linux/drivers/dax/super.c
Jane Chu 1ea7ca1b09 dax: enable dax fault handler to report VM_FAULT_HWPOISON
When multiple processes mmap() a dax file, then at some point,
a process issues a 'load' and consumes a hwpoison, the process
receives a SIGBUS with si_code = BUS_MCEERR_AR and with si_lsb
set for the poison scope. Soon after, any other process issues
a 'load' to the poisoned page (that is unmapped from the kernel
side by memory_failure), it receives a SIGBUS with
si_code = BUS_ADRERR and without valid si_lsb.

This is confusing to user, and is different from page fault due
to poison in RAM memory, also some helpful information is lost.

Channel dax backend driver's poison detection to the filesystem
such that instead of reporting VM_FAULT_SIGBUS, it could report
VM_FAULT_HWPOISON.

If user level block IO syscalls fail due to poison, the errno will
be converted to EIO to maintain block API consistency.

Signed-off-by: Jane Chu <jane.chu@oracle.com>
Link: https://lore.kernel.org/r/20230615181325.1327259-2-jane.chu@oracle.com
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>
2023-06-26 07:54:23 -06:00

598 lines
14 KiB
C

// 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
* @holder_data: holder of a dax_device: could be filesystem or mapped device
* @holder_ops: operations for the inner holder
*/
struct dax_device {
struct inode inode;
struct cdev cdev;
void *private;
unsigned long flags;
const struct dax_operations *ops;
void *holder_data;
const struct dax_holder_operations *holder_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
* @holder: filesystem or mapped device inside the dax_device
* @ops: operations for the inner holder
*/
struct dax_device *fs_dax_get_by_bdev(struct block_device *bdev, u64 *start_off,
void *holder, const struct dax_holder_operations *ops)
{
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;
else if (holder) {
if (!cmpxchg(&dax_dev->holder_data, NULL, holder))
dax_dev->holder_ops = ops;
else
dax_dev = NULL;
}
dax_read_unlock(id);
return dax_dev;
}
EXPORT_SYMBOL_GPL(fs_dax_get_by_bdev);
void fs_put_dax(struct dax_device *dax_dev, void *holder)
{
if (dax_dev && holder &&
cmpxchg(&dax_dev->holder_data, holder, NULL) == holder)
dax_dev->holder_ops = NULL;
put_dax(dax_dev);
}
EXPORT_SYMBOL_GPL(fs_put_dax);
#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)
{
int ret;
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;
ret = dax_dev->ops->zero_page_range(dax_dev, pgoff, nr_pages);
return dax_mem2blk_err(ret);
}
EXPORT_SYMBOL_GPL(dax_zero_page_range);
size_t dax_recovery_write(struct dax_device *dax_dev, pgoff_t pgoff,
void *addr, size_t bytes, struct iov_iter *iter)
{
if (!dax_dev->ops->recovery_write)
return 0;
return dax_dev->ops->recovery_write(dax_dev, pgoff, addr, bytes, iter);
}
EXPORT_SYMBOL_GPL(dax_recovery_write);
int dax_holder_notify_failure(struct dax_device *dax_dev, u64 off,
u64 len, int mf_flags)
{
int rc, id;
id = dax_read_lock();
if (!dax_alive(dax_dev)) {
rc = -ENXIO;
goto out;
}
if (!dax_dev->holder_ops) {
rc = -EOPNOTSUPP;
goto out;
}
rc = dax_dev->holder_ops->notify_failure(dax_dev, off, len, mf_flags);
out:
dax_read_unlock(id);
return rc;
}
EXPORT_SYMBOL_GPL(dax_holder_notify_failure);
#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;
if (dax_dev->holder_data != NULL)
dax_holder_notify_failure(dax_dev, 0, U64_MAX, 0);
clear_bit(DAXDEV_ALIVE, &dax_dev->flags);
synchronize_srcu(&dax_srcu);
/* clear holder data */
dax_dev->holder_ops = NULL;
dax_dev->holder_data = NULL;
}
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_free(&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_alloc_max(&dax_minor_ida, MINORMASK, 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_free(&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);
/**
* dax_holder() - obtain the holder of a dax device
* @dax_dev: a dax_device instance
*
* Return: the holder's data which represents the holder if registered,
* otherwize NULL.
*/
void *dax_holder(struct dax_device *dax_dev)
{
return dax_dev->holder_data;
}
EXPORT_SYMBOL_GPL(dax_holder);
/**
* 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);