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 3372058005SDan Williams #define DAX_HASH_SIZE (PAGE_SIZE / sizeof(struct hlist_head)) 3472058005SDan Williams static struct hlist_head dax_host_list[DAX_HASH_SIZE]; 3572058005SDan Williams static DEFINE_SPINLOCK(dax_host_lock); 3672058005SDan Williams 377b6be844SDan Williams int dax_read_lock(void) 387b6be844SDan Williams { 397b6be844SDan Williams return srcu_read_lock(&dax_srcu); 407b6be844SDan Williams } 417b6be844SDan Williams EXPORT_SYMBOL_GPL(dax_read_lock); 427b6be844SDan Williams 437b6be844SDan Williams void dax_read_unlock(int id) 447b6be844SDan Williams { 457b6be844SDan Williams srcu_read_unlock(&dax_srcu, id); 467b6be844SDan Williams } 477b6be844SDan Williams EXPORT_SYMBOL_GPL(dax_read_unlock); 487b6be844SDan Williams 497b6be844SDan Williams /** 507b6be844SDan Williams * struct dax_device - anchor object for dax services 517b6be844SDan Williams * @inode: core vfs 527b6be844SDan Williams * @cdev: optional character interface for "device dax" 5372058005SDan Williams * @host: optional name for lookups where the device path is not available 547b6be844SDan Williams * @private: dax driver private data 557b6be844SDan Williams * @alive: !alive + rcu grace period == no new operations / mappings 567b6be844SDan Williams */ 577b6be844SDan Williams struct dax_device { 5872058005SDan Williams struct hlist_node list; 597b6be844SDan Williams struct inode inode; 607b6be844SDan Williams struct cdev cdev; 6172058005SDan Williams const char *host; 627b6be844SDan Williams void *private; 637b6be844SDan Williams bool alive; 647b6be844SDan Williams }; 657b6be844SDan Williams 667b6be844SDan Williams bool dax_alive(struct dax_device *dax_dev) 677b6be844SDan Williams { 687b6be844SDan Williams lockdep_assert_held(&dax_srcu); 697b6be844SDan Williams return dax_dev->alive; 707b6be844SDan Williams } 717b6be844SDan Williams EXPORT_SYMBOL_GPL(dax_alive); 727b6be844SDan Williams 7372058005SDan Williams static int dax_host_hash(const char *host) 7472058005SDan Williams { 7572058005SDan Williams return hashlen_hash(hashlen_string("DAX", host)) % DAX_HASH_SIZE; 7672058005SDan Williams } 7772058005SDan Williams 787b6be844SDan Williams /* 797b6be844SDan Williams * Note, rcu is not protecting the liveness of dax_dev, rcu is ensuring 807b6be844SDan Williams * that any fault handlers or operations that might have seen 817b6be844SDan Williams * dax_alive(), have completed. Any operations that start after 827b6be844SDan Williams * synchronize_srcu() has run will abort upon seeing !dax_alive(). 837b6be844SDan Williams */ 847b6be844SDan Williams void kill_dax(struct dax_device *dax_dev) 857b6be844SDan Williams { 867b6be844SDan Williams if (!dax_dev) 877b6be844SDan Williams return; 887b6be844SDan Williams 897b6be844SDan Williams dax_dev->alive = false; 9072058005SDan Williams 917b6be844SDan Williams synchronize_srcu(&dax_srcu); 9272058005SDan Williams 9372058005SDan Williams spin_lock(&dax_host_lock); 9472058005SDan Williams hlist_del_init(&dax_dev->list); 9572058005SDan Williams spin_unlock(&dax_host_lock); 9672058005SDan Williams 977b6be844SDan Williams dax_dev->private = NULL; 987b6be844SDan Williams } 997b6be844SDan