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-rw-r--r--block/blk-lib.c233
1 files changed, 233 insertions, 0 deletions
diff --git a/block/blk-lib.c b/block/blk-lib.c
new file mode 100644
index 00000000000..d0216b9f22d
--- /dev/null
+++ b/block/blk-lib.c
@@ -0,0 +1,233 @@
+/*
+ * Functions related to generic helpers functions
+ */
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/bio.h>
+#include <linux/blkdev.h>
+#include <linux/scatterlist.h>
+
+#include "blk.h"
+
+static void blkdev_discard_end_io(struct bio *bio, int err)
+{
+ if (err) {
+ if (err == -EOPNOTSUPP)
+ set_bit(BIO_EOPNOTSUPP, &bio->bi_flags);
+ clear_bit(BIO_UPTODATE, &bio->bi_flags);
+ }
+
+ if (bio->bi_private)
+ complete(bio->bi_private);
+ __free_page(bio_page(bio));
+
+ bio_put(bio);
+}
+
+/**
+ * blkdev_issue_discard - queue a discard
+ * @bdev: blockdev to issue discard for
+ * @sector: start sector
+ * @nr_sects: number of sectors to discard
+ * @gfp_mask: memory allocation flags (for bio_alloc)
+ * @flags: BLKDEV_IFL_* flags to control behaviour
+ *
+ * Description:
+ * Issue a discard request for the sectors in question.
+ */
+int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
+ sector_t nr_sects, gfp_t gfp_mask, unsigned long flags)
+{
+ DECLARE_COMPLETION_ONSTACK(wait);
+ struct request_queue *q = bdev_get_queue(bdev);
+ int type = flags & BLKDEV_IFL_BARRIER ?
+ DISCARD_BARRIER : DISCARD_NOBARRIER;
+ struct bio *bio;
+ struct page *page;
+ int ret = 0;
+
+ if (!q)
+ return -ENXIO;
+
+ if (!blk_queue_discard(q))
+ return -EOPNOTSUPP;
+
+ while (nr_sects && !ret) {
+ unsigned int sector_size = q->limits.logical_block_size;
+ unsigned int max_discard_sectors =
+ min(q->limits.max_discard_sectors, UINT_MAX >> 9);
+
+ bio = bio_alloc(gfp_mask, 1);
+ if (!bio)
+ goto out;
+ bio->bi_sector = sector;
+ bio->bi_end_io = blkdev_discard_end_io;
+ bio->bi_bdev = bdev;
+ if (flags & BLKDEV_IFL_WAIT)
+ bio->bi_private = &wait;
+
+ /*
+ * Add a zeroed one-sector payload as that's what
+ * our current implementations need. If we'll ever need
+ * more the interface will need revisiting.
+ */
+ page = alloc_page(gfp_mask | __GFP_ZERO);
+ if (!page)
+ goto out_free_bio;
+ if (bio_add_pc_page(q, bio, page, sector_size, 0) < sector_size)
+ goto out_free_page;
+
+ /*
+ * And override the bio size - the way discard works we
+ * touch many more blocks on disk than the actual payload
+ * length.
