1 files changed, 395 insertions, 0 deletions
diff --git a/c_src/linux/bio.c b/c_src/linux/bio.c
new file mode 100644
index 00000000..93a791c4
--- /dev/null
+++ b/c_src/linux/bio.c
@@ -0,0 +1,395 @@
+/*
+ * Copyright (C) 2001 Jens Axboe <axboe@kernel.dk>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public Licens
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-
+ *
+ */
+#include <linux/bio.h>
+#include <linux/blkdev.h>
+#include <linux/slab.h>
+#include <linux/kernel.h>
+
+static const struct {
+	int		err;
+	const char	*name;
+} blk_errors[] = {
+	[BLK_STS_OK]		= { 0,		"" },
+	[BLK_STS_NOTSUPP]	= { -EOPNOTSUPP, "operation not supported" },
+	[BLK_STS_TIMEOUT]	= { -ETIMEDOUT,	"timeout" },
+	[BLK_STS_NOSPC]		= { -ENOSPC,	"critical space allocation" },
+	[BLK_STS_TRANSPORT]	= { -ENOLINK,	"recoverable transport" },
+	[BLK_STS_TARGET]	= { -EREMOTEIO,	"critical target" },
+	[BLK_STS_NEXUS]		= { -EBADE,	"critical nexus" },
+	[BLK_STS_MEDIUM]	= { -ENODATA,	"critical medium" },
+	[BLK_STS_PROTECTION]	= { -EILSEQ,	"protection" },
+	[BLK_STS_RESOURCE]	= { -ENOMEM,	"kernel resource" },
+	[BLK_STS_AGAIN]		= { -EAGAIN,	"nonblocking retry" },
+
+	/* device mapper special case, should not leak out: */
+	[BLK_STS_DM_REQUEUE]	= { -EREMCHG, "dm internal retry" },
+
+	/* everything else not covered above: */
+	[BLK_STS_IOERR]		= { -EIO,	"I/O" },
+};
+
+int blk_status_to_errno(blk_status_t status)
+{
+	int idx = (__force int)status;
+
+	if (WARN_ON_ONCE(idx >= ARRAY_SIZE(blk_errors)))
+		return -EIO;
+	return blk_errors[idx].err;
+}
+
+const char *blk_status_to_str(blk_status_t status)
+{
+	int idx = (__force int)status;
+
+	if (WARN_ON_ONCE(idx >= ARRAY_SIZE(blk_errors)))
+		return "(invalid error)";
+	return blk_errors[idx].name;
+}
+
+void bio_copy_data_iter(struct bio *dst, struct bvec_iter *dst_iter,
+			struct bio *src, struct bvec_iter *src_iter)
+{
+	struct bio_vec src_bv, dst_bv;
+	void *src_p, *dst_p;
+	unsigned bytes;
+
+	while (src_iter->bi_size && dst_iter->bi_size) {
+		src_bv = bio_iter_iovec(src, *src_iter);
+		dst_bv = bio_iter_iovec(dst, *dst_iter);
+
+		bytes = min(src_bv.bv_len, dst_bv.bv_len);
+
+		src_p = kmap_atomic(src_bv.bv_page);
+		dst_p = kmap_atomic(dst_bv.bv_page);
+
+		memcpy(dst_p + dst_bv.bv_offset,
+		       src_p + src_bv.bv_offset,
+		       bytes);
+
+		kunmap_atomic(dst_p);
+		kunmap_atomic(src_p);
+
+		flush_dcache_page(dst_bv.bv_page);
+
+		bio_advance_iter(src, src_iter, bytes);
+		bio_advance_iter(dst, dst_iter, bytes);
+	}
+}
+
+/**
+ * bio_copy_data - copy contents of data buffers from one bio to another
+ * @src: source bio
+ * @dst: destination bio
+ *
+ * Stops when it reaches the end of either @src or @dst - that is, copies
+ * min(src->bi_size, dst->bi_size) bytes (or the equivalent for lists of bios).
