| // SPDX-License-Identifier: GPL-2.0-only |
| /* |
| * Copyright(c) 2017 Intel Corporation. All rights reserved. |
| */ |
| #include <linux/pagemap.h> |
| #include <linux/module.h> |
| #include <linux/mount.h> |
| #include <linux/pseudo_fs.h> |
| #include <linux/magic.h> |
| #include <linux/pfn_t.h> |
| #include <linux/cdev.h> |
| #include <linux/slab.h> |
| #include <linux/uio.h> |
| #include <linux/dax.h> |
| #include <linux/fs.h> |
| #include "dax-private.h" |
| |
| /** |
| * struct dax_device - anchor object for dax services |
| * @inode: core vfs |
| * @cdev: optional character interface for "device dax" |
| * @private: dax driver private data |
| * @flags: state and boolean properties |
| * @ops: operations for this device |
| */ |
| struct dax_device { |
| struct inode inode; |
| struct cdev cdev; |
| void *private; |
| unsigned long flags; |
| const struct dax_operations *ops; |
| }; |
| |
| 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; |
| |
| 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); |
| |
| #if defined(CONFIG_BLOCK) && defined(CONFIG_FS_DAX) |
| #include <linux/blkdev.h> |
| |
| static DEFINE_XARRAY(dax_hosts); |
| |
| int dax_add_host(struct dax_device *dax_dev, struct gendisk *disk) |
| { |
| return xa_insert(&dax_hosts, (unsigned long)disk, dax_dev, GFP_KERNEL); |
| } |
| EXPORT_SYMBOL_GPL(dax_add_host); |
| |
| void dax_remove_host(struct gendisk *disk) |
| { |
| xa_erase(&dax_hosts, (unsigned long)disk); |
| } |
| EXPORT_SYMBOL_GPL(dax_remove_host); |
| |
| /** |
| * fs_dax_get_by_bdev() - temporary lookup mechanism for filesystem-dax |
| * @bdev: block device to find a dax_device for |
| * @start_off: returns the byte offset into the dax_device that @bdev starts |
| */ |
| struct dax_device *fs_dax_get_by_bdev(struct block_device *bdev, u64 *start_off) |
| { |
| struct dax_device *dax_dev; |
| u64 part_size; |
| int id; |
| |
| if (!blk_queue_dax(bdev->bd_disk->queue)) |
| return NULL; |
| |
| *start_off = get_start_sect(bdev) * SECTOR_SIZE; |
| part_size = bdev_nr_sectors(bdev) * SECTOR_SIZE; |
| if (*start_off % PAGE_SIZE || part_size % PAGE_SIZE) { |
| pr_info("%pg: error: unaligned partition for dax\n", bdev); |
| return NULL; |
| } |
| |
| id = dax_read_lock(); |
| dax_dev = xa_load(&dax_hosts, (unsigned long)bdev->bd_disk); |
| if (!dax_dev || !dax_alive(dax_dev) || !igrab(&dax_dev->inode)) |
| dax_dev = NULL; |
| dax_read_unlock(id); |
| |
| return dax_dev; |
| } |
| EXPORT_SYMBOL_GPL(fs_dax_get_by_bdev); |
| #endif /* CONFIG_BLOCK && CONFIG_FS_DAX */ |
| |
| 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, |
| /* flag to check if device supports synchronous flush */ |
| DAXDEV_SYNC, |
| /* do not leave the caches dirty after writes */ |
| DAXDEV_NOCACHE, |
| /* handle CPU fetch exceptions during reads */ |
| DAXDEV_NOMC, |
| }; |
| |
| /** |
| * 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 |
| * @mode: indicator on normal access or recovery write |
| * @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, |
| enum dax_access_mode mode, void **kaddr, pfn_t *pfn) |
| { |
| long avail; |
| |
| if (!dax_dev) |
| return -EOPNOTSUPP; |
| |
| if (!dax_alive(dax_dev)) |
| return -ENXIO; |
| |
| if (nr_pages < 0) |
| return -EINVAL; |
| |
| avail = dax_dev->ops->direct_access(dax_dev, pgoff, nr_pages, |
| mode, 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; |
| |
| /* |
| * The userspace address for the memory copy has already been validated |
| * via access_ok() in vfs_write, so use the 'no check' version to bypass |
| * the HARDENED_USERCOPY overhead. |
| */ |
| if (test_bit(DAXDEV_NOCACHE, &dax_dev->flags)) |
| return _copy_from_iter_flushcache(addr, bytes, i); |
| return _copy_from_iter(addr, bytes, i); |
| } |
| |
| 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; |
| |
| /* |
