btrfs: rename btrfs_bio to btrfs_io_context

The structure btrfs_bio is used by two different sites:

- bio->bi_private for mirror based profiles
  For those profiles (SINGLE/DUP/RAID1*/RAID10), this structures records
  how many mirrors are still pending, and save the original endio
  function of the bio.

- RAID56 code
  In that case, RAID56 only utilize the stripes info, and no long uses
  that to trace the pending mirrors.

So btrfs_bio is not always bind to a bio, and contains more info for IO
context, thus renaming it will make the naming less confusing.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/check-integrity.c

@@ -1455,7 +1455,7 @@ static int btrfsic_map_block(struct btrfsic_state *state, u64 bytenr, u32 len,
 	struct btrfs_fs_info *fs_info = state->fs_info;
 	int ret;
 	u64 length;
-	struct btrfs_bio *multi = NULL;
+	struct btrfs_io_context *multi = NULL;
 	struct btrfs_device *device;
 
 	length = len;

fs/btrfs/extent-tree.c

@@ -1266,7 +1266,7 @@ static int btrfs_issue_discard(struct block_device *bdev, u64 start, u64 len,
 	return ret;
 }
 
-static int do_discard_extent(struct btrfs_bio_stripe *stripe, u64 *bytes)
+static int do_discard_extent(struct btrfs_io_stripe *stripe, u64 *bytes)
 {
 	struct btrfs_device *dev = stripe->dev;
 	struct btrfs_fs_info *fs_info = dev->fs_info;
@@ -1313,22 +1313,21 @@ int btrfs_discard_extent(struct btrfs_fs_info *fs_info, u64 bytenr,
 	u64 discarded_bytes = 0;
 	u64 end = bytenr + num_bytes;
 	u64 cur = bytenr;
-	struct btrfs_bio *bbio = NULL;
-
+	struct btrfs_io_context *bioc = NULL;
 
 	/*
-	 * Avoid races with device replace and make sure our bbio has devices
+	 * Avoid races with device replace and make sure our bioc has devices
 	 * associated to its stripes that don't go away while we are discarding.
 	 */
 	btrfs_bio_counter_inc_blocked(fs_info);
 	while (cur < end) {
-		struct btrfs_bio_stripe *stripe;
+		struct btrfs_io_stripe *stripe;
 		int i;
 
 		num_bytes = end - cur;
 		/* Tell the block device(s) that the sectors can be discarded */
 		ret = btrfs_map_block(fs_info, BTRFS_MAP_DISCARD, cur,
-				      &num_bytes, &bbio, 0);
+				      &num_bytes, &bioc, 0);
 		/*
 		 * Error can be -ENOMEM, -ENOENT (no such chunk mapping) or
 		 * -EOPNOTSUPP. For any such error, @num_bytes is not updated,
@@ -1337,8 +1336,8 @@ int btrfs_discard_extent(struct btrfs_fs_info *fs_info, u64 bytenr,
 		if (ret < 0)
 			goto out;
 
-		stripe = bbio->stripes;
-		for (i = 0; i < bbio->num_stripes; i++, stripe++) {
+		stripe = bioc->stripes;
+		for (i = 0; i < bioc->num_stripes; i++, stripe++) {
 			u64 bytes;
 			struct btrfs_device *device = stripe->dev;
 
@@ -1361,7 +1360,7 @@ int btrfs_discard_extent(struct btrfs_fs_info *fs_info, u64 bytenr,
 				 * And since there are two loops, explicitly
 				 * go to out to avoid confusion.
 				 */
-				btrfs_put_bbio(bbio);
+				btrfs_put_bioc(bioc);
 				goto out;
 			}
 
@@ -1372,7 +1371,7 @@ int btrfs_discard_extent(struct btrfs_fs_info *fs_info, u64 bytenr,
 			 */
 			ret = 0;
 		}
-		btrfs_put_bbio(bbio);
+		btrfs_put_bioc(bioc);
 		cur += num_bytes;
 	}
 out:

fs/btrfs/extent_io.c

@@ -2290,7 +2290,7 @@ static int repair_io_failure(struct btrfs_fs_info *fs_info, u64 ino, u64 start,
 	struct btrfs_device *dev;
 	u64 map_length = 0;
 	u64 sector;
-	struct btrfs_bio *bbio = NULL;
+	struct btrfs_io_context *bioc = NULL;
 	int ret;
 
 	ASSERT(!(fs_info->sb->s_flags & SB_RDONLY));
@@ -2304,7 +2304,7 @@ static int repair_io_failure(struct btrfs_fs_info *fs_info, u64 ino, u64 start,
 	map_length = length;
 
