| /* |
| * Copyright(c) 2017 Intel Corporation. All rights reserved. |
| * |
| * This program is free software; you can redistribute it and/or modify |
| * it under the terms of version 2 of the GNU General Public License as |
| * published by the Free Software Foundation. |
| * |
| * 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/pagemap.h> |
| #include <linux/module.h> |
| #include <linux/mount.h> |
| #include <linux/magic.h> |
| #include <linux/genhd.h> |
| #include <linux/pfn_t.h> |
| #include <linux/cdev.h> |
| #include <linux/hash.h> |
| #include <linux/slab.h> |
| #include <linux/uio.h> |
| #include <linux/dax.h> |
| #include <linux/fs.h> |
| #include "dax-private.h" |
| |
| static dev_t dax_devt; |
| DEFINE_STATIC_SRCU(dax_srcu); |
| static struct vfsmount *dax_mnt; |
| static DEFINE_IDA(dax_minor_ida); |
| static struct kmem_cache *dax_cache __read_mostly; |
| static struct super_block *dax_superblock __read_mostly; |
| |
| #define DAX_HASH_SIZE (PAGE_SIZE / sizeof(struct hlist_head)) |
| static struct hlist_head dax_host_list[DAX_HASH_SIZE]; |
| static DEFINE_SPINLOCK(dax_host_lock); |
| |
| int dax_read_lock(void) |
| { |
| return srcu_read_lock(&dax_srcu); |
| } |
| EXPORT_SYMBOL_GPL(dax_read_lock); |
| |
| void dax_read_unlock(int id) |
| { |
| srcu_read_unlock(&dax_srcu, id); |
| } |
| EXPORT_SYMBOL_GPL(dax_read_unlock); |
| |
| #ifdef CONFIG_BLOCK |
| #include <linux/blkdev.h> |
| |
| int bdev_dax_pgoff(struct block_device *bdev, sector_t sector, size_t size, |
| pgoff_t *pgoff) |
| { |
| phys_addr_t phys_off = (get_start_sect(bdev) + sector) * 512; |
| |
| if (pgoff) |
| *pgoff = PHYS_PFN(phys_off); |
| if (phys_off % PAGE_SIZE || size % PAGE_SIZE) |
| return -EINVAL; |
| return 0; |
| } |
| EXPORT_SYMBOL(bdev_dax_pgoff); |
| |
| #if IS_ENABLED(CONFIG_FS_DAX) |
| struct dax_device *fs_dax_get_by_bdev(struct block_device *bdev) |
| { |
| if (!blk_queue_dax(bdev->bd_queue)) |
| return NULL; |
| return fs_dax_get_by_host(bdev->bd_disk->disk_name); |
| } |
| EXPORT_SYMBOL_GPL(fs_dax_get_by_bdev); |
| #endif |
| |
| /** |
| * __bdev_dax_supported() - Check if the device supports dax for filesystem |
| * @bdev: block device to check |
| * @blocksize: The block size of the device |
| * |
| * This is a library function for filesystems to check if the block device |
| * can be mounted with dax option. |
| * |
| * Return: true if supported, false if unsupported |
| */ |
| bool __bdev_dax_supported(struct block_device *bdev, int blocksize) |
| { |
| struct dax_device *dax_dev; |
| bool dax_enabled = false; |
| pgoff_t pgoff, pgoff_end; |
| struct request_queue *q; |
| char buf[BDEVNAME_SIZE]; |
| void *kaddr, *end_kaddr; |
| pfn_t pfn, end_pfn; |
| sector_t last_page; |
| long len, len2; |
| int err, id; |
| |
| if (blocksize != PAGE_SIZE) { |
| pr_debug("%s: error: unsupported blocksize for dax\n", |
| bdevname(bdev, buf)); |
| return false; |
| } |
| |
| q = bdev_get_queue(bdev); |
| if (!q || !blk_queue_dax(q)) { |
| pr_debug("%s: error: request queue doesn't support dax\n", |
| bdevname(bdev, buf)); |
| return false; |
| } |
