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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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9f3acc3140
Initial splitoff of the low-level stuff; taken to fdtable.h Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
195 lines
4.6 KiB
C
195 lines
4.6 KiB
C
/*
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* Directory notifications for Linux.
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*
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* Copyright (C) 2000,2001,2002 Stephen Rothwell
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the
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* Free Software Foundation; either version 2, or (at your option) any
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* later version.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*/
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#include <linux/fs.h>
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#include <linux/module.h>
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#include <linux/sched.h>
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#include <linux/dnotify.h>
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#include <linux/init.h>
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#include <linux/spinlock.h>
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#include <linux/slab.h>
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#include <linux/fdtable.h>
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int dir_notify_enable __read_mostly = 1;
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static struct kmem_cache *dn_cache __read_mostly;
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static void redo_inode_mask(struct inode *inode)
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{
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unsigned long new_mask;
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struct dnotify_struct *dn;
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new_mask = 0;
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for (dn = inode->i_dnotify; dn != NULL; dn = dn->dn_next)
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new_mask |= dn->dn_mask & ~DN_MULTISHOT;
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inode->i_dnotify_mask = new_mask;
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}
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void dnotify_flush(struct file *filp, fl_owner_t id)
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{
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struct dnotify_struct *dn;
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struct dnotify_struct **prev;
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struct inode *inode;
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inode = filp->f_path.dentry->d_inode;
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if (!S_ISDIR(inode->i_mode))
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return;
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spin_lock(&inode->i_lock);
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prev = &inode->i_dnotify;
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while ((dn = *prev) != NULL) {
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if ((dn->dn_owner == id) && (dn->dn_filp == filp)) {
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*prev = dn->dn_next;
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redo_inode_mask(inode);
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kmem_cache_free(dn_cache, dn);
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break;
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}
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prev = &dn->dn_next;
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}
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spin_unlock(&inode->i_lock);
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}
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int fcntl_dirnotify(int fd, struct file *filp, unsigned long arg)
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{
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struct dnotify_struct *dn;
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struct dnotify_struct *odn;
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struct dnotify_struct **prev;
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struct inode *inode;
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fl_owner_t id = current->files;
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struct file *f;
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int error = 0;
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if ((arg & ~DN_MULTISHOT) == 0) {
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dnotify_flush(filp, id);
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return 0;
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}
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if (!dir_notify_enable)
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return -EINVAL;
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inode = filp->f_path.dentry->d_inode;
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if (!S_ISDIR(inode->i_mode))
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return -ENOTDIR;
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dn = kmem_cache_alloc(dn_cache, GFP_KERNEL);
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if (dn == NULL)
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return -ENOMEM;
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spin_lock(&inode->i_lock);
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prev = &inode->i_dnotify;
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while ((odn = *prev) != NULL) {
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if ((odn->dn_owner == id) && (odn->dn_filp == filp)) {
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odn->dn_fd = fd;
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odn->dn_mask |= arg;
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inode->i_dnotify_mask |= arg & ~DN_MULTISHOT;
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goto out_free;
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}
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prev = &odn->dn_next;
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}
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rcu_read_lock();
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f = fcheck(fd);
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rcu_read_unlock();
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/* we'd lost the race with close(), sod off silently */
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/* note that inode->i_lock prevents reordering problems
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* between accesses to descriptor table and ->i_dnotify */
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if (f != filp)
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goto out_free;
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error = __f_setown(filp, task_pid(current), PIDTYPE_PID, 0);
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if (error)
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goto out_free;
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dn->dn_mask = arg;
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dn->dn_fd = fd;
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dn->dn_filp = filp;
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dn->dn_owner = id;
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inode->i_dnotify_mask |= arg & ~DN_MULTISHOT;
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dn->dn_next = inode->i_dnotify;
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inode->i_dnotify = dn;
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spin_unlock(&inode->i_lock);
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if (filp->f_op && filp->f_op->dir_notify)
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return filp->f_op->dir_notify(filp, arg);
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return 0;
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out_free:
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spin_unlock(&inode->i_lock);
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kmem_cache_free(dn_cache, dn);
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return error;
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}
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void __inode_dir_notify(struct inode *inode, unsigned long event)
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{
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struct dnotify_struct * dn;
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struct dnotify_struct **prev;
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struct fown_struct * fown;
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int changed = 0;
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spin_lock(&inode->i_lock);
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prev = &inode->i_dnotify;
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while ((dn = *prev) != NULL) {
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if ((dn->dn_mask & event) == 0) {
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prev = &dn->dn_next;
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continue;
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}
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fown = &dn->dn_filp->f_owner;
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send_sigio(fown, dn->dn_fd, POLL_MSG);
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if (dn->dn_mask & DN_MULTISHOT)
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prev = &dn->dn_next;
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else {
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*prev = dn->dn_next;
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changed = 1;
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kmem_cache_free(dn_cache, dn);
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}
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}
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if (changed)
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redo_inode_mask(inode);
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spin_unlock(&inode->i_lock);
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}
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EXPORT_SYMBOL(__inode_dir_notify);
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/*
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* This is hopelessly wrong, but unfixable without API changes. At
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* least it doesn't oops the kernel...
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*
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* To safely access ->d_parent we need to keep d_move away from it. Use the
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* dentry's d_lock for this.
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*/
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void dnotify_parent(struct dentry *dentry, unsigned long event)
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{
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struct dentry *parent;
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if (!dir_notify_enable)
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return;
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spin_lock(&dentry->d_lock);
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parent = dentry->d_parent;
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if (parent->d_inode->i_dnotify_mask & event) {
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dget(parent);
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spin_unlock(&dentry->d_lock);
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__inode_dir_notify(parent->d_inode, event);
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dput(parent);
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} else {
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spin_unlock(&dentry->d_lock);
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}
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}
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EXPORT_SYMBOL_GPL(dnotify_parent);
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static int __init dnotify_init(void)
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{
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dn_cache = kmem_cache_create("dnotify_cache",
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sizeof(struct dnotify_struct), 0, SLAB_PANIC, NULL);
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return 0;
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}
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module_init(dnotify_init)
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