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> 206568b08bSDan Williams #include <linux/dax.h> 217b6be844SDan Williams #include <linux/fs.h> 227b6be844SDan Williams 237b6be844SDan Williams static int nr_dax = CONFIG_NR_DEV_DAX; 247b6be844SDan Williams module_param(nr_dax, int, S_IRUGO); 257b6be844SDan Williams MODULE_PARM_DESC(nr_dax, "max number of dax device instances"); 267b6be844SDan Williams 277b6be844SDan Williams static dev_t dax_devt; 287b6be844SDan Williams DEFINE_STATIC_SRCU(dax_srcu); 297b6be844SDan Williams static struct vfsmount *dax_mnt; 307b6be844SDan Williams static DEFINE_IDA(dax_minor_ida); 317b6be844SDan Williams static struct kmem_cache *dax_cache __read_mostly; 327b6be844SDan Williams static struct super_block *dax_superblock __read_mostly; 337b6be844SDan Williams 3472058005SDan Williams #define DAX_HASH_SIZE (PAGE_SIZE / sizeof(struct hlist_head)) 3572058005SDan Williams static struct hlist_head dax_host_list[DAX_HASH_SIZE]; 3672058005SDan Williams static DEFINE_SPINLOCK(dax_host_lock); 3772058005SDan Williams 387b6be844SDan Williams int dax_read_lock(void) 397b6be844SDan Williams { 407b6be844SDan Williams return srcu_read_lock(&dax_srcu); 417b6be844SDan Williams } 427b6be844SDan Williams EXPORT_SYMBOL_GPL(dax_read_lock); 437b6be844SDan Williams 447b6be844SDan Williams void dax_read_unlock(int id) 457b6be844SDan Williams { 467b6be844SDan Williams srcu_read_unlock(&dax_srcu, id); 477b6be844SDan Williams } 487b6be844SDan Williams EXPORT_SYMBOL_GPL(dax_read_unlock); 497b6be844SDan Williams 507b6be844SDan Williams /** 517b6be844SDan Williams * struct dax_device - anchor object for dax services 527b6be844SDan Williams * @inode: core vfs 537b6be844SDan Williams * @cdev: optional character interface for "device dax" 5472058005SDan Williams * @host: optional name for lookups where the device path is not available 557b6be844SDan Williams * @private: dax driver private data 567b6be844SDan Williams * @alive: !alive + rcu grace period == no new operations / mappings 577b6be844SDan Williams */ 587b6be844SDan Williams struct dax_device { 5972058005SDan Williams struct hlist_node list; 607b6be844SDan Williams struct inode inode; 617b6be844SDan Williams struct cdev cdev; 6272058005SDan Williams const char *host; 637b6be844SDan Williams void *private; 647b6be844SDan Williams bool alive; 656568b08bSDan Williams const struct dax_operations *ops; 667b6be844SDan Williams }; 677b6be844SDan Williams 68b0686260SDan Williams /** 69b0686260SDan Williams * dax_direct_access() - translate a device pgoff to an absolute pfn 70b0686260SDan Williams * @dax_dev: a dax_device instance representing the logical memory range 71b0686260SDan Williams * @pgoff: offset in pages from the start of the device to translate 72b0686260SDan Williams * @nr_pages: number of consecutive pages caller can handle relative to @pfn 73b0686260SDan Williams * @kaddr: output parameter that returns a virtual address mapping of pfn 74b0686260SDan Williams * @pfn: output parameter that returns an absolute pfn translation of @pgoff 75b0686260SDan Williams * 76b0686260SDan Williams * Return: negative errno if an error occurs, otherwise the number of 77b0686260SDan Williams * pages accessible at the device relative @pgoff. 