diff options
author | Dan Williams | 2017-05-04 23:38:43 -0700 |
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committer | Dan Williams | 2017-05-04 23:38:43 -0700 |
commit | 736163671bcb163fc82600b46c83dfa89d532d95 (patch) | |
tree | 0639dc9d9fa180450b4e8fbda706eaae5f1876da /drivers/dax/super.c | |
parent | d5483feda85a8f39ee2e940e279547c686aac30c (diff) | |
parent | 1ef97fe4f8abd3317d5c3c860f990e02c2633959 (diff) |
Merge branch 'for-4.12/dax' into libnvdimm-for-next
Diffstat (limited to 'drivers/dax/super.c')
-rw-r--r-- | drivers/dax/super.c | 425 |
1 files changed, 425 insertions, 0 deletions
diff --git a/drivers/dax/super.c b/drivers/dax/super.c new file mode 100644 index 000000000000..465dcd7317d5 --- /dev/null +++ b/drivers/dax/super.c @@ -0,0 +1,425 @@ +/* + * 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/cdev.h> +#include <linux/hash.h> +#include <linux/slab.h> +#include <linux/dax.h> +#include <linux/fs.h> + +static int nr_dax = CONFIG_NR_DEV_DAX; +module_param(nr_dax, int, S_IRUGO); +MODULE_PARM_DESC(nr_dax, "max number of dax device instances"); + +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); + +/** + * 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 + * @alive: !alive + rcu grace period == no new operations / mappings + */ +struct dax_device { + struct hlist_node list; + struct inode inode; + struct cdev cdev; + const char *host; + void *private; + bool alive; + const struct dax_operations *ops; +}; + +/** + * 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; + + /* + * The device driver is allowed to sleep, in order to make the + * memory directly accessible. + */ + might_sleep(); + + 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); + +bool dax_alive(struct dax_device *dax_dev) +{ + lockdep_assert_held(&dax_srcu); + return dax_dev->alive; +} +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; + + dax_dev->alive = false; + + synchronize_srcu(&dax_srcu); + + spin_lock(&dax_host_lock); + hlist_del_init(&dax_dev->list); + spin_unlock(&dax_host_lock); + + dax_dev->private = NULL; +} +EXPORT_SYMBOL_GPL(kill_dax); + +static struct inode *dax_alloc_inode(struct super_block *sb) +{ + struct dax_device *dax_dev; + + dax_dev = kmem_cache_alloc(dax_cache, GFP_KERNEL); + return &dax_dev->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; + 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(dax_dev->alive, + "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) { + dax_dev->alive = true; + 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, nr_dax, 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) +{ + 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; + + 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_fs_init(void) +{ + int rc; + + rc = __dax_fs_init(); + if (rc) + return rc; + + nr_dax = max(nr_dax, 256); + rc = alloc_chrdev_region(&dax_devt, 0, nr_dax, "dax"); + if (rc) + __dax_fs_exit(); + return rc; +} + +static void __exit dax_fs_exit(void) +{ + unregister_chrdev_region(dax_devt, nr_dax); + ida_destroy(&dax_minor_ida); + __dax_fs_exit(); +} + +MODULE_AUTHOR("Intel Corporation"); +MODULE_LICENSE("GPL v2"); +subsys_initcall(dax_fs_init); +module_exit(dax_fs_exit); |