 	/*
-	 * Avoid races with device replace and make sure our bbio has devices
+	 * Avoid races with device replace and make sure our bioc has devices
 	 * associated to its stripes that don't go away while we are doing the
 	 * read repair operation.
 	 */
@@ -2317,28 +2317,28 @@ static int repair_io_failure(struct btrfs_fs_info *fs_info, u64 ino, u64 start,
 		 * stripe's dev and sector.
 		 */
 		ret = btrfs_map_block(fs_info, BTRFS_MAP_READ, logical,
-				      &map_length, &bbio, 0);
+				      &map_length, &bioc, 0);
 		if (ret) {
 			btrfs_bio_counter_dec(fs_info);
 			bio_put(bio);
 			return -EIO;
 		}
-		ASSERT(bbio->mirror_num == 1);
+		ASSERT(bioc->mirror_num == 1);
 	} else {
 		ret = btrfs_map_block(fs_info, BTRFS_MAP_WRITE, logical,
-				      &map_length, &bbio, mirror_num);
+				      &map_length, &bioc, mirror_num);
 		if (ret) {
 			btrfs_bio_counter_dec(fs_info);
 			bio_put(bio);
 			return -EIO;
 		}
-		BUG_ON(mirror_num != bbio->mirror_num);
+		BUG_ON(mirror_num != bioc->mirror_num);
 	}
 
-	sector = bbio->stripes[bbio->mirror_num - 1].physical >> 9;
+	sector = bioc->stripes[bioc->mirror_num - 1].physical >> 9;
 	bio->bi_iter.bi_sector = sector;
-	dev = bbio->stripes[bbio->mirror_num - 1].dev;
-	btrfs_put_bbio(bbio);
+	dev = bioc->stripes[bioc->mirror_num - 1].dev;
+	btrfs_put_bioc(bioc);
 	if (!dev || !dev->bdev ||
 	    !test_bit(BTRFS_DEV_STATE_WRITEABLE, &dev->dev_state)) {
 		btrfs_bio_counter_dec(fs_info);

fs/btrfs/extent_map.c

@@ -360,7 +360,7 @@ static void extent_map_device_set_bits(struct extent_map *em, unsigned bits)
 	int i;
 
 	for (i = 0; i < map->num_stripes; i++) {
-		struct btrfs_bio_stripe *stripe = &map->stripes[i];
+		struct btrfs_io_stripe *stripe = &map->stripes[i];
 		struct btrfs_device *device = stripe->dev;
 
 		set_extent_bits_nowait(&device->alloc_state, stripe->physical,
@@ -375,7 +375,7 @@ static void extent_map_device_clear_bits(struct extent_map *em, unsigned bits)
 	int i;
 
 	for (i = 0; i < map->num_stripes; i++) {
-		struct btrfs_bio_stripe *stripe = &map->stripes[i];
+		struct btrfs_io_stripe *stripe = &map->stripes[i];
 		struct btrfs_device *device = stripe->dev;
 
 		__clear_extent_bit(&device->alloc_state, stripe->physical,

fs/btrfs/raid56.h

@@ -31,24 +31,24 @@ struct btrfs_raid_bio;
 struct btrfs_device;
 
 int raid56_parity_recover(struct btrfs_fs_info *fs_info, struct bio *bio,
-			  struct btrfs_bio *bbio, u64 stripe_len,
+			  struct btrfs_io_context *bioc, u64 stripe_len,
 			  int mirror_num, int generic_io);
 int raid56_parity_write(struct btrfs_fs_info *fs_info, struct bio *bio,
-			       struct btrfs_bio *bbio, u64 stripe_len);
+			struct btrfs_io_context *bioc, u64 stripe_len);
 
 void raid56_add_scrub_pages(struct btrfs_raid_bio *rbio, struct page *page,
 			    u64 logical);
 
 struct btrfs_raid_bio *
 raid56_parity_alloc_scrub_rbio(struct btrfs_fs_info *fs_info, struct bio *bio,
-			       struct btrfs_bio *bbio, u64 stripe_len,
+			       struct btrfs_io_context *bioc, u64 stripe_len,
 			       struct btrfs_device *scrub_dev,
 			       unsigned long *dbitmap, int stripe_nsectors);
 void raid56_parity_submit_scrub_rbio(struct btrfs_raid_bio *rbio);
 
 struct btrfs_raid_bio *
 raid56_alloc_missing_rbio(struct btrfs_fs_info *fs_info, struct bio *bio,
-			  struct btrfs_bio *bbio, u64 length);
+			  struct btrfs_io_context *bioc, u64 length);
 void raid56_submit_missing_rbio(struct btrfs_raid_bio *rbio);
 
 int btrfs_alloc_stripe_hash_table(struct btrfs_fs_info *info);

fs/btrfs/reada.c

@@ -227,7 +227,7 @@ int btree_readahead_hook(struct extent_buffer *eb, int err)
 }
 
