bio-integrity: fold bio_integrity_enabled to bio_integrity_prep

Currently all integrity prep hooks are open-coded, and if prepare fails
we ignore it's code and fail bio with EIO. Let's return real error to
upper layer, so later caller may react accordingly.

In fact no one want to use bio_integrity_prep() w/o bio_integrity_enabled,
so it is reasonable to fold it in to one function.

Signed-off-by: Dmitry Monakhov <[e-mail]>
Reviewed-by: Martin K. Petersen <[e-mail]>
[hch: merged with the latest block tree,
return bool from bio_integrity_prep]
Signed-off-by: Christoph Hellwig <[e-mail]>
Signed-off-by: Jens Axboe <[e-mail]>

Documentation/block/data-integrity.txt

···
     supported by the block device.
 
 
-    int bio_integrity_prep(bio);
+    bool bio_integrity_prep(bio);
 
       To generate IMD for WRITE and to set up buffers for READ, the
       filesystem must call bio_integrity_prep(bio).
···
       sector must be set, and the bio should have all data pages
       added.  It is up to the caller to ensure that the bio does not
       change while I/O is in progress.
-
-      bio_integrity_prep() should only be called if
-      bio_integrity_enabled() returned 1.
+      Complete bio with error if prepare failed for some reson.
 
 
 5.3 PASSING EXISTING INTEGRITY METADATA

block/bio-integrity.c

···
 EXPORT_SYMBOL(bio_integrity_add_page);
 
 /**
- * bio_integrity_enabled - Check whether integrity can be passed
- * @bio:	bio to check
- *
- * Description: Determines whether bio_integrity_prep() can be called
- * on this bio or not.	bio data direction and target device must be
- * set prior to calling.  The functions honors the write_generate and
- * read_verify flags in sysfs.
- */
-bool bio_integrity_enabled(struct bio *bio)
-{
-	struct blk_integrity *bi = bdev_get_integrity(bio->bi_bdev);
-
-	if (bio_op(bio) != REQ_OP_READ && bio_op(bio) != REQ_OP_WRITE)
-		return false;
-
-	if (!bio_sectors(bio))
-		return false;
-
-	/* Already protected? */
-	if (bio_integrity(bio))
-		return false;
-
-	if (bi == NULL)
-		return false;
-
-	if (bio_data_dir(bio) == READ && bi->profile->verify_fn != NULL &&
-	    (bi->flags & BLK_INTEGRITY_VERIFY))
-		return true;
-
-	if (bio_data_dir(bio) == WRITE && bi->profile->generate_fn != NULL &&
-	    (bi->flags & BLK_INTEGRITY_GENERATE))
-		return true;
-
-	return false;
-}
-EXPORT_SYMBOL(bio_integrity_enabled);
-
-/**
  * bio_integrity_intervals - Return number of integrity intervals for a bio
  * @bi:		blk_integrity profile for device
  * @sectors:	Size of the bio in 512-byte sectors
···
  * bio_integrity_prep - Prepare bio for integrity I/O
  * @bio:	bio to prepare
  *
- * Description: Allocates a buffer for integrity metadata, maps the
- * pages and attaches them to a bio.  The bio must have data
- * direction, target device and start sector set priot to calling.  In
- * the WRITE case, integrity metadata will be generated using the
- * block device's integrity function.  In the READ case, the buffer
+ * Description:  Checks if the bio already has an integrity payload attached.
+ * If it does, the payload has been generated by another kernel subsystem,
+ * and we just pass it through. Otherwise allocates integrity payload.
+ * The bio must have data direction, target device and start sector set priot
+ * to calling.  In the WRITE case, integrity metadata will be generated using
+ * the block device's integrity function.  In the READ case, the buffer
  * will be prepared for DMA and a suitable end_io handler set up.
  */
-int bio_integrity_prep(struct bio *bio)
+bool bio_integrity_prep(struct bio *bio)
 {
 	struct bio_integrity_payload *bip;
 	struct blk_integrity *bi;
···
 	unsigned int len, nr_pages;
 	unsigned int bytes, offset, i;
 	unsigned int intervals;
+	blk_status_t status;
 
 	bi = bdev_get_integrity(bio->bi_bdev);
 	q = bdev_get_queue(bio->bi_bdev);
-	BUG_ON(bi == NULL);
-	BUG_ON(bio_integrity(bio));
+	if (bio_op(bio) != REQ_OP_READ && bio_op(bio) != REQ_OP_WRITE)
+		return true;
 
+	if (!bio_sectors(bio))
+		return true;
+
+	/* Already protected? */
+	if (bio_integrity(bio))
+		return true;
+
+	if (bi == NULL)
+		return true;
+
+	if (bio_data_dir(bio) == READ) {
+		if (!bi->profile->verify_fn ||
+		    !(bi->flags & BLK_INTEGRITY_VERIFY))
+			return true;
+	} else {
+		if (!bi->profile->generate_fn ||
+		    !(bi->flags & BLK_INTEGRITY_GENERATE))
+			return true;
+	}
 	intervals = bio_integrity_intervals(bi, bio_sectors(bio));
 
