17b6be844SDan Williams /* 27b6be844SDan Williams * Copyright(c) 2017 Intel Corporation. All rights reserved. 37b6be844SDan Williams * 47b6be844SDan Williams * This program is free software; you can redistribute it and/or modify 57b6be844SDan Williams * it under the terms of version 2 of the GNU General Public License as 67b6be844SDan Williams * published by the Free Software Foundation. 77b6be844SDan Williams * 87b6be844SDan Williams * This program is distributed in the hope that it will be useful, but 97b6be844SDan Williams * WITHOUT ANY WARRANTY; without even the implied warranty of 107b6be844SDan Williams * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 117b6be844SDan Williams * General Public License for more details. 127b6be844SDan Williams */ 137b6be844SDan Williams #include <linux/pagemap.h> 147b6be844SDan Williams #include <linux/module.h> 157b6be844SDan Williams #include <linux/mount.h> 167b6be844SDan Williams #include <linux/magic.h> 177b6be844SDan Williams #include <linux/cdev.h> 187b6be844SDan Williams #include <linux/hash.h> 197b6be844SDan Williams #include <linux/slab.h> 207b6be844SDan Williams #include <linux/fs.h> 217b6be844SDan Williams 227b6be844SDan Williams static int nr_dax = CONFIG_NR_DEV_DAX; 237b6be844SDan Williams module_param(nr_dax, int, S_IRUGO); 247b6be844SDan Williams MODULE_PARM_DESC(nr_dax, "max number of dax device instances"); 257b6be844SDan Williams 267b6be844SDan Williams static dev_t dax_devt; 277b6be844SDan Williams DEFINE_STATIC_SRCU(dax_srcu); 287b6be844SDan Williams static struct vfsmount *dax_mnt; 297b6be844SDan Williams static DEFINE_IDA(dax_minor_ida); 307b6be844SDan Williams static struct kmem_cache *dax_cache __read_mostly; 317b6be844SDan Williams static struct super_block *dax_superblock __read_mostly; 327b6be844SDan Williams 337b6be844SDan Williams int dax_read_lock(void) 347b6be844SDan Williams { 357b6be844SDan Williams return srcu_read_lock(&dax_srcu); 367b6be844SDan Williams } 377b6be844SDan Williams EXPORT_SYMBOL_GPL(dax_read_lock); 387b6be844SDan Williams 397b6be844SDan Williams void dax_read_unlock(int id) 407b6be844SDan Williams { 417b6be844SDan Williams srcu_read_unlock(&dax_srcu, id); 427b6be844SDan Williams } 437b6be844SDan Williams EXPORT_SYMBOL_GPL(dax_read_unlock); 447b6be844SDan Williams 457b6be844SDan Williams /** 467b6be844SDan Williams * struct dax_device - anchor object for dax services 477b6be844SDan Williams * @inode: core vfs 487b6be844SDan Williams * @cdev: optional character interface for "device dax" 497b6be844SDan Williams * @private: dax driver private data 507b6be844SDan Williams * @alive: !alive + rcu grace period == no new operations / mappings 517b6be844SDan Williams */ 527b6be844SDan Williams struct dax_device { 537b6be844SDan Williams struct inode inode; 547b6be844SDan Williams struct cdev cdev; 557b6be844SDan Williams void *private; 567b6be844SDan Williams bool alive; 577b6be844SDan Williams }; 587b6be844SDan Williams 597b6be844SDan Williams bool dax_alive(struct dax_device *dax_dev) 607b6be844SDan Williams { 617b6be844SDan Williams lockdep_assert_held(&dax_srcu); 627b6be844SDan Williams return dax_dev->alive; 637b6be844SDan Williams } 647b6be844SDan Williams EXPORT_SYMBOL_GPL(dax_alive); 657b6be844SDan Williams 667b6be844SDan Williams /* 677b6be844SDan Williams * Note, rcu is not protecting the liveness of dax_dev, rcu is ensuring 687b6be844SDan Williams * that any fault handlers or operations that might have seen 697b6be844SDan Williams * dax_alive(), have completed. Any operations that start after 707b6be844SDan Williams * synchronize_srcu() has run will abort upon seeing !dax_alive(). 