78b0686260SDan Williams */ 79b0686260SDan Williams long dax_direct_access(struct dax_device *dax_dev, pgoff_t pgoff, long nr_pages, 80b0686260SDan Williams void **kaddr, pfn_t *pfn) 81b0686260SDan Williams { 82b0686260SDan Williams long avail; 83b0686260SDan Williams 84b0686260SDan Williams /* 85b0686260SDan Williams * The device driver is allowed to sleep, in order to make the 86b0686260SDan Williams * memory directly accessible. 87b0686260SDan Williams */ 88b0686260SDan Williams might_sleep(); 89b0686260SDan Williams 90b0686260SDan Williams if (!dax_dev) 91b0686260SDan Williams return -EOPNOTSUPP; 92b0686260SDan Williams 93b0686260SDan Williams if (!dax_alive(dax_dev)) 94b0686260SDan Williams return -ENXIO; 95b0686260SDan Williams 96b0686260SDan Williams if (nr_pages < 0) 97b0686260SDan Williams return nr_pages; 98b0686260SDan Williams 99b0686260SDan Williams avail = dax_dev->ops->direct_access(dax_dev, pgoff, nr_pages, 100b0686260SDan Williams kaddr, pfn); 101b0686260SDan Williams if (!avail) 102b0686260SDan Williams return -ERANGE; 103b0686260SDan Williams return min(avail, nr_pages); 104b0686260SDan Williams } 105b0686260SDan Williams EXPORT_SYMBOL_GPL(dax_direct_access); 106b0686260SDan Williams 1077b6be844SDan Williams bool dax_alive(struct dax_device *dax_dev) 1087b6be844SDan Williams { 1097b6be844SDan Williams lockdep_assert_held(&dax_srcu); 1107b6be844SDan Williams return dax_dev->alive; 1117b6be844SDan Williams } 1127b6be844SDan Williams EXPORT_SYMBOL_GPL(dax_alive); 1137b6be844SDan Williams 11472058005SDan Williams static int dax_host_hash(const char *host) 11572058005SDan Williams { 11672058005SDan Williams return hashlen_hash(hashlen_string("DAX", host)) % DAX_HASH_SIZE; 11772058005SDan Williams } 11872058005SDan Williams 1197b6be844SDan Williams /* 1207b6be844SDan Williams * Note, rcu is not protecting the liveness of dax_dev, rcu is ensuring 1217b6be844SDan Williams * that any fault handlers or operations that might have seen 1227b6be844SDan Williams * dax_alive(), have completed. Any operations that start after 1237b6be844SDan Williams * synchronize_srcu() has run will abort upon seeing !dax_alive(). 1247b6be844SDan Williams */ 1257b6be844SDan Williams void kill_dax(struct dax_device *dax_dev) 1267b6be844SDan Williams { 1277b6be844SDan Williams if (!dax_dev) 1287b6be844SDan Williams return; 1297b6be844SDan Williams 1307b6be844SDan Williams dax_dev->alive = false; 13172058005SDan Williams 1327b6be844SDan Williams synchronize_srcu(&dax_srcu); 13372058005SDan Williams 13472058005SDan Williams spin_lock(&dax_host_lock); 13572058005SDan Williams hlist_del_init(&dax_dev->list); 13672058005SDan Williams spin_unlock(&dax_host_lock); 13772058005SDan Williams 1387b6be844SDan Williams dax_dev->private = NULL; 1397b6be844SDan Williams } 1407b6be844SDan Williams EXPORT_SYMBOL_GPL(kill_dax); 1417b6be844SDan Williams 1427b6be844SDan Williams static struct inode *dax_alloc_inode(struct super_block *sb) 1437b6be844SDan Williams { 1447b6be844SDan Williams struct dax_device *dax_dev; 1457b6be844SDan Williams 