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authorChristoph Hellwig <hch@lst.de>2018-07-24 14:04:12 +0200
committerJens Axboe <axboe@kernel.dk>2018-07-24 14:39:27 -0600
commit24d5493f207ce0ce38df80ce86c907417e04594a (patch)
tree5b4239636db01bf3f2a173ae4f32228afc8ce873
parent76f17d8ba1cbc3d2786955b2f15e071da93527cd (diff)
downloadlinux-24d5493f207ce0ce38df80ce86c907417e04594a.tar.bz2
block: simplify bio_check_pages_dirty
bio_check_pages_dirty currently inviolates the invariant that bv_page of a bio_vec inside bi_vcnt shouldn't be zero, and that is going to become really annoying with multpath biovecs. Fortunately there isn't any all that good reason for it - once we decide to defer freeing the bio to a workqueue holding onto a few additional pages isn't really an issue anymore. So just check if there is a clean page that needs dirtying in the first path, and do a second pass to free them if there was none, while the cache is still hot. Also use the chance to micro-optimize bio_dirty_fn a bit by not saving irq state - we know we are called from a workqueue. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
-rw-r--r--block/bio.c56
1 files changed, 21 insertions, 35 deletions
diff --git a/block/bio.c b/block/bio.c
index 8ecc95615941..504b42278099 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -1649,19 +1649,15 @@ static void bio_release_pages(struct bio *bio)
struct bio_vec *bvec;
int i;
- bio_for_each_segment_all(bvec, bio, i) {
- struct page *page = bvec->bv_page;
-
- if (page)
- put_page(page);
- }
+ bio_for_each_segment_all(bvec, bio, i)
+ put_page(bvec->bv_page);
}
/*
* bio_check_pages_dirty() will check that all the BIO's pages are still dirty.
* If they are, then fine. If, however, some pages are clean then they must
* have been written out during the direct-IO read. So we take another ref on
- * the BIO and the offending pages and re-dirty the pages in process context.
+ * the BIO and re-dirty the pages in process context.
*
* It is expected that bio_check_pages_dirty() will wholly own the BIO from
* here on. It will run one put_page() against each page and will run one
@@ -1679,52 +1675,42 @@ static struct bio *bio_dirty_list;
*/
static void bio_dirty_fn(struct work_struct *work)
{
- unsigned long flags;
- struct bio *bio;
+ struct bio *bio, *next;
- spin_lock_irqsave(&bio_dirty_lock, flags);
- bio = bio_dirty_list;
+ spin_lock_irq(&bio_dirty_lock);
+ next = bio_dirty_list;
bio_dirty_list = NULL;
- spin_unlock_irqrestore(&bio_dirty_lock, flags);
+ spin_unlock_irq(&bio_dirty_lock);
- while (bio) {
- struct bio *next = bio->bi_private;
+ while ((bio = next) != NULL) {
+ next = bio->bi_private;
bio_set_pages_dirty(bio);
bio_release_pages(bio);
bio_put(bio);
- bio = next;
}
}
void bio_check_pages_dirty(struct bio *bio)
{
struct bio_vec *bvec;
- int nr_clean_pages = 0;
+ unsigned long flags;
int i;
bio_for_each_segment_all(bvec, bio, i) {
- struct page *page = bvec->bv_page;
-
- if (PageDirty(page) || PageCompound(page)) {
- put_page(page);
- bvec->bv_page = NULL;
- } else {
- nr_clean_pages++;
- }
+ if (!PageDirty(bvec->bv_page) && !PageCompound(bvec->bv_page))
+ goto defer;
}
- if (nr_clean_pages) {
- unsigned long flags;
-
- spin_lock_irqsave(&bio_dirty_lock, flags);
- bio->bi_private = bio_dirty_list;
- bio_dirty_list = bio;
- spin_unlock_irqrestore(&bio_dirty_lock, flags);
- schedule_work(&bio_dirty_work);
- } else {
- bio_put(bio);
- }
+ bio_release_pages(bio);
+ bio_put(bio);
+ return;
+defer:
+ spin_lock_irqsave(&bio_dirty_lock, flags);
+ bio->bi_private = bio_dirty_list;
+ bio_dirty_list = bio;
+ spin_unlock_irqrestore(&bio_dirty_lock, flags);
+ schedule_work(&bio_dirty_work);
}
EXPORT_SYMBOL_GPL(bio_check_pages_dirty);