block: move the block layer auto-integrity code into a new file

The code that automatically creates a integrity payload and generates and
verifies the checksums for bios that don't have submitter-provided
integrity payload currently sits right in the middle of the block
integrity metadata infrastructure.  Split it into a separate file to
make the different layers clear.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Anuj Gupta <anuj20.g@samsung.com>
Reviewed-by: Kanchan Joshi <joshi.k@samsung.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20250225154449.422989-3-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block/bio-integrity-auto.c

@@ -0,0 +1,162 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2007, 2008, 2009 Oracle Corporation
+ * Written by: Martin K. Petersen <martin.petersen@oracle.com>
+ *
+ * Automatically generate and verify integrity data on PI capable devices if the
+ * bio submitter didn't provide PI itself.  This ensures that kernel verifies
+ * data integrity even if the file system (or other user of the block device) is
+ * not aware of PI.
+ */
+#include <linux/blk-integrity.h>
+#include <linux/workqueue.h>
+#include "blk.h"
+
+static struct workqueue_struct *kintegrityd_wq;
+
+static void bio_integrity_verify_fn(struct work_struct *work)
+{
+	struct bio_integrity_payload *bip =
+		container_of(work, struct bio_integrity_payload, bip_work);
+	struct bio *bio = bip->bip_bio;
+
+	blk_integrity_verify(bio);
+
+	kfree(bvec_virt(bip->bip_vec));
+	bio_integrity_free(bio);
+	bio_endio(bio);
+}
+
+/**
+ * __bio_integrity_endio - Integrity I/O completion function
+ * @bio:	Protected bio
+ *
+ * Normally I/O completion is done in interrupt context.  However, verifying I/O
+ * integrity is a time-consuming task which must be run in process context.
+ *
+ * This function postpones completion accordingly.
+ */
+bool __bio_integrity_endio(struct bio *bio)
+{
+	struct blk_integrity *bi = blk_get_integrity(bio->bi_bdev->bd_disk);
+	struct bio_integrity_payload *bip = bio_integrity(bio);
+
+	if (bio_op(bio) == REQ_OP_READ && !bio->bi_status && bi->csum_type) {
+		INIT_WORK(&bip->bip_work, bio_integrity_verify_fn);
+		queue_work(kintegrityd_wq, &bip->bip_work);
+		return false;
+	}
+
+	kfree(bvec_virt(bip->bip_vec));
+	bio_integrity_free(bio);
+	return true;
+}
+
+/**
+ * bio_integrity_prep - Prepare bio for integrity I/O
+ * @bio:	bio to prepare
+ *
+ * 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 and for writes the integrity metadata
+ * will be generated.  For reads, the completion handler will verify the
+ * metadata.
+ */
+bool bio_integrity_prep(struct bio *bio)
+{
+	struct bio_integrity_payload *bip;
+	struct blk_integrity *bi = blk_get_integrity(bio->bi_bdev->bd_disk);
+	gfp_t gfp = GFP_NOIO;
+	unsigned int len;
+	void *buf;
+
+	if (!bi)
+		return true;
+
+	if (!bio_sectors(bio))
+		return true;
+
+	/* Already protected? */
+	if (bio_integrity(bio))
+		return true;
+
+	switch (bio_op(bio)) {
+	case REQ_OP_READ:
+		if (bi->flags & BLK_INTEGRITY_NOVERIFY)
+			return true;
+		break;
+	case REQ_OP_WRITE:
+		if (bi->flags & BLK_INTEGRITY_NOGENERATE)
+			return true;
+
+		/*
+		 * Zero the memory allocated to not leak uninitialized kernel
+		 * memory to disk for non-integrity metadata where nothing else
+		 * initializes the memory.
+		 */
+		if (bi->csum_type == BLK_INTEGRITY_CSUM_NONE)
+			gfp |= __GFP_ZERO;
+		break;
+	default:
+		return true;
+	}
+
+	/* Allocate kernel buffer for protection data */
+	len = bio_integrity_bytes(bi, bio_sectors(bio));
+	buf = kmalloc(len, gfp);
+	if (!buf)
+		goto err_end_io;
+
+	bip = bio_integrity_alloc(bio, GFP_NOIO, 1);
+	if (IS_ERR(bip)) {
+		kfree(buf);
+		goto err_end_io;
+	}
+
+	bip->bip_flags |= BIP_BLOCK_INTEGRITY;
+	bip_set_seed(bip, bio->bi_iter.bi_sector);
+
+	if (bi->csum_type == BLK_INTEGRITY_CSUM_IP)
+		bip->bip_flags |= BIP_IP_CHECKSUM;
+	if (bi->csum_type)
+		bip->bip_flags |= BIP_CHECK_GUARD;
+	if (bi->flags & BLK_INTEGRITY_REF_TAG)
+		bip->bip_flags |= BIP_CHECK_REFTAG;
+
+	if (bio_integrity_add_page(bio, virt_to_page(buf), len,
+			offset_in_page(buf)) < len)
+		goto err_end_io;
+
+	/* Auto-generate integrity metadata if this is a write */
+	if (bio_data_dir(bio) == WRITE)
+		blk_integrity_generate(bio);
+	else
+		bip->bio_iter = bio->bi_iter;
+	return true;
+
+err_end_io:
+	bio->bi_status = BLK_STS_RESOURCE;
+	bio_endio(bio);
+	return false;
+}
+EXPORT_SYMBOL(bio_integrity_prep);
+
+void blk_flush_integrity(void)
+{
+	flush_workqueue(kintegrityd_wq);
+}
+
+static int __init blk_integrity_auto_init(void)
+{
+	/*
+	 * kintegrityd won't block much but may burn a lot of CPU cycles.
+	 * Make it highpri CPU intensive wq with max concurrency of 1.
+	 */
+	kintegrityd_wq = alloc_workqueue("kintegrityd", WQ_MEM_RECLAIM |
+					 WQ_HIGHPRI | WQ_CPU_INTENSIVE, 1);
+	if (!kintegrityd_wq)
+		panic("Failed to create kintegrityd\n");
+	return 0;
+}
+subsys_initcall(blk_integrity_auto_init);