717b6be844SDan Williams */ 727b6be844SDan Williams void kill_dax(struct dax_device *dax_dev) 737b6be844SDan Williams { 747b6be844SDan Williams if (!dax_dev) 757b6be844SDan Williams return; 767b6be844SDan Williams 777b6be844SDan Williams dax_dev->alive = false; 787b6be844SDan Williams synchronize_srcu(&dax_srcu); 797b6be844SDan Williams dax_dev->private = NULL; 807b6be844SDan Williams } 817b6be844SDan Williams EXPORT_SYMBOL_GPL(kill_dax); 827b6be844SDan Williams 837b6be844SDan Williams static struct inode *dax_alloc_inode(struct super_block *sb) 847b6be844SDan Williams { 857b6be844SDan Williams struct dax_device *dax_dev; 867b6be844SDan Williams 877b6be844SDan Williams dax_dev = kmem_cache_alloc(dax_cache, GFP_KERNEL); 887b6be844SDan Williams return &dax_dev->inode; 897b6be844SDan Williams } 907b6be844SDan Williams 917b6be844SDan Williams static struct dax_device *to_dax_dev(struct inode *inode) 927b6be844SDan Williams { 937b6be844SDan Williams return container_of(inode, struct dax_device, inode); 947b6be844SDan Williams } 957b6be844SDan Williams 967b6be844SDan Williams static void dax_i_callback(struct rcu_head *head) 977b6be844SDan Williams { 987b6be844SDan Williams struct inode *inode = container_of(head, struct inode, i_rcu); 997b6be844SDan Williams struct dax_device *dax_dev = to_dax_dev(inode); 1007b6be844SDan Williams 1017b6be844SDan Williams ida_simple_remove(&dax_minor_ida, MINOR(inode->i_rdev)); 1027b6be844SDan Williams kmem_cache_free(dax_cache, dax_dev); 1037b6be844SDan Williams } 1047b6be844SDan Williams 1057b6be844SDan Williams static void dax_destroy_inode(struct inode *inode) 1067b6be844SDan Williams { 1077b6be844SDan Williams struct dax_device *dax_dev = to_dax_dev(inode); 1087b6be844SDan Williams 1097b6be844SDan Williams WARN_ONCE(dax_dev->alive, 1107b6be844SDan Williams "kill_dax() must be called before final iput()\n"); 1117b6be844SDan Williams call_rcu(&inode->i_rcu, dax_i_callback); 1127b6be844SDan Williams } 1137b6be844SDan Williams 1147b6be844SDan Williams static const struct super_operations dax_sops = { 1157b6be844SDan Williams .statfs = simple_statfs, 1167b6be844SDan Williams .alloc_inode = dax_alloc_inode, 1177b6be844SDan Williams .destroy_inode = dax_destroy_inode, 1187b6be844SDan Williams .drop_inode = generic_delete_inode, 1197b6be844SDan Williams }; 1207b6be844SDan Williams 1217b6be844SDan Williams static struct dentry *dax_mount(struct file_system_type *fs_type, 1227b6be844SDan Williams int flags, const char *dev_name, void *data) 1237b6be844SDan Williams { 1247b6be844SDan Williams return mount_pseudo(fs_type, "dax:", &dax_sops, NULL, DAXFS_MAGIC); 1257b6be844SDan Williams } 1267b6be844SDan Williams 1277b6be844SDan Williams static struct file_system_type dax_fs_type = { 1287b6be844SDan Williams .name = "dax", 1297b6be844SDan Williams .mount = dax_mount, 1307b6be844SDan Williams .kill_sb = kill_anon_super, 1317b6be844SDan Williams }; 1327b6be844SDan Williams 1337b6be844SDan Williams static int dax_test(struct inode *inode, void *data) 1347b6be844SDan Williams { 1357b6be844SDan Williams dev_t devt = *(dev_t *) data; 1367b6be844SDan Williams 1377b6be844SDan Williams return inode->i_rdev == devt; 1387b6be844SDan Williams } 1397b6be844SDan Williams 1407b6be844SDan Williams static int dax_set(struct inode *inode, void *data) 1417b6be844SDan Williams { 1427b6be844SDan Williams dev_t devt = *(dev_t *) data; 