Williams EXPORT_SYMBOL_GPL(kill_dax); 1007b6be844SDan Williams 1017b6be844SDan Williams static struct inode *dax_alloc_inode(struct super_block *sb) 1027b6be844SDan Williams { 1037b6be844SDan Williams struct dax_device *dax_dev; 1047b6be844SDan Williams 1057b6be844SDan Williams dax_dev = kmem_cache_alloc(dax_cache, GFP_KERNEL); 1067b6be844SDan Williams return &dax_dev->inode; 1077b6be844SDan Williams } 1087b6be844SDan Williams 1097b6be844SDan Williams static struct dax_device *to_dax_dev(struct inode *inode) 1107b6be844SDan Williams { 1117b6be844SDan Williams return container_of(inode, struct dax_device, inode); 1127b6be844SDan Williams } 1137b6be844SDan Williams 1147b6be844SDan Williams static void dax_i_callback(struct rcu_head *head) 1157b6be844SDan Williams { 1167b6be844SDan Williams struct inode *inode = container_of(head, struct inode, i_rcu); 1177b6be844SDan Williams struct dax_device *dax_dev = to_dax_dev(inode); 1187b6be844SDan Williams 11972058005SDan Williams kfree(dax_dev->host); 12072058005SDan Williams dax_dev->host = NULL; 1217b6be844SDan Williams ida_simple_remove(&dax_minor_ida, MINOR(inode->i_rdev)); 1227b6be844SDan Williams kmem_cache_free(dax_cache, dax_dev); 1237b6be844SDan Williams } 1247b6be844SDan Williams 1257b6be844SDan Williams static void dax_destroy_inode(struct inode *inode) 1267b6be844SDan Williams { 1277b6be844SDan Williams struct dax_device *dax_dev = to_dax_dev(inode); 1287b6be844SDan Williams 1297b6be844SDan Williams WARN_ONCE(dax_dev->alive, 1307b6be844SDan Williams "kill_dax() must be called before final iput()\n"); 1317b6be844SDan Williams call_rcu(&inode->i_rcu, dax_i_callback); 1327b6be844SDan Williams } 1337b6be844SDan Williams 1347b6be844SDan Williams static const struct super_operations dax_sops = { 1357b6be844SDan Williams .statfs = simple_statfs, 1367b6be844SDan Williams .alloc_inode = dax_alloc_inode, 1377b6be844SDan Williams .destroy_inode = dax_destroy_inode, 1387b6be844SDan Williams .drop_inode = generic_delete_inode, 1397b6be844SDan Williams }; 1407b6be844SDan Williams 1417b6be844SDan Williams static struct dentry *dax_mount(struct file_system_type *fs_type, 1427b6be844SDan Williams int flags, const char *dev_name, void *data) 1437b6be844SDan Williams { 1447b6be844SDan Williams return mount_pseudo(fs_type, "dax:", &dax_sops, NULL, DAXFS_MAGIC); 1457b6be844SDan Williams } 1467b6be844SDan Williams 1477b6be844SDan Williams static struct file_system_type dax_fs_type = { 1487b6be844SDan Williams .name = "dax", 1497b6be844SDan Williams .mount = dax_mount, 1507b6be844SDan Williams .kill_sb = kill_anon_super, 1517b6be844SDan Williams }; 1527b6be844SDan Williams 1537b6be844SDan Williams static int dax_test(struct inode *inode, void *data) 1547b6be844SDan Williams { 1557b6be844SDan Williams dev_t devt = *(dev_t *) data; 1567b6be844SDan Williams 1577b6be844SDan Williams return inode->i_rdev == devt; 1587b6be844SDan Williams } 1597b6be844SDan Williams 1607b6be844SDan Williams static int dax_set(struct inode *inode, void *data) 1617b6be844SDan Williams { 1627b6be844SDan Williams dev_t devt = *(dev_t *) data; 1637b6be844SDan Williams 1647b6be844SDan Williams inode->i_rdev = devt; 1657b6be844SDan Williams