1467b6be844SDan Williams dax_dev = kmem_cache_alloc(dax_cache, GFP_KERNEL); 1477b6be844SDan Williams return &dax_dev->inode; 1487b6be844SDan Williams } 1497b6be844SDan Williams 1507b6be844SDan Williams static struct dax_device *to_dax_dev(struct inode *inode) 1517b6be844SDan Williams { 1527b6be844SDan Williams return container_of(inode, struct dax_device, inode); 1537b6be844SDan Williams } 1547b6be844SDan Williams 1557b6be844SDan Williams static void dax_i_callback(struct rcu_head *head) 1567b6be844SDan Williams { 1577b6be844SDan Williams struct inode *inode = container_of(head, struct inode, i_rcu); 1587b6be844SDan Williams struct dax_device *dax_dev = to_dax_dev(inode); 1597b6be844SDan Williams 16072058005SDan Williams kfree(dax_dev->host); 16172058005SDan Williams dax_dev->host = NULL; 1627b6be844SDan Williams ida_simple_remove(&dax_minor_ida, MINOR(inode->i_rdev)); 1637b6be844SDan Williams kmem_cache_free(dax_cache, dax_dev); 1647b6be844SDan Williams } 1657b6be844SDan Williams 1667b6be844SDan Williams static void dax_destroy_inode(struct inode *inode) 1677b6be844SDan Williams { 1687b6be844SDan Williams struct dax_device *dax_dev = to_dax_dev(inode); 1697b6be844SDan Williams 1707b6be844SDan Williams WARN_ONCE(dax_dev->alive, 1717b6be844SDan Williams "kill_dax() must be called before final iput()\n"); 1727b6be844SDan Williams call_rcu(&inode->i_rcu, dax_i_callback); 1737b6be844SDan Williams } 1747b6be844SDan Williams 1757b6be844SDan Williams static const struct super_operations dax_sops = { 1767b6be844SDan Williams .statfs = simple_statfs, 1777b6be844SDan Williams .alloc_inode = dax_alloc_inode, 1787b6be844SDan Williams .destroy_inode = dax_destroy_inode, 1797b6be844SDan Williams .drop_inode = generic_delete_inode, 1807b6be844SDan Williams }; 1817b6be844SDan Williams 1827b6be844SDan Williams static struct dentry *dax_mount(struct file_system_type *fs_type, 1837b6be844SDan Williams int flags, const char *dev_name, void *data) 1847b6be844SDan Williams { 1857b6be844SDan Williams return mount_pseudo(fs_type, "dax:", &dax_sops, NULL, DAXFS_MAGIC); 1867b6be844SDan Williams } 1877b6be844SDan Williams 1887b6be844SDan Williams static struct file_system_type dax_fs_type = { 1897b6be844SDan Williams .name = "dax", 1907b6be844SDan Williams .mount = dax_mount, 1917b6be844SDan Williams .kill_sb = kill_anon_super, 1927b6be844SDan Williams }; 1937b6be844SDan Williams 1947b6be844SDan Williams static int dax_test(struct inode *inode, void *data) 1957b6be844SDan Williams { 1967b6be844SDan Williams dev_t devt = *(dev_t *) data; 1977b6be844SDan Williams 1987b6be844SDan Williams return inode->i_rdev == devt; 1997b6be844SDan Williams } 2007b6be844SDan Williams 2017b6be844SDan Williams static int dax_set(struct inode *inode, void *data) 2027b6be844SDan Williams { 2037b6be844SDan Williams dev_t devt = *(dev_t *) data; 2047b6be844SDan Williams 2057b6be844SDan Williams inode->i_rdev = devt; 2067b6be844SDan Williams return 0; 2077b6be844SDan Williams } 2087b6be844SDan Williams 2097b6be844SDan Williams static struct dax_device *dax_dev_get(dev_t devt) 2107b6be844SDan Williams { 2117b6be844SDan Williams struct dax_device *dax_dev; 