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f0614eefbf
- Fix a crash due to a missing rcu_barrier() in dax_fs_exit() - Fix two miscellaneous doc issues -----BEGIN PGP SIGNATURE----- iHUEABYIAB0WIQSbo+XnGs+rwLz9XGXfioYZHlFsZwUCYjp4zgAKCRDfioYZHlFs ZwgDAQD/jJE/uyFozwZR/YD8G293Hzs/acPUEQ/09t06W68SIAEAtwBr3WHKiFJL M+utFlm05fShOQl3lGwqiPS5/mQvzwc= =7AnI -----END PGP SIGNATURE----- Merge tag 'dax-for-5.18' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm Pull DAX updates from Dan Williams: "Andrew has been shepherding major dax features that touch the core -mm through his tree, but I still collect the dax updates that are core-mm independent. - Fix a crash due to a missing rcu_barrier() in dax_fs_exit() - Fix two miscellaneous doc issues" * tag 'dax-for-5.18' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm: dax: Fix missing kdoc for dax_device dax: make sure inodes are flushed before destroy cache fsdax: fix function description
520 lines
12 KiB
C
520 lines
12 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Copyright(c) 2017 Intel Corporation. All rights reserved.
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*/
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#include <linux/pagemap.h>
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#include <linux/module.h>
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#include <linux/mount.h>
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#include <linux/pseudo_fs.h>
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#include <linux/magic.h>
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#include <linux/pfn_t.h>
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#include <linux/cdev.h>
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#include <linux/slab.h>
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#include <linux/uio.h>
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#include <linux/dax.h>
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#include <linux/fs.h>
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#include "dax-private.h"
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/**
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* struct dax_device - anchor object for dax services
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* @inode: core vfs
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* @cdev: optional character interface for "device dax"
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* @private: dax driver private data
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* @flags: state and boolean properties
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* @ops: operations for this device
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*/
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struct dax_device {
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struct inode inode;
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struct cdev cdev;
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void *private;
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unsigned long flags;
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const struct dax_operations *ops;
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};
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static dev_t dax_devt;
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DEFINE_STATIC_SRCU(dax_srcu);
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static struct vfsmount *dax_mnt;
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static DEFINE_IDA(dax_minor_ida);
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static struct kmem_cache *dax_cache __read_mostly;
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static struct super_block *dax_superblock __read_mostly;
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int dax_read_lock(void)
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{
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return srcu_read_lock(&dax_srcu);
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}
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EXPORT_SYMBOL_GPL(dax_read_lock);
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void dax_read_unlock(int id)
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{
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srcu_read_unlock(&dax_srcu, id);
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}
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EXPORT_SYMBOL_GPL(dax_read_unlock);
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#if defined(CONFIG_BLOCK) && defined(CONFIG_FS_DAX)
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#include <linux/blkdev.h>
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static DEFINE_XARRAY(dax_hosts);
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int dax_add_host(struct dax_device *dax_dev, struct gendisk *disk)
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{
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return xa_insert(&dax_hosts, (unsigned long)disk, dax_dev, GFP_KERNEL);
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}
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EXPORT_SYMBOL_GPL(dax_add_host);
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void dax_remove_host(struct gendisk *disk)
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{
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xa_erase(&dax_hosts, (unsigned long)disk);
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}
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EXPORT_SYMBOL_GPL(dax_remove_host);
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/**
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* fs_dax_get_by_bdev() - temporary lookup mechanism for filesystem-dax
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* @bdev: block device to find a dax_device for
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* @start_off: returns the byte offset into the dax_device that @bdev starts
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*/
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struct dax_device *fs_dax_get_by_bdev(struct block_device *bdev, u64 *start_off)
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{
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struct dax_device *dax_dev;
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u64 part_size;
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int id;
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if (!blk_queue_dax(bdev->bd_disk->queue))
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return NULL;
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*start_off = get_start_sect(bdev) * SECTOR_SIZE;
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part_size = bdev_nr_sectors(bdev) * SECTOR_SIZE;
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if (*start_off % PAGE_SIZE || part_size % PAGE_SIZE) {
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pr_info("%pg: error: unaligned partition for dax\n", bdev);
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return NULL;
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}
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id = dax_read_lock();
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dax_dev = xa_load(&dax_hosts, (unsigned long)bdev->bd_disk);
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if (!dax_dev || !dax_alive(dax_dev) || !igrab(&dax_dev->inode))
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dax_dev = NULL;
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dax_read_unlock(id);
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return dax_dev;
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}
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EXPORT_SYMBOL_GPL(fs_dax_get_by_bdev);
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#endif /* CONFIG_BLOCK && CONFIG_FS_DAX */
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enum dax_device_flags {
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/* !alive + rcu grace period == no new operations / mappings */
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DAXDEV_ALIVE,
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/* gate whether dax_flush() calls the low level flush routine */
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DAXDEV_WRITE_CACHE,
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/* flag to check if device supports synchronous flush */
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DAXDEV_SYNC,
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/* do not leave the caches dirty after writes */
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DAXDEV_NOCACHE,
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/* handle CPU fetch exceptions during reads */
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DAXDEV_NOMC,
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};
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/**
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* dax_direct_access() - translate a device pgoff to an absolute pfn
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* @dax_dev: a dax_device instance representing the logical memory range
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* @pgoff: offset in pages from the start of the device to translate
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* @nr_pages: number of consecutive pages caller can handle relative to @pfn
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* @kaddr: output parameter that returns a virtual address mapping of pfn
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* @pfn: output parameter that returns an absolute pfn translation of @pgoff
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*
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* Return: negative errno if an error occurs, otherwise the number of
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* pages accessible at the device relative @pgoff.
