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  1. 23 Aug, 2017 10 commits
    • Shaohua Li's avatar
      nullb: emulate cache · deb78b41
      Shaohua Li authored 
      Software must flush disk cache to guarantee data safety. To check if
software correctly does disk cache flush, we must know the behavior of
disk. But physical disk behavior is uncontrollable. Even software
doesn't do the flush, the disk probably does the flush. This patch tries
to emulate a cache in the test disk.

All write will go to a cache first, when the cache is full, we then
flush some data to disk storage. A flush request will flush all data of
the cache to disk storage. A FUA write will write to memory store
directly and revalidate data in cache. If there is a power failure (by
writing to power attribute, 'echo 0 > disk_name/power'), we discard all
data in the cache, but preserve the data in disk storage. Later we can
power on the disk again as usual (write 1 to 'power' attribute), then we
can check data integrity and very if software does everything correctly.

A new attribute 'cache_size' (in MB) is added to configure cache size.

Based on original patch from Kyungchan Koh
Signed-off-by: default avatarKyungchan Koh <kkc6196@fb.com>
Signed-off-by: default avatarShaohua Li <shli@fb.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
      deb78b41
    • Shaohua Li's avatar
      nullb: bandwidth control · eff2c4f1
      Shaohua Li authored 
      In test, we usually expect controllable disk speed. For example, in a
raid array, we'd like some disks are fast and some are slow. MD RAID
actually has a feature for this. To test the feature, we'd like to make
the disk run in specific speed.

block throttling probably can be used for this purpose, but it requires
cgroup setup. Here we just implement a simple throttling mechanism in
the driver. There is slight fluctuation in the mechanism, but it's good
enough for test.

To configure the bandwidth cap, user sets the 'mbps' attribute. mbps is
MB/s.

Based on original patch from Kyungchan Koh
Signed-off-by: default avatarKyungchan Koh <kkc6196@fb.com>
Signed-off-by: default avatarShaohua Li <shli@fb.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
      eff2c4f1
    • Shaohua Li's avatar
      nullb: support discard · 306eb6b4
      Shaohua Li authored 
      discard makes sense for memory backed disk. And also it's useful to test
if upper layer supports dicard correctly.

User configures 'discard' attribute to enable/disable dicard support.

Based on original patch from Kyungchan Koh
Signed-off-by: default avatarKyungchan Koh <kkc6196@fb.com>
Signed-off-by: default avatarShaohua Li <shli@fb.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
      306eb6b4
    • Shaohua Li's avatar
      nullb: support memory backed store · 5bcd0e0c
      Shaohua Li authored 
      This adds memory backed store in nullb.

User configure 'memory_backed' attribute for this. By default, nullb
disk doesn't use memory backed store.

Based on original patch from Kyungchan Koh
Signed-off-by: default avatarKyungchan Koh <kkc6196@fb.com>
Signed-off-by: default avatarShaohua Li <shli@fb.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
      5bcd0e0c
    • Shaohua Li's avatar
      nullb: use ida to manage index · 94bc02e3
      Shaohua Li authored 
      We now dynamically create disks. Managing the disk index with ida to
avoid bump up the index too much.
Signed-off-by: default avatarShaohua Li <shli@fb.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
      94bc02e3
    • Shaohua Li's avatar
      nullb: add interface to power on disk · cedcafad
      Shaohua Li authored 
      The device created in nullb configfs interface isn't power on by
default. After user configures the device, user can do 'echo 1 >
xxx/nullb/device_name/power' to power on the device, which will create a
disk. the xxx/nullb/device_name/index is the disk index, so if the index
is 2, the new created disk should be named as /dev/nullb2. Note, the
'index' is only valid after disk is power on.

'echo 0 > xxx/nullb/device_name/power' will remove the disk. Note, this
doesn't remove the device. To remove the device, user should do 'rmdir
xxx/nullb/device_name'. Removing the device will remove the disk too.
Signed-off-by: default avatarShaohua Li <shli@fb.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
      cedcafad
    • Shaohua Li's avatar
      nullb: add configfs interface · 3bf2bd20
      Shaohua Li authored 
      Add configfs interface for nullb. configfs interface is more flexible
and easy to configure in a per-disk basis.

Configuration is something like this:
mount -t configfs none /mnt

Checking which features the driver supports:
cat /mnt/nullb/features

The 'features' attribute is for future extension. We probably will add
new features into the driver, userspace can check this attribute to find
the supported features.

Create/remove a device:
mkdir/rmdir /mnt/nullb/a

Then configure the device by setting attributes under /mnt/nullb/a, most
of nullb supported module parameters are converted to attributes:
size; /* device size in MB */
completion_nsec; /* time in ns to complete a request */
submit_queues; /* number of submission queues */
home_node; /* home node for the device */
queue_mode; /* block interface */
blocksize; /* block size */
irqmode; /* IRQ completion handler */
hw_queue_depth; /* queue depth */
use_lightnvm; /* register as a LightNVM device */
blocking; /* blocking blk-mq device */
use_per_node_hctx; /* use per-node allocation for hardware context */

Note, creating a device doesn't create a disk immediately. Creating a
disk is done in two phases: create a device and then power on the
device. Next patch will introduce device power on.

Based on original patch from Kyungchan Koh
Signed-off-by: default avatarKyungchan Koh <kkc6196@fb.com>
Signed-off-by: default avatarShaohua Li <shli@fb.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
      3bf2bd20
    • Shaohua Li's avatar
      nullb: factor disk parameters · 2984c868
      Shaohua Li authored 
      When we switch to configfs interface, each disk could have different
configuration. To prepare for the change, we move most disk setting to a
separate data structure. The existing module parameter interface is
kept. The 'nr_devices' and 'shared_tags' don't make sense for per-disk
setting, so they are remained as global settings.
Signed-off-by: default avatarShaohua Li <shli@fb.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
      2984c868
    • Dan Carpenter's avatar
      skd: error pointer dereference in skd_cons_disk() · 92d499d4
      Dan Carpenter authored 
      My initial impulse was to check for IS_ERR_OR_NULL() but when I looked
at this code a bit more closely, we should only need to check for
IS_ERR().

The blk_mq_alloc_tag_set() returns negative error codes and zero on
success so we can just do an "if (rc) goto err_out;".  It's better to
preserve the error code anyhow.  The blk_mq_init_queue() returns error
pointers on failure, it never returns NULL.  We can also remove the
"q = NULL;" at the start because that's no longer needed.

Fixes: ca33dd92 ("skd: Convert to blk-mq")
Signed-off-by: default avatarDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
      92d499d4
    • Dan Carpenter's avatar
      skd: Uninitialized variable in skd_isr_completion_posted() · c0b3dda7
      Dan Carpenter authored 
      Someone got too agressive about removing initializations and
accidentally removed the "rc = 0;" which is required.

Fixes: c830da8c ("skd: Remove superfluous initializations from skd_isr_completion_posted()")
Signed-off-by: default avatarDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
      c0b3dda7
  3. 18 Aug, 2017 30 commits
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