simplify gendisk lookup and remove struct block_device aliases v2

Christoph Hellwig
2020-08-30T06:25:29Z

Hi all,

this series removes the annoying struct block_device aliases, which can
happen for a bunch of old floppy drivers (and z2ram). In that case
multiple struct block device instances for different dev_t's can point
to the same gendisk, without being partitions. The cause for that
is the probe/get callback registered through blk_register_regions.

This series removes blk_register_region entirely, splitting it it into
a simple xarray lookup of registered gendisks, and a probe callback
stored in the major_names array that can be used for modprobe overrides
or creating devices on demands when no gendisk is found. The old
remapping is gone entirely, and instead the 4 remaining drivers just
register a gendisk for each operating mode. In case of the two drivers
that have lots of aliases that is done on-demand using the new probe
callback, while for the other two I simply register all at probe time
to keep things simple.

Note that the m68k drivers are compile tested only.

Changes since v1:
- add back a missing kobject_put in the cdev code
- improve the xarray delete loops

Diffstat:
b/block/genhd.c | 183 +++++++--------
b/drivers/base/Makefile | 2
b/drivers/block/amiflop.c | 98 ++++----
b/drivers/block/ataflop.c | 135 +++++++----
b/drivers/block/brd.c | 39 ---
b/drivers/block/floppy.c | 154 ++++++++----
b/drivers/block/loop.c | 30 --
b/drivers/block/swim.c | 17 -
b/drivers/block/z2ram.c | 547 ++++++++++++++++++++++------------------------
b/drivers/ide/ide-probe.c | 66 -----
b/drivers/ide/ide-tape.c | 2
b/drivers/md/md.c | 21 -
b/drivers/scsi/sd.c | 19 -
b/fs/char_dev.c | 94 +++----
b/fs/dcache.c | 1
b/fs/internal.h | 5
b/include/linux/genhd.h | 12 -
b/include/linux/ide.h | 3
drivers/base/map.c | 154 ------------
include/linux/kobj_map.h | 20 -
20 files changed, 686 insertions(+), 916 deletions(-)