linux-stable.git/include/linux/blk_types.h, branch v4.2.1

Revert "block, dm: don't copy bios for request clones"

2015-06-26T14:11:58+00:00

This reverts commit 5f1b670d0bef508a5554d92525f5f6d00d640b38.

Justification for revert as reported in this dm-devel post:
https://www.redhat.com/archives/dm-devel/2015-June/msg00160.html

this change should not be pushed to mainline yet.

Firstly, Christoph has a newer version of the patch that fixes silent
data corruption problem:
  https://www.redhat.com/archives/dm-devel/2015-May/msg00229.html

And the new version still depends on LLDDs to always complete requests
to the end when error happens, while block API doesn't enforce such a
requirement. If the assumption is ever broken, the inconsistency between
request and bio (e.g. rq->__sector and rq->bio) will cause silent data
corruption:
  https://www.redhat.com/archives/dm-devel/2015-June/msg00022.html

Reported-by: Junichi Nomura 
Signed-off-by: Mike Snitzer

Merge remote-tracking branch 'jens/for-4.2/core' into dm-4.2

2015-05-29T18:17:16+00:00

block, dm: don't copy bios for request clones

2015-05-22T14:58:57+00:00

Currently dm-multipath has to clone the bios for every request sent
to the lower devices, which wastes cpu cycles and ties down memory.

This patch instead adds a new REQ_CLONE flag that instructs req_bio_endio
to not complete bios attached to a request, which we set on clone
requests similar to bios in a flush sequence.  With this change I/O
errors on a path failure only get propagated to dm-multipath, which
can then either resubmit the I/O or complete the bios on the original
request.

I've done some basic testing of this on a Linux target with ALUA support,
and it survives path failures during I/O nicely.

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

block: collapse bio bit space

2015-05-19T15:18:28+00:00

Various previous patches removed bits and left holes, collapse them
all. Leave the reset start bit where it is, we don't need to change
that.

Signed-off-by: Jens Axboe

block: remove unused BIO_RW_BLOCK and BIO_EOF flags

2015-05-19T15:17:05+00:00

Signed-off-by: Christoph Hellwig 
Acked-by: Tejun Heo 
Signed-off-by: Jens Axboe

block: remove BIO_EOPNOTSUPP

2015-05-19T15:17:03+00:00

Since the big barrier rewrite/removal in 2007 we never fail FLUSH or
FUA requests, which means we can remove the magic BIO_EOPNOTSUPP flag
to help propagating those to the buffer_head layer.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Jeff Moyer 
Acked-by: Tejun Heo 
Signed-off-by: Jens Axboe

bio: skip atomic inc/dec of ->bi_cnt for most use cases

2015-05-05T19:32:49+00:00

Struct bio has a reference count that controls when it can be freed.
Most uses cases is allocating the bio, which then returns with a
single reference to it, doing IO, and then dropping that single
reference. We can remove this atomic_dec_and_test() in the completion
path, if nobody else is holding a reference to the bio.

If someone does call bio_get() on the bio, then we flag the bio as
now having valid count and that we must properly honor the reference
count when it's being put.

Tested-by: Robert Elliott 
Signed-off-by: Jens Axboe

bio: skip atomic inc/dec of ->bi_remaining for non-chains

2015-05-05T19:32:47+00:00

Struct bio has an atomic ref count for chained bio's, and we use this
to know when to end IO on the bio. However, most bio's are not chained,
so we don't need to always introduce this atomic operation as part of
ending IO.

Add a helper to elevate the bi_remaining count, and flag the bio as
now actually needing the decrement at end_io time. Rename the field
to __bi_remaining to catch any current users of this doing the
incrementing manually.

For high IOPS workloads, this reduces the overhead of bio_endio()
substantially.

Tested-by: Robert Elliott 
Acked-by: Kent Overstreet 
Reviewed-by: Jan Kara 
Signed-off-by: Jens Axboe

blk-mq: fix FUA request hang

2015-05-04T19:09:55+00:00

When a FUA request enters its DATA stage of flush pipeline, the
request is added to mq requeue list, the request will then be added to
ctx->rq_list. blk_mq_attempt_merge() might merge the request with a bio.
Later when the request is finished the flush pipeline, the
request->__data_len is 0. Then I only saw the bio gets endio called, the
original request never finish.

Adding REQ_FLUSH_SEQ into REQ_NOMERGE_FLAGS looks an easy fix.

stable: 3.15+

Signed-off-by: Shaohua Li 
Signed-off-by: Jens Axboe

Defer processing of REQ_PREEMPT requests for blocked devices

2015-04-08T16:41:41+00:00

SCSI transport drivers and SCSI LLDs block a SCSI device if the
transport layer is not operational. This means that in this state
no requests should be processed, even if the REQ_PREEMPT flag has
been set. This patch avoids that a rescan shortly after a cable
pull sporadically triggers the following kernel oops:

BUG: unable to handle kernel paging request at ffffc9001a6bc084
IP: [] mlx4_ib_post_send+0xd2/0xb30 [mlx4_ib]
Process rescan-scsi-bus (pid: 9241, threadinfo ffff88053484a000, task ffff880534aae100)
Call Trace:
 [] srp_post_send+0x65/0x70 [ib_srp]
 [] srp_queuecommand+0x1cf/0x3e0 [ib_srp]
 [] scsi_dispatch_cmd+0x101/0x280 [scsi_mod]
 [] scsi_request_fn+0x411/0x4d0 [scsi_mod]
 [] __blk_run_queue+0x27/0x30
 [] blk_execute_rq_nowait+0x82/0x110
 [] blk_execute_rq+0x62/0xf0
 [] scsi_execute+0xe8/0x190 [scsi_mod]
 [] scsi_execute_req+0xa3/0x130 [scsi_mod]
 [] scsi_probe_lun+0x17a/0x450 [scsi_mod]
 [] scsi_probe_and_add_lun+0x156/0x480 [scsi_mod]
 [] __scsi_scan_target+0xdf/0x1f0 [scsi_mod]
 [] scsi_scan_host_selected+0x183/0x1c0 [scsi_mod]
 [] scsi_scan+0xdb/0xe0 [scsi_mod]
 [] store_scan+0x13/0x20 [scsi_mod]
 [] sysfs_write_file+0xcb/0x160
 [] vfs_write+0xce/0x140
 [] sys_write+0x53/0xa0
 [] system_call_fastpath+0x16/0x1b
 [<00007f611c9d9300>] 0x7f611c9d92ff

Reported-by: Max Gurtuvoy 
Signed-off-by: Bart Van Assche 
Reviewed-by: Mike Christie 
Cc: 
Signed-off-by: James Bottomley