| * The userspace address for the memory copy has already been validated |
| * via access_ok() in vfs_red, so use the 'no check' version to bypass |
| * the HARDENED_USERCOPY overhead. |
| */ |
| if (test_bit(DAXDEV_NOMC, &dax_dev->flags)) |
| return _copy_mc_to_iter(addr, bytes, i); |
| return _copy_to_iter(addr, bytes, i); |
| } |
| |
| int dax_zero_page_range(struct dax_device *dax_dev, pgoff_t pgoff, |
| size_t nr_pages) |
| { |
| if (!dax_alive(dax_dev)) |
| return -ENXIO; |
| /* |
| * There are no callers that want to zero more than one page as of now. |
| * Once users are there, this check can be removed after the |
| * device mapper code has been updated to split ranges across targets. |
| */ |
| if (nr_pages != 1) |
| return -EIO; |
| |
| return dax_dev->ops->zero_page_range(dax_dev, pgoff, nr_pages); |
| } |
| EXPORT_SYMBOL_GPL(dax_zero_page_range); |
| |
| #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_synchronous(struct dax_device *dax_dev) |
| { |
| return test_bit(DAXDEV_SYNC, &dax_dev->flags); |
| } |
| EXPORT_SYMBOL_GPL(dax_synchronous); |
| |
| void set_dax_synchronous(struct dax_device *dax_dev) |
| { |
| set_bit(DAXDEV_SYNC, &dax_dev->flags); |
| } |
| EXPORT_SYMBOL_GPL(set_dax_synchronous); |
| |
| void set_dax_nocache(struct dax_device *dax_dev) |
| { |
| set_bit(DAXDEV_NOCACHE, &dax_dev->flags); |
| } |
| EXPORT_SYMBOL_GPL(set_dax_nocache); |
| |
| void set_dax_nomc(struct dax_device *dax_dev) |
| { |
| set_bit(DAXDEV_NOMC, &dax_dev->flags); |
| } |
| EXPORT_SYMBOL_GPL(set_dax_nomc); |
| |
| 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); |
| |
| /* |
| * 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); |
| } |
| 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 = alloc_inode_sb(sb, 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_free_inode(struct inode *inode) |
| { |
| struct dax_device *dax_dev = to_dax_dev(inode); |
| if (inode->i_rdev) |
| ida_simple_remove(&dax_minor_ida, iminor(inode)); |
| 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"); |
| } |
| |
| static const struct super_operations dax_sops = { |
| .statfs = simple_statfs, |
| .alloc_inode = dax_alloc_inode, |
| .destroy_inode = dax_destroy_inode, |
| .free_inode = dax_free_inode, |
| .drop_inode = generic_delete_inode, |
| }; |
| |
| static int dax_init_fs_context(struct fs_context *fc) |
| { |
| struct pseudo_fs_context *ctx = init_pseudo(fc, DAXFS_MAGIC); |
| if (!ctx) |
| return -ENOMEM; |
| ctx->ops = &dax_sops; |
| return 0; |
| } |
| |
| static struct file_system_type dax_fs_type = { |
| .name = "dax", |
| .init_fs_context = dax_init_fs_context, |
| .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; |
| } |
| |
| struct dax_device *alloc_dax(void *private, const struct dax_operations *ops) |
| { |
| struct dax_device *dax_dev; |
| dev_t devt; |
| int minor; |
| |
| if (WARN_ON_ONCE(ops && !ops->zero_page_range)) |
| return ERR_PTR(-EINVAL); |
| |
| minor = ida_simple_get(&dax_minor_ida, 0, MINORMASK+1, GFP_KERNEL); |
| if (minor < 0) |
| return ERR_PTR(-ENOMEM); |
| |
| devt = MKDEV(MAJOR(dax_devt), minor); |
| dax_dev = dax_dev_get(devt); |
| if (!dax_dev) |
| goto err_dev; |
| |
| dax_dev->ops = ops; |
| dax_dev->private = private; |
| return dax_dev; |
| |
| err_dev: |
| ida_simple_remove(&dax_minor_ida, minor); |
| return ERR_PTR(-ENOMEM); |
| } |
| 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); |
| |
| /** |
| * 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; |
| |
| 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: |
| kmem_cache_destroy(dax_cache); |
| |
| return rc; |
| } |
| |
| static void dax_fs_exit(void) |
| { |
| kern_unmount(dax_mnt); |
| rcu_barrier(); |
| 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) |
| { |
| dax_bus_exit(); |
| 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); |