentry *dentry, const struct inode *inode,
-		struct qstr *str)
+static int gfs2_dhash(const struct dentry *dentry, struct qstr *str)
 {
 	str->hash = gfs2_disk_hash(str->name, str->len);
 	return 0;

fs/hfs/hfs_fs.h

@@ -229,13 +229,10 @@ extern int hfs_part_find(struct super_block *, sector_t *, sector_t *);
 /* string.c */
 extern const struct dentry_operations hfs_dentry_operations;
 
-extern int hfs_hash_dentry(const struct dentry *, const struct inode *,
-		struct qstr *);
+extern int hfs_hash_dentry(const struct dentry *, struct qstr *);
 extern int hfs_strcmp(const unsigned char *, unsigned int,
 		      const unsigned char *, unsigned int);
-extern int hfs_compare_dentry(const struct dentry *parent,
-		const struct inode *pinode,
-		const struct dentry *dentry, const struct inode *inode,
+extern int hfs_compare_dentry(const struct dentry *parent, const struct dentry *dentry,
 		unsigned int len, const char *str, const struct qstr *name);
 
 /* trans.c */