[RFC PATCH 16/17] fs: convert buffer head etc. to use immutable biovecs API.

Dongsu Park
2014-12-22T11:50:48Z

From: Kent Overstreet <kmo@daterainc.com>

Increase bio->bi_remaining instead of calling bio_get(),
and call bio_end() instead of bio_put() upon buffer_head submission.
Also make bio submission in kernel/power/block_io.c to properly submit
bios by checking whether bio_chain is available or not.

Doing that, some codes that have been still using the older API
can be converted in order to use the immutable biovecs API.

Signed-off-by: Kent Overstreet <kmo@daterainc.com>
[dpark: add more description in commit message]
Signed-off-by: Dongsu Park <dongsu.park@profitbricks.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Cc: linux-pm@vger.kernel.org
---
fs/buffer.c | 4 ++--
kernel/power/block_io.c | 23 ++++++++++++++++++-----
2 files changed, 20 insertions(+), 7 deletions(-)

diff --git a/fs/buffer.c b/fs/buffer.c
index 35ac0ec..78e63e3 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -3038,13 +3038,13 @@ int _submit_bh(int rw, struct buffer_head *bh, unsigned long bio_flags)
if (buffer_prio(bh))
rw |= REQ_PRIO;

- bio_get(bio);
+ atomic_inc(&bio->bi_remaining);
submit_bio(rw, bio);

if (bio_flagged(bio, BIO_EOPNOTSUPP))
ret = -EOPNOTSUPP;

- bio_put(bio);
+ bio_endio(bio, 0);
return ret;
}
EXPORT_SYMBOL_GPL(_submit_bh);
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;
--
2.1.0