2127b6be844SDan Williams struct inode *inode; 2137b6be844SDan Williams 2147b6be844SDan Williams inode = iget5_locked(dax_superblock, hash_32(devt + DAXFS_MAGIC, 31), 2157b6be844SDan Williams dax_test, dax_set, &devt); 2167b6be844SDan Williams 2177b6be844SDan Williams if (!inode) 2187b6be844SDan Williams return NULL; 2197b6be844SDan Williams 2207b6be844SDan Williams dax_dev = to_dax_dev(inode); 2217b6be844SDan Williams if (inode->i_state & I_NEW) { 2227b6be844SDan Williams dax_dev->alive = true; 2237b6be844SDan Williams inode->i_cdev = &dax_dev->cdev; 2247b6be844SDan Williams inode->i_mode = S_IFCHR; 2257b6be844SDan Williams inode->i_flags = S_DAX; 2267b6be844SDan Williams mapping_set_gfp_mask(&inode->i_data, GFP_USER); 2277b6be844SDan Williams unlock_new_inode(inode); 2287b6be844SDan Williams } 2297b6be844SDan Williams 2307b6be844SDan Williams return dax_dev; 2317b6be844SDan Williams } 2327b6be844SDan Williams 23372058005SDan Williams static void dax_add_host(struct dax_device *dax_dev, const char *host) 23472058005SDan Williams { 23572058005SDan Williams int hash; 23672058005SDan Williams 23772058005SDan Williams /* 23872058005SDan Williams * Unconditionally init dax_dev since it's coming from a 23972058005SDan Williams * non-zeroed slab cache 24072058005SDan Williams */ 24172058005SDan Williams INIT_HLIST_NODE(&dax_dev->list); 24272058005SDan Williams dax_dev->host = host; 24372058005SDan Williams if (!host) 24472058005SDan Williams return; 24572058005SDan Williams 24672058005SDan Williams hash = dax_host_hash(host); 24772058005SDan Williams spin_lock(&dax_host_lock); 24872058005SDan Williams hlist_add_head(&dax_dev->list, &dax_host_list[hash]); 24972058005SDan Williams spin_unlock(&dax_host_lock); 25072058005SDan Williams } 25172058005SDan Williams 2526568b08bSDan Williams struct dax_device *alloc_dax(void *private, const char *__host, 2536568b08bSDan Williams const struct dax_operations *ops) 2547b6be844SDan Williams { 2557b6be844SDan Williams struct dax_device *dax_dev; 25672058005SDan Williams const char *host; 2577b6be844SDan Williams dev_t devt; 2587b6be844SDan Williams int minor; 2597b6be844SDan Williams 26072058005SDan Williams host = kstrdup(__host, GFP_KERNEL); 26172058005SDan Williams if (__host && !host) 26272058005SDan Williams return NULL; 26372058005SDan Williams 2647b6be844SDan Williams minor = ida_simple_get(&dax_minor_ida, 0, nr_dax, GFP_KERNEL); 2657b6be844SDan Williams if (minor < 0) 26672058005SDan Williams goto err_minor; 2677b6be844SDan Williams 2687b6be844SDan Williams devt = MKDEV(MAJOR(dax_devt), minor); 2697b6be844SDan Williams dax_dev = dax_dev_get(devt); 2707b6be844SDan Williams if (!dax_dev) 27172058005SDan Williams goto err_dev; 2727b6be844SDan Williams 27372058005SDan Williams dax_add_host(dax_dev, host); 2746568b08bSDan Williams dax_dev->ops = ops; 2757b6be844SDan Williams dax_dev->private = private; 2767b6be844SDan Williams return dax_dev; 2777b6be844SDan Williams 27872058005SDan Williams err_dev: 2797b6be844SDan Williams ida_simple_remove(&dax_minor_ida, minor); 28072058005SDan Williams err_minor: 28172058005SDan Williams kfree(host); 2827b6be844SDan Williams return NULL; 