return 0; 1667b6be844SDan Williams } 1677b6be844SDan Williams 1687b6be844SDan Williams static struct dax_device *dax_dev_get(dev_t devt) 1697b6be844SDan Williams { 1707b6be844SDan Williams struct dax_device *dax_dev; 1717b6be844SDan Williams struct inode *inode; 1727b6be844SDan Williams 1737b6be844SDan Williams inode = iget5_locked(dax_superblock, hash_32(devt + DAXFS_MAGIC, 31), 1747b6be844SDan Williams dax_test, dax_set, &devt); 1757b6be844SDan Williams 1767b6be844SDan Williams if (!inode) 1777b6be844SDan Williams return NULL; 1787b6be844SDan Williams 1797b6be844SDan Williams dax_dev = to_dax_dev(inode); 1807b6be844SDan Williams if (inode->i_state & I_NEW) { 1817b6be844SDan Williams dax_dev->alive = true; 1827b6be844SDan Williams inode->i_cdev = &dax_dev->cdev; 1837b6be844SDan Williams inode->i_mode = S_IFCHR; 1847b6be844SDan Williams inode->i_flags = S_DAX; 1857b6be844SDan Williams mapping_set_gfp_mask(&inode->i_data, GFP_USER); 1867b6be844SDan Williams unlock_new_inode(inode); 1877b6be844SDan Williams } 1887b6be844SDan Williams 1897b6be844SDan Williams return dax_dev; 1907b6be844SDan Williams } 1917b6be844SDan Williams 19272058005SDan Williams static void dax_add_host(struct dax_device *dax_dev, const char *host) 19372058005SDan Williams { 19472058005SDan Williams int hash; 19572058005SDan Williams 19672058005SDan Williams /* 19772058005SDan Williams * Unconditionally init dax_dev since it's coming from a 19872058005SDan Williams * non-zeroed slab cache 19972058005SDan Williams */ 20072058005SDan Williams INIT_HLIST_NODE(&dax_dev->list); 20172058005SDan Williams dax_dev->host = host; 20272058005SDan Williams if (!host) 20372058005SDan Williams return; 20472058005SDan Williams 20572058005SDan Williams hash = dax_host_hash(host); 20672058005SDan Williams spin_lock(&dax_host_lock); 20772058005SDan Williams hlist_add_head(&dax_dev->list, &dax_host_list[hash]); 20872058005SDan Williams spin_unlock(&dax_host_lock); 20972058005SDan Williams } 21072058005SDan Williams 21172058005SDan Williams struct dax_device *alloc_dax(void *private, const char *__host) 2127b6be844SDan Williams { 2137b6be844SDan Williams struct dax_device *dax_dev; 21472058005SDan Williams const char *host; 2157b6be844SDan Williams dev_t devt; 2167b6be844SDan Williams int minor; 2177b6be844SDan Williams 21872058005SDan Williams host = kstrdup(__host, GFP_KERNEL); 21972058005SDan Williams if (__host && !host) 22072058005SDan Williams return NULL; 22172058005SDan Williams 2227b6be844SDan Williams minor = ida_simple_get(&dax_minor_ida, 0, nr_dax, GFP_KERNEL); 2237b6be844SDan Williams if (minor < 0) 22472058005SDan Williams goto err_minor; 2257b6be844SDan Williams 2267b6be844SDan Williams devt = MKDEV(MAJOR(dax_devt), minor); 2277b6be844SDan Williams dax_dev = dax_dev_get(devt); 2287b6be844SDan Williams if (!dax_dev) 22972058005SDan Williams goto err_dev; 2307b6be844SDan Williams 23172058005SDan Williams dax_add_host(dax_dev, host); 2327b6be844SDan Williams dax_dev->private = private; 2337b6be844SDan Williams return dax_dev; 2347b6be844SDan Williams 23572058005SDan Williams err_dev: 2367b6be844SDan Williams ida_simple_remove(&dax_minor_ida, minor); 23772058005SDan Williams err_minor: 