| |
| err = bdev_dax_pgoff(bdev, 0, PAGE_SIZE, &pgoff); |
| if (err) { |
| pr_debug("%s: error: unaligned partition for dax\n", |
| bdevname(bdev, buf)); |
| return false; |
| } |
| |
| last_page = PFN_DOWN(i_size_read(bdev->bd_inode) - 1) * 8; |
| err = bdev_dax_pgoff(bdev, last_page, PAGE_SIZE, &pgoff_end); |
| if (err) { |
| pr_debug("%s: error: unaligned partition for dax\n", |
| bdevname(bdev, buf)); |
| return false; |
| } |
| |
| dax_dev = dax_get_by_host(bdev->bd_disk->disk_name); |
| if (!dax_dev) { |
| pr_debug("%s: error: device does not support dax\n", |
| bdevname(bdev, buf)); |
| return false; |
| } |
| |
| id = dax_read_lock(); |
| len = dax_direct_access(dax_dev, pgoff, 1, &kaddr, &pfn); |
| len2 = dax_direct_access(dax_dev, pgoff_end, 1, &end_kaddr, &end_pfn); |
| dax_read_unlock(id); |
| |
| put_dax(dax_dev); |
| |
| if (len < 1 || len2 < 1) { |
| pr_debug("%s: error: dax access failed (%ld)\n", |
| bdevname(bdev, buf), len < 1 ? len : len2); |
| return false; |
| } |
| |
| if (IS_ENABLED(CONFIG_FS_DAX_LIMITED) && pfn_t_special(pfn)) { |
| /* |
| * An arch that has enabled the pmem api should also |
| * have its drivers support pfn_t_devmap() |
| * |
| * This is a developer warning and should not trigger in |
| * production. dax_flush() will crash since it depends |
| * on being able to do (page_address(pfn_to_page())). |
| */ |
| WARN_ON(IS_ENABLED(CONFIG_ARCH_HAS_PMEM_API)); |
| dax_enabled = true; |
| } else if (pfn_t_devmap(pfn) && pfn_t_devmap(end_pfn)) { |
| struct dev_pagemap *pgmap, *end_pgmap; |
| |
| pgmap = get_dev_pagemap(pfn_t_to_pfn(pfn), NULL); |
| end_pgmap = get_dev_pagemap(pfn_t_to_pfn(end_pfn), NULL); |
| if (pgmap && pgmap == end_pgmap && pgmap->type == MEMORY_DEVICE_FS_DAX |
| && pfn_t_to_page(pfn)->pgmap == pgmap |
| && pfn_t_to_page(end_pfn)->pgmap == pgmap |
| && pfn_t_to_pfn(pfn) == PHYS_PFN(__pa(kaddr)) |
| && pfn_t_to_pfn(end_pfn) == PHYS_PFN(__pa(end_kaddr))) |
| dax_enabled = true; |
| put_dev_pagemap(pgmap); |
| put_dev_pagemap(end_pgmap); |
| |
| } |
| |
| if (!dax_enabled) { |
| pr_debug("%s: error: dax support not enabled\n", |
| bdevname(bdev, buf)); |
| return false; |
| } |
| return true; |
| } |
| EXPORT_SYMBOL_GPL(__bdev_dax_supported); |
| #endif |
| |
| enum dax_device_flags { |
| /* !alive + rcu grace period == no new operations / mappings */ |
| DAXDEV_ALIVE, |
| /* gate whether dax_flush() calls the low level flush routine */ |
| DAXDEV_WRITE_CACHE, |
| }; |
| |
| /** |
| * struct dax_device - anchor object for dax services |
| * @inode: core vfs |
| * @cdev: optional character interface for "device dax" |
| * @host: optional name for lookups where the device path is not available |
| * @private: dax driver private data |
| * @flags: state and boolean properties |
| */ |
| struct dax_device { |
| struct hlist_node list; |
| struct inode inode; |
| struct cdev cdev; |
| const char *host; |
| void *private; |
| unsigned long flags; |
| const struct dax_operations *ops; |
| }; |
| |
| static ssize_t write_cache_show(struct device *dev, |
| struct device_attribute *attr, char *buf) |
