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-rw-r--r--include/linux/dcache.h338
1 files changed, 338 insertions, 0 deletions
diff --git a/include/linux/dcache.h b/include/linux/dcache.h
new file mode 100644
index 000000000000..50be290d24d2
--- /dev/null
+++ b/include/linux/dcache.h
@@ -0,0 +1,338 @@
+#ifndef __LINUX_DCACHE_H
+#define __LINUX_DCACHE_H
+
+#ifdef __KERNEL__
+
+#include <asm/atomic.h>
+#include <linux/list.h>
+#include <linux/spinlock.h>
+#include <linux/cache.h>
+#include <linux/rcupdate.h>
+#include <asm/bug.h>
+
+struct nameidata;
+struct vfsmount;
+
+/*
+ * linux/include/linux/dcache.h
+ *
+ * Dirent cache data structures
+ *
+ * (C) Copyright 1997 Thomas Schoebel-Theuer,
+ * with heavy changes by Linus Torvalds
+ */
+
+#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).
+ *
+ * hash comes first so it snuggles against d_parent in the
+ * dentry.
+ */
+struct qstr {
+ unsigned int hash;
+ unsigned int len;
+ const unsigned char *name;
+};
+
+struct dentry_stat_t {
+ int nr_dentry;
+ int nr_unused;
+ int age_limit; /* age in seconds */
+ int want_pages; /* pages requested by system */
+ int dummy[2];
+};
+extern struct dentry_stat_t dentry_stat;
+
+/* Name hashing routines. Initial hash value */
+/* Hash courtesy of the R5 hash in reiserfs modulo sign bits */
+#define init_name_hash() 0
+
+/* partial hash update function. Assume roughly 4 bits per character */
+static inline unsigned long
+partial_name_hash(unsigned long c, unsigned long prevhash)
+{
+ return (prevhash + (c << 4) + (c >> 4)) * 11;
+}
+
+/*
+ * 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)
+{
+ return (unsigned int) hash;
+}
+
+/* Compute the hash for a name string. */
+static inline unsigned int
+full_name_hash(const unsigned char *name, unsigned int len)
+{
+ unsigned long hash = init_name_hash();
+ while (len--)
+ hash = partial_name_hash(*name++, hash);
+ return end_name_hash(hash);
+}
+
+struct dcookie_struct;
+
+#define DNAME_INLINE_LEN_MIN 36
+
+struct dentry {
+ atomic_t d_count;
+ unsigned int d_flags; /* protected by d_lock */
+ spinlock_t d_lock; /* per dentry lock */
+ struct inode *d_inode; /* Where the name belongs to - NULL is
+ * negative */
+ /*
+ * The next three fields are touched by __d_lookup. Place them here
+ * so they all fit in a 16-byte range, with 16-byte alignment.
+ */
+ struct dentry *d_parent; /* parent directory */
+ struct qstr d_name;
+
+ struct list_head d_lru; /* LRU list */
+ struct list_head d_child; /* child of parent list */
+ struct list_head d_subdirs; /* our children */
+ struct list_head d_alias; /* inode alias list */
+ unsigned long d_time; /* used by d_revalidate */
+ struct dentry_operations *d_op;
+ struct super_block *d_sb; /* The root of the dentry tree */
+ void *d_fsdata; /* fs-specific data */
+ struct rcu_head d_rcu;
+ struct dcookie_struct *d_cookie; /* cookie, if any */
+ struct hlist_node d_hash; /* lookup hash list */
+ int d_mounted;
+ unsigned char d_iname[DNAME_INLINE_LEN_MIN]; /* small names */
+};
+
+struct dentry_operations {
+ int (*d_revalidate)(struct dentry *, struct nameidata *);
+ int (*d_hash) (struct dentry *, struct qstr *);
+ int (*d_compare) (struct dentry *, struct qstr *, struct qstr *);
+ int (*d_delete)(struct dentry *);
+ void (*d_release)(struct dentry *);
+ void (*d_iput)(struct dentry *, struct inode *);
+};
+
+/* the dentry parameter passed to d_hash and d_compare is the parent
+ * directory of the entries to be compared. It is used in case these
+ * functions need any directory specific information for determining
+ * equivalency classes. Using the dentry itself might not work, as it
+ * might be a negative dentry which has no information associated with
+ * it */
+
+/*
+locking rules:
+ big lock dcache_lock d_lock may block
+d_revalidate: no no no yes
+d_hash no no no yes
+d_compare: no yes yes no
+d_delete: no yes no no
+d_release: no no no yes
+d_iput: no no no yes
+ */
+
+/* d_flags entries */
+#define DCACHE_AUTOFS_PENDING 0x0001 /* autofs: "under construction" */
+#define DCACHE_NFSFS_RENAMED 0x0002 /* this dentry has been "silly
+ * renamed" and has to be
+ * deleted on the last dput()
+ */
+#define DCACHE_DISCONNECTED 0x0004
+ /* This dentry is possibly not currently connected to the dcache tree,
+ * in which case its parent will either be itself, or will have this
+ * flag as well. nfsd will not use a dentry with this bit set, but will
+ * first endeavour to clear the bit either by discovering that it is
+ * connected, or by performing lookup operations. Any filesystem which
+ * supports nfsd_operations MUST have a lookup function which, if it finds
+ * a directory inode with a DCACHE_DISCONNECTED dentry, will d_move
+ * that dentry into place and return that dentry rather than the passed one,
+ * typically using d_splice_alias.
+ */
+
+#define DCACHE_REFERENCED 0x0008 /* Recently used, don't discard. */
+#define DCACHE_UNHASHED 0x0010
+
+extern spinlock_t dcache_lock;
+
+/**
+ * d_drop - drop a dentry
+ * @dentry: dentry to drop
+ *
+ * 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).