1437b6be844SDan Williams 1447b6be844SDan Williams inode->i_rdev = devt; 1457b6be844SDan Williams return 0; 1467b6be844SDan Williams } 1477b6be844SDan Williams 1487b6be844SDan Williams static struct dax_device *dax_dev_get(dev_t devt) 1497b6be844SDan Williams { 1507b6be844SDan Williams struct dax_device *dax_dev; 1517b6be844SDan Williams struct inode *inode; 1527b6be844SDan Williams 1537b6be844SDan Williams inode = iget5_locked(dax_superblock, hash_32(devt + DAXFS_MAGIC, 31), 1547b6be844SDan Williams dax_test, dax_set, &devt); 1557b6be844SDan Williams 1567b6be844SDan Williams if (!inode) 1577b6be844SDan Williams return NULL; 1587b6be844SDan Williams 1597b6be844SDan Williams dax_dev = to_dax_dev(inode); 1607b6be844SDan Williams if (inode->i_state & I_NEW) { 1617b6be844SDan Williams dax_dev->alive = true; 1627b6be844SDan Williams inode->i_cdev = &dax_dev->cdev; 1637b6be844SDan Williams inode->i_mode = S_IFCHR; 1647b6be844SDan Williams inode->i_flags = S_DAX; 1657b6be844SDan Williams mapping_set_gfp_mask(&inode->i_data, GFP_USER); 1667b6be844SDan Williams unlock_new_inode(inode); 1677b6be844SDan Williams } 1687b6be844SDan Williams 1697b6be844SDan Williams return dax_dev; 1707b6be844SDan Williams } 1717b6be844SDan Williams 1727b6be844SDan Williams struct dax_device *alloc_dax(void *private) 1737b6be844SDan Williams { 1747b6be844SDan Williams struct dax_device *dax_dev; 1757b6be844SDan Williams dev_t devt; 1767b6be844SDan Williams int minor; 1777b6be844SDan Williams 1787b6be844SDan Williams minor = ida_simple_get(&dax_minor_ida, 0, nr_dax, GFP_KERNEL); 1797b6be844SDan Williams if (minor < 0) 1807b6be844SDan Williams return NULL; 1817b6be844SDan Williams 1827b6be844SDan Williams devt = MKDEV(MAJOR(dax_devt), minor); 1837b6be844SDan Williams dax_dev = dax_dev_get(devt); 1847b6be844SDan Williams if (!dax_dev) 1857b6be844SDan Williams goto err_inode; 1867b6be844SDan Williams 1877b6be844SDan Williams dax_dev->private = private; 1887b6be844SDan Williams return dax_dev; 1897b6be844SDan Williams 1907b6be844SDan Williams err_inode: 1917b6be844SDan Williams ida_simple_remove(&dax_minor_ida, minor); 1927b6be844SDan Williams return NULL; 1937b6be844SDan Williams } 1947b6be844SDan Williams EXPORT_SYMBOL_GPL(alloc_dax); 1957b6be844SDan Williams 1967b6be844SDan Williams void put_dax(struct dax_device *dax_dev) 1977b6be844SDan Williams { 1987b6be844SDan Williams if (!dax_dev) 1997b6be844SDan Williams return; 2007b6be844SDan Williams iput(&dax_dev->inode); 2017b6be844SDan Williams } 2027b6be844SDan Williams EXPORT_SYMBOL_GPL(put_dax); 2037b6be844SDan Williams 2047b6be844SDan Williams /** 2057b6be844SDan Williams * inode_dax: convert a public inode into its dax_dev 2067b6be844SDan Williams * @inode: An inode with i_cdev pointing to a dax_dev 2077b6be844SDan Williams * 2087b6be844SDan Williams * Note this is not equivalent to to_dax_dev() which is for private 2097b6be844SDan Williams * internal use where we know the inode filesystem type == dax_fs_type. 2107b6be844SDan Williams */ 2117b6be844SDan Williams struct dax_device *inode_dax(struct inode *inode) 2127b6be844SDan Williams { 2137b6be844SDan Williams struct cdev *cdev = inode->i_cdev; 2147b6be844SDan Williams 2157b6be844SDan Williams return container_of(cdev, struct dax_device, cdev); 2167b6be844SDan Williams } 2177b6be844SDan Williams EXPORT_SYMBOL_GPL(inode_dax); 2187b6be844SDan Williams 2197b6be844SDan Williams struct inode *dax_inode(struct dax_device *dax_dev) 2207b6be844SDan Williams { 2217b6be844SDan Williams return &dax_dev->inode; 2227b6be844SDan Williams } 2237b6be844SDan Williams EXPORT_SYMBOL_GPL(dax_inode); 2247b6be844SDan Williams 2257b6be844SDan Williams void *dax_get_private(struct dax_device *dax_dev) 2267b6be844SDan Williams { 2277b6be844SDan Williams return dax_dev->private; 2287b6be844SDan Williams } 2297b6be844SDan Williams EXPORT_SYMBOL_GPL(dax_get_private); 2307b6be844SDan Williams 2317b6be844SDan Williams static void init_once(void *_dax_dev) 2327b6be844SDan Williams { 2337b6be844SDan Williams struct dax_device *dax_dev = _dax_dev; 2347b6be844SDan Williams struct inode *inode = &dax_dev->inode; 2357b6be844SDan Williams 2367b6be844SDan Williams inode_init_once(inode); 2377b6be844SDan Williams } 2387b6be844SDan Williams 2397b6be844SDan Williams static int __dax_fs_init(void) 2407b6be844SDan Williams { 2417b6be844SDan Williams int rc; 2427b6be844SDan Williams 2437b6be844SDan Williams dax_cache = kmem_cache_create("dax_cache", sizeof(struct dax_device), 0, 2447b6be844SDan Williams (SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT| 2457b6be844SDan Williams SLAB_MEM_SPREAD|SLAB_ACCOUNT), 2467b6be844SDan Williams init_once); 2477b6be844SDan Williams if (!dax_cache) 2487b6be844SDan Williams return -ENOMEM; 2497b6be844SDan Williams 2507b6be844SDan Williams rc = register_filesystem(&dax_fs_type); 2517b6be844SDan Williams if (rc) 2527b6be844SDan Williams goto err_register_fs; 2537b6be844SDan Williams 2547b6be844SDan Williams dax_mnt = kern_mount(&dax_fs_type); 2557b6be844SDan Williams if (IS_ERR(dax_mnt)) { 2567b6be844SDan Williams rc = PTR_ERR(dax_mnt); 2577b6be844SDan Williams goto err_mount; 2587b6be844SDan Williams } 2597b6be844SDan Williams dax_superblock = dax_mnt->mnt_sb; 2607b6be844SDan Williams 2617b6be844SDan Williams return 0; 2627b6be844SDan Williams 2637b6be844SDan Williams err_mount: 2647b6be844SDan Williams unregister_filesystem(&dax_fs_type); 2657b6be844SDan Williams err_register_fs: 2667b6be844SDan Williams kmem_cache_destroy(dax_cache); 2677b6be844SDan Williams 2687b6be844SDan Williams return rc; 2697b6be844SDan Williams } 2707b6be844SDan Williams 2717b6be844SDan Williams static void __dax_fs_exit(void) 2727b6be844SDan Williams { 2737b6be844SDan Williams kern_unmount(dax_mnt); 2747b6be844SDan Williams unregister_filesystem(&dax_fs_type); 2757b6be844SDan Williams kmem_cache_destroy(dax_cache); 2767b6be844SDan Williams } 2777b6be844SDan Williams 2787b6be844SDan Williams static int __init dax_fs_init(void) 2797b6be844SDan Williams { 2807b6be844SDan Williams int rc; 2817b6be844SDan Williams 2827b6be844SDan Williams rc = __dax_fs_init(); 2837b6be844SDan Williams if (rc) 2847b6be844SDan Williams return rc; 2857b6be844SDan Williams 2867b6be844SDan Williams nr_dax = max(nr_dax, 256); 2877b6be844SDan Williams rc = alloc_chrdev_region(&dax_devt, 0, nr_dax, "dax"); 2887b6be844SDan Williams if (rc) 2897b6be844SDan Williams __dax_fs_exit(); 2907b6be844SDan Williams return rc; 2917b6be844SDan Williams } 2927b6be844SDan Williams 2937b6be844SDan Williams static void __exit dax_fs_exit(void) 2947b6be844SDan Williams { 2957b6be844SDan Williams unregister_chrdev_region(dax_devt, nr_dax); 2967b6be844SDan Williams ida_destroy(&dax_minor_ida); 2977b6be844SDan Williams __dax_fs_exit(); 2987b6be844SDan Williams } 2997b6be844SDan Williams 3007b6be844SDan Williams MODULE_AUTHOR("Intel Corporation"); 3017b6be844SDan Williams MODULE_LICENSE("GPL v2"); 3027b6be844SDan Williams subsys_initcall(dax_fs_init); 3037b6be844SDan Williams module_exit(dax_fs_exit); 304