/* * 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; 30 static void redo_inode_mask(struct inode *inode) { unsigned long new_mask; struct dnotify_struct *dn; new_mask = 0; 36 for (dn = inode->i_dnotify; dn != NULL; dn = dn->dn_next) new_mask |= dn->dn_mask & ~DN_MULTISHOT; inode->i_dnotify_mask = new_mask; } 41 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; 49 if (!turning_off && !dir_notify_enable) 50 return -EINVAL; inode = filp->f_dentry->d_inode; 52 if (!S_ISDIR(inode->i_mode)) 53 return -ENOTDIR; 54 if (!turning_off) { dn = kmem_cache_alloc(dn_cache, SLAB_KERNEL); 56 if (dn == NULL) 57 return -ENOMEM; } write_lock(&dn_lock); prev = &inode->i_dnotify; 61 for (odn = *prev; odn != NULL; prev = &odn->dn_next, odn = *prev) 62 if (odn->dn_filp == filp) 63 break; 64 if (odn != NULL) { 65 if (turning_off) { *prev = odn->dn_next; redo_inode_mask(inode); dn = odn; 69 goto out_free; } odn->dn_fd = fd; odn->dn_mask |= arg; inode->i_dnotify_mask |= arg & ~DN_MULTISHOT; 74 goto out_free; } 76 if (turning_off) 77 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: 89 write_unlock(&dn_lock); 90 return 0; out_free: kmem_cache_free(dn_cache, dn); 93 goto out; } 96 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; 105 while ((dn = *prev) != NULL) { 106 if (dn->dn_magic != DNOTIFY_MAGIC) { printk(KERN_ERR "__inode_dir_notify: bad magic " "number in dnotify_struct!\n"); 109 goto out; } 111 if ((dn->dn_mask & event) == 0) { prev = &dn->dn_next; 113 continue; } fown = &dn->dn_filp->f_owner; 116 if (fown->pid) send_sigio(fown, dn->dn_fd, POLL_MSG); 118 if (dn->dn_mask & DN_MULTISHOT) prev = &dn->dn_next; 120 else { *prev = dn->dn_next; changed = 1; kmem_cache_free(dn_cache, dn); } } 126 if (changed) redo_inode_mask(inode); out: 129 write_unlock(&dn_lock); } 132 static int __init dnotify_init(void) { dn_cache = kmem_cache_create("dnotify cache", sizeof(struct dnotify_struct), 0, 0, NULL, NULL); 136 if (!dn_cache) panic("cannot create dnotify slab cache"); 138 return 0; } module_init(dnotify_init)