| { |
| struct dax_device *dax_dev = dax_get_by_host(dev_name(dev)); |
| ssize_t rc; |
| |
| WARN_ON_ONCE(!dax_dev); |
| if (!dax_dev) |
| return -ENXIO; |
| |
| rc = sprintf(buf, "%d\n", !!dax_write_cache_enabled(dax_dev)); |
| put_dax(dax_dev); |
| return rc; |
| } |
| |
| static ssize_t write_cache_store(struct device *dev, |
| struct device_attribute *attr, const char *buf, size_t len) |
| { |
| bool write_cache; |
| int rc = strtobool(buf, &write_cache); |
| struct dax_device *dax_dev = dax_get_by_host(dev_name(dev)); |
| |
| WARN_ON_ONCE(!dax_dev); |
| if (!dax_dev) |
| return -ENXIO; |
| |
| if (rc) |
| len = rc; |
| else |
| dax_write_cache(dax_dev, write_cache); |
| |
| put_dax(dax_dev); |
| return len; |
| } |
| static DEVICE_ATTR_RW(write_cache); |
| |
| static umode_t dax_visible(struct kobject *kobj, struct attribute *a, int n) |
| { |
| struct device *dev = container_of(kobj, typeof(*dev), kobj); |
| struct dax_device *dax_dev = dax_get_by_host(dev_name(dev)); |
| |
| WARN_ON_ONCE(!dax_dev); |
| if (!dax_dev) |
| return 0; |
| |
| #ifndef CONFIG_ARCH_HAS_PMEM_API |
| if (a == &dev_attr_write_cache.attr) |
| return 0; |
| #endif |
| return a->mode; |
| } |
| |
| static struct attribute *dax_attributes[] = { |
| &dev_attr_write_cache.attr, |
| NULL, |
| }; |
| |
| struct attribute_group dax_attribute_group = { |
| .name = "dax", |
| .attrs = dax_attributes, |
| .is_visible = dax_visible, |
| }; |
| EXPORT_SYMBOL_GPL(dax_attribute_group); |
| |
| /** |
| * dax_direct_access() - translate a device pgoff to an absolute pfn |
| * @dax_dev: a dax_device instance representing the logical memory range |
| * @pgoff: offset in pages from the start of the device to translate |
| * @nr_pages: number of consecutive pages caller can handle relative to @pfn |
| * @kaddr: output parameter that returns a virtual address mapping of pfn |
| * @pfn: output parameter that returns an absolute pfn translation of @pgoff |
| * |
| * Return: negative errno if an error occurs, otherwise the number of |
| * pages accessible at the device relative @pgoff. |
| */ |
| long dax_direct_access(struct dax_device *dax_dev, pgoff_t pgoff, long nr_pages, |
| void **kaddr, pfn_t *pfn) |
| { |
| long avail; |
| |
| if (!dax_dev) |
| return -EOPNOTSUPP; |
| |
| if (!dax_alive(dax_dev)) |
| return -ENXIO; |
| |
| if (nr_pages < 0) |
| return nr_pages; |
| |
| avail = dax_dev->ops->direct_access(dax_dev, pgoff, nr_pages, |
| kaddr, pfn); |
| if (!avail) |
| return -ERANGE; |
| return min(avail, nr_pages); |
| } |
| EXPORT_SYMBOL_GPL(dax_direct_access); |
| |
| size_t dax_copy_from_iter(struct dax_device *dax_dev, pgoff_t pgoff, void *addr, |
| size_t bytes, struct iov_iter *i) |
| { |
| if (!dax_alive(dax_dev)) |
| return 0; |
| |
| return dax_dev->ops->copy_from_iter(dax_dev, pgoff, addr, bytes, i); |
| } |
| EXPORT_SYMBOL_GPL(dax_copy_from_iter); |
| |
| size_t dax_copy_to_iter(struct dax_device *dax_dev, pgoff_t pgoff, void *addr, |
| size_t bytes, struct iov_iter *i) |
| { |
| if (!dax_alive(dax_dev)) |
| return 0; |
| |
| return dax_dev->ops->copy_to_iter(dax_dev, pgoff, addr, bytes, i); |
