patch-2.4.0-test9 linux/fs/dnotify.c

• Lines: 141
• Date: Fri Sep 22 14:21:18 2000
• Orig file: v2.4.0-test8/linux/fs/dnotify.c
• Orig date: Wed Dec 31 16:00:00 1969

diff -u --recursive --new-file v2.4.0-test8/linux/fs/dnotify.c linux/fs/dnotify.c
@@ -0,0 +1,140 @@
+/*
+ * Directory notifications for Linux.
+ *
+ * Copyright (C) 2000 Stephen Rothwell
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2, or (at your option) any
+ * later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ */
+#include <linux/fs.h>
+#include <linux/sched.h>
+#include <linux/dnotify.h>
+#include <linux/init.h>
+#include <linux/spinlock.h>
+#include <linux/slab.h>
+
+extern void send_sigio(struct fown_struct *fown, int fd, int band);
+
+int dir_notify_enable = 1;
+
+static rwlock_t dn_lock = RW_LOCK_UNLOCKED;
+static kmem_cache_t *dn_cache;
+
+static void redo_inode_mask(struct inode *inode)
+{
+	unsigned long new_mask;
+	struct dnotify_struct *dn;
+
+	new_mask = 0;
+	for (dn = inode->i_dnotify; dn != NULL; dn = dn->dn_next)
+		new_mask |= dn->dn_mask & ~DN_MULTISHOT;
+	inode->i_dnotify_mask = new_mask;
+}
+
+int fcntl_dirnotify(int fd, struct file *filp, unsigned long arg)
+{
+	struct dnotify_struct *dn = NULL;
+	struct dnotify_struct *odn;
+	struct dnotify_struct **prev;
+	struct inode *inode;
+	int turning_off = (arg & ~DN_MULTISHOT) == 0;
+
+	if (!turning_off && !dir_notify_enable)
+		return -EINVAL;
+	inode = filp->f_dentry->d_inode;
+	if (!S_ISDIR(inode->i_mode))
+		return -ENOTDIR;
+	if (!turning_off) {
+		dn = kmem_cache_alloc(dn_cache, SLAB_KERNEL);
+		if (dn == NULL)
+			return -ENOMEM;
+	}
+	write_lock(&dn_lock);
+	prev = &inode->i_dnotify;
+	for (odn = *prev; odn != NULL; prev = &odn->dn_next, odn = *prev)
+		if (odn->dn_filp == filp)
+			break;
+	if (odn != NULL) {
+		if (turning_off) {
+			*prev = odn->dn_next;
+			redo_inode_mask(inode);
+			dn = odn;
+			goto out_free;
+		}
+		odn->dn_fd = fd;
+		odn->dn_mask |= arg;
+		inode->i_dnotify_mask |= arg & ~DN_MULTISHOT;
+		goto out_free;
+	}
+	if (turning_off)
+		goto out;
+	filp->f_owner.pid = current->pid;
+	filp->f_owner.uid = current->uid;
+	filp->f_owner.euid = current->euid;
+	dn->dn_magic = DNOTIFY_MAGIC;
+	dn->dn_mask = arg;
+	dn->dn_fd = fd;
+	dn->dn_filp = filp;
+	inode->i_dnotify_mask |= arg & ~DN_MULTISHOT;
+	dn->dn_next = inode->i_dnotify;
+	inode->i_dnotify = dn;
+out:
+	write_unlock(&dn_lock);
+	return 0;
+out_free:
+	kmem_cache_free(dn_cache, dn);
+	goto out;
+}
+
+void __inode_dir_notify(struct inode *inode, unsigned long event)
+{
+	struct dnotify_struct *	dn;
+	struct dnotify_struct **prev;
+	struct fown_struct *	fown;
+	int			changed = 0;
+
+	write_lock(&dn_lock);
+	prev = &inode->i_dnotify;
+	while ((dn = *prev) != NULL) {
+		if ((dn->dn_mask & event) == 0) {
+			prev = &dn->dn_next;
+			continue;
+		}
+		if (dn->dn_magic != DNOTIFY_MAGIC) {
+		        printk(KERN_ERR "__inode_dir_notify: bad magic "
+				"number in dnotify_struct!\n");
+		        return;
+		}
+		fown = &dn->dn_filp->f_owner;
+		if (fown->pid)
+		        send_sigio(fown, dn->dn_fd, POLL_MSG);
+		if (dn->dn_mask & DN_MULTISHOT)
+			prev = &dn->dn_next;
+		else {
+			*prev = dn->dn_next;
+			changed = 1;
+			kmem_cache_free(dn_cache, dn);
+		}
+	}
+	if (changed)
+		redo_inode_mask(inode);
+	write_unlock(&dn_lock);
+}
+
+static int __init dnotify_init(void)
+{
+	dn_cache = kmem_cache_create("dnotify cache",
+		sizeof(struct dnotify_struct), 0, 0, NULL, NULL);
+	if (!dn_cache)
+		panic("cannot create dnotify slab cache");
+	return 0;
+}
+
+module_init(dnotify_init)