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authorDan Williams <dan.j.williams@intel.com>2015-11-30 10:20:29 -0800
committerDan Williams <dan.j.williams@intel.com>2016-01-09 06:30:49 -0800
commit5a023cdba50c5f5f2bc351783b3131699deb3937 (patch)
treebae047e7bf8fb28e48563b33afc2881c226f4e31 /block/ioctl.c
parent4ebb16ca9a06a54cdb2e7f2ce1e506fa4d432445 (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.c61
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: