// 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 * @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 -EINVAL; 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; /* * 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);