Revert "block, dm: don't copy bios for request clones"
This reverts commit 5f1b670d0bef508a5554d92525f5f6d00d640b38.
Justification for revert as reported in this dm-devel post:
https://www.redhat.com/archives/dm-devel/2015-June/msg00160.html
this change should not be pushed to mainline yet.
Firstly, Christoph has a newer version of the patch that fixes silent
data corruption problem:
https://www.redhat.com/archives/dm-devel/2015-May/msg00229.html
And the new version still depends on LLDDs to always complete requests
to the end when error happens, while block API doesn't enforce such a
requirement. If the assumption is ever broken, the inconsistency between
request and bio (e.g. rq->__sector and rq->bio) will cause silent data
corruption:
https://www.redhat.com/archives/dm-devel/2015-June/msg00022.html
Reported-by: Junichi Nomura <j-nomura@ce.jp.nec.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
diff --git a/block/blk-core.c b/block/blk-core.c
index f6ab750..706dd08 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -117,7 +117,7 @@
static void req_bio_endio(struct request *rq, struct bio *bio,
unsigned int nbytes, int error)
{
- if (error && !(rq->cmd_flags & REQ_CLONE))
+ if (error)
clear_bit(BIO_UPTODATE, &bio->bi_flags);
else if (!test_bit(BIO_UPTODATE, &bio->bi_flags))
error = -EIO;
@@ -128,8 +128,7 @@
bio_advance(bio, nbytes);
/* don't actually finish bio if it's part of flush sequence */
- if (bio->bi_iter.bi_size == 0 &&
- !(rq->cmd_flags & (REQ_FLUSH_SEQ|REQ_CLONE)))
+ if (bio->bi_iter.bi_size == 0 && !(rq->cmd_flags & REQ_FLUSH_SEQ))
bio_endio(bio, error);
}
@@ -2913,22 +2912,95 @@
}
EXPORT_SYMBOL_GPL(blk_lld_busy);
-void blk_rq_prep_clone(struct request *dst, struct request *src)
+/**
+ * blk_rq_unprep_clone - Helper function to free all bios in a cloned request
+ * @rq: the clone request to be cleaned up
+ *
+ * Description:
+ * Free all bios in @rq for a cloned request.
+ */
+void blk_rq_unprep_clone(struct request *rq)
+{
+ struct bio *bio;
+
+ while ((bio = rq->bio) != NULL) {
+ rq->bio = bio->bi_next;
+
+ bio_put(bio);
+ }
+}
+EXPORT_SYMBOL_GPL(blk_rq_unprep_clone);
+
+/*
+ * Copy attributes of the original request to the clone request.
+ * The actual data parts (e.g. ->cmd, ->sense) are not copied.
+ */
+static void __blk_rq_prep_clone(struct request *dst, struct request *src)
{
dst->cpu = src->cpu;
- dst->cmd_flags |= (src->cmd_flags & REQ_CLONE_MASK);
- dst->cmd_flags |= REQ_NOMERGE | REQ_CLONE;
+ dst->cmd_flags |= (src->cmd_flags & REQ_CLONE_MASK) | REQ_NOMERGE;
dst->cmd_type = src->cmd_type;
dst->__sector = blk_rq_pos(src);
dst->__data_len = blk_rq_bytes(src);
dst->nr_phys_segments = src->nr_phys_segments;
dst->ioprio = src->ioprio;
dst->extra_len = src->extra_len;
- dst->bio = src->bio;
- dst->biotail = src->biotail;
- dst->cmd = src->cmd;
- dst->cmd_len = src->cmd_len;
- dst->sense = src->sense;
+}
+
+/**
+ * blk_rq_prep_clone - Helper function to setup clone request
+ * @rq: the request to be setup
+ * @rq_src: original request to be cloned
+ * @bs: bio_set that bios for clone are allocated from
+ * @gfp_mask: memory allocation mask for bio
+ * @bio_ctr: setup function to be called for each clone bio.
+ * Returns %0 for success, non %0 for failure.
+ * @data: private data to be passed to @bio_ctr
+ *
+ * Description:
+ * Clones bios in @rq_src to @rq, and copies attributes of @rq_src to @rq.
+ * The actual data parts of @rq_src (e.g. ->cmd, ->sense)
+ * are not copied, and copying such parts is the caller's responsibility.
+ * Also, pages which the original bios are pointing to are not copied
+ * and the cloned bios just point same pages.
