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    Subject[PATCH v9 5/9] block: Make bio_iov_iter_get_pages() respect bio_required_sector_alignment()
    From
    Previously, bio_iov_iter_get_pages() wasn't used with bios that could have
    an encryption context. However, direct I/O support using blk-crypto
    introduces this possibility, so this function must now respect
    bio_required_sector_alignment() (otherwise, xfstests like generic/465 with
    ext4 will fail).

    Signed-off-by: Satya Tangirala <satyat@google.com>
    ---
    block/bio.c | 13 ++++++++++++-
    1 file changed, 12 insertions(+), 1 deletion(-)

    diff --git a/block/bio.c b/block/bio.c
    index 32f75f31bb5c..99c510f706e2 100644
    --- a/block/bio.c
    +++ b/block/bio.c
    @@ -1099,7 +1099,8 @@ static int __bio_iov_append_get_pages(struct bio *bio, struct iov_iter *iter)
    * The function tries, but does not guarantee, to pin as many pages as
    * fit into the bio, or are requested in @iter, whatever is smaller. If
    * MM encounters an error pinning the requested pages, it stops. Error
    - * is returned only if 0 pages could be pinned.
    + * is returned only if 0 pages could be pinned. It also ensures that the number
    + * of sectors added to the bio is aligned to bio_required_sector_alignment().
    *
    * It's intended for direct IO, so doesn't do PSI tracking, the caller is
    * responsible for setting BIO_WORKINGSET if necessary.
    @@ -1107,6 +1108,7 @@ static int __bio_iov_append_get_pages(struct bio *bio, struct iov_iter *iter)
    int bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter)
    {
    int ret = 0;
    + unsigned int aligned_sectors;

    if (iov_iter_is_bvec(iter)) {
    if (bio_op(bio) == REQ_OP_ZONE_APPEND)
    @@ -1121,6 +1123,15 @@ int bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter)
    ret = __bio_iov_iter_get_pages(bio, iter);
    } while (!ret && iov_iter_count(iter) && !bio_full(bio, 0));

    + /*
    + * Ensure that number of sectors in bio is aligned to
    + * bio_required_sector_align()
    + */
    + aligned_sectors = round_down(bio_sectors(bio),
    + bio_required_sector_alignment(bio));
    + iov_iter_revert(iter, (bio_sectors(bio) - aligned_sectors) << SECTOR_SHIFT);
    + bio_truncate(bio, aligned_sectors << SECTOR_SHIFT);
    +
    /* don't account direct I/O as memory stall */
    bio_clear_flag(bio, BIO_WORKINGSET);
    return bio->bi_vcnt ? 0 : ret;
    --
    2.32.0.rc1.229.g3e70b5a671-goog
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