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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-23 01:10:04 +00:00
block: enable dax for raw block devices
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>
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parent
4ebb16ca9a
commit
5a023cdba5
4 changed files with 169 additions and 8 deletions
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@ -406,6 +406,62 @@ static inline int is_unrecognized_ioctl(int ret)
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ret == -ENOIOCTLCMD;
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}
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#ifdef CONFIG_FS_DAX
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bool blkdev_dax_capable(struct block_device *bdev)
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{
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struct gendisk *disk = bdev->bd_disk;
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if (!disk->fops->direct_access)
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return false;
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/*
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* If the partition is not aligned on a page boundary, we can't
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* do dax I/O to it.
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*/
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if ((bdev->bd_part->start_sect % (PAGE_SIZE / 512))
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|| (bdev->bd_part->nr_sects % (PAGE_SIZE / 512)))
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return false;
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return true;
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}
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static int blkdev_daxset(struct block_device *bdev, unsigned long argp)
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{
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unsigned long arg;
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int rc = 0;
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if (!capable(CAP_SYS_ADMIN))
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return -EACCES;
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if (get_user(arg, (int __user *)(argp)))
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return -EFAULT;
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arg = !!arg;
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if (arg == !!(bdev->bd_inode->i_flags & S_DAX))
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return 0;
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if (arg)
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arg = S_DAX;
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if (arg && !blkdev_dax_capable(bdev))
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return -ENOTTY;
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mutex_lock(&bdev->bd_inode->i_mutex);
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if (bdev->bd_map_count == 0)
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inode_set_flags(bdev->bd_inode, arg, S_DAX);
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else
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rc = -EBUSY;
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mutex_unlock(&bdev->bd_inode->i_mutex);
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return rc;
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}
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#else
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static int blkdev_daxset(struct block_device *bdev, int arg)
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{
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if (arg)
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return -ENOTTY;
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return 0;
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}
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#endif
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static int blkdev_flushbuf(struct block_device *bdev, fmode_t mode,
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unsigned cmd, unsigned long arg)
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{
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@ -568,6 +624,11 @@ int blkdev_ioctl(struct block_device *bdev, fmode_t mode, unsigned cmd,
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case BLKTRACESETUP:
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case BLKTRACETEARDOWN:
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return blk_trace_ioctl(bdev, cmd, argp);
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case BLKDAXSET:
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return blkdev_daxset(bdev, arg);
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case BLKDAXGET:
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return put_int(arg, !!(bdev->bd_inode->i_flags & S_DAX));
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break;
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case IOC_PR_REGISTER:
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return blkdev_pr_register(bdev, argp);
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case IOC_PR_RESERVE:
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103
fs/block_dev.c
103
fs/block_dev.c
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@ -1235,8 +1235,11 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
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}
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}
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if (!ret)
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if (!ret) {
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bd_set_size(bdev,(loff_t)get_capacity(disk)<<9);
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if (!blkdev_dax_capable(bdev))
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bdev->bd_inode->i_flags &= ~S_DAX;
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}
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/*
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* If the device is invalidated, rescan partition
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@ -1250,6 +1253,7 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
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else if (ret == -ENOMEDIUM)
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invalidate_partitions(disk, bdev);
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}
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if (ret)
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goto out_clear;
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} else {
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@ -1270,12 +1274,7 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
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goto out_clear;
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}
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bd_set_size(bdev, (loff_t)bdev->bd_part->nr_sects << 9);
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/*
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* If the partition is not aligned on a page
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* boundary, we can't do dax I/O to it.
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*/
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if ((bdev->bd_part->start_sect % (PAGE_SIZE / 512)) ||
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(bdev->bd_part->nr_sects % (PAGE_SIZE / 512)))
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if (!blkdev_dax_capable(bdev))
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bdev->bd_inode->i_flags &= ~S_DAX;
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}
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} else {
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@ -1713,13 +1712,101 @@ static const struct address_space_operations def_blk_aops = {
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.is_dirty_writeback = buffer_check_dirty_writeback,
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};
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#ifdef CONFIG_FS_DAX
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/*
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* In the raw block case we do not need to contend with truncation nor
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* unwritten file extents. Without those concerns there is no need for
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* additional locking beyond the mmap_sem context that these routines
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* are already executing under.
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*
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* Note, there is no protection if the block device is dynamically
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* resized (partition grow/shrink) during a fault. A stable block device
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* size is already not enforced in the blkdev_direct_IO path.
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*
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* For DAX, it is the responsibility of the block device driver to
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* ensure the whole-disk device size is stable while requests are in
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* flight.
