linux-stable.git/block/genhd.c, branch v5.8

block: remove rcu_read_lock() from part_stat_lock()

2020-05-27T11:21:23+00:00

The RCU lock is required only in disk_map_sector_rcu() to lookup the
partition.  After that request holds reference to related hd_struct.

Replace get_cpu() with preempt_disable() - returned cpu index is unused.

[hch: rebased]

Signed-off-by: Konstantin Khlebnikov 
Signed-off-by: Christoph Hellwig 
Signed-off-by: Jens Axboe

block: always use a percpu variable for disk stats

2020-05-27T11:21:23+00:00

percpu variables have a perfectly fine working stub implementation
for UP kernels, so use that.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Konstantin Khlebnikov 
Signed-off-by: Jens Axboe

block: merge part_{inc,dev}_in_flight into their only callers

2020-05-19T15:35:24+00:00

part_inc_in_flight and part_dec_in_flight only have one caller each, and
those callers are purely for bio based drivers.  Merge each function into
the only caller, and remove the superflous blk-mq checks.

Signed-off-by: Christoph Hellwig 
Signed-off-by: Jens Axboe

block: move the blk-mq calls out of part_in_flight{,_rw}

2020-05-19T15:35:24+00:00

Don't bother to call part_in_flight / part_in_flight_rw on blk-mq
devices, just call the blk-mq versions directly.

Signed-off-by: Christoph Hellwig 
Signed-off-by: Jens Axboe

block: don't hold part0's refcount in IO path

2020-05-13T02:31:40+00:00

gendisk can't be gone when there is IO activity, so not hold
part0's refcount in IO path.

Signed-off-by: Ming Lei 
Reviewed-by: Christoph Hellwig 
Cc: Yufen Yu 
Cc: Christoph Hellwig 
Cc: Hou Tao 
Signed-off-by: Jens Axboe

block: only define 'nr_sects_seq' in hd_part for 32bit SMP

2020-05-13T02:31:39+00:00

The seqcount of 'nr_sects_seq' is only needed in case of 32bit SMP,
so define it just for 32bit SMP.

Signed-off-by: Ming Lei 
Reviewed-by: Christoph Hellwig 
Cc: Yufen Yu 
Cc: Christoph Hellwig 
Cc: Hou Tao 
Signed-off-by: Jens Axboe

block: fix use-after-free on cached last_lookup partition

2020-05-13T02:31:39+00:00

delete_partition() clears the cached last_lookup partition. However the
.last_lookup cache may be overwritten by one IO path after it is cleared
from delete_partition(). Then another IO path may use the cached deleting
partition after hd_struct_free() is called, then use-after-free is triggered
on the cached partition.

Fixes the issue by the following approach:

1) always get the partition's refcount via hd_struct_try_get() before
setting .last_lookup

2) move clearing .last_lookup from delete_partition() to hd_struct_free()
which is the release handle of the partition's percpu-refcount, so that no
IO path can cache deleteing partition via .last_lookup.

It is one candidate approach of Yufen's patch[1] which adds overhead
in fast path by indirect lookup which may introduce one extra cacheline
in IO path. Also this patch relies on percpu-refcount's protection, and
it is easier to understand and verify.

[1] https://lore.kernel.org/linux-block/20200109013551.GB9655@ming.t460p/T/#t

Reported-by: Yufen Yu 
Signed-off-by: Ming Lei 
Reviewed-by: Christoph Hellwig 
Cc: Christoph Hellwig 
Cc: Hou Tao 
Signed-off-by: Jens Axboe

bdi: remove bdi_register_owner

2020-05-09T22:15:13+00:00

Split out a new bdi_set_owner helper to set the owner, and move the policy
for creating the bdi name back into genhd.c, where it belongs.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Jan Kara 
Reviewed-by: Greg Kroah-Hartman 
Reviewed-by: Bart Van Assche 
Signed-off-by: Jens Axboe

block: fold bdev_unhash_inode into invalidate_partition

2020-04-20T17:33:00+00:00

invalidate_partition and bdev_unhash_inode are always paired, and
invalidate_partition already does an icache lookup for the block device
inode.  Piggy back on that to remove the inode from the hash.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Johannes Thumshirn 
Signed-off-by: Jens Axboe

block: mark invalidate_partition static

2020-04-20T17:32:59+00:00

invalidate_partition is only used in genhd.c, so mark it static.  Also
drop the return value given that is is always ignored.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Johannes Thumshirn 
Signed-off-by: Jens Axboe