diff options
| author | Dan Williams <dan.j.williams@intel.com> | 2015-11-30 10:20:29 -0800 |
|---|---|---|
| committer | Dan Williams <dan.j.williams@intel.com> | 2016-01-09 06:30:49 -0800 |
| commit | 5a023cdba50c5f5f2bc351783b3131699deb3937 (patch) | |
| tree | bae047e7bf8fb28e48563b33afc2881c226f4e31 /block/ioctl.c | |
| parent | 4ebb16ca9a06a54cdb2e7f2ce1e506fa4d432445 (diff) | |
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>
Diffstat (limited to 'block/ioctl.c')
| -rw-r--r-- | block/ioctl.c | 61 |
1 files changed, 61 insertions, 0 deletions
diff --git a/block/ioctl.c b/block/ioctl.c index 0918aed2d847..7a964d842913 100644 --- a/block/ioctl.c +++ b/block/ioctl.c @@ -406,6 +406,62 @@ static inline int is_unrecognized_ioctl(int ret) ret == -ENOIOCTLCMD; } +#ifdef CONFIG_FS_DAX +bool blkdev_dax_capable(struct block_device *bdev) +{ + struct gendisk *disk = bdev->bd_disk; + + if (!disk->fops->direct_access) + return false; + + /* + * 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))) + return false; + + return true; +} + +static int blkdev_daxset(struct block_device *bdev, unsigned long argp) +{ + unsigned long arg; + int rc = 0; + + if (!capable(CAP_SYS_ADMIN)) + return -EACCES; + + if (get_user(arg, (int __user *)(argp))) + return -EFAULT; + arg = !!arg; + if (arg == !!(bdev->bd_inode->i_flags & S_DAX)) + return 0; + + if (arg) + arg = S_DAX; + + if (arg && !blkdev_dax_capable(bdev)) + return -ENOTTY; + + mutex_lock(&bdev->bd_inode->i_mutex); + if (bdev->bd_map_count == 0) + inode_set_flags(bdev->bd_inode, arg, S_DAX); + else + rc = -EBUSY; + mutex_unlock(&bdev->bd_inode->i_mutex); + return rc; +} +#else +static int blkdev_daxset(struct block_device *bdev, int arg) +{ + if (arg) + return -ENOTTY; + return 0; +} +#endif + static int blkdev_flushbuf(struct block_device *bdev, fmode_t mode, unsigned cmd, unsigned long arg) { @@ -568,6 +624,11 @@ int blkdev_ioctl(struct block_device *bdev, fmode_t mode, unsigned cmd, case BLKTRACESETUP: case BLKTRACETEARDOWN: return blk_trace_ioctl(bdev, cmd, argp); + case BLKDAXSET: + return blkdev_daxset(bdev, arg); + case BLKDAXGET: + return put_int(arg, !!(bdev->bd_inode->i_flags & S_DAX)); + break; case IOC_PR_REGISTER: return blkdev_pr_register(bdev, argp); case IOC_PR_RESERVE: |