| } |
| EXPORT_SYMBOL_GPL(dax_copy_to_iter); |
| |
| #ifdef CONFIG_ARCH_HAS_PMEM_API |
| void arch_wb_cache_pmem(void *addr, size_t size); |
| void dax_flush(struct dax_device *dax_dev, void *addr, size_t size) |
| { |
| if (unlikely(!dax_write_cache_enabled(dax_dev))) |
| return; |
| |
| arch_wb_cache_pmem(addr, size); |
| } |
| #else |
| void dax_flush(struct dax_device *dax_dev, void *addr, size_t size) |
| { |
| } |
| #endif |
| EXPORT_SYMBOL_GPL(dax_flush); |
| |
| void dax_write_cache(struct dax_device *dax_dev, bool wc) |
| { |
| if (wc) |
| set_bit(DAXDEV_WRITE_CACHE, &dax_dev->flags); |
| else |
| clear_bit(DAXDEV_WRITE_CACHE, &dax_dev->flags); |
| } |
| EXPORT_SYMBOL_GPL(dax_write_cache); |
| |
| bool dax_write_cache_enabled(struct dax_device *dax_dev) |
| { |
| return test_bit(DAXDEV_WRITE_CACHE, &dax_dev->flags); |
| } |
| EXPORT_SYMBOL_GPL(dax_write_cache_enabled); |
| |
| bool dax_alive(struct dax_device *dax_dev) |
| { |
| lockdep_assert_held(&dax_srcu); |
| return test_bit(DAXDEV_ALIVE, &dax_dev->flags); |
| } |
| EXPORT_SYMBOL_GPL(dax_alive); |
| |
| static int dax_host_hash(const char *host) |
| { |
| return hashlen_hash(hashlen_string("DAX", host)) % DAX_HASH_SIZE; |
| } |
| |
| /* |
| * Note, rcu is not protecting the liveness of dax_dev, rcu is ensuring |
| * that any fault handlers or operations that might have seen |
| * dax_alive(), have completed. Any operations that start after |
| * synchronize_srcu() has run will abort upon seeing !dax_alive(). |
| */ |
| void kill_dax(struct dax_device *dax_dev) |
| { |
| if (!dax_dev) |
| return; |
| |
| clear_bit(DAXDEV_ALIVE, &dax_dev->flags); |
| |
| synchronize_srcu(&dax_srcu); |
| |
| spin_lock(&dax_host_lock); |
| hlist_del_init(&dax_dev->list); |
| spin_unlock(&dax_host_lock); |
| } |
| EXPORT_SYMBOL_GPL(kill_dax); |
| |
| void run_dax(struct dax_device *dax_dev) |
| { |
| set_bit(DAXDEV_ALIVE, &dax_dev->flags); |
| } |
| EXPORT_SYMBOL_GPL(run_dax); |
| |
| static struct inode *dax_alloc_inode(struct super_block *sb) |
| { |
| struct dax_device *dax_dev; |
| struct inode *inode; |
| |
| dax_dev = kmem_cache_alloc(dax_cache, GFP_KERNEL); |
| if (!dax_dev) |
| return NULL; |
| |
| inode = &dax_dev->inode; |
| inode->i_rdev = 0; |
| return inode; |
| } |
| |
| static struct dax_device *to_dax_dev(struct inode *inode) |
| { |
| return container_of(inode, struct dax_device, inode); |
| } |
| |
| static void dax_i_callback(struct rcu_head *head) |
| { |
| struct inode *inode = container_of(head, struct inode, i_rcu); |
| struct dax_device *dax_dev = to_dax_dev(inode); |
| |
| kfree(dax_dev->host); |
| dax_dev->host = NULL; |
| if (inode->i_rdev) |
| ida_simple_remove(&dax_minor_ida, MINOR(inode->i_rdev)); |
| kmem_cache_free(dax_cache, dax_dev); |
| } |
| |
| static void dax_destroy_inode(struct inode *inode) |
| { |
| struct dax_device *dax_dev = to_dax_dev(inode); |
| |
| WARN_ONCE(test_bit(DAXDEV_ALIVE, &dax_dev->flags), |
| "kill_dax() must be called before final iput()\n"); |
| call_rcu(&inode->i_rcu, dax_i_callback); |
| } |
| |
