QUEUE_FLAG_NO_SG_MERGE has been killed, so kill BLK_MQ_F_SG_MERGE too.
Reviewed-by: Christoph Hellwig
Reviewed-by: Omar Sandoval
Signed-off-by: Ming Lei
---
block/blk-mq-debugfs.c | 1 -
drivers/block/loop.c | 2 +-
drivers/block/nbd.c | 2 +-
drivers/block/rbd.c
Now multi-page bvec is supported, some helpers may return page by
page, meantime some may return segment by segment, this patch
documents the usage.
Signed-off-by: Ming Lei
---
Documentation/block/biovecs.txt | 25 +
1 file changed, 25 insertions(+)
diff --git
Since bdced438acd83ad83a6c ("block: setup bi_phys_segments after splitting"),
physical segment number is mainly figured out in blk_queue_split() for
fast path, and the flag of BIO_SEG_VALID is set there too.
Now only blk_recount_segments() and blk_recalc_rq_segments() use this
flag.
Basically
This patch pulls the trigger for multi-page bvecs.
Signed-off-by: Ming Lei
---
block/bio.c | 22 +++---
fs/iomap.c | 4 ++--
fs/xfs/xfs_aops.c | 4 ++--
include/linux/bio.h | 2 +-
4 files changed, 20 insertions(+), 12 deletions(-)
diff --git a/block/bio.c
Once multi-page bvec is enabled, the last bvec may include more than one
page, this patch use bvec_last_segment() to truncate the bio.
Reviewed-by: Omar Sandoval
Reviewed-by: Christoph Hellwig
Signed-off-by: Ming Lei
---
fs/buffer.c | 5 -
1 file changed, 4 insertions(+), 1 deletion(-)
bch_bio_alloc_pages() is always called on one new bio, so it is safe
to access the bvec table directly. Given it is the only kind of this
case, open code the bvec table access since bio_for_each_segment_all()
will be changed to support for iterating over multipage bvec.
Acked-by: Coly Li
iov_iter is implemented on bvec itererator helpers, so it is safe to pass
multi-page bvec to it, and this way is much more efficient than passing one
page in each bvec.
Reviewed-by: Christoph Hellwig
Signed-off-by: Ming Lei
---
drivers/block/loop.c | 20 ++--
1 file changed, 10
This patch introduces one extra iterator variable to bio_for_each_segment_all(),
then we can allow bio_for_each_segment_all() to iterate over multi-page bvec.
Given it is just one mechannical & simple change on all
bio_for_each_segment_all()
users, this patch does tree-wide change in one single
First it is more efficient to use bio_for_each_bvec() in both
blk_bio_segment_split() and __blk_recalc_rq_segments() to compute how
many multi-page bvecs there are in the bio.
Secondly once bio_for_each_bvec() is used, the bvec may need to be
splitted because its length can be very longer than
It is more efficient to use bio_for_each_bvec() to map sg, meantime
we have to consider splitting multipage bvec as done in blk_bio_segment_split().
Reviewed-by: Omar Sandoval
Signed-off-by: Ming Lei
---
block/blk-merge.c | 70 +++
1 file
BTRFS and guard_bio_eod() need to get the last singlepage segment
from one multipage bvec, so introduce this helper to make them happy.
Reviewed-by: Omar Sandoval
Signed-off-by: Ming Lei
---
include/linux/bvec.h | 22 ++
1 file changed, 22 insertions(+)
diff --git
Now multi-page bvec can cover CONFIG_THP_SWAP, so we don't need to
increase BIO_MAX_PAGES for it.
CONFIG_THP_SWAP needs to split one THP into normal pages and adds
them all to one bio. With multipage-bvec, it just takes one bvec to
hold them all.
Reviewed-by: Christoph Hellwig
Signed-off-by:
From: Christoph Hellwig
The btrfs write path passes a bio_offset argument through some deep
callchains including async offloading. In the end this is easily
calculatable using page_offset plus the bvec offset for the first
page in the bio, and only actually used by by a single function.
Just
Hi,
This patchset brings multi-page bvec into block layer:
1) what is multi-page bvec?
Multipage bvecs means that one 'struct bio_bvec' can hold multiple pages
which are physically contiguous instead of one single page used in linux
kernel for long time.
2) why is multi-page bvec introduced?
Commit 7759eb23fd980 ("block: remove bio_rewind_iter()") removes
bio_rewind_iter(), then no one uses bvec_iter_rewind() any more,
so remove it.
Signed-off-by: Ming Lei
---
include/linux/bvec.h | 24
1 file changed, 24 deletions(-)
diff --git a/include/linux/bvec.h
This patch introduces helpers of 'bvec_iter_*' for multi-page bvec
support.
The introduced helpers treate one bvec as real multi-page segment,
which may include more than one pages.
The existed helpers of bvec_iter_* are interfaces for supporting current
bvec iterator which is thought as
From: Christoph Hellwig
bio_readpage_error currently uses bi_vcnt to decide if it is worth
retrying an I/O. But the vector count is mostly an implementation
artifact - it really should figure out if there is more than a
single sector worth retrying. Use bi_size for that and shift by
We will support multi-page bvec soon, and have to deal with
single-page vs multi-page bvec. This patch follows Christoph's
suggestion to rename all the following helpers:
for_each_bvec
bvec_iter_bvec
bvec_iter_len
bvec_iter_page
bvec_iter_offset
into:
From: Christoph Hellwig
The cluster flag implements some very old SCSI behavior. As far as I
can tell the original intent was to enable or disable any kind of
segment merging. But the actually visible effect to the LLDD is that
it limits each segments to be inside a single page, which we can
bio_for_each_bvec() is used for iterating over multi-page bvec for bio
split & merge code.
rq_for_each_bvec() can be used for drivers which may handle the
multi-page bvec directly, so far loop is one perfect use case.
Reviewed-by: Omar Sandoval
Signed-off-by: Ming Lei
---
include/linux/bio.h
It is wrong to use bio->bi_vcnt to figure out how many segments
there are in the bio even though CLONED flag isn't set on this bio,
because this bio may be splitted or advanced.
So always use bio_segments() in blk_recount_segments(), and it shouldn't
cause any performance loss now because the
2018年11月22日(木) 16:06 Al Viro :
>
> Can you show me where does POSIX/SuS/whatever it's called these days promise
> that kind of atomicity?
No. I couldn't found it.
That's why I previously posted RFC Patch:
https://marc.info/?t=15423727791=1=2
I wasn't sure this is a bug in the kernel or not.
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