+ */
+ if (nr_sects > max_discard_sectors) {
+ bio->bi_size = max_discard_sectors << 9;
+ nr_sects -= max_discard_sectors;
+ sector += max_discard_sectors;
+ } else {
+ bio->bi_size = nr_sects << 9;
+ nr_sects = 0;
+ }
+
+ bio_get(bio);
+ submit_bio(type, bio);
+
+ if (flags & BLKDEV_IFL_WAIT)
+ wait_for_completion(&wait);
+
+ if (bio_flagged(bio, BIO_EOPNOTSUPP))
+ ret = -EOPNOTSUPP;
+ else if (!bio_flagged(bio, BIO_UPTODATE))
+ ret = -EIO;
+ bio_put(bio);
+ }
+ return ret;
+out_free_page:
+ __free_page(page);
+out_free_bio:
+ bio_put(bio);
+out:
+ return -ENOMEM;
+}
+EXPORT_SYMBOL(blkdev_issue_discard);
+
+struct bio_batch
+{
+ atomic_t done;
+ unsigned long flags;
+ struct completion *wait;
+ bio_end_io_t *end_io;
+};
+
+static void bio_batch_end_io(struct bio *bio, int err)
+{
+ struct bio_batch *bb = bio->bi_private;
+
+ if (err) {
+ if (err == -EOPNOTSUPP)
+ set_bit(BIO_EOPNOTSUPP, &bb->flags);
+ else
+ clear_bit(BIO_UPTODATE, &bb->flags);
+ }
+ if (bb) {
+ if (bb->end_io)
+ bb->end_io(bio, err);
+ atomic_inc(&bb->done);
+ complete(bb->wait);
+ }
+ bio_put(bio);
+}
+
+/**
+ * blkdev_issue_zeroout generate number of zero filed write bios
+ * @bdev: blockdev to issue
+ * @sector: start sector
+ * @nr_sects: number of sectors to write
+ * @gfp_mask: memory allocation flags (for bio_alloc)
+ * @flags: BLKDEV_IFL_* flags to control behaviour
+ *
+ * Description:
+ * Generate and issue number of bios with zerofiled pages.
+ * Send barrier at the beginning and at the end if requested. This guarantie
+ * correct request ordering. Empty barrier allow us to avoid post queue flush.
+ */
+
+int blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
+ sector_t nr_sects, gfp_t gfp_mask, unsigned long flags)
+{
+ int ret = 0;
+ struct bio *bio;
+ struct bio_batch bb;
+ unsigned int sz, issued = 0;
+ DECLARE_COMPLETION_ONSTACK(wait);
+
+ atomic_set(&bb.done, 0);
+ bb.flags = 1 << BIO_UPTODATE;
+ bb.wait = &wait;
+ bb.end_io = NULL;
+
+ if (flags & BLKDEV_IFL_BARRIER) {
+ /* issue async barrier before the data */
+ ret = blkdev_issue_flush(bdev, gfp_mask, NULL, 0);
+ if (ret)
+ return ret;
+ }
+submit:
+ while (nr_sects != 0) {
+ bio = bio_alloc(gfp_mask,
+ min(nr_sects, (sector_t)BIO_MAX_PAGES));
+ if (!bio)
+ break;
+
+ bio->bi_sector = sector;
+ bio->bi_bdev = bdev;
+ bio->bi_end_io = bio_batch_end_io;
+ if (flags & BLKDEV_IFL_WAIT)
+ bio->bi_private = &bb;
+
+ while (nr_sects != 0) {
+ sz = min((sector_t) PAGE_SIZE >> 9 , nr_sects);
+ if (sz == 0)
+ /* bio has maximum size possible */
+ break;
+ ret = bio_add_page(bio, ZERO_PAGE(0), sz << 9, 0);
+ nr_sects -= ret >> 9;
+ sector += ret >> 9;
+ if (ret < (sz << 9))
+ break;
+ }
+ issued++;
+ submit_bio(WRITE, bio);
+ }
+ /*
+ * When all data bios are in flight. Send final barrier if requeted.
+ */
+ if (nr_sects == 0 && flags & BLKDEV_IFL_BARRIER)
+ ret = blkdev_issue_flush(bdev, gfp_mask, NULL,
+ flags & BLKDEV_IFL_WAIT);
+
+
+ if (flags & BLKDEV_IFL_WAIT)
+ /* Wait for bios in-flight */
+ while ( issued != atomic_read(&bb.done))
+ wait_for_completion(&wait);
+
+ if (!test_bit(BIO_UPTODATE, &bb.flags))
+ /* One of bios in the batch was completed with error.*/
+ ret = -EIO;
+
+ if (ret)
+ goto out;
+
+ if (test_bit(BIO_EOPNOTSUPP, &bb.flags)) {
+ ret = -EOPNOTSUPP;
+ goto out;
+ }
+ if (nr_sects != 0)
+ goto submit;
+out:
+ return ret;
+}
+EXPORT_SYMBOL(blkdev_issue_zeroout);