md/raid1: split out two sub-functions from sync_request_write

sync_request_write is too big and too deep.
So split out two self-contains bits of functionality into separate
function.
Signed-off-by: NeilBrown <neilb@suse.de>

drivers/md/raid1.c

@@ -1181,101 +1181,9 @@ static void end_sync_write(struct bio *bio, int error)
 	}
 }
 
-static void sync_request_write(mddev_t *mddev, r1bio_t *r1_bio)
+static int fix_sync_read_error(r1bio_t *r1_bio)
 {
-	conf_t *conf = mddev->private;
-	int i;
-	int disks = conf->raid_disks;
-	struct bio *bio, *wbio;
-
-	bio = r1_bio->bios[r1_bio->read_disk];
-
-
-	if (test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery)) {
-		/* We have read all readable devices.  If we haven't
-		 * got the block, then there is no hope left.
-		 * If we have, then we want to do a comparison
-		 * and skip the write if everything is the same.
-		 * If any blocks failed to read, then we need to
-		 * attempt an over-write
-		 */
-		int primary;
-		if (!test_bit(R1BIO_Uptodate, &r1_bio->state)) {
-			for (i=0; i<mddev->raid_disks; i++)
-				if (r1_bio->bios[i]->bi_end_io == end_sync_read)
-					md_error(mddev, conf->mirrors[i].rdev);
-
-			md_done_sync(mddev, r1_bio->sectors, 1);
-			put_buf(r1_bio);
-			return;
-		}
-		for (primary=0; primary<mddev->raid_disks; primary++)
-			if (r1_bio->bios[primary]->bi_end_io == end_sync_read &&
-			    test_bit(BIO_UPTODATE, &r1_bio->bios[primary]->bi_flags)) {
-				r1_bio->bios[primary]->bi_end_io = NULL;
-				rdev_dec_pending(conf->mirrors[primary].rdev, mddev);
-				break;
-			}
-		r1_bio->read_disk = primary;
-		for (i=0; i<mddev->raid_disks; i++)
-			if (r1_bio->bios[i]->bi_end_io == end_sync_read) {
-				int j;
-				int vcnt = r1_bio->sectors >> (PAGE_SHIFT- 9);
-				struct bio *pbio = r1_bio->bios[primary];
-				struct bio *sbio = r1_bio->bios[i];
-
-				if (test_bit(BIO_UPTODATE, &sbio->bi_flags)) {
-					for (j = vcnt; j-- ; ) {
-						struct page *p, *s;
-						p = pbio->bi_io_vec[j].bv_page;
-						s = sbio->bi_io_vec[j].bv_page;
-						if (memcmp(page_address(p),
-							   page_address(s),
-							   PAGE_SIZE))
-							break;
-					}
-				} else
-					j = 0;
-				if (j >= 0)
-					mddev->resync_mismatches += r1_bio->sectors;
-				if (j < 0 || (test_bit(MD_RECOVERY_CHECK, &mddev->recovery)
-					      && test_bit(BIO_UPTODATE, &sbio->bi_flags))) {
-					sbio->bi_end_io = NULL;
-					rdev_dec_pending(conf->mirrors[i].rdev, mddev);
-				} else {
-					/* fixup the bio for reuse */
-					int size;
-					sbio->bi_vcnt = vcnt;
-					sbio->bi_size = r1_bio->sectors << 9;
-					sbio->bi_idx = 0;
-					sbio->bi_phys_segments = 0;
-					sbio->bi_flags &= ~(BIO_POOL_MASK - 1);
-					sbio->bi_flags |= 1 << BIO_UPTODATE;
-					sbio->bi_next = NULL;
-					sbio->bi_sector = r1_bio->sector +
-						conf->mirrors[i].rdev->data_offset;
-					sbio->bi_bdev = conf->mirrors[i].rdev->bdev;
-					size = sbio->bi_size;
-					for (j = 0; j < vcnt ; j++) {
-						struct bio_vec *bi;
-						bi = &sbio->bi_io_vec[j];
-						bi->bv_offset = 0;
-						if (size > PAGE_SIZE)
-							bi->bv_len = PAGE_SIZE;
-						else
-							bi->bv_len = size;
-						size -= PAGE_SIZE;
-						memcpy(page_address(bi->bv_page),
-						       page_address(pbio->bi_io_vec[j].bv_page),
-						       PAGE_SIZE);
-					}
-
-				}
-			}
-	}
-	if (!test_bit(R1BIO_Uptodate, &r1_bio->state)) {
-		/* ouch - failed to read all of that.
-		 * Try some synchronous reads of other devices to get
+	/* Try some synchronous reads of other devices to get
 	 * good data, much like with normal read errors.  Only
 	 * read into the pages we already have so we don't
 	 * need to re-issue the read request.
@@ -1283,6 +1191,9 @@ static void sync_request_write(mddev_t *mddev, r1bio_t *r1_bio)