2837b6be844SDan Williams } 2847b6be844SDan Williams EXPORT_SYMBOL_GPL(alloc_dax); 2857b6be844SDan Williams 2867b6be844SDan Williams void put_dax(struct dax_device *dax_dev) 2877b6be844SDan Williams { 2887b6be844SDan Williams if (!dax_dev) 2897b6be844SDan Williams return; 2907b6be844SDan Williams iput(&dax_dev->inode); 2917b6be844SDan Williams } 2927b6be844SDan Williams EXPORT_SYMBOL_GPL(put_dax); 2937b6be844SDan Williams 2947b6be844SDan Williams /** 29572058005SDan Williams * dax_get_by_host() - temporary lookup mechanism for filesystem-dax 29672058005SDan Williams * @host: alternate name for the device registered by a dax driver 29772058005SDan Williams */ 29872058005SDan Williams struct dax_device *dax_get_by_host(const char *host) 29972058005SDan Williams { 30072058005SDan Williams struct dax_device *dax_dev, *found = NULL; 30172058005SDan Williams int hash, id; 30272058005SDan Williams 30372058005SDan Williams if (!host) 30472058005SDan Williams return NULL; 30572058005SDan Williams 30672058005SDan Williams hash = dax_host_hash(host); 30772058005SDan Williams 30872058005SDan Williams id = dax_read_lock(); 30972058005SDan Williams spin_lock(&dax_host_lock); 31072058005SDan Williams hlist_for_each_entry(dax_dev, &dax_host_list[hash], list) { 31172058005SDan Williams if (!dax_alive(dax_dev) 31272058005SDan Williams || strcmp(host, dax_dev->host) != 0) 31372058005SDan Williams continue; 31472058005SDan Williams 31572058005SDan Williams if (igrab(&dax_dev->inode)) 31672058005SDan Williams found = dax_dev; 31772058005SDan Williams break; 31872058005SDan Williams } 31972058005SDan Williams spin_unlock(&dax_host_lock); 32072058005SDan Williams dax_read_unlock(id); 32172058005SDan Williams 32272058005SDan Williams return found; 32372058005SDan Williams } 32472058005SDan Williams EXPORT_SYMBOL_GPL(dax_get_by_host); 32572058005SDan Williams 32672058005SDan Williams /** 3277b6be844SDan Williams * inode_dax: convert a public inode into its dax_dev 3287b6be844SDan Williams * @inode: An inode with i_cdev pointing to a dax_dev 3297b6be844SDan Williams * 3307b6be844SDan Williams * Note this is not equivalent to to_dax_dev() which is for private 3317b6be844SDan Williams * internal use where we know the inode filesystem type == dax_fs_type. 3327b6be844SDan Williams */ 3337b6be844SDan Williams struct dax_device *inode_dax(struct inode *inode) 3347b6be844SDan Williams { 3357b6be844SDan Williams struct cdev *cdev = inode->i_cdev; 3367b6be844SDan Williams 3377b6be844SDan Williams return container_of(cdev, struct dax_device, cdev); 3387b6be844SDan Williams } 3397b6be844SDan Williams EXPORT_SYMBOL_GPL(inode_dax); 3407b6be844SDan Williams 3417b6be844SDan Williams struct inode *dax_inode(struct dax_device *dax_dev) 3427b6be844SDan Williams { 3437b6be844SDan Williams return &dax_dev->inode; 3447b6be844SDan Williams } 3457b6be844SDan Williams EXPORT_SYMBOL_GPL(dax_inode); 3467b6be844SDan Williams 3477b6be844SDan Williams void *dax_get_private(struct dax_device *dax_dev) 3487b6be844SDan Williams { 3497b6be844SDan Williams return dax_dev->private; 3507b6be844SDan Williams } 3517b6be844SDan Williams EXPORT_SYMBOL_GPL(dax_get_private); 