 static struct reada_zone *reada_find_zone(struct btrfs_device *dev, u64 logical,
-					  struct btrfs_bio *bbio)
+					  struct btrfs_io_context *bioc)
 {
 	struct btrfs_fs_info *fs_info = dev->fs_info;
 	int ret;
@@ -275,11 +275,11 @@ static struct reada_zone *reada_find_zone(struct btrfs_device *dev, u64 logical,
 	kref_init(&zone->refcnt);
 	zone->elems = 0;
 	zone->device = dev; /* our device always sits at index 0 */
-	for (i = 0; i < bbio->num_stripes; ++i) {
+	for (i = 0; i < bioc->num_stripes; ++i) {
 		/* bounds have already been checked */
-		zone->devs[i] = bbio->stripes[i].dev;
+		zone->devs[i] = bioc->stripes[i].dev;
 	}
-	zone->ndevs = bbio->num_stripes;
+	zone->ndevs = bioc->num_stripes;
 
 	spin_lock(&fs_info->reada_lock);
 	ret = radix_tree_insert(&dev->reada_zones,
@@ -309,7 +309,7 @@ static struct reada_extent *reada_find_extent(struct btrfs_fs_info *fs_info,
 	int ret;
 	struct reada_extent *re = NULL;
 	struct reada_extent *re_exist = NULL;
-	struct btrfs_bio *bbio = NULL;
+	struct btrfs_io_context *bioc = NULL;
 	struct btrfs_device *dev;
 	struct btrfs_device *prev_dev;
 	u64 length;
@@ -345,28 +345,28 @@ static struct reada_extent *reada_find_extent(struct btrfs_fs_info *fs_info,
 	 */
 	length = fs_info->nodesize;
 	ret = btrfs_map_block(fs_info, BTRFS_MAP_GET_READ_MIRRORS, logical,
-			&length, &bbio, 0);
-	if (ret || !bbio || length < fs_info->nodesize)
+			      &length, &bioc, 0);
+	if (ret || !bioc || length < fs_info->nodesize)
 		goto error;
 
-	if (bbio->num_stripes > BTRFS_MAX_MIRRORS) {
+	if (bioc->num_stripes > BTRFS_MAX_MIRRORS) {
 		btrfs_err(fs_info,
 			   "readahead: more than %d copies not supported",
 			   BTRFS_MAX_MIRRORS);
 		goto error;
 	}
 
-	real_stripes = bbio->num_stripes - bbio->num_tgtdevs;
+	real_stripes = bioc->num_stripes - bioc->num_tgtdevs;
 	for (nzones = 0; nzones < real_stripes; ++nzones) {
 		struct reada_zone *zone;
 
-		dev = bbio->stripes[nzones].dev;
+		dev = bioc->stripes[nzones].dev;
 
 		/* cannot read ahead on missing device. */
 		if (!dev->bdev)
 			continue;
 
-		zone = reada_find_zone(dev, logical, bbio);
+		zone = reada_find_zone(dev, logical, bioc);
 		if (!zone)
 			continue;
 
@@ -464,7 +464,7 @@ static struct reada_extent *reada_find_extent(struct btrfs_fs_info *fs_info,
 	if (!have_zone)
 		goto error;
 
-	btrfs_put_bbio(bbio);
+	btrfs_put_bioc(bioc);
 	return re;
 
 error:
@@ -488,7 +488,7 @@ static struct reada_extent *reada_find_extent(struct btrfs_fs_info *fs_info,
 		kref_put(&zone->refcnt, reada_zone_release);
 		spin_unlock(&fs_info->reada_lock);
 	}
-	btrfs_put_bbio(bbio);
+	btrfs_put_bioc(bioc);
 	kfree(re);
 	return re_exist;
 }

fs/btrfs/volumes.h

@@ -306,11 +306,11 @@ struct btrfs_fs_devices {
 /*
  * we need the mirror number and stripe index to be passed around
  * the call chain while we are processing end_io (especially errors).
- * Really, what we need is a btrfs_bio structure that has this info
+ * Really, what we need is a btrfs_io_context structure that has this info
  * and is properly sized with its stripe array, but we're not there
  * quite yet.  We have our own btrfs bioset, and all of the bios
  * we allocate are actually btrfs_io_bios.  We'll cram as much of
- * struct btrfs_bio as we can into this over time.
+ * struct btrfs_io_context as we can into this over time.
  */
 struct btrfs_io_bio {
 	unsigned int mirror_num;
@@ -339,13 +339,29 @@ static inline void btrfs_io_bio_free_csum(struct btrfs_io_bio *io_bio)
 	}
 }
 
-struct btrfs_bio_stripe {
+struct btrfs_io_stripe {
 	struct btrfs_device *dev;
 	u64 physical;
 	u64 length; /* only used for discard mappings */
 };
 
