kernel/linux.git/drivers/block/null_blk/null_blk.h, branch v6.18.22

null_blk: do partial IO for bad blocks

2025-03-03T18:17:52+00:00

The current null_blk implementation checks if any bad blocks exist in the target blocks of each IO. If so, the IO fails and data is not transferred for all of the IO target blocks. However, when real storage devices have bad blocks, the devices may transfer data partially up to the first bad blocks (e.g., SAS drives). Especially, when the IO is a write operation, such partial IO leaves partially written data on the device. To simulate such partial IO using null_blk, introduce the new parameter 'badblocks_partial_io'. When this parameter is set, null_handle_badblocks() returns the number of the sectors for the partial IO as its third pointer argument. Pass the returned number of sectors to the following calls to null_handle_memory_backend() in null_process_cmd() and null_zone_write(). Reviewed-by: Damien Le Moal Reviewed-by: Chaitanya Kulkarni Reviewed-by: Johannes Thumshirn Signed-off-by: Shin'ichiro Kawasaki Link: https://lore.kernel.org/r/20250226100613.1622564-6-shinichiro.kawasaki@wdc.com Signed-off-by: Jens Axboe

null_blk: replace null_process_cmd() call in null_zone_write()

2025-03-03T18:17:52+00:00

As a preparation to support partial data transfer due to badblocks, replace the null_process_cmd() call in null_zone_write() with equivalent calls to null_handle_badblocks() and null_handle_memory_backed(). This commit does not change behavior. It will enable null_handle_badblocks() to return the size of partial data transfer in the following commit, allowing null_zone_write() to move write pointers appropriately. Reviewed-by: Damien Le Moal Reviewed-by: Johannes Thumshirn Signed-off-by: Shin'ichiro Kawasaki Link: https://lore.kernel.org/r/20250226100613.1622564-4-shinichiro.kawasaki@wdc.com Signed-off-by: Jens Axboe

null_blk: introduce badblocks_once parameter

2025-03-03T18:17:52+00:00

When IO errors happen on real storage devices, the IOs repeated to the same target range can success by virtue of recovery features by devices, such as reserved block assignment. To simulate such IO errors and recoveries, introduce the new parameter badblocks_once parameter. When this parameter is set to 1, the specified badblocks are cleared after the first IO error, so that the next IO to the blocks succeed. Reviewed-by: Damien Le Moal Reviewed-by: Chaitanya Kulkarni Reviewed-by: Johannes Thumshirn Signed-off-by: Shin'ichiro Kawasaki Link: https://lore.kernel.org/r/20250226100613.1622564-3-shinichiro.kawasaki@wdc.com Signed-off-by: Jens Axboe

null_blk: Add rotational feature support

2024-12-23T15:17:22+00:00

To facilitate testing of kernel functions related to the rotational feature (BLK_FEAT_ROTATIONAL) of a block device (e.g. NVMe rotational bit support), add the rotational boolean configfs attribute and module parameter to the null_blk driver. If set, a null block device will report being a rotational device through it queue limits features with the BLK_FEAT_ROTATIONAL flag. Signed-off-by: Damien Le Moal Reviewed-by: Christoph Hellwig Reviewed-by: Johannes Thumshirn Reviewed-by: Hannes Reinecke Link: https://lore.kernel.org/r/20241126000956.95983-1-dlemoal@kernel.org Signed-off-by: Jens Axboe

null_blk: Introduce the zone_full parameter

2024-07-05T06:42:04+00:00

Allow creating a zoned null_blk device with the initial state of its sequential write required zones to be FULL. This is convenient to avoid having to first write these zones to perform read performance evaluation or test zone management operations such as zone reset (and zone reset all). Signed-off-by: Damien Le Moal Reviewed-by: Christoph Hellwig Reviewed-by: Johannes Thumshirn Reviewed-by: Martin K. Petersen Link: https://lore.kernel.org/r/20240704052816.623865-2-dlemoal@kernel.org Signed-off-by: Jens Axboe

