linux-stable.git/block/bio.c, branch v6.8

block: support adding less than len in bio_add_hw_page

2023-12-15T14:34:27+00:00

bio_add_hw_page currently always fails or succeeds.  This is fine for
the existing callers that always add PAGE_SIZE worth given that the
max_segment_size and max_sectors must always allow at least a page
worth of data.  But when we want to add it for bigger amounts of data
this means it can also fail when adding the data to a bio, and creating
a fallback for that becomes really annoying in the callers.

Make use of the existing API design that allows to return a smaller
length than the one passed in and add up to max_segment_size worth
of data from a larger input.  All the existing callers are fine with
this - not because they handle this return correctly, but because they
never pass more than a page in.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Johannes Thumshirn 
Link: https://lore.kernel.org/r/20231204173419.782378-3-hch@lst.de
Signed-off-by: Jens Axboe

block: prevent an integer overflow in bvec_try_merge_hw_page

2023-12-15T14:34:27+00:00

Reordered a check to avoid a possible overflow when adding len to bv_len.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Johannes Thumshirn 
Link: https://lore.kernel.org/r/20231204173419.782378-2-hch@lst.de
Signed-off-by: Jens Axboe

block: Remove special-casing of compound pages

2023-12-07T21:02:20+00:00

The special casing was originally added in pre-git history; reproducing
the commit log here:

> commit a318a92567d77
> Author: Andrew Morton 
> Date:   Sun Sep 21 01:42:22 2003 -0700
>
>     [PATCH] Speed up direct-io hugetlbpage handling
>
>     This patch short-circuits all the direct-io page dirtying logic for
>     higher-order pages.  Without this, we pointlessly bounce BIOs up to
>     keventd all the time.

In the last twenty years, compound pages have become used for more than
just hugetlb.  Rewrite these functions to operate on folios instead
of pages and remove the special case for hugetlbfs; I don't think
it's needed any more (and if it is, we can put it back in as a call
to folio_test_hugetlb()).

This was found by inspection; as far as I can tell, this bug can lead
to pages used as the destination of a direct I/O read not being marked
as dirty.  If those pages are then reclaimed by the MM without being
dirtied for some other reason, they won't be written out.  Then when
they're faulted back in, they will not contain the data they should.
It'll take a pretty unusual setup to produce this problem with several
races all going the wrong way.

This problem predates the folio work; it could for example have been
triggered by mmaping a THP in tmpfs and using that as the target of an
O_DIRECT read.

Fixes: 800d8c63b2e98 ("shmem: add huge pages support")
Cc:  
Signed-off-by: Matthew Wilcox (Oracle) 
Signed-off-by: Jens Axboe

block: Bring back zero_fill_bio_iter

2023-08-14T21:40:42+00:00

This reverts 6f822e1b5d9dda3d20e87365de138046e3baa03a - this helper is
used by bcachefs.

Signed-off-by: Kent Overstreet 
Cc: Jens Axboe 
Cc: linux-block@vger.kernel.org
Link: https://lore.kernel.org/r/20230813182636.2966159-4-kent.overstreet@linux.dev
Signed-off-by: Jens Axboe

block: Allow bio_iov_iter_get_pages() with bio->bi_bdev unset

2023-08-14T21:40:42+00:00

bio_iov_iter_get_pages() trims the IO based on the block size of the
block device the IO will be issued to.

However, bcachefs is a multi device filesystem; when we're creating the
bio we don't yet know which block device the bio will be submitted to -
we have to handle the alignment checks elsewhere.

Thus this is needed to avoid a null ptr deref.

Signed-off-by: Kent Overstreet 
Cc: Jens Axboe 
Cc: linux-block@vger.kernel.org
Link: https://lore.kernel.org/r/20230813182636.2966159-3-kent.overstreet@linux.dev
Signed-off-by: Jens Axboe

block: Add some exports for bcachefs

2023-08-14T21:40:42+00:00

 - bio_set_pages_dirty(), bio_check_pages_dirty() - dio path
 - blk_status_to_str() - error messages
 - bio_add_folio() - this should definitely be exported for everyone,
   it's the modern version of bio_add_page()

Signed-off-by: Kent Overstreet 
Cc: linux-block@vger.kernel.org
Cc: Jens Axboe 
Signed-off-by: Kent Overstreet 
Link: https://lore.kernel.org/r/20230813182636.2966159-2-kent.overstreet@linux.dev
Signed-off-by: Jens Axboe

block: make bvec_try_merge_hw_page() non-static

2023-08-09T22:05:35+00:00

This will be used for multi-page configuration for integrity payload.

Cc: Christoph Hellwig 
Cc: Martin K. Petersen 

Reviewed-by: Christoph Hellwig 
Signed-off-by: Jinyoung Choi 
Tested-by: "Martin K. Petersen" 
Reviewed-by: "Martin K. Petersen" 
Link: https://lore.kernel.org/r/20230803024827epcms2p838d9e9131492c86a159fff25d195658f@epcms2p8
Signed-off-by: Jens Axboe

block: don't pass a bio to bio_try_merge_hw_seg

2023-07-25T01:55:16+00:00

There is no good reason to pass the bio to bio_try_merge_hw_seg.  Just
pass the current bvec and rename the function to bvec_try_merge_hw_page.
This will allow reusing this function for supporting multi-page integrity
payload bvecs.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Jinyoung Choi 
Link: https://lore.kernel.org/r/20230724165433.117645-9-hch@lst.de
Signed-off-by: Jens Axboe

block: move the bi_size update out of __bio_try_merge_page

2023-07-25T01:55:16+00:00

The update of bi_size is the only thing in __bio_try_merge_page that
needs a bio.  Move it to the callers, and merge __bio_try_merge_page
and page_is_mergeable into a single bvec_try_merge_page that only takes
the current bvec instead of a full bio.  This will allow reusing this
function for supporting multi-page integrity payload bvecs.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Jinyoung Choi 
Link: https://lore.kernel.org/r/20230724165433.117645-8-hch@lst.de
Signed-off-by: Jens Axboe

block: downgrade a bio_full call in bio_add_page

2023-07-25T01:55:16+00:00

bio_add_page already checks that there is space in bi_size a little
earlier.  So after we failed to add to an existing segment, just check
that there is another one available instead of duplicating the bi_size
check.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Jinyoung Choi 
Link: https://lore.kernel.org/r/20230724165433.117645-7-hch@lst.de
Signed-off-by: Jens Axboe