3527b6be844SDan Williams 3537b6be844SDan Williams static void init_once(void *_dax_dev) 3547b6be844SDan Williams { 3557b6be844SDan Williams struct dax_device *dax_dev = _dax_dev; 3567b6be844SDan Williams struct inode *inode = &dax_dev->inode; 3577b6be844SDan Williams 3587b6be844SDan Williams inode_init_once(inode); 3597b6be844SDan Williams } 3607b6be844SDan Williams 3617b6be844SDan Williams static int __dax_fs_init(void) 3627b6be844SDan Williams { 3637b6be844SDan Williams int rc; 3647b6be844SDan Williams 3657b6be844SDan Williams dax_cache = kmem_cache_create("dax_cache", sizeof(struct dax_device), 0, 3667b6be844SDan Williams (SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT| 3677b6be844SDan Williams SLAB_MEM_SPREAD|SLAB_ACCOUNT), 3687b6be844SDan Williams init_once); 3697b6be844SDan Williams if (!dax_cache) 3707b6be844SDan Williams return -ENOMEM; 3717b6be844SDan Williams 3727b6be844SDan Williams rc = register_filesystem(&dax_fs_type); 3737b6be844SDan Williams if (rc) 3747b6be844SDan Williams goto err_register_fs; 3757b6be844SDan Williams 3767b6be844SDan Williams dax_mnt = kern_mount(&dax_fs_type); 3777b6be844SDan Williams if (IS_ERR(dax_mnt)) { 3787b6be844SDan Williams rc = PTR_ERR(dax_mnt); 3797b6be844SDan Williams goto err_mount; 3807b6be844SDan Williams } 3817b6be844SDan Williams dax_superblock = dax_mnt->mnt_sb; 3827b6be844SDan Williams 3837b6be844SDan Williams return 0; 3847b6be844SDan Williams 3857b6be844SDan Williams err_mount: 3867b6be844SDan Williams unregister_filesystem(&dax_fs_type); 3877b6be844SDan Williams err_register_fs: 3887b6be844SDan Williams kmem_cache_destroy(dax_cache); 3897b6be844SDan Williams 3907b6be844SDan Williams return rc; 3917b6be844SDan Williams } 3927b6be844SDan Williams 3937b6be844SDan Williams static void __dax_fs_exit(void) 3947b6be844SDan Williams { 3957b6be844SDan Williams kern_unmount(dax_mnt); 3967b6be844SDan Williams unregister_filesystem(&dax_fs_type); 3977b6be844SDan Williams kmem_cache_destroy(dax_cache); 3987b6be844SDan Williams } 3997b6be844SDan Williams 4007b6be844SDan Williams static int __init dax_fs_init(void) 4017b6be844SDan Williams { 4027b6be844SDan Williams int rc; 4037b6be844SDan Williams 4047b6be844SDan Williams rc = __dax_fs_init(); 4057b6be844SDan Williams if (rc) 4067b6be844SDan Williams return rc; 4077b6be844SDan Williams 4087b6be844SDan Williams nr_dax = max(nr_dax, 256); 4097b6be844SDan Williams rc = alloc_chrdev_region(&dax_devt, 0, nr_dax, "dax"); 4107b6be844SDan Williams if (rc) 4117b6be844SDan Williams __dax_fs_exit(); 4127b6be844SDan Williams return rc; 4137b6be844SDan Williams } 4147b6be844SDan Williams 4157b6be844SDan Williams static void __exit dax_fs_exit(void) 4167b6be844SDan Williams { 4177b6be844SDan Williams unregister_chrdev_region(dax_devt, nr_dax); 4187b6be844SDan Williams ida_destroy(&dax_minor_ida); 4197b6be844SDan Williams __dax_fs_exit(); 4207b6be844SDan Williams } 4217b6be844SDan Williams 4227b6be844SDan Williams MODULE_AUTHOR("Intel Corporation"); 4237b6be844SDan Williams MODULE_LICENSE("GPL v2"); 4247b6be844SDan Williams subsys_initcall(dax_fs_init); 4257b6be844SDan Williams module_exit(dax_fs_exit); 426