+ */
+void bio_copy_data(struct bio *dst, struct bio *src)
+{
+	struct bvec_iter src_iter = src->bi_iter;
+	struct bvec_iter dst_iter = dst->bi_iter;
+
+	bio_copy_data_iter(dst, &dst_iter, src, &src_iter);
+}
+
+void zero_fill_bio_iter(struct bio *bio, struct bvec_iter start)
+{
+	unsigned long flags;
+	struct bio_vec bv;
+	struct bvec_iter iter;
+
+	__bio_for_each_segment(bv, bio, iter, start) {
+		char *data = bvec_kmap_irq(&bv, &flags);
+		memset(data, 0, bv.bv_len);
+		bvec_kunmap_irq(data, &flags);
+	}
+}
+
+static int __bio_clone(struct bio *bio, struct bio *bio_src, gfp_t gfp)
+{
+	bio_set_flag(bio, BIO_CLONED);
+	bio->bi_ioprio = bio_src->bi_ioprio;
+	bio->bi_iter = bio_src->bi_iter;
+	return 0;
+}
+
+struct bio *bio_alloc_clone(struct block_device *bdev, struct bio *bio_src,
+		gfp_t gfp, struct bio_set *bs)
+{
+	struct bio *bio;
+
+	bio = bio_alloc_bioset(bdev, 0, bio_src->bi_opf, gfp, bs);
+	if (!bio)
+		return NULL;
+
+	if (__bio_clone(bio, bio_src, gfp) < 0) {
+		bio_put(bio);
+		return NULL;
+	}
+	bio->bi_io_vec = bio_src->bi_io_vec;
+
+	return bio;
+}
+
+struct bio *bio_split(struct bio *bio, int sectors,
+		      gfp_t gfp, struct bio_set *bs)
+{
+	struct bio *split = NULL;
+
+	BUG_ON(sectors <= 0);
+	BUG_ON(sectors >= bio_sectors(bio));
+
+	split = bio_alloc_clone(bio->bi_bdev, bio, gfp, bs);
+	if (!split)
+		return NULL;
+
+	split->bi_iter.bi_size = sectors << 9;
+
+	bio_advance(bio, split->bi_iter.bi_size);
+
+	return split;
+}
+
+void bio_free_pages(struct bio *bio)
+{
+	struct bvec_iter_all iter;
+	struct bio_vec *bvec;
+
+	bio_for_each_segment_all(bvec, bio, iter)
+		__free_page(bvec->bv_page);
+}
+
+void bio_advance(struct bio *bio, unsigned bytes)
+{
+	bio_advance_iter(bio, &bio->bi_iter, bytes);
+}
+
+static void bio_free(struct bio *bio)
+{
+	struct bio_set *bs = bio->bi_pool;
+
+	if (bs) {
+		if (bio->bi_max_vecs > BIO_INLINE_VECS)
+			mempool_free(bio->bi_io_vec, &bs->bvec_pool);
+
+		mempool_free((void *) bio - bs->front_pad, &bs->bio_pool);
+	} else {
+		kfree(bio);
+	}
+}
+
+void bio_put(struct bio *bio)
+{
+	if (!bio_flagged(bio, BIO_REFFED))
+		bio_free(bio);
+	else {
+		BUG_ON(!atomic_read(&bio->__bi_cnt));
+
+		/*
+		 * last put frees it
+		 */
+		if (atomic_dec_and_test(&bio->__bi_cnt))
+			bio_free(bio);
+	}
+}
+
+int bio_add_page(struct bio *bio, struct page *page,
+		 unsigned int len, unsigned int off)
+{
+	struct bio_vec *bv = &bio->bi_io_vec[bio->bi_vcnt];
+
+	WARN_ON_ONCE(bio_flagged(bio, BIO_CLONED));
+	WARN_ON_ONCE(bio->bi_vcnt >= bio->bi_max_vecs);
+
+	bv->bv_page = page;
+	bv->bv_offset = off;
+	bv->bv_len = len;
+
+	bio->bi_iter.bi_size += len;
+	bio->bi_vcnt++;
+	return len;
+}
+
+static inline bool bio_remaining_done(struct bio *bio)
+{
+	/*
+	 * If we're not chaining, then ->__bi_remaining is always 1 and
+	 * we always end io on the first invocation.
+	 */
+	if (!bio_flagged(bio, BIO_CHAIN))
+		return true;
+
+	BUG_ON(atomic_read(&bio->__bi_remaining) <= 0);
+
+	if (atomic_dec_and_test(&bio->__bi_remaining)) {
+		bio_clear_flag(bio, BIO_CHAIN);
+		return true;
+	}
+
+	return false;
+}
+
+static struct bio *__bio_chain_endio(struct bio *bio)
+{
+	struct bio *parent = bio->bi_private;
+
+	if (!parent->bi_status)
+		parent->bi_status = bio->bi_status;
+	bio_put(bio);
+	return parent;
+}
+
+static void bio_chain_endio(struct bio *bio)
+{
+	bio_endio(__bio_chain_endio(bio));
+}
+
+void bio_endio(struct bio *bio)
+{
+again:
+	if (!bio_remaining_done(bio))
+		return;
+
+	/*
+	 * Need to have a real endio function for chained bios, otherwise
+	 * various corner cases will break (like stacking block devices that
+	 * save/restore bi_end_io) - however, we want to avoid unbounded
+	 * recursion and blowing the stack. Tail call optimization would
+	 * handle this, but compiling with frame pointers also disables
+	 * gcc's sibling call optimization.