23872058005SDan Williams kfree(host); 2397b6be844SDan Williams return NULL; 2407b6be844SDan Williams } 2417b6be844SDan Williams EXPORT_SYMBOL_GPL(alloc_dax); 2427b6be844SDan Williams 2437b6be844SDan Williams void put_dax(struct dax_device *dax_dev) 2447b6be844SDan Williams { 2457b6be844SDan Williams if (!dax_dev) 2467b6be844SDan Williams return; 2477b6be844SDan Williams iput(&dax_dev->inode); 2487b6be844SDan Williams } 2497b6be844SDan Williams EXPORT_SYMBOL_GPL(put_dax); 2507b6be844SDan Williams 2517b6be844SDan Williams /** 25272058005SDan Williams * dax_get_by_host() - temporary lookup mechanism for filesystem-dax 25372058005SDan Williams * @host: alternate name for the device registered by a dax driver 25472058005SDan Williams */ 25572058005SDan Williams struct dax_device *dax_get_by_host(const char *host) 25672058005SDan Williams { 25772058005SDan Williams struct dax_device *dax_dev, *found = NULL; 25872058005SDan Williams int hash, id; 25972058005SDan Williams 26072058005SDan Williams if (!host) 26172058005SDan Williams return NULL; 26272058005SDan Williams 26372058005SDan Williams hash = dax_host_hash(host); 26472058005SDan Williams 26572058005SDan Williams id = dax_read_lock(); 26672058005SDan Williams spin_lock(&dax_host_lock); 26772058005SDan Williams hlist_for_each_entry(dax_dev, &dax_host_list[hash], list) { 26872058005SDan Williams if (!dax_alive(dax_dev) 26972058005SDan Williams || strcmp(host, dax_dev->host) != 0) 27072058005SDan Williams continue; 27172058005SDan Williams 27272058005SDan Williams if (igrab(&dax_dev->inode)) 27372058005SDan Williams found = dax_dev; 27472058005SDan Williams break; 27572058005SDan Williams } 27672058005SDan Williams spin_unlock(&dax_host_lock); 27772058005SDan Williams dax_read_unlock(id); 27872058005SDan Williams 27972058005SDan Williams return found; 28072058005SDan Williams } 28172058005SDan Williams EXPORT_SYMBOL_GPL(dax_get_by_host); 28272058005SDan Williams 28372058005SDan Williams /** 2847b6be844SDan Williams * inode_dax: convert a public inode into its dax_dev 2857b6be844SDan Williams * @inode: An inode with i_cdev pointing to a dax_dev 2867b6be844SDan Williams * 2877b6be844SDan Williams * Note this is not equivalent to to_dax_dev() which is for private 2887b6be844SDan Williams * internal use where we know the inode filesystem type == dax_fs_type. 2897b6be844SDan Williams */ 2907b6be844SDan Williams struct dax_device *inode_dax(struct inode *inode) 2917b6be844SDan Williams { 2927b6be844SDan Williams struct cdev *cdev = inode->i_cdev; 2937b6be844SDan Williams 2947b6be844SDan Williams return container_of(cdev, struct dax_device, cdev); 2957b6be844SDan Williams } 2967b6be844SDan Williams EXPORT_SYMBOL_GPL(inode_dax); 2977b6be844SDan Williams 2987b6be844SDan Williams struct inode *dax_inode(struct dax_device *dax_dev) 2997b6be844SDan Williams { 3007b6be844SDan Williams return &dax_dev->inode; 3017b6be844SDan Williams } 3027b6be844SDan Williams EXPORT_SYMBOL_GPL(dax_inode); 3037b6be844SDan Williams 3047b6be844SDan Williams void *dax_get_private(struct dax_device *dax_dev) 3057b6be844SDan Williams { 3067b6be844SDan Williams return dax_dev->private; 3077b6be844SDan Williams } 3087b6be844SDan