-struct btrfs_bio {
+/*
+ * Context for IO subsmission for device stripe.
+ *
+ * - Track the unfinished mirrors for mirror based profiles
+ *   Mirror based profiles are SINGLE/DUP/RAID1/RAID10.
+ *
+ * - Contain the logical -> physical mapping info
+ *   Used by submit_stripe_bio() for mapping logical bio
+ *   into physical device address.
+ *
+ * - Contain device replace info
+ *   Used by handle_ops_on_dev_replace() to copy logical bios
+ *   into the new device.
+ *
+ * - Contain RAID56 full stripe logical bytenrs
+ */
+struct btrfs_io_context {
 	refcount_t refs;
 	atomic_t stripes_pending;
 	struct btrfs_fs_info *fs_info;
@@ -365,7 +381,7 @@ struct btrfs_bio {
 	 * so raid_map[0] is the start of our full stripe
 	 */
 	u64 *raid_map;
-	struct btrfs_bio_stripe stripes[];
+	struct btrfs_io_stripe stripes[];
 };
 
 struct btrfs_device_info {
@@ -400,11 +416,11 @@ struct map_lookup {
 	int num_stripes;
 	int sub_stripes;
 	int verified_stripes; /* For mount time dev extent verification */
-	struct btrfs_bio_stripe stripes[];
+	struct btrfs_io_stripe stripes[];
 };
 
 #define map_lookup_size(n) (sizeof(struct map_lookup) + \
-			    (sizeof(struct btrfs_bio_stripe) * (n)))
+			    (sizeof(struct btrfs_io_stripe) * (n)))
 
 struct btrfs_balance_args;
 struct btrfs_balance_progress;
@@ -441,14 +457,14 @@ static inline enum btrfs_map_op btrfs_op(struct bio *bio)
 	}
 }
 
-void btrfs_get_bbio(struct btrfs_bio *bbio);
-void btrfs_put_bbio(struct btrfs_bio *bbio);
+void btrfs_get_bioc(struct btrfs_io_context *bioc);
+void btrfs_put_bioc(struct btrfs_io_context *bioc);
 int btrfs_map_block(struct btrfs_fs_info *fs_info, enum btrfs_map_op op,
 		    u64 logical, u64 *length,
-		    struct btrfs_bio **bbio_ret, int mirror_num);
+		    struct btrfs_io_context **bioc_ret, int mirror_num);
 int btrfs_map_sblock(struct btrfs_fs_info *fs_info, enum btrfs_map_op op,
 		     u64 logical, u64 *length,
-		     struct btrfs_bio **bbio_ret);
+		     struct btrfs_io_context **bioc_ret);
 int btrfs_get_io_geometry(struct btrfs_fs_info *fs_info, struct extent_map *map,
 			  enum btrfs_map_op op, u64 logical,
 			  struct btrfs_io_geometry *io_geom);

fs/btrfs/zoned.c

@@ -1637,27 +1637,27 @@ int btrfs_zoned_issue_zeroout(struct btrfs_device *device, u64 physical, u64 len
 static int read_zone_info(struct btrfs_fs_info *fs_info, u64 logical,
 			  struct blk_zone *zone)
 {
-	struct btrfs_bio *bbio = NULL;
+	struct btrfs_io_context *bioc = NULL;
 	u64 mapped_length = PAGE_SIZE;
 	unsigned int nofs_flag;
 	int nmirrors;
 	int i, ret;
 
 	ret = btrfs_map_sblock(fs_info, BTRFS_MAP_GET_READ_MIRRORS, logical,
-			       &mapped_length, &bbio);
-	if (ret || !bbio || mapped_length < PAGE_SIZE) {
-		btrfs_put_bbio(bbio);
+			       &mapped_length, &bioc);
+	if (ret || !bioc || mapped_length < PAGE_SIZE) {
+		btrfs_put_bioc(bioc);
 		return -EIO;
 	}
 
-	if (bbio->map_type & BTRFS_BLOCK_GROUP_RAID56_MASK)
+	if (bioc->map_type & BTRFS_BLOCK_GROUP_RAID56_MASK)
 		return -EINVAL;
 
 	nofs_flag = memalloc_nofs_save();
-	nmirrors = (int)bbio->num_stripes;
+	nmirrors = (int)bioc->num_stripes;
 	for (i = 0; i < nmirrors; i++) {
-		u64 physical = bbio->stripes[i].physical;
-		struct btrfs_device *dev = bbio->stripes[i].dev;
+		u64 physical = bioc->stripes[i].physical;
+		struct btrfs_device *dev = bioc->stripes[i].dev;
 
 		/* Missing device */
 		if (!dev->bdev)