null_blk: Introduce fua attribute

2024-04-17T14:44:03+00:00

Add the fua configfs attribute and module parameter to allow configuring if the device supports FUA or not. Using this attribute has an effect on the null_blk device only if memory backing is enabled together with a write cache (cache_size option). This new attribute allows configuring a null_blk device with a write cache but without FUA support. This is convenient to test the block layer flush machinery. Signed-off-by: Damien Le Moal Reviewed-by: Hannes Reinecke Reviewed-by: Christoph Hellwig Reviewed-by: Bart Van Assche Reviewed-by: Chaitanya Kulkarni Tested-by: Hans Holmberg Tested-by: Dennis Maisenbacher Reviewed-by: Martin K. Petersen Link: https://lore.kernel.org/r/20240408014128.205141-18-dlemoal@kernel.org Signed-off-by: Jens Axboe

null_blk: Introduce zone_append_max_sectors attribute

2024-04-17T14:44:03+00:00

Add the zone_append_max_sectors configfs attribute and module parameter to allow configuring the maximum number of 512B sectors of zone append operations. This attribute is meaningful only for zoned null block devices. If not specified, the default is unchanged and the zoned device max append sectors limit is set to the device max sectors limit. If a non 0 value is used for this attribute, which is the default, then native support for zone append operations is enabled. Setting a 0 value disables native zone append operations support to instead use the block layer emulation. Signed-off-by: Damien Le Moal Reviewed-by: Hannes Reinecke Reviewed-by: Christoph Hellwig Reviewed-by: Chaitanya Kulkarni Reviewed-by: Bart Van Assche Tested-by: Hans Holmberg Tested-by: Dennis Maisenbacher Reviewed-by: Martin K. Petersen Link: https://lore.kernel.org/r/20240408014128.205141-17-dlemoal@kernel.org Signed-off-by: Jens Axboe

null_blk: Delete nullb.{queue_depth, nr_queues}

2024-02-22T17:08:47+00:00

Since commit 8b631f9cf0b8 ("null_blk: remove the bio based I/O path"), struct nullb members queue_depth and nr_queues are only ever written, so delete them. With that, null_exit_hctx() can also be deleted. Signed-off-by: John Garry Link: https://lore.kernel.org/r/20240222083420.6026-1-john.g.garry@oracle.com Signed-off-by: Jens Axboe

null_blk: pass queue_limits to blk_mq_alloc_disk

2024-02-20T13:21:27+00:00

Pass the queue limits directly to blk_mq_alloc_disk instead of setting them one at a time. Signed-off-by: Christoph Hellwig Reviewed-by: Damien Le Moal Reviewed-by: Hannes Reinecke Reviewed-by: Johannes Thumshirn Tested-by: Damien Le Moal Link: https://lore.kernel.org/r/20240220093248.3290292-6-hch@lst.de Signed-off-by: Jens Axboe

null_blk: remove the bio based I/O path

2024-02-20T13:21:27+00:00

The bio based I/O path complicates null_blk and also make various data structures, including the per-command one way bigger than required for the main request based interface. As the bio-based path is mostly used by stacking drivers and simple memory based drivers, and brd is a good example driver for the latter there is no need to have a bio based path in null_blk. Remove the path to simplify the driver and make future block layer API changes simpler by not having to deal with the complex two API setup in null_blk. Note that the queue_mode field in struct nullb_device is kept as that is simpler than having two different places to check the value and fully open coding the debugfs helpers as the existing ones won't work without a named struct member. Signed-off-by: Christoph Hellwig Reviewed-by: Damien Le Moal Reviewed-by: Hannes Reinecke Reviewed-by: Johannes Thumshirn Tested-by: Damien Le Moal Link: https://lore.kernel.org/r/20240220093248.3290292-2-hch@lst.de Signed-off-by: Jens Axboe