linux-toradex.git/block/blk-merge.c, branch v3.19.7

Fix bug in blk_rq_merge_ok

2015-04-19T08:10:12+00:00

commit 7ee8e4f3983c4ff700958a6099c8fd212ea67b94 upstream.

Use the right array index to reference the last
element of rq->biotail->bi_io_vec[]

Signed-off-by: Wenbo Wang 
Reviewed-by: Chong Yuan 
Fixes: 66cb45aa41315 ("block: add support for limiting gaps in SG lists")
Signed-off-by: Jens Axboe 
Signed-off-by: Greg Kroah-Hartman

block: blk-merge: fix blk_recount_segments()

2014-11-11T23:24:15+00:00

For cloned bio, bio->bi_vcnt can't be used at all, and we
have resort to bio_segments() to figure out how many
segment there are in the bio.

Signed-off-by: Ming Lei 
Signed-off-by: Jens Axboe

blk-merge: recaculate segment if it isn't less than max segments

2014-10-22T01:00:32+00:00

The problem is introduced by commit 764f612c6c3c231b(blk-merge:
don't compute bi_phys_segments from bi_vcnt for cloned bio),
and merge is needed if number of current segment isn't less than
max segments.

Strictly speaking, bio->bi_vcnt shouldn't be used here since
it may not be accurate in cases of both cloned bio or bio cloned
from, but bio_segments() is a bit expensive, and bi_vcnt is still
the biggest number, so the approach should work.

Signed-off-by: Ming Lei 
Signed-off-by: Jens Axboe

blk-merge: don't compute bi_phys_segments from bi_vcnt for cloned bio

2014-10-09T19:11:44+00:00

It isn't correct to figure out req->bi_phys_segments from bio->bi_vcnt
if the bio is cloned.

Signed-off-by: Ming Lei 
Tested-by: Jeff Mahoney 
Signed-off-by: Jens Axboe

block: Don't merge requests if integrity flags differ

2014-09-27T15:14:57+00:00

We'd occasionally merge requests with conflicting integrity flags.
Introduce a merge helper which checks that the requests have compatible
integrity payloads.

Signed-off-by: Martin K. Petersen 
Reviewed-by: Christoph Hellwig 
Reviewed-by: Sagi Grimberg 
Signed-off-by: Jens Axboe

blk-merge: fix blk_recount_segments

2014-09-02T16:25:12+00:00

QUEUE_FLAG_NO_SG_MERGE is set at default for blk-mq devices,
so bio->bi_phys_segment computed may be bigger than
queue_max_segments(q) for blk-mq devices, then drivers will
fail to handle the case, for example, BUG_ON() in
virtio_queue_rq() can be triggerd for virtio-blk:

	https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1359146

This patch fixes the issue by ignoring the QUEUE_FLAG_NO_SG_MERGE
flag if the computed bio->bi_phys_segment is bigger than
queue_max_segments(q), and the regression is caused by commit
05f1dd53152173(block: add queue flag for disabling SG merging).

Reported-by: Kick In 
Tested-by: Chris J Arges 
Signed-off-by: Ming Lei 
Signed-off-by: Jens Axboe

block: add support for limiting gaps in SG lists

2014-06-24T22:22:24+00:00

Another restriction inherited for NVMe - those devices don't support
SG lists that have "gaps" in them. Gaps refers to cases where the
previous SG entry doesn't end on a page boundary. For NVMe, all SG
entries must start at offset 0 (except the first) and end on a page
boundary (except the last).

Signed-off-by: Jens Axboe

block: add queue flag for disabling SG merging

2014-05-29T15:53:32+00:00

If devices are not SG starved, we waste a lot of time potentially
collapsing SG segments. Enough that 1.5% of the CPU time goes
to this, at only 400K IOPS. Add a queue flag, QUEUE_FLAG_NO_SG_MERGE,
which just returns the number of vectors in a bio instead of looping
over all segments and checking for collapsible ones.

Add a BLK_MQ_F_SG_MERGE flag so that drivers can opt-in on the sg
merging, if they so desire.

Signed-off-by: Jens Axboe

block: Explicitly handle discard/write same segments

2014-02-07T20:54:08+00:00

Immutable biovecs changed the way biovecs are interpreted - drivers no
longer use bi_vcnt, they have to go by bi_iter.bi_size (to allow for
using part of an existing segment without modifying it).

This breaks with discards and write_same bios, since for those bi_size
has nothing to do with segments in the biovec. So for now, we need a
fairly gross hack - we fortunately know that there will never be more
than one segment for the entire request, so we can special case
discard/write_same.

Signed-off-by: Kent Overstreet 
Tested-by: Hugh Dickins 
Signed-off-by: Jens Axboe

block: Really silence spurious compiler warnings

2013-12-03T21:29:09+00:00

The uninitialized_var() macro appears to not work on structs...
Get rid of it, and manually initialize instead.

Signed-off-by: Kent Overstreet 
Signed-off-by: Jens Axboe