+ *
+ * __d_drop requires dentry->d_lock.
+ */
+
+static inline void __d_drop(struct dentry *dentry)
+{
+ if (!(dentry->d_flags & DCACHE_UNHASHED)) {
+ dentry->d_flags |= DCACHE_UNHASHED;
+ hlist_del_rcu(&dentry->d_hash);
+ }
+}
+
+static inline void d_drop(struct dentry *dentry)
+{
+ spin_lock(&dcache_lock);
+ spin_lock(&dentry->d_lock);
+ __d_drop(dentry);
+ spin_unlock(&dentry->d_lock);
+ spin_unlock(&dcache_lock);
+}
+
+static inline int dname_external(struct dentry *dentry)
+{
+ return dentry->d_name.name != dentry->d_iname;
+}
+
+/*
+ * These are the low-level FS interfaces to the dcache..
+ */
+extern void d_instantiate(struct dentry *, struct inode *);
+extern struct dentry * d_instantiate_unique(struct dentry *, struct inode *);
+extern void d_delete(struct dentry *);
+
+/* allocate/de-allocate */
+extern struct dentry * d_alloc(struct dentry *, const struct qstr *);
+extern struct dentry * d_alloc_anon(struct inode *);
+extern struct dentry * d_splice_alias(struct inode *, struct dentry *);
+extern void shrink_dcache_sb(struct super_block *);
+extern void shrink_dcache_parent(struct dentry *);
+extern void shrink_dcache_anon(struct hlist_head *);
+extern int d_invalidate(struct dentry *);
+
+/* only used at mount-time */
+extern struct dentry * d_alloc_root(struct inode *);
+
+/* <clickety>-<click> the ramfs-type tree */
+extern void d_genocide(struct dentry *);
+
+extern struct dentry *d_find_alias(struct inode *);
+extern void d_prune_aliases(struct inode *);
+
+/* test whether we have any submounts in a subdir tree */
+extern int have_submounts(struct dentry *);
+
+/*
+ * This adds the entry to the hash queues.
+ */
+extern void d_rehash(struct dentry *);
+
+/**
+ * d_add - add dentry to hash queues
+ * @entry: dentry to add
+ * @inode: The inode to attach to this dentry
+ *
+ * This adds the entry to the hash queues and initializes @inode.
+ * The entry was actually filled in earlier during d_alloc().
+ */
+
+static inline void d_add(struct dentry *entry, struct inode *inode)
+{
+ d_instantiate(entry, inode);
+ d_rehash(entry);
+}
+
+/**
+ * d_add_unique - add dentry to hash queues without aliasing
+ * @entry: dentry to add
+ * @inode: The inode to attach to this dentry
+ *
+ * This adds the entry to the hash queues and initializes @inode.
+ * The entry was actually filled in earlier during d_alloc().
+ */
+static inline struct dentry *d_add_unique(struct dentry *entry, struct inode *inode)
+{
+ struct dentry *res;
+
+ res = d_instantiate_unique(entry, inode);
+ d_rehash(res != NULL ? res : entry);
+ return res;
+}
+
+/* used for rename() and baskets */
+extern void d_move(struct dentry *, struct dentry *);
+
+/* appendix may either be NULL or be used for transname suffixes */
+extern struct dentry * d_lookup(struct dentry *, struct qstr *);
+extern struct dentry * __d_lookup(struct dentry *, struct qstr *);
+
+/* validate "insecure" dentry pointer */
+extern int d_validate(struct dentry *, struct dentry *);
+
+extern char * d_path(struct dentry *, struct vfsmount *, char *, int);
+
+/* Allocation counts.. */
+
+/**
+ * dget, dget_locked - get a reference to a dentry
+ * @dentry: dentry to get a reference to
+ *
+ * Given a dentry or %NULL pointer increment the reference count
+ * if appropriate and return the dentry. A dentry will not be
+ * destroyed when it has references. dget() should never be
+ * called for dentries with zero reference counter. For these cases
+ * (preferably none, functions in dcache.c are sufficient for normal
+ * needs and they take necessary precautions) you should hold dcache_lock
+ * and call dget_locked() instead of dget().
+ */
+
+static inline struct dentry *dget(struct dentry *dentry)
+{
+ if (dentry) {
+ BUG_ON(!atomic_read(&dentry->d_count));
+ atomic_inc(&dentry->d_count);
+ }
+ return dentry;
+}
+
+extern struct dentry * dget_locked(struct dentry *);
+
+/**
+ * d_unhashed - is dentry hashed
+ * @dentry: entry to check
+ *
+ * Returns true if the dentry passed is not currently hashed.
+ */
+
+static inline int d_unhashed(struct dentry *dentry)
+{
+ return (dentry->d_flags & DCACHE_UNHASHED);
+}
+
+static inline struct dentry *dget_parent(struct dentry *dentry)
+{
+ struct dentry *ret;
+
+ spin_lock(&dentry->d_lock);
+ ret = dget(dentry->d_parent);
+ spin_unlock(&dentry->d_lock);
+ return ret;
+}
+
+extern void dput(struct dentry *);
+
+static inline int d_mountpoint(struct dentry *dentry)
+{
+ return dentry->d_mounted;
+}
+
+extern struct vfsmount *lookup_mnt(struct vfsmount *, struct dentry *);
+extern struct dentry *lookup_create(struct nameidata *nd, int is_dir);
+
+extern int sysctl_vfs_cache_pressure;
+
+#endif /* __KERNEL__ */
+
+#endif /* __LINUX_DCACHE_H */