 	 * active sync request, there is no normal IO, and
 	 * no overlapping syncs.
 	 */
+	mddev_t *mddev = r1_bio->mddev;
+	conf_t *conf = mddev->private;
+	struct bio *bio = r1_bio->bios[r1_bio->read_disk];
 	sector_t sect = r1_bio->sector;
 	int sectors = r1_bio->sectors;
 	int idx = 0;
@@ -1361,14 +1272,122 @@ static void sync_request_write(mddev_t *mddev, r1bio_t *r1_bio)
 			       (unsigned long long)r1_bio->sector);
 			md_done_sync(mddev, r1_bio->sectors, 0);
 			put_buf(r1_bio);
-				return;
+			return 0;
 		}
 		sectors -= s;
 		sect += s;
 		idx ++;
 	}
+	return 1;
+}
+
+static int process_checks(r1bio_t *r1_bio)
+{
+	/* We have read all readable devices.  If we haven't
+	 * got the block, then there is no hope left.
+	 * If we have, then we want to do a comparison
+	 * and skip the write if everything is the same.
+	 * If any blocks failed to read, then we need to
+	 * attempt an over-write
+	 */
+	mddev_t *mddev = r1_bio->mddev;
+	conf_t *conf = mddev->private;
+	int primary;
+	int i;
+
+	if (!test_bit(R1BIO_Uptodate, &r1_bio->state)) {
+		for (i=0; i<mddev->raid_disks; i++)
+			if (r1_bio->bios[i]->bi_end_io == end_sync_read)
+				md_error(mddev, conf->mirrors[i].rdev);
+
+		md_done_sync(mddev, r1_bio->sectors, 1);
+		put_buf(r1_bio);
+		return -1;
+	}
+	for (primary=0; primary<mddev->raid_disks; primary++)
+		if (r1_bio->bios[primary]->bi_end_io == end_sync_read &&
+		    test_bit(BIO_UPTODATE, &r1_bio->bios[primary]->bi_flags)) {
+			r1_bio->bios[primary]->bi_end_io = NULL;
+			rdev_dec_pending(conf->mirrors[primary].rdev, mddev);
+			break;
+		}
+	r1_bio->read_disk = primary;
+	for (i=0; i<mddev->raid_disks; i++)
+		if (r1_bio->bios[i]->bi_end_io == end_sync_read) {
+			int j;
+			int vcnt = r1_bio->sectors >> (PAGE_SHIFT- 9);
+			struct bio *pbio = r1_bio->bios[primary];
+			struct bio *sbio = r1_bio->bios[i];
+
+			if (test_bit(BIO_UPTODATE, &sbio->bi_flags)) {
+				for (j = vcnt; j-- ; ) {
+					struct page *p, *s;
+					p = pbio->bi_io_vec[j].bv_page;
+					s = sbio->bi_io_vec[j].bv_page;
+					if (memcmp(page_address(p),
+						   page_address(s),
+						   PAGE_SIZE))
+						break;
+				}
+			} else
+				j = 0;
+			if (j >= 0)
+				mddev->resync_mismatches += r1_bio->sectors;
+			if (j < 0 || (test_bit(MD_RECOVERY_CHECK, &mddev->recovery)
+				      && test_bit(BIO_UPTODATE, &sbio->bi_flags))) {
+				sbio->bi_end_io = NULL;
+				rdev_dec_pending(conf->mirrors[i].rdev, mddev);
+			} else {
+				/* fixup the bio for reuse */
+				int size;
+				sbio->bi_vcnt = vcnt;
+				sbio->bi_size = r1_bio->sectors << 9;
+				sbio->bi_idx = 0;
+				sbio->bi_phys_segments = 0;
+				sbio->bi_flags &= ~(BIO_POOL_MASK - 1);
+				sbio->bi_flags |= 1 << BIO_UPTODATE;
+				sbio->bi_next = NULL;
+				sbio->bi_sector = r1_bio->sector +
+					conf->mirrors[i].rdev->data_offset;
+				sbio->bi_bdev = conf->mirrors[i].rdev->bdev;
+				size = sbio->bi_size;
+				for (j = 0; j < vcnt ; j++) {
+					struct bio_vec *bi;
+					bi = &sbio->bi_io_vec[j];
+					bi->bv_offset = 0;
+					if (size > PAGE_SIZE)
+						bi->bv_len = PAGE_SIZE;
+					else
+						bi->bv_len = size;
+					size -= PAGE_SIZE;
+					memcpy(page_address(bi->bv_page),
+					       page_address(pbio->bi_io_vec[j].bv_page),
+					       PAGE_SIZE);
 				}
 
+			}
+		}
+	return 0;
+}
+
+static void sync_request_write(mddev_t *mddev, r1bio_t *r1_bio)
+{
+	conf_t *conf = mddev->private;
+	int i;
+	int disks = conf->raid_disks;
+	struct bio *bio, *wbio;
+
+	bio = r1_bio->bios[r1_bio->read_disk];
+
+
+	if (test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery))
+		if (process_checks(r1_bio) < 0)
+			return;
+
+	if (!test_bit(R1BIO_Uptodate, &r1_bio->state))
+		/* ouch - failed to read all of that. */
+		if (!fix_sync_read_error(r1_bio))
+			return;
 	/*
 	 * schedule writes
 	 */