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*/
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long dax_direct_access(struct dax_device *dax_dev, pgoff_t pgoff, long nr_pages,
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void **kaddr, pfn_t *pfn)
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{
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long avail;
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if (!dax_dev)
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return -EOPNOTSUPP;
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if (!dax_alive(dax_dev))
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return -ENXIO;
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if (nr_pages < 0)
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return -EINVAL;
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avail = dax_dev->ops->direct_access(dax_dev, pgoff, nr_pages,
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kaddr, pfn);
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if (!avail)
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return -ERANGE;
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return min(avail, nr_pages);
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}
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EXPORT_SYMBOL_GPL(dax_direct_access);
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size_t dax_copy_from_iter(struct dax_device *dax_dev, pgoff_t pgoff, void *addr,
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size_t bytes, struct iov_iter *i)
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{
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if (!dax_alive(dax_dev))
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return 0;
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/*
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* The userspace address for the memory copy has already been validated
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* via access_ok() in vfs_write, so use the 'no check' version to bypass
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* the HARDENED_USERCOPY overhead.
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*/
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if (test_bit(DAXDEV_NOCACHE, &dax_dev->flags))
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return _copy_from_iter_flushcache(addr, bytes, i);
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return _copy_from_iter(addr, bytes, i);
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}
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size_t dax_copy_to_iter(struct dax_device *dax_dev, pgoff_t pgoff, void *addr,
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size_t bytes, struct iov_iter *i)
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{
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if (!dax_alive(dax_dev))
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return 0;
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/*
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* The userspace address for the memory copy has already been validated
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* via access_ok() in vfs_red, so use the 'no check' version to bypass
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* the HARDENED_USERCOPY overhead.
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*/
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if (test_bit(DAXDEV_NOMC, &dax_dev->flags))
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return _copy_mc_to_iter(addr, bytes, i);
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return _copy_to_iter(addr, bytes, i);
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}
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int dax_zero_page_range(struct dax_device *dax_dev, pgoff_t pgoff,
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size_t nr_pages)
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{
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if (!dax_alive(dax_dev))
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return -ENXIO;
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/*
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* There are no callers that want to zero more than one page as of now.
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* Once users are there, this check can be removed after the
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* device mapper code has been updated to split ranges across targets.