| static const struct super_operations dax_sops = { |
| .statfs = simple_statfs, |
| .alloc_inode = dax_alloc_inode, |
| .destroy_inode = dax_destroy_inode, |
| .drop_inode = generic_delete_inode, |
| }; |
| |
| static struct dentry *dax_mount(struct file_system_type *fs_type, |
| int flags, const char *dev_name, void *data) |
| { |
| return mount_pseudo(fs_type, "dax:", &dax_sops, NULL, DAXFS_MAGIC); |
| } |
| |
| static struct file_system_type dax_fs_type = { |
| .name = "dax", |
| .mount = dax_mount, |
| .kill_sb = kill_anon_super, |
| }; |
| |
| static int dax_test(struct inode *inode, void *data) |
| { |
| dev_t devt = *(dev_t *) data; |
| |
| return inode->i_rdev == devt; |
| } |
| |
| static int dax_set(struct inode *inode, void *data) |
| { |
| dev_t devt = *(dev_t *) data; |
| |
| inode->i_rdev = devt; |
| return 0; |
| } |
| |
| static struct dax_device *dax_dev_get(dev_t devt) |
| { |
| struct dax_device *dax_dev; |
| struct inode *inode; |
| |
| inode = iget5_locked(dax_superblock, hash_32(devt + DAXFS_MAGIC, 31), |
| dax_test, dax_set, &devt); |
| |
| if (!inode) |
| return NULL; |
| |
| dax_dev = to_dax_dev(inode); |
| if (inode->i_state & I_NEW) { |
| set_bit(DAXDEV_ALIVE, &dax_dev->flags); |
| inode->i_cdev = &dax_dev->cdev; |
| inode->i_mode = S_IFCHR; |
| inode->i_flags = S_DAX; |
| mapping_set_gfp_mask(&inode->i_data, GFP_USER); |
| unlock_new_inode(inode); |
| } |
| |
| return dax_dev; |
| } |
| |
| static void dax_add_host(struct dax_device *dax_dev, const char *host) |
| { |
| int hash; |
| |
| /* |
| * Unconditionally init dax_dev since it's coming from a |
| * non-zeroed slab cache |
| */ |
| INIT_HLIST_NODE(&dax_dev->list); |
| dax_dev->host = host; |
| if (!host) |
| return; |
| |
| hash = dax_host_hash(host); |
| spin_lock(&dax_host_lock); |
| hlist_add_head(&dax_dev->list, &dax_host_list[hash]); |
| spin_unlock(&dax_host_lock); |
| } |
| |
| struct dax_device *alloc_dax(void *private, const char *__host, |
| const struct dax_operations *ops) |
| { |
| struct dax_device *dax_dev; |
| const char *host; |
| dev_t devt; |
| int minor; |
| |
| host = kstrdup(__host, GFP_KERNEL); |
| if (__host && !host) |
| return NULL; |
| |
| minor = ida_simple_get(&dax_minor_ida, 0, MINORMASK+1, GFP_KERNEL); |
| if (minor < 0) |
| goto err_minor; |
| |
| devt = MKDEV(MAJOR(dax_devt), minor); |
| dax_dev = dax_dev_get(devt); |
| if (!dax_dev) |
| goto err_dev; |
| |
| dax_add_host(dax_dev, host); |
| dax_dev->ops = ops; |
| dax_dev->private = private; |
| return dax_dev; |
| |
| err_dev: |
| ida_simple_remove(&dax_minor_ida, minor); |
| err_minor: |
| kfree(host); |
| return NULL; |
| } |
| EXPORT_SYMBOL_GPL(alloc_dax); |
| |
| void put_dax(struct dax_device *dax_dev) |
| { |
| if (!dax_dev) |
| return; |
| iput(&dax_dev->inode); |
| } |
| EXPORT_SYMBOL_GPL(put_dax); |
| |
| /** |
| * dax_get_by_host() - temporary lookup mechanism for filesystem-dax |
| * @host: alternate name for the device registered by a dax driver |
| */ |
| struct dax_device *dax_get_by_host(const char *host) |
| { |
| struct dax_device *dax_dev, *found = NULL; |
| int hash, id; |
