1 files changed, 249 insertions, 0 deletions
diff --git a/fs/autofs/dirhash.c b/fs/autofs/dirhash.c
new file mode 100644
index 000000000000..448143fd0796
--- /dev/null
+++ b/fs/autofs/dirhash.c
@@ -0,0 +1,249 @@
+/* -*- linux-c -*- --------------------------------------------------------- *
+ *
+ * linux/fs/autofs/dirhash.c
+ *
+ *  Copyright 1997-1998 Transmeta Corporation -- All Rights Reserved
+ *
+ * This file is part of the Linux kernel and is made available under
+ * the terms of the GNU General Public License, version 2, or at your
+ * option, any later version, incorporated herein by reference.
+ *
+ * ------------------------------------------------------------------------- */
+
+#include "autofs_i.h"
+
+/* Functions for maintenance of expiry queue */
+
+static void autofs_init_usage(struct autofs_dirhash *dh,
+			      struct autofs_dir_ent *ent)
+{
+	list_add_tail(&ent->exp, &dh->expiry_head);
+	ent->last_usage = jiffies;
+}
+
+static void autofs_delete_usage(struct autofs_dir_ent *ent)
+{
+	list_del(&ent->exp);
+}
+
+void autofs_update_usage(struct autofs_dirhash *dh,
+			 struct autofs_dir_ent *ent)
+{
+	autofs_delete_usage(ent);   /* Unlink from current position */
+	autofs_init_usage(dh,ent);  /* Relink at queue tail */
+}
+
+struct autofs_dir_ent *autofs_expire(struct super_block *sb,
+				     struct autofs_sb_info *sbi,
+				     struct vfsmount *mnt)
+{
+	struct autofs_dirhash *dh = &sbi->dirhash;
+	struct autofs_dir_ent *ent;
+	struct dentry *dentry;
+	unsigned long timeout = sbi->exp_timeout;
+
+	while (1) {
+		if ( list_empty(&dh->expiry_head) || sbi->catatonic )
+			return NULL;	/* No entries */
+		/* We keep the list sorted by last_usage and want old stuff */
+		ent = list_entry(dh->expiry_head.next, struct autofs_dir_ent, exp);
+		if (jiffies - ent->last_usage < timeout)
+			break;
+		/* Move to end of list in case expiry isn't desirable */
+		autofs_update_usage(dh, ent);
+
+		/* Check to see that entry is expirable */
+		if ( ent->ino < AUTOFS_FIRST_DIR_INO )
+			return ent; /* Symlinks are always expirable */
+
+		/* Get the dentry for the autofs subdirectory */
+		dentry = ent->dentry;
+
+		if ( !dentry ) {
+			/* Should only happen in catatonic mode */
+			printk("autofs: dentry == NULL but inode range is directory, entry %s\n", ent->name);
+			autofs_delete_usage(ent);
+			continue;
+		}
+
+		if ( !dentry->d_inode ) {
+			dput(dentry);
+			printk("autofs: negative dentry on expiry queue: %s\n",
+			       ent->name);
+			autofs_delete_usage(ent);
+			continue;
+		}
+
+		/* Make sure entry is mounted and unused; note that dentry will
+		   point to the mounted-on-top root. */
+		if (!S_ISDIR(dentry->d_inode->i_mode)||!d_mountpoint(dentry)) {
+			DPRINTK(("autofs: not expirable (not a mounted directory): %s\n", ent->name));
+			continue;
+		}
+		mntget(mnt);
+		dget(dentry);
+		if (!follow_down(&mnt, &dentry)) {
+			dput(dentry);
+			mntput(mnt);
+			DPRINTK(("autofs: not expirable (not a mounted directory): %s\n", ent->name));
+			continue;
+		}
+		while (d_mountpoint(dentry) && follow_down(&mnt, &dentry))
+			;
+		dput(dentry);
+
+		if ( may_umount(mnt) == 0 ) {
+			mntput(mnt);
+			DPRINTK(("autofs: signaling expire on %s\n", ent->name));
+			return ent; /* Expirable! */
+		}
+		DPRINTK(("autofs: didn't expire due to may_umount: %s\n", ent->name));
+		mntput(mnt);
+	}
+	return NULL;		/* No expirable entries */
+}
+
+void autofs_initialize_hash(struct autofs_dirhash *dh) {
