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block: enable dax for raw block devices

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If an application wants exclusive access to all of the persistent memory
provided by an NVDIMM namespace it can use this raw-block-dax facility
to forgo establishing a filesystem.  This capability is targeted
primarily to hypervisors wanting to provision persistent memory for
guests.  It can be disabled / enabled dynamically via the new BLKDAXSET
ioctl.

Cc: Jeff Moyer <jmoyer@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Reported-by: kbuild test robot <fengguang.wu@intel.com>
Reviewed-by: Jan Kara <jack@suse.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
This commit is contained in:
Dan Williams
2015-11-30 10:20:29 -08:00
parent 4ebb16ca9a
commit 5a023cdba5
4 changed files with 169 additions and 8 deletions
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103
fs/block_dev.c
View File

@@ -1235,8 +1235,11 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
}
}
if (!ret)
if (!ret) {
bd_set_size(bdev,(loff_t)get_capacity(disk)<<9);
if (!blkdev_dax_capable(bdev))
bdev->bd_inode->i_flags &= ~S_DAX;
}
/*
* If the device is invalidated, rescan partition
@@ -1250,6 +1253,7 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
else if (ret == -ENOMEDIUM)
invalidate_partitions(disk, bdev);
}
if (ret)
goto out_clear;
} else {
@@ -1270,12 +1274,7 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
goto out_clear;
}
bd_set_size(bdev, (loff_t)bdev->bd_part->nr_sects << 9);
/*
* If the partition is not aligned on a page
* boundary, we can't do dax I/O to it.
*/
if ((bdev->bd_part->start_sect % (PAGE_SIZE / 512)) ||
(bdev->bd_part->nr_sects % (PAGE_SIZE / 512)))
if (!blkdev_dax_capable(bdev))
bdev->bd_inode->i_flags &= ~S_DAX;
}
} else {
@@ -1713,13 +1712,101 @@ static const struct address_space_operations def_blk_aops = {
.is_dirty_writeback = buffer_check_dirty_writeback,
};
#ifdef CONFIG_FS_DAX
/*
* In the raw block case we do not need to contend with truncation nor
* unwritten file extents. Without those concerns there is no need for
* additional locking beyond the mmap_sem context that these routines
* are already executing under.
*
* Note, there is no protection if the block device is dynamically
* resized (partition grow/shrink) during a fault. A stable block device
* size is already not enforced in the blkdev_direct_IO path.
*
* For DAX, it is the responsibility of the block device driver to
* ensure the whole-disk device size is stable while requests are in
* flight.
*
* Finally, unlike the filemap_page_mkwrite() case there is no
* filesystem superblock to sync against freezing. We still include a
* pfn_mkwrite callback for dax drivers to receive write fault
* notifications.
*/
static int blkdev_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
{
return __dax_fault(vma, vmf, blkdev_get_block, NULL);
}
static int blkdev_dax_pmd_fault(struct vm_area_struct *vma, unsigned long addr,
pmd_t *pmd, unsigned int flags)
{
return __dax_pmd_fault(vma, addr, pmd, flags, blkdev_get_block, NULL);
}
static void blkdev_vm_open(struct vm_area_struct *vma)
{
struct inode *bd_inode = bdev_file_inode(vma->vm_file);
struct block_device *bdev = I_BDEV(bd_inode);
mutex_lock(&bd_inode->i_mutex);
bdev->bd_map_count++;
mutex_unlock(&bd_inode->i_mutex);
}
static void blkdev_vm_close(struct vm_area_struct *vma)
{
struct inode *bd_inode = bdev_file_inode(vma->vm_file);
struct block_device *bdev = I_BDEV(bd_inode);
mutex_lock(&bd_inode->i_mutex);
bdev->bd_map_count--;
mutex_unlock(&bd_inode->i_mutex);
}
static const struct vm_operations_struct blkdev_dax_vm_ops = {
.open = blkdev_vm_open,
.close = blkdev_vm_close,
.fault = blkdev_dax_fault,
.pmd_fault = blkdev_dax_pmd_fault,
.pfn_mkwrite = blkdev_dax_fault,
};
static const struct vm_operations_struct blkdev_default_vm_ops = {
.open = blkdev_vm_open,
.close = blkdev_vm_close,
.fault = filemap_fault,
.map_pages = filemap_map_pages,
};
static int blkdev_mmap(struct file *file, struct vm_area_struct *vma)
{
struct inode *bd_inode = bdev_file_inode(file);
struct block_device *bdev = I_BDEV(bd_inode);
file_accessed(file);
mutex_lock(&bd_inode->i_mutex);
bdev->bd_map_count++;
if (IS_DAX(bd_inode)) {
vma->vm_ops = &blkdev_dax_vm_ops;
vma->vm_flags |= VM_MIXEDMAP | VM_HUGEPAGE;
} else {
vma->vm_ops = &blkdev_default_vm_ops;
}
mutex_unlock(&bd_inode->i_mutex);
return 0;
}
#else
#define blkdev_mmap generic_file_mmap
#endif
const struct file_operations def_blk_fops = {
.open = blkdev_open,
.release = blkdev_close,
.llseek = block_llseek,
.read_iter = blkdev_read_iter,
.write_iter = blkdev_write_iter,
.mmap = generic_file_mmap,
.mmap = blkdev_mmap,
.fsync = blkdev_fsync,
.unlocked_ioctl = block_ioctl,
#ifdef CONFIG_COMPAT