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*/
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if (nr_pages != 1)
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return -EIO;
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return dax_dev->ops->zero_page_range(dax_dev, pgoff, nr_pages);
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}
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EXPORT_SYMBOL_GPL(dax_zero_page_range);
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#ifdef CONFIG_ARCH_HAS_PMEM_API
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void arch_wb_cache_pmem(void *addr, size_t size);
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void dax_flush(struct dax_device *dax_dev, void *addr, size_t size)
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{
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if (unlikely(!dax_write_cache_enabled(dax_dev)))
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return;
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arch_wb_cache_pmem(addr, size);
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}
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#else
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void dax_flush(struct dax_device *dax_dev, void *addr, size_t size)
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{
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}
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#endif
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EXPORT_SYMBOL_GPL(dax_flush);
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void dax_write_cache(struct dax_device *dax_dev, bool wc)
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{
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if (wc)
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set_bit(DAXDEV_WRITE_CACHE, &dax_dev->flags);
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else
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clear_bit(DAXDEV_WRITE_CACHE, &dax_dev->flags);
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}
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EXPORT_SYMBOL_GPL(dax_write_cache);
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bool dax_write_cache_enabled(struct dax_device *dax_dev)
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{
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return test_bit(DAXDEV_WRITE_CACHE, &dax_dev->flags);
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}
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EXPORT_SYMBOL_GPL(dax_write_cache_enabled);
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bool dax_synchronous(struct dax_device *dax_dev)
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{
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return test_bit(DAXDEV_SYNC, &dax_dev->flags);
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}
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EXPORT_SYMBOL_GPL(dax_synchronous);
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void set_dax_synchronous(struct dax_device *dax_dev)
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{
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set_bit(DAXDEV_SYNC, &dax_dev->flags);
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}
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EXPORT_SYMBOL_GPL(set_dax_synchronous);
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void set_dax_nocache(struct dax_device *dax_dev)
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{
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set_bit(DAXDEV_NOCACHE, &dax_dev->flags);
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}
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EXPORT_SYMBOL_GPL(set_dax_nocache);
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void set_dax_nomc(struct dax_device *dax_dev)
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{
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set_bit(DAXDEV_NOMC, &dax_dev->flags);
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}
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EXPORT_SYMBOL_GPL(set_dax_nomc);
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bool dax_alive(struct dax_device *dax_dev)
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{
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lockdep_assert_held(&dax_srcu);
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return test_bit(DAXDEV_ALIVE, &dax_dev->flags);
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}
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EXPORT_SYMBOL_GPL(dax_alive);
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/*
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* Note, rcu is not protecting the liveness of dax_dev, rcu is ensuring
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* that any fault handlers or operations that might have seen
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* dax_alive(), have completed. Any operations that start after
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* synchronize_srcu() has run will abort upon seeing !dax_alive().
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*/
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void kill_dax(struct dax_device *dax_dev)
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{
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if (!dax_dev)
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return;
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clear_bit(DAXDEV_ALIVE, &dax_dev->flags);
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synchronize_srcu(&dax_srcu);
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}
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EXPORT_SYMBOL_GPL(kill_dax);
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void run_dax(struct dax_device *dax_dev)
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{
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set_bit(DAXDEV_ALIVE, &dax_dev->flags);
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}
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EXPORT_SYMBOL_GPL(run_dax);
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static struct inode *dax_alloc_inode(struct super_block *sb)
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{
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struct dax_device *dax_dev;
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struct inode *inode;
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dax_dev = alloc_inode_sb(sb, dax_cache, GFP_KERNEL);
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if (!dax_dev)
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return NULL;
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inode = &dax_dev->inode;
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inode->i_rdev = 0;
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return inode;
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}
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static struct dax_device *to_dax_dev(struct inode *inode)
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{
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return container_of(inode, struct dax_device, inode);
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}
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static void dax_free_inode(struct inode *inode)
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{
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struct dax_device *dax_dev = to_dax_dev(inode);
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if (inode->i_rdev)
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ida_simple_remove(&dax_minor_ida, iminor(inode));
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kmem_cache_free(dax_cache, dax_dev);
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}
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static void dax_destroy_inode(struct inode *inode)
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{
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struct dax_device *dax_dev = to_dax_dev(inode);
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WARN_ONCE(test_bit(DAXDEV_ALIVE, &dax_dev->flags),
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"kill_dax() must be called before final iput()\n");
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}
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static const struct super_operations dax_sops = {
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.statfs = simple_statfs,
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.alloc_inode = dax_alloc_inode,
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.destroy_inode = dax_destroy_inode,
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.free_inode = dax_free_inode,
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.drop_inode = generic_delete_inode,
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};
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static int dax_init_fs_context(struct fs_context *fc)
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{
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struct pseudo_fs_context *ctx = init_pseudo(fc, DAXFS_MAGIC);
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if (!ctx)
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return -ENOMEM;
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ctx->ops = &dax_sops;
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return 0;
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}
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static struct file_system_type dax_fs_type = {
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.name = "dax",
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.init_fs_context = dax_init_fs_context,
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.kill_sb = kill_anon_super,
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};
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static int dax_test(struct inode *inode, void *data)
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{
