patch-2.1.45 linux/include/linux/dcache.h

• Lines: 123
• Date: Wed Jul 16 07:50:16 1997
• Orig file: v2.1.44/linux/include/linux/dcache.h
• Orig date: Wed Dec 31 16:00:00 1969

diff -u --recursive --new-file v2.1.44/linux/include/linux/dcache.h linux/include/linux/dcache.h
@@ -0,0 +1,122 @@
+#ifndef __LINUX_DCACHE_H
+#define __LINUX_DCACHE_H
+
+/*
+ * linux/include/linux/dcache.h
+ *
+ * Directory cache data structures
+ */
+
+#define D_MAXLEN 1024
+
+#define IS_ROOT(x) ((x) == (x)->d_parent)
+
+/*
+ * "quick string" -- eases parameter passing, but more importantly
+ * saves "metadata" about the string (ie length and the hash).
+ */
+struct qstr {
+	const unsigned char * name;
+	unsigned int len, hash;
+};
+
+/* Name hashing routines. Initial hash value */
+#define init_name_hash()		0
+
+/* partial hash update function. Assume roughly 4 bits per character */
+static inline unsigned long partial_name_hash(unsigned char c, unsigned long prevhash)
+{
+	prevhash = (prevhash << 4) | (prevhash >> (8*sizeof(unsigned long)-4));
+	return prevhash ^ c;
+}
+
+/* Finally: cut down the number of bits to a int value (and try to avoid losing bits) */
+static inline unsigned long end_name_hash(unsigned long hash)
+{
+	if (sizeof(hash) > sizeof(unsigned int))
+		hash += hash >> 4*sizeof(hash);
+	return (unsigned int) hash;
+}
+
+struct dentry {
+	int d_count;
+	unsigned int d_flags;
+	struct inode  * d_inode;	/* Where the name belongs to - NULL is negative */
+	struct dentry * d_parent;	/* parent directory */
+	struct dentry * d_mounts;	/* mount information */
+	struct dentry * d_covers;
+	struct list_head d_hash;	/* lookup hash list */
+	struct list_head d_alias;	/* inode alias list */
+	struct list_head d_lru;		/* d_count = 0 LRU list */
+	struct qstr d_name;
+	struct dentry * (*d_revalidate)(struct dentry *);
+};
+
+/*
+ * d_drop() unhashes the entry from the parent
+ * dentry hashes, so that it won't be found through
+ * a VFS lookup any more. Note that this is different
+ * from deleting the dentry - d_delete will try to
+ * mark the dentry negative if possible, giving a
+ * successful _negative_ lookup, while d_drop will
+ * just make the cache lookup fail.
+ *
+ * d_drop() is used mainly for stuff that wants
+ * to invalidate a dentry for some reason (NFS
+ * timeouts or autofs deletes).
+ */
+static inline void d_drop(struct dentry * dentry)
+{
+	list_del(&dentry->d_hash);
+	INIT_LIST_HEAD(&dentry->d_hash);
+}
+
+/*
+ * These are the low-level FS interfaces to the dcache..
+ */
+extern void d_instantiate(struct dentry *, struct inode *);
+extern void d_delete(struct dentry *);
+
+
+/* allocate/de-allocate */
+extern void d_free(struct dentry *);
+extern struct dentry * d_alloc(struct dentry * parent, const struct qstr *name);
+extern void shrink_dcache(void);
+
+/* only used at mount-time */
+extern struct dentry * d_alloc_root(struct inode * root_inode, struct dentry * old_root);
+
+/*
+ * This adds the entry to the hash queues and initializes "d_inode".
+ * The entry was actually filled in earlier during "d_alloc()"
+ */
+extern void d_add(struct dentry * entry, struct inode * inode);
+
+/* used for rename() and baskets */
+extern void d_move(struct dentry * entry, struct dentry * newparent, struct qstr * newname);
+
+/* appendix may either be NULL or be used for transname suffixes */
+extern struct dentry * d_lookup(struct dentry * dir, struct qstr * name);
+
+/* write full pathname into buffer and return length */
+extern int d_path(struct dentry * entry, struct dentry * chroot, char * buf);
+
+/* Allocation counts.. */
+static inline struct dentry * dget(struct dentry *dentry)
+{
+	if (dentry)
+		dentry->d_count++;
+	return dentry;
+}
+
+extern void dput(struct dentry *);
+
+/*
+ * This is ugly. The inode:dentry relationship is a 1:n
+ * relationship, so we have to return one (random) dentry
+ * from the alias list. We select the first one..
+ */
+#define i_dentry(inode) \
+	list_entry((inode)->i_dentry.next, struct dentry, d_alias)
+
+#endif	/* __LINUX_DCACHE_H */