+	 */
+	if (bio->bi_end_io == bio_chain_endio) {
+		bio = __bio_chain_endio(bio);
+		goto again;
+	}
+
+	if (bio->bi_end_io)
+		bio->bi_end_io(bio);
+}
+
+void bio_reset(struct bio *bio, struct block_device *bdev, unsigned int opf)
+{
+	unsigned long flags = bio->bi_flags & (~0UL << BIO_RESET_BITS);
+
+	memset(bio, 0, BIO_RESET_BYTES);
+	bio->bi_bdev	= bdev;
+	bio->bi_opf	= opf;
+	bio->bi_flags	= flags;
+	atomic_set(&bio->__bi_remaining, 1);
+}
+
+struct bio *bio_kmalloc(unsigned int nr_iovecs, gfp_t gfp_mask)
+{
+	struct bio *bio;
+
+	bio = kmalloc(sizeof(struct bio) +
+		      sizeof(struct bio_vec) * nr_iovecs, gfp_mask);
+	if (unlikely(!bio))
+		return NULL;
+	bio_init(bio, NULL, nr_iovecs ? bio->bi_inline_vecs : NULL, nr_iovecs, 0);
+	bio->bi_pool = NULL;
+	return bio;
+}
+
+static struct bio_vec *bvec_alloc(mempool_t *pool, int *nr_vecs,
+		gfp_t gfp_mask)
+{
+	*nr_vecs = roundup_pow_of_two(*nr_vecs);
+	/*
+	 * Try a slab allocation first for all smaller allocations.  If that
+	 * fails and __GFP_DIRECT_RECLAIM is set retry with the mempool.
+	 * The mempool is sized to handle up to BIO_MAX_VECS entries.
+	 */
+	if (*nr_vecs < BIO_MAX_VECS) {
+		struct bio_vec *bvl;
+
+		bvl = kmalloc(sizeof(*bvl) * *nr_vecs, gfp_mask);
+		if (likely(bvl))
+			return bvl;
+		*nr_vecs = BIO_MAX_VECS;
+	}
+
+	return mempool_alloc(pool, gfp_mask);
+}
+
+struct bio *bio_alloc_bioset(struct block_device *bdev,
+			     unsigned nr_iovecs,
+			     unsigned opf,
+			     gfp_t gfp_mask,
+			     struct bio_set *bs)
+{
+	struct bio *bio;
+	void *p;
+
+	if (nr_iovecs > BIO_MAX_VECS)
+		return NULL;
+
+	p = mempool_alloc(&bs->bio_pool, gfp_mask);
+	if (unlikely(!p))
+		return NULL;
+
+	bio = p + bs->front_pad;
+	if (nr_iovecs > BIO_INLINE_VECS) {
+		struct bio_vec *bvl = NULL;
+
+		bvl = bvec_alloc(&bs->bvec_pool, &nr_iovecs, gfp_mask);
+		if (unlikely(!bvl))
+			goto err_free;
+
+		bio_init(bio, bdev, bvl, nr_iovecs, opf);
+	} else if (nr_iovecs) {
+		bio_init(bio, bdev, bio->bi_inline_vecs, BIO_INLINE_VECS, opf);
+	} else {
+		bio_init(bio, bdev, NULL, 0, opf);
+	}
+
+	bio->bi_pool = bs;
+	return bio;
+
+err_free:
+	mempool_free(p, &bs->bio_pool);
+	return NULL;
+}
+
+void bioset_exit(struct bio_set *bs)
+{
+	mempool_exit(&bs->bio_pool);
+	mempool_exit(&bs->bvec_pool);
+}
+
+int bioset_init(struct bio_set *bs,
+		unsigned int pool_size,
+		unsigned int front_pad,
+		int flags)
+{
+	int ret;
+
+	bs->front_pad = front_pad;
+	if (flags & BIOSET_NEED_BVECS)
+		bs->back_pad = BIO_INLINE_VECS * sizeof(struct bio_vec);
+	else
+		bs->back_pad = 0;
+
+	ret   = mempool_init_kmalloc_pool(&bs->bio_pool, pool_size, bs->front_pad +
+					  sizeof(struct bio) + bs->back_pad) ?:
+		mempool_init_kmalloc_pool(&bs->bvec_pool, pool_size,
+					  sizeof(struct bio_vec) * BIO_MAX_VECS);
+	if (ret)
+		bioset_exit(bs);
+	return ret;
+}