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dev_t devt = *(dev_t *) data;
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return inode->i_rdev == devt;
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}
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static int dax_set(struct inode *inode, void *data)
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{
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dev_t devt = *(dev_t *) data;
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inode->i_rdev = devt;
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return 0;
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}
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static struct dax_device *dax_dev_get(dev_t devt)
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{
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struct dax_device *dax_dev;
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struct inode *inode;
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inode = iget5_locked(dax_superblock, hash_32(devt + DAXFS_MAGIC, 31),
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dax_test, dax_set, &devt);
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if (!inode)
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return NULL;
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dax_dev = to_dax_dev(inode);
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if (inode->i_state & I_NEW) {
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set_bit(DAXDEV_ALIVE, &dax_dev->flags);
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inode->i_cdev = &dax_dev->cdev;
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inode->i_mode = S_IFCHR;
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inode->i_flags = S_DAX;
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mapping_set_gfp_mask(&inode->i_data, GFP_USER);
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unlock_new_inode(inode);
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}
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return dax_dev;
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}
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struct dax_device *alloc_dax(void *private, const struct dax_operations *ops)
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{
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struct dax_device *dax_dev;
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dev_t devt;
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int minor;
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if (WARN_ON_ONCE(ops && !ops->zero_page_range))
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return ERR_PTR(-EINVAL);
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minor = ida_simple_get(&dax_minor_ida, 0, MINORMASK+1, GFP_KERNEL);
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if (minor < 0)
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return ERR_PTR(-ENOMEM);
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devt = MKDEV(MAJOR(dax_devt), minor);
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dax_dev = dax_dev_get(devt);
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if (!dax_dev)
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goto err_dev;
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dax_dev->ops = ops;
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dax_dev->private = private;
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return dax_dev;
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err_dev:
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ida_simple_remove(&dax_minor_ida, minor);
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return ERR_PTR(-ENOMEM);
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}
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EXPORT_SYMBOL_GPL(alloc_dax);
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void put_dax(struct dax_device *dax_dev)
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{
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if (!dax_dev)
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return;
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iput(&dax_dev->inode);
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}
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EXPORT_SYMBOL_GPL(put_dax);
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/**
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* inode_dax: convert a public inode into its dax_dev
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* @inode: An inode with i_cdev pointing to a dax_dev
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*
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* Note this is not equivalent to to_dax_dev() which is for private
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* internal use where we know the inode filesystem type == dax_fs_type.
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*/
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struct dax_device *inode_dax(struct inode *inode)
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{
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struct cdev *cdev = inode->i_cdev;
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return container_of(cdev, struct dax_device, cdev);
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}
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EXPORT_SYMBOL_GPL(inode_dax);
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struct inode *dax_inode(struct dax_device *dax_dev)
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{
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return &dax_dev->inode;
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}
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EXPORT_SYMBOL_GPL(dax_inode);
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void *dax_get_private(struct dax_device *dax_dev)
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{
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if (!test_bit(DAXDEV_ALIVE, &dax_dev->flags))
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return NULL;
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return dax_dev->private;
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}
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EXPORT_SYMBOL_GPL(dax_get_private);
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static void init_once(void *_dax_dev)
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{
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struct dax_device *dax_dev = _dax_dev;
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struct inode *inode = &dax_dev->inode;
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memset(dax_dev, 0, sizeof(*dax_dev));
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inode_init_once(inode);
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}
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static int dax_fs_init(void)
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{
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int rc;
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dax_cache = kmem_cache_create("dax_cache", sizeof(struct dax_device), 0,
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(SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT|
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SLAB_MEM_SPREAD|SLAB_ACCOUNT),
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init_once);
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if (!dax_cache)
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return -ENOMEM;
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dax_mnt = kern_mount(&dax_fs_type);
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if (IS_ERR(dax_mnt)) {
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rc = PTR_ERR(dax_mnt);
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goto err_mount;
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}
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dax_superblock = dax_mnt->mnt_sb;
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return 0;
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err_mount:
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kmem_cache_destroy(dax_cache);
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return rc;
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}
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static void dax_fs_exit(void)
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|
{
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|
kern_unmount(dax_mnt);
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|
rcu_barrier();
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|
kmem_cache_destroy(dax_cache);
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}
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|
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static int __init dax_core_init(void)
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|
{
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|
int rc;
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|
|
|
rc = dax_fs_init();
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|
if (rc)
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|
return rc;
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|
|
|
rc = alloc_chrdev_region(&dax_devt, 0, MINORMASK+1, "dax");
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|
if (rc)
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|
goto err_chrdev;
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|
|
|
rc = dax_bus_init();
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|
if (rc)
|
|
goto err_bus;
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|
return 0;
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|
|
|
err_bus:
|
|
unregister_chrdev_region(dax_devt, MINORMASK+1);
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|
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");
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|
MODULE_LICENSE("GPL v2");
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|
subsys_initcall(dax_core_init);
|
|
module_exit(dax_core_exit);
|