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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 | /* * Directory notifications for Linux. * * Copyright (C) 2000,2001,2002 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/module.h> #include <linux/sched.h> #include <linux/dnotify.h> #include <linux/init.h> #include <linux/spinlock.h> #include <linux/slab.h> int dir_notify_enable __read_mostly = 1; static struct kmem_cache *dn_cache __read_mostly; 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; } void dnotify_flush(struct file *filp, fl_owner_t id) { struct dnotify_struct *dn; struct dnotify_struct **prev; struct inode *inode; inode = filp->f_path.dentry->d_inode; if (!S_ISDIR(inode->i_mode)) return; spin_lock(&inode->i_lock); prev = &inode->i_dnotify; while ((dn = *prev) != NULL) { if ((dn->dn_owner == id) && (dn->dn_filp == filp)) { *prev = dn->dn_next; redo_inode_mask(inode); kmem_cache_free(dn_cache, dn); break; } prev = &dn->dn_next; } spin_unlock(&inode->i_lock); } int fcntl_dirnotify(int fd, struct file *filp, unsigned long arg) { struct dnotify_struct *dn; struct dnotify_struct *odn; struct dnotify_struct **prev; struct inode *inode; fl_owner_t id = current->files; int error = 0; if ((arg & ~DN_MULTISHOT) == 0) { dnotify_flush(filp, id); return 0; } if (!dir_notify_enable) return -EINVAL; inode = filp->f_path.dentry->d_inode; if (!S_ISDIR(inode->i_mode)) return -ENOTDIR; dn = kmem_cache_alloc(dn_cache, GFP_KERNEL); if (dn == NULL) return -ENOMEM; spin_lock(&inode->i_lock); prev = &inode->i_dnotify; while ((odn = *prev) != NULL) { if ((odn->dn_owner == id) && (odn->dn_filp == filp)) { odn->dn_fd = fd; odn->dn_mask |= arg; inode->i_dnotify_mask |= arg & ~DN_MULTISHOT; goto out_free; } prev = &odn->dn_next; } error = __f_setown(filp, task_pid(current), PIDTYPE_PID, 0); if (error) goto out_free; dn->dn_mask = arg; dn->dn_fd = fd; dn->dn_filp = filp; dn->dn_owner = id; inode->i_dnotify_mask |= arg & ~DN_MULTISHOT; dn->dn_next = inode->i_dnotify; inode->i_dnotify = dn; spin_unlock(&inode->i_lock); if (filp->f_op && filp->f_op->dir_notify) return filp->f_op->dir_notify(filp, arg); return 0; out_free: spin_unlock(&inode->i_lock); kmem_cache_free(dn_cache, dn); return error; } 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; spin_lock(&inode->i_lock); prev = &inode->i_dnotify; while ((dn = *prev) != NULL) { if ((dn->dn_mask & event) == 0) { prev = &dn->dn_next; continue; } fown = &dn->dn_filp->f_owner; 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); spin_unlock(&inode->i_lock); } EXPORT_SYMBOL(__inode_dir_notify); /* * This is hopelessly wrong, but unfixable without API changes. At * least it doesn't oops the kernel... * * To safely access ->d_parent we need to keep d_move away from it. Use the * dentry's d_lock for this. */ void dnotify_parent(struct dentry *dentry, unsigned long event) { struct dentry *parent; if (!dir_notify_enable) return; spin_lock(&dentry->d_lock); parent = dentry->d_parent; if (parent->d_inode->i_dnotify_mask & event) { dget(parent); spin_unlock(&dentry->d_lock); __inode_dir_notify(parent->d_inode, event); dput(parent); } else { spin_unlock(&dentry->d_lock); } } EXPORT_SYMBOL_GPL(dnotify_parent); static int __init dnotify_init(void) { dn_cache = kmem_cache_create("dnotify_cache", sizeof(struct dnotify_struct), 0, SLAB_PANIC, NULL, NULL); return 0; } module_init(dnotify_init) |