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SubjectRe: [PATCH v2 7/7] PM: submit bio in a sane way in cases without bio_chain
Date
On Monday, January 12, 2015 12:44:04 PM Dongsu Park wrote:
> From: Kent Overstreet <kmo@daterainc.com>
>
> Make bio submission in kernel/power/block_io.c to properly submit
> bios also when bio_chain is not available. In that case, it's not
> necessary to handle refcount with bio_get(), but it's saner to simply
> call a predefined helper submit_bio_wait(). So call bio_get() only
> when bio_chain is given.
>
> Cc: Christoph Hellwig <hch@infradead.org>
> Cc: linux-pm@vger.kernel.org
> Signed-off-by: Kent Overstreet <kmo@daterainc.com>
> [dpark: add more description in commit message]
> Signed-off-by: Dongsu Park <dongsu.park@profitbricks.com>

This is fine by me, but I'd like to have an ACK from a block layer
expert here if I'm to apply it.

If you want to push this through the block layer subsystem tree,
please feel free to add my ACK to it.

> ---
> kernel/power/block_io.c | 23 ++++++++++++++++++-----
> 1 file changed, 18 insertions(+), 5 deletions(-)
>
> diff --git a/kernel/power/block_io.c b/kernel/power/block_io.c
> index 9a58bc2..7206408 100644
> --- a/kernel/power/block_io.c
> +++ b/kernel/power/block_io.c
> @@ -34,7 +34,6 @@ static int submit(int rw, struct block_device *bdev, sector_t sector,
> bio = bio_alloc(__GFP_WAIT | __GFP_HIGH, 1);
> bio->bi_iter.bi_sector = sector;
> bio->bi_bdev = bdev;
> - bio->bi_end_io = end_swap_bio_read;
>
> if (bio_add_page(bio, page, PAGE_SIZE, 0) < PAGE_SIZE) {
> printk(KERN_ERR "PM: Adding page to bio failed at %llu\n",
> @@ -44,15 +43,29 @@ static int submit(int rw, struct block_device *bdev, sector_t sector,
> }
>
> lock_page(page);
> - bio_get(bio);
>
> if (bio_chain == NULL) {
> - submit_bio(bio_rw, bio);
> - wait_on_page_locked(page);
> + int err = submit_bio_wait(bio_rw, bio);
> +
> + if (err) {
> + SetPageError(page);
> + ClearPageUptodate(page);
> + pr_alert("Read-error on swap-device (%u:%u:%llu)\n",
> + imajor(bio->bi_bdev->bd_inode),
> + iminor(bio->bi_bdev->bd_inode),
> + (unsigned long long)bio->bi_iter.bi_sector);
> + } else {
> + SetPageUptodate(page);
> + }
> +
> if (rw == READ)
> - bio_set_pages_dirty(bio);
> + set_page_dirty_lock(page);
> + unlock_page(page);
> bio_put(bio);
> } else {
> + bio->bi_end_io = end_swap_bio_read;
> + bio_get(bio);
> +
> if (rw == READ)
> get_page(page); /* These pages are freed later */
> bio->bi_private = *bio_chain;
>

--
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.


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