+ * So cloned bios must be completed before original bios, which means
+ * the caller must complete @rq before @rq_src.
+ */
+int blk_rq_prep_clone(struct request *rq, struct request *rq_src,
+ struct bio_set *bs, gfp_t gfp_mask,
+ int (*bio_ctr)(struct bio *, struct bio *, void *),
+ void *data)
+{
+ struct bio *bio, *bio_src;
+
+ if (!bs)
+ bs = fs_bio_set;
+
+ __rq_for_each_bio(bio_src, rq_src) {
+ bio = bio_clone_fast(bio_src, gfp_mask, bs);
+ if (!bio)
+ goto free_and_out;
+
+ if (bio_ctr && bio_ctr(bio, bio_src, data))
+ goto free_and_out;
+
+ if (rq->bio) {
+ rq->biotail->bi_next = bio;
+ rq->biotail = bio;
+ } else
+ rq->bio = rq->biotail = bio;
+ }
+
+ __blk_rq_prep_clone(rq, rq_src);
+
+ return 0;
+
+free_and_out:
+ if (bio)
+ bio_put(bio);
+ blk_rq_unprep_clone(rq);
+
+ return -ENOMEM;
}
EXPORT_SYMBOL_GPL(blk_rq_prep_clone);
diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index a5f9412..16ba55a 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -942,28 +942,21 @@
{
unsigned type = dm_table_get_type(t);
unsigned per_bio_data_size = 0;
+ struct dm_target *tgt;
unsigned i;
- switch (type) {
- case DM_TYPE_BIO_BASED:
- for (i = 0; i < t->num_targets; i++) {
- struct dm_target *tgt = t->targets + i;
-
- per_bio_data_size = max(per_bio_data_size,
- tgt->per_bio_data_size);
- }
- t->mempools = dm_alloc_bio_mempools(t->integrity_supported,
- per_bio_data_size);
- break;
- case DM_TYPE_REQUEST_BASED:
- case DM_TYPE_MQ_REQUEST_BASED:
- t->mempools = dm_alloc_rq_mempools(md, type);
- break;
- default:
+ if (unlikely(type == DM_TYPE_NONE)) {
DMWARN("no table type is set, can't allocate mempools");
return -EINVAL;
}
+ if (type == DM_TYPE_BIO_BASED)
+ for (i = 0; i < t->num_targets; i++) {
+ tgt = t->targets + i;
+ per_bio_data_size = max(per_bio_data_size, tgt->per_bio_data_size);
+ }
+
+ t->mempools = dm_alloc_md_mempools(md, type, t->integrity_supported, per_bio_data_size);
if (!t->mempools)
return -ENOMEM;
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 492181e..9d942ae 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -993,6 +993,57 @@
dec_pending(io, error);
}
+/*
+ * Partial completion handling for request-based dm
+ */
+static void end_clone_bio(struct bio *clone, int error)
+{
+ struct dm_rq_clone_bio_info *info =
+ container_of(clone, struct dm_rq_clone_bio_info, clone);
+ struct dm_rq_target_io *tio = info->tio;
+ struct bio *bio = info->orig;
+ unsigned int nr_bytes = info->orig->bi_iter.bi_size;
+
+ bio_put(clone);
+
+ if (tio->error)
+ /*
+ * An error has already been detected on the request.
+ * Once error occurred, just let clone->end_io() handle
+ * the remainder.
+ */
+ return;
+ else if (error) {
+ /*
+ * Don't notice the error to the upper layer yet.
+ * The error handling decision is made by the target driver,
+ * when the request is completed.
+ */
+ tio->error = error;
+ return;
+ }
+
+ /*
+ * I/O for the bio successfully completed.
+ * Notice the data completion to the upper layer.
+ */
+
+ /*
+ * bios are processed from the head of the list.
+ * So the completing bio should always be rq->bio.
+ * If it's not, something wrong is happening.
+ */
+ if (tio->orig->bio != bio)
+ DMERR("bio completion is going in the middle of the request");
+
+ /*
+ * Update the original request.
+ * Do not use blk_end_request() here, because it may complete
+ * the original request before the clone, and break the ordering.
+ */
+ blk_update_request(tio->orig, 0, nr_bytes);
+}
+
static struct dm_rq_target_io *tio_from_request(struct request *rq)
{
return (rq->q->mq_ops ? blk_mq_rq_to_pdu(rq) : rq->special);
@@ -1050,6 +1101,8 @@
struct dm_rq_target_io *tio = clone->end_io_data;
struct mapped_device *md = tio->md;
+ blk_rq_unprep_clone(clone);
+
if (md->type == DM_TYPE_MQ_REQUEST_BASED)
/* stacked on blk-mq queue(s) */
tio->ti->type->release_clone_rq(clone);
@@ -1784,13 +1837,39 @@
dm_complete_request(rq, r);
}
-static void setup_clone(struct request *clone, struct request *rq,
- struct dm_rq_target_io *tio)
+static int dm_rq_bio_constructor(struct bio *bio, struct bio *bio_orig,
+ void *data)
{
- blk_rq_prep_clone(clone, rq);
+ struct dm_rq_target_io *tio = data;
+ struct dm_rq_clone_bio_info *info =
+ container_of(bio, struct dm_rq_clone_bio_info, clone);
+
+ info->orig = bio_orig;
+ info->tio = tio;
+ bio->bi_end_io = end_clone_bio;
+
+ return 0;
+}
+
+static int setup_clone(struct request *clone, struct request *rq,
+ struct dm_rq_target_io *tio, gfp_t gfp_mask)
+{
+ int r;
+
+ r = blk_rq_prep_clone(clone, rq, tio->md->bs, gfp_mask,
+ dm_rq_bio_constructor, tio);
+ if (r)
+ return r;
+
+ clone->cmd = rq->cmd;
+ clone->cmd_len = rq->cmd_len;
+ clone->sense = rq->sense;
clone->end_io = end_clone_request;
clone->end_io_data = tio;
+
tio->clone = clone;
+
+ return 0;
}
static struct request *clone_rq(struct request *rq, struct mapped_device *md,
@@ -1811,7 +1890,12 @@
clone = tio->clone;
blk_rq_init(NULL, clone);
- setup_clone(clone, rq, tio);
+ if (setup_clone(clone, rq, tio, gfp_mask)) {
+ /* -ENOMEM */
+ if (alloc_clone)
+ free_clone_request(md, clone);
+ return NULL;
+ }
return clone;
}
@@ -1905,7 +1989,11 @@
}
if (r != DM_MAPIO_REMAPPED)
return r;
- setup_clone(clone, rq, tio);
+ if (setup_clone(clone, rq, tio, GFP_ATOMIC)) {
+ /* -ENOMEM */
+ ti->type->release_clone_rq(clone);
+ return DM_MAPIO_REQUEUE;
+ }
}
switch (r) {
@@ -2375,6 +2463,8 @@
goto out;
}
+ BUG_ON(!p || md->io_pool || md->rq_pool || md->bs);
+
md->io_pool = p->io_pool;
p->io_pool = NULL;
md->rq_pool = p->rq_pool;
@@ -3481,23 +3571,48 @@
}
EXPORT_SYMBOL_GPL(dm_noflush_suspending);
-struct dm_md_mempools *dm_alloc_bio_mempools(unsigned integrity,
- unsigned per_bio_data_size)
+struct dm_md_mempools *dm_alloc_md_mempools(struct mapped_device *md, unsigned type,
+ unsigned integrity, unsigned per_bio_data_size)
{
- struct dm_md_mempools *pools;
- unsigned int pool_size = dm_get_reserved_bio_based_ios();
+ struct dm_md_mempools *pools = kzalloc(sizeof(*pools), GFP_KERNEL);
+ struct kmem_cache *cachep = NULL;
+ unsigned int pool_size = 0;
unsigned int front_pad;
- pools = kzalloc(sizeof(*pools), GFP_KERNEL);
if (!pools)
return NULL;
- front_pad = roundup(per_bio_data_size, __alignof__(struct dm_target_io)) +
- offsetof(struct dm_target_io, clone);
+ type = filter_md_type(type, md);
- pools->io_pool = mempool_create_slab_pool(pool_size, _io_cache);
- if (!pools->io_pool)
- goto out;
+ switch (type) {
+ case DM_TYPE_BIO_BASED:
+ cachep = _io_cache;
+ pool_size = dm_get_reserved_bio_based_ios();
+ front_pad = roundup(per_bio_data_size, __alignof__(struct dm_target_io)) + offsetof(struct dm_target_io, clone);
+ break;
+ case DM_TYPE_REQUEST_BASED:
+ cachep = _rq_tio_cache;
