centos man page for blkdev_get_by_dev

BLKDEV_GET_BY_DEV(9)						   The Linux VFS					      BLKDEV_GET_BY_DEV(9)

NAME
       blkdev_get_by_dev - open a block device by device number

SYNOPSIS
       struct block_device * blkdev_get_by_dev(dev_t dev, fmode_t mode, void * holder);

ARGUMENTS
       dev
	   device number of block device to open

       mode
	   FMODE_* mask

       holder
	   exclusive holder identifier

DESCRIPTION
       Open the blockdevice described by device number dev.  mode and holder are identical to blkdev_get.

       Use it ONLY if you really do not have anything better - i.e. when you are behind a truly sucky interface and all you are given is a device
       number. _Never_ to be used for internal purposes. If you ever need it - reconsider your API.

       On success, the returned block_device has reference count of one.

CONTEXT
       Might sleep.

RETURNS
       Pointer to block_device on success, ERR_PTR(-errno) on failure.

COPYRIGHT
Kernel Hackers Manual 3.10					     June 2014						      BLKDEV_GET_BY_DEV(9)