 	/* Allocate kernel buffer for protection data */
 	len = intervals * bi->tuple_size;
 	buf = kmalloc(len, GFP_NOIO | q->bounce_gfp);
+	status = BLK_STS_RESOURCE;
 	if (unlikely(buf == NULL)) {
 		printk(KERN_ERR "could not allocate integrity buffer\n");
-		return -ENOMEM;
+		goto err_end_io;
 	}
 
 	end = (((unsigned long) buf) + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
···
 	if (IS_ERR(bip)) {
 		printk(KERN_ERR "could not allocate data integrity bioset\n");
 		kfree(buf);
-		return PTR_ERR(bip);
+		status = BLK_STS_RESOURCE;
+		goto err_end_io;
 	}
 
 	bip->bip_flags |= BIP_BLOCK_INTEGRITY;
···
 	/* Auto-generate integrity metadata if this is a write */
 	if (bio_data_dir(bio) == WRITE)
 		bio_integrity_process(bio, bi->profile->generate_fn);
+	return true;
 
-	return 0;
+err_end_io:
+	bio->bi_status = status;
+	bio_endio(bio);
+	return false;
+
 }
 EXPORT_SYMBOL(bio_integrity_prep);
 

block/blk-core.c

···
 
 	blk_queue_split(q, &bio);
 
-	if (bio_integrity_enabled(bio) && bio_integrity_prep(bio)) {
-		bio->bi_status = BLK_STS_IOERR;
-		bio_endio(bio);
+	if (!bio_integrity_prep(bio))
 		return BLK_QC_T_NONE;
-	}
 
 	if (op_is_flush(bio->bi_opf)) {
 		spin_lock_irq(q->queue_lock);

block/blk-mq.c

···
 
 	blk_queue_split(q, &bio);
 
-	if (bio_integrity_enabled(bio) && bio_integrity_prep(bio)) {
-		bio_io_error(bio);
+	if (!bio_integrity_prep(bio))
 		return BLK_QC_T_NONE;
-	}
 
 	if (!is_flush_fua && !blk_queue_nomerges(q) &&
 	    blk_attempt_plug_merge(q, bio, &request_count, &same_queue_rq))

drivers/nvdimm/blk.c

···
 	int err = 0, rw;
 	bool do_acct;
 
-	/*
-	 * bio_integrity_enabled also checks if the bio already has an
-	 * integrity payload attached. If it does, we *don't* do a
-	 * bio_integrity_prep here - the payload has been generated by
-	 * another kernel subsystem, and we just pass it through.
-	 */
-	if (bio_integrity_enabled(bio) && bio_integrity_prep(bio)) {
-		bio->bi_status = BLK_STS_IOERR;
-		goto out;
-	}
+	if (!bio_integrity_prep(bio))
+		return BLK_QC_T_NONE;
 
 	bip = bio_integrity(bio);
 	nsblk = q->queuedata;
···
 	if (do_acct)
 		nd_iostat_end(bio, start);
 
- out:
 	bio_endio(bio);
 	return BLK_QC_T_NONE;
 }

drivers/nvdimm/btt.c

···
 	int err = 0;
 	bool do_acct;
 
-	/*
-	 * bio_integrity_enabled also checks if the bio already has an
-	 * integrity payload attached. If it does, we *don't* do a
-	 * bio_integrity_prep here - the payload has been generated by
-	 * another kernel subsystem, and we just pass it through.
-	 */
-	if (bio_integrity_enabled(bio) && bio_integrity_prep(bio)) {
-		bio->bi_status = BLK_STS_IOERR;
-		goto out;
-	}
+	if (!bio_integrity_prep(bio))
+		return BLK_QC_T_NONE;
 
 	do_acct = nd_iostat_start(bio, &start);
 	bio_for_each_segment(bvec, bio, iter) {
···
 	if (do_acct)
 		nd_iostat_end(bio, start);
 
-out:
 	bio_endio(bio);
 	return BLK_QC_T_NONE;
 }

include/linux/bio.h

···
 extern struct bio_integrity_payload *bio_integrity_alloc(struct bio *, gfp_t, unsigned int);
 extern void bio_integrity_free(struct bio *);
 extern int bio_integrity_add_page(struct bio *, struct page *, unsigned int, unsigned int);
-extern bool bio_integrity_enabled(struct bio *bio);
-extern int bio_integrity_prep(struct bio *);
+extern bool bio_integrity_prep(struct bio *);
 extern void bio_integrity_endio(struct bio *);
 extern void bio_integrity_advance(struct bio *, unsigned int);
 extern void bio_integrity_trim(struct bio *);
···
 	return NULL;
 }
 
-static inline bool bio_integrity_enabled(struct bio *bio)
-{
-	return false;
-}
-
 static inline int bioset_integrity_create(struct bio_set *bs, int pool_size)
 {
 	return 0;
···
 	return;
 }
 
-static inline int bio_integrity_prep(struct bio *bio)
+static inline bool bio_integrity_prep(struct bio *bio)
 {
-	return 0;
+	return true;
 }
 
 static inline void bio_integrity_free(struct bio *bio)