+ pool_size = dm_get_reserved_rq_based_ios();
+ pools->rq_pool = mempool_create_slab_pool(pool_size, _rq_cache);
+ if (!pools->rq_pool)
+ goto out;
+ /* fall through to setup remaining rq-based pools */
+ case DM_TYPE_MQ_REQUEST_BASED:
+ if (!pool_size)
+ pool_size = dm_get_reserved_rq_based_ios();
+ front_pad = offsetof(struct dm_rq_clone_bio_info, clone);
+ /* per_bio_data_size is not used. See __bind_mempools(). */
+ WARN_ON(per_bio_data_size != 0);
+ break;
+ default:
+ BUG();
+ }
+
+ if (cachep) {
+ pools->io_pool = mempool_create_slab_pool(pool_size, cachep);
+ if (!pools->io_pool)
+ goto out;
+ }
pools->bs = bioset_create_nobvec(pool_size, front_pad);
if (!pools->bs)
@@ -3507,34 +3622,10 @@
goto out;
return pools;
+
out:
dm_free_md_mempools(pools);
- return NULL;
-}
-struct dm_md_mempools *dm_alloc_rq_mempools(struct mapped_device *md,
- unsigned type)
-{
- unsigned int pool_size = dm_get_reserved_rq_based_ios();
- struct dm_md_mempools *pools;
-
- pools = kzalloc(sizeof(*pools), GFP_KERNEL);
- if (!pools)
- return NULL;
-
- if (filter_md_type(type, md) == DM_TYPE_REQUEST_BASED) {
- pools->rq_pool = mempool_create_slab_pool(pool_size, _rq_cache);
- if (!pools->rq_pool)
- goto out;
- }
-
- pools->io_pool = mempool_create_slab_pool(pool_size, _rq_tio_cache);
- if (!pools->io_pool)
- goto out;
-
- return pools;
-out:
- dm_free_md_mempools(pools);
return NULL;
}
diff --git a/drivers/md/dm.h b/drivers/md/dm.h
index e6e66d0..6123c2b 100644
--- a/drivers/md/dm.h
+++ b/drivers/md/dm.h
@@ -222,9 +222,8 @@
/*
* Mempool operations
*/
-struct dm_md_mempools *dm_alloc_bio_mempools(unsigned integrity,
- unsigned per_bio_data_size);
-struct dm_md_mempools *dm_alloc_rq_mempools(struct mapped_device *md, unsigned type);
+struct dm_md_mempools *dm_alloc_md_mempools(struct mapped_device *md, unsigned type,
+ unsigned integrity, unsigned per_bio_data_size);
void dm_free_md_mempools(struct dm_md_mempools *pools);
/*
diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
index 6ab9d12..7303b34 100644
--- a/include/linux/blk_types.h
+++ b/include/linux/blk_types.h
@@ -192,7 +192,6 @@
__REQ_HASHED, /* on IO scheduler merge hash */
__REQ_MQ_INFLIGHT, /* track inflight for MQ */
__REQ_NO_TIMEOUT, /* requests may never expire */
- __REQ_CLONE, /* cloned bios */
__REQ_NR_BITS, /* stops here */
};
@@ -247,6 +246,5 @@
#define REQ_HASHED (1ULL << __REQ_HASHED)
#define REQ_MQ_INFLIGHT (1ULL << __REQ_MQ_INFLIGHT)
#define REQ_NO_TIMEOUT (1ULL << __REQ_NO_TIMEOUT)
-#define REQ_CLONE (1ULL << __REQ_CLONE)
#endif /* __LINUX_BLK_TYPES_H */
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 776d2ee..41c0fb5 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -775,7 +775,11 @@
unsigned int len);
extern int blk_rq_check_limits(struct request_queue *q, struct request *rq);
extern int blk_lld_busy(struct request_queue *q);
-extern void blk_rq_prep_clone(struct request *rq, struct request *rq_src);
+extern int blk_rq_prep_clone(struct request *rq, struct request *rq_src,
+ struct bio_set *bs, gfp_t gfp_mask,
+ int (*bio_ctr)(struct bio *, struct bio *, void *),
+ void *data);
+extern void blk_rq_unprep_clone(struct request *rq);
extern int blk_insert_cloned_request(struct request_queue *q,
struct request *rq);
extern void blk_delay_queue(struct request_queue *, unsigned long);