Williams EXPORT_SYMBOL_GPL(dax_get_private); 3097b6be844SDan Williams 3107b6be844SDan Williams static void init_once(void *_dax_dev) 3117b6be844SDan Williams { 3127b6be844SDan Williams struct dax_device *dax_dev = _dax_dev; 3137b6be844SDan Williams struct inode *inode = &dax_dev->inode; 3147b6be844SDan Williams 3157b6be844SDan Williams inode_init_once(inode); 3167b6be844SDan Williams } 3177b6be844SDan Williams 3187b6be844SDan Williams static int __dax_fs_init(void) 3197b6be844SDan Williams { 3207b6be844SDan Williams int rc; 3217b6be844SDan Williams 3227b6be844SDan Williams dax_cache = kmem_cache_create("dax_cache", sizeof(struct dax_device), 0, 3237b6be844SDan Williams (SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT| 3247b6be844SDan Williams SLAB_MEM_SPREAD|SLAB_ACCOUNT), 3257b6be844SDan Williams init_once); 3267b6be844SDan Williams if (!dax_cache) 3277b6be844SDan Williams return -ENOMEM; 3287b6be844SDan Williams 3297b6be844SDan Williams rc = register_filesystem(&dax_fs_type); 3307b6be844SDan Williams if (rc) 3317b6be844SDan Williams goto err_register_fs; 3327b6be844SDan Williams 3337b6be844SDan Williams dax_mnt = kern_mount(&dax_fs_type); 3347b6be844SDan Williams if (IS_ERR(dax_mnt)) { 3357b6be844SDan Williams rc = PTR_ERR(dax_mnt); 3367b6be844SDan Williams goto err_mount; 3377b6be844SDan Williams } 3387b6be844SDan Williams dax_superblock = dax_mnt->mnt_sb; 3397b6be844SDan Williams 3407b6be844SDan Williams return 0; 3417b6be844SDan Williams 3427b6be844SDan Williams err_mount: 3437b6be844SDan Williams unregister_filesystem(&dax_fs_type); 3447b6be844SDan Williams err_register_fs: 3457b6be844SDan Williams kmem_cache_destroy(dax_cache); 3467b6be844SDan Williams 3477b6be844SDan Williams return rc; 3487b6be844SDan Williams } 3497b6be844SDan Williams 3507b6be844SDan Williams static void __dax_fs_exit(void) 3517b6be844SDan Williams { 3527b6be844SDan Williams kern_unmount(dax_mnt); 3537b6be844SDan Williams unregister_filesystem(&dax_fs_type); 3547b6be844SDan Williams kmem_cache_destroy(dax_cache); 3557b6be844SDan Williams } 3567b6be844SDan Williams 3577b6be844SDan Williams static int __init dax_fs_init(void) 3587b6be844SDan Williams { 3597b6be844SDan Williams int rc; 3607b6be844SDan Williams 3617b6be844SDan Williams rc = __dax_fs_init(); 3627b6be844SDan Williams if (rc) 3637b6be844SDan Williams return rc; 3647b6be844SDan Williams 3657b6be844SDan Williams nr_dax = max(nr_dax, 256); 3667b6be844SDan Williams rc = alloc_chrdev_region(&dax_devt, 0, nr_dax, "dax"); 3677b6be844SDan Williams if (rc) 3687b6be844SDan Williams __dax_fs_exit(); 3697b6be844SDan Williams return rc; 3707b6be844SDan Williams } 3717b6be844SDan Williams 3727b6be844SDan Williams static void __exit dax_fs_exit(void) 3737b6be844SDan Williams { 3747b6be844SDan Williams unregister_chrdev_region(dax_devt, nr_dax); 3757b6be844SDan Williams ida_destroy(&dax_minor_ida); 3767b6be844SDan Williams __dax_fs_exit(); 3777b6be844SDan Williams } 3787b6be844SDan Williams 3797b6be844SDan Williams MODULE_AUTHOR("Intel Corporation"); 3807b6be844SDan Williams MODULE_LICENSE("GPL v2"); 3817b6be844SDan Williams subsys_initcall(dax_fs_init); 3827b6be844SDan Williams module_exit(dax_fs_exit); 383