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*
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* Finally, unlike the filemap_page_mkwrite() case there is no
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* filesystem superblock to sync against freezing. We still include a
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* pfn_mkwrite callback for dax drivers to receive write fault
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* notifications.
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*/
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static int blkdev_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
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{
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return __dax_fault(vma, vmf, blkdev_get_block, NULL);
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}
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static int blkdev_dax_pmd_fault(struct vm_area_struct *vma, unsigned long addr,
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pmd_t *pmd, unsigned int flags)
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{
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return __dax_pmd_fault(vma, addr, pmd, flags, blkdev_get_block, NULL);
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}
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static void blkdev_vm_open(struct vm_area_struct *vma)
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{
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struct inode *bd_inode = bdev_file_inode(vma->vm_file);
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struct block_device *bdev = I_BDEV(bd_inode);
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mutex_lock(&bd_inode->i_mutex);
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bdev->bd_map_count++;
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mutex_unlock(&bd_inode->i_mutex);
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}
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static void blkdev_vm_close(struct vm_area_struct *vma)
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{
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struct inode *bd_inode = bdev_file_inode(vma->vm_file);
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struct block_device *bdev = I_BDEV(bd_inode);
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mutex_lock(&bd_inode->i_mutex);
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bdev->bd_map_count--;
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mutex_unlock(&bd_inode->i_mutex);
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}
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static const struct vm_operations_struct blkdev_dax_vm_ops = {
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.open = blkdev_vm_open,
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.close = blkdev_vm_close,
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.fault = blkdev_dax_fault,
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.pmd_fault = blkdev_dax_pmd_fault,
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.pfn_mkwrite = blkdev_dax_fault,
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};
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static const struct vm_operations_struct blkdev_default_vm_ops = {
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.open = blkdev_vm_open,
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.close = blkdev_vm_close,
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.fault = filemap_fault,
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.map_pages = filemap_map_pages,
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};
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static int blkdev_mmap(struct file *file, struct vm_area_struct *vma)
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{
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struct inode *bd_inode = bdev_file_inode(file);
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struct block_device *bdev = I_BDEV(bd_inode);
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file_accessed(file);
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mutex_lock(&bd_inode->i_mutex);
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bdev->bd_map_count++;
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if (IS_DAX(bd_inode)) {
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vma->vm_ops = &blkdev_dax_vm_ops;
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vma->vm_flags |= VM_MIXEDMAP | VM_HUGEPAGE;
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} else {
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vma->vm_ops = &blkdev_default_vm_ops;
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}
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mutex_unlock(&bd_inode->i_mutex);
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return 0;
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}
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#else
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#define blkdev_mmap generic_file_mmap
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#endif
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const struct file_operations def_blk_fops = {
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.open = blkdev_open,
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.release = blkdev_close,
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.llseek = block_llseek,
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.read_iter = blkdev_read_iter,
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.write_iter = blkdev_write_iter,
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.mmap = generic_file_mmap,
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.mmap = blkdev_mmap,
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.fsync = blkdev_fsync,
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.unlocked_ioctl = block_ioctl,
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#ifdef CONFIG_COMPAT
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@ -482,6 +482,9 @@ struct block_device {
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int bd_fsfreeze_count;
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/* Mutex for freeze */
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struct mutex bd_fsfreeze_mutex;
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#ifdef CONFIG_FS_DAX
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int bd_map_count;
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#endif
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};
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/*
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@ -2264,6 +2267,14 @@ extern struct super_block *freeze_bdev(struct block_device *);
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extern void emergency_thaw_all(void);
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extern int thaw_bdev(struct block_device *bdev, struct super_block *sb);
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extern int fsync_bdev(struct block_device *);
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#ifdef CONFIG_FS_DAX
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extern bool blkdev_dax_capable(struct block_device *bdev);
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#else
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static inline bool blkdev_dax_capable(struct block_device *bdev)
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{
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return false;
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}
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#endif
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extern struct super_block *blockdev_superblock;
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@ -152,6 +152,8 @@ struct inodes_stat_t {
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#define BLKSECDISCARD _IO(0x12,125)
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#define BLKROTATIONAL _IO(0x12,126)
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#define BLKZEROOUT _IO(0x12,127)
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#define BLKDAXSET _IO(0x12,128)
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#define BLKDAXGET _IO(0x12,129)
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#define BMAP_IOCTL 1 /* obsolete - kept for compatibility */
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#define FIBMAP _IO(0x00,1) /* bmap access */
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