| |
| if (!host) |
| return NULL; |
| |
| hash = dax_host_hash(host); |
| |
| id = dax_read_lock(); |
| spin_lock(&dax_host_lock); |
| hlist_for_each_entry(dax_dev, &dax_host_list[hash], list) { |
| if (!dax_alive(dax_dev) |
| || strcmp(host, dax_dev->host) != 0) |
| continue; |
| |
| if (igrab(&dax_dev->inode)) |
| found = dax_dev; |
| break; |
| } |
| spin_unlock(&dax_host_lock); |
| dax_read_unlock(id); |
| |
| return found; |
| } |
| EXPORT_SYMBOL_GPL(dax_get_by_host); |
| |
| /** |
| * inode_dax: convert a public inode into its dax_dev |
| * @inode: An inode with i_cdev pointing to a dax_dev |
| * |
| * Note this is not equivalent to to_dax_dev() which is for private |
| * internal use where we know the inode filesystem type == dax_fs_type. |
| */ |
| struct dax_device *inode_dax(struct inode *inode) |
| { |
| struct cdev *cdev = inode->i_cdev; |
| |
| return container_of(cdev, struct dax_device, cdev); |
| } |
| EXPORT_SYMBOL_GPL(inode_dax); |
| |
| struct inode *dax_inode(struct dax_device *dax_dev) |
| { |
| return &dax_dev->inode; |
| } |
| EXPORT_SYMBOL_GPL(dax_inode); |
| |
| void *dax_get_private(struct dax_device *dax_dev) |
| { |
| if (!test_bit(DAXDEV_ALIVE, &dax_dev->flags)) |
| return NULL; |
| return dax_dev->private; |
| } |
| EXPORT_SYMBOL_GPL(dax_get_private); |
| |
| static void init_once(void *_dax_dev) |
| { |
| struct dax_device *dax_dev = _dax_dev; |
| struct inode *inode = &dax_dev->inode; |
| |
| memset(dax_dev, 0, sizeof(*dax_dev)); |
| inode_init_once(inode); |
| } |
| |
| static int dax_fs_init(void) |
| { |
| int rc; |
| |
| dax_cache = kmem_cache_create("dax_cache", sizeof(struct dax_device), 0, |
| (SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT| |
| SLAB_MEM_SPREAD|SLAB_ACCOUNT), |
| init_once); |
| if (!dax_cache) |
| return -ENOMEM; |
| |
| rc = register_filesystem(&dax_fs_type); |
| if (rc) |
| goto err_register_fs; |
| |
| dax_mnt = kern_mount(&dax_fs_type); |
| if (IS_ERR(dax_mnt)) { |
| rc = PTR_ERR(dax_mnt); |
| goto err_mount; |
| } |
| dax_superblock = dax_mnt->mnt_sb; |
| |
| return 0; |
| |
| err_mount: |
| unregister_filesystem(&dax_fs_type); |
| err_register_fs: |
| kmem_cache_destroy(dax_cache); |
| |
| return rc; |
| } |
| |
| static void dax_fs_exit(void) |
| { |
| kern_unmount(dax_mnt); |
| unregister_filesystem(&dax_fs_type); |
| kmem_cache_destroy(dax_cache); |
| } |
| |
| static int __init dax_core_init(void) |
| { |
| int rc; |
| |
| rc = dax_fs_init(); |
| if (rc) |
| return rc; |
| |
| rc = alloc_chrdev_region(&dax_devt, 0, MINORMASK+1, "dax"); |
| if (rc) |
| goto err_chrdev; |
| |
| rc = dax_bus_init(); |
| if (rc) |
| goto err_bus; |
| return 0; |
| |
| err_bus: |
| unregister_chrdev_region(dax_devt, MINORMASK+1); |
| err_chrdev: |
| dax_fs_exit(); |
| return 0; |
| } |
| |
| static void __exit dax_core_exit(void) |
| { |
| unregister_chrdev_region(dax_devt, MINORMASK+1); |
| ida_destroy(&dax_minor_ida); |
| dax_fs_exit(); |
| } |
| |
| MODULE_AUTHOR("Intel Corporation"); |
| MODULE_LICENSE("GPL v2"); |
| subsys_initcall(dax_core_init); |
| module_exit(dax_core_exit); |