diff options
Diffstat (limited to 'drivers/dax')
| -rw-r--r-- | drivers/dax/super.c | 70 |
1 files changed, 70 insertions, 0 deletions
diff --git a/drivers/dax/super.c b/drivers/dax/super.c index 465dcd7317d5..e8998d15f3cd 100644 --- a/drivers/dax/super.c +++ b/drivers/dax/super.c @@ -14,6 +14,7 @@ #include <linux/module.h> #include <linux/mount.h> #include <linux/magic.h> +#include <linux/genhd.h> #include <linux/cdev.h> #include <linux/hash.h> #include <linux/slab.h> @@ -47,6 +48,75 @@ void dax_read_unlock(int id) } EXPORT_SYMBOL_GPL(dax_read_unlock); +int bdev_dax_pgoff(struct block_device *bdev, sector_t sector, size_t size, + pgoff_t *pgoff) +{ + phys_addr_t phys_off = (get_start_sect(bdev) + sector) * 512; + + if (pgoff) + *pgoff = PHYS_PFN(phys_off); + if (phys_off % PAGE_SIZE || size % PAGE_SIZE) + return -EINVAL; + return 0; +} +EXPORT_SYMBOL(bdev_dax_pgoff); + +/** + * __bdev_dax_supported() - Check if the device supports dax for filesystem + * @sb: The superblock of the device + * @blocksize: The block size of the device + * + * This is a library function for filesystems to check if the block device + * can be mounted with dax option. + * + * Return: negative errno if unsupported, 0 if supported. + */ +int __bdev_dax_supported(struct super_block *sb, int blocksize) +{ + struct block_device *bdev = sb->s_bdev; + struct dax_device *dax_dev; + pgoff_t pgoff; + int err, id; + void *kaddr; + pfn_t pfn; + long len; + + if (blocksize != PAGE_SIZE) { + pr_err("VFS (%s): error: unsupported blocksize for dax\n", + sb->s_id); + return -EINVAL; + } + + err = bdev_dax_pgoff(bdev, 0, PAGE_SIZE, &pgoff); + if (err) { + pr_err("VFS (%s): error: unaligned partition for dax\n", + sb->s_id); + return err; + } + + dax_dev = dax_get_by_host(bdev->bd_disk->disk_name); + if (!dax_dev) { + pr_err("VFS (%s): error: device does not support dax\n", + sb->s_id); + return -EOPNOTSUPP; + } + + id = dax_read_lock(); + len = dax_direct_access(dax_dev, pgoff, 1, &kaddr, &pfn); + dax_read_unlock(id); + + put_dax(dax_dev); + + if (len < 1) { + pr_err("VFS (%s): error: dax access failed (%ld)", + sb->s_id, len); + return len < 0 ? len : -EIO; + } + + return 0; +} +EXPORT_SYMBOL_GPL(__bdev_dax_supported); + /** * struct dax_device - anchor object for dax services * @inode: core vfs |