+	memset(&dh->h, 0, AUTOFS_HASH_SIZE*sizeof(struct autofs_dir_ent *));
+	INIT_LIST_HEAD(&dh->expiry_head);
+}
+
+struct autofs_dir_ent *autofs_hash_lookup(const struct autofs_dirhash *dh, struct qstr *name)
+{
+	struct autofs_dir_ent *dhn;
+
+	DPRINTK(("autofs_hash_lookup: hash = 0x%08x, name = ", name->hash));
+	autofs_say(name->name,name->len);
+
+	for ( dhn = dh->h[(unsigned) name->hash % AUTOFS_HASH_SIZE] ; dhn ; dhn = dhn->next ) {
+		if ( name->hash == dhn->hash &&
+		     name->len == dhn->len &&
+		     !memcmp(name->name, dhn->name, name->len) )
+			break;
+	}
+
+	return dhn;
+}
+
+void autofs_hash_insert(struct autofs_dirhash *dh, struct autofs_dir_ent *ent)
+{
+	struct autofs_dir_ent **dhnp;
+
+	DPRINTK(("autofs_hash_insert: hash = 0x%08x, name = ", ent->hash));
+	autofs_say(ent->name,ent->len);
+
+	autofs_init_usage(dh,ent);
+	if (ent->dentry)
+		dget(ent->dentry);
+
+	dhnp = &dh->h[(unsigned) ent->hash % AUTOFS_HASH_SIZE];
+	ent->next = *dhnp;
+	ent->back = dhnp;
+	*dhnp = ent;
+	if ( ent->next )
+		ent->next->back = &(ent->next);
+}
+
+void autofs_hash_delete(struct autofs_dir_ent *ent)
+{
+	*(ent->back) = ent->next;
+	if ( ent->next )
+		ent->next->back = ent->back;
+
+	autofs_delete_usage(ent);
+
+	if ( ent->dentry )
+		dput(ent->dentry);
+	kfree(ent->name);
+	kfree(ent);
+}
+
+/*
+ * Used by readdir().  We must validate "ptr", so we can't simply make it
+ * a pointer.  Values below 0xffff are reserved; calling with any value
+ * <= 0x10000 will return the first entry found.
+ *
+ * "last" can be NULL or the value returned by the last search *if* we
+ * want the next sequential entry.
+ */
+struct autofs_dir_ent *autofs_hash_enum(const struct autofs_dirhash *dh,
+					off_t *ptr, struct autofs_dir_ent *last)
+{
+	int bucket, ecount, i;
+	struct autofs_dir_ent *ent;
+
+	bucket = (*ptr >> 16) - 1;
+	ecount = *ptr & 0xffff;
+
+	if ( bucket < 0 ) {
+		bucket = ecount = 0;
+	} 
+
+	DPRINTK(("autofs_hash_enum: bucket %d, entry %d\n", bucket, ecount));
+
+	ent = last ? last->next : NULL;
+
+	if ( ent ) {
+		ecount++;
+	} else {
+		while  ( bucket < AUTOFS_HASH_SIZE ) {
+			ent = dh->h[bucket];
+			for ( i = ecount ; ent && i ; i-- )
+				ent = ent->next;
+			
+			if (ent) {
+				ecount++; /* Point to *next* entry */
+				break;
+			}
+			
+			bucket++; ecount = 0;
+		}
+	}
+
+#ifdef DEBUG
+	if ( !ent )
+		printk("autofs_hash_enum: nothing found\n");
+	else {
+		printk("autofs_hash_enum: found hash %08x, name", ent->hash);
+		autofs_say(ent->name,ent->len);
+	}
+#endif
+
+	*ptr = ((bucket+1) << 16) + ecount;
+	return ent;
+}
+
+/* Iterate over all the ents, and remove all dentry pointers.  Used on
+   entering catatonic mode, in order to make the filesystem unmountable. */
+void autofs_hash_dputall(struct autofs_dirhash *dh)
+{
+	int i;
+	struct autofs_dir_ent *ent;
+
+	for ( i = 0 ; i < AUTOFS_HASH_SIZE ; i++ ) {
+		for ( ent = dh->h[i] ; ent ; ent = ent->next ) {
+			if ( ent->dentry ) {
+				dput(ent->dentry);
+				ent->dentry = NULL;
+			}
+		}
+	}
+}
+
+/* Delete everything.  This is used on filesystem destruction, so we
+   make no attempt to keep the pointers valid */
+void autofs_hash_nuke(struct autofs_dirhash *dh)
+{
+	int i;
+	struct autofs_dir_ent *ent, *nent;
+
+	for ( i = 0 ; i < AUTOFS_HASH_SIZE ; i++ ) {
+		for ( ent = dh->h[i] ; ent ; ent = nent ) {
+			nent = ent->next;
+			if ( ent->dentry )
+				dput(ent->dentry);
+			kfree(ent->name);
+			kfree(ent);
+		}
+	}
+}