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Commit 472262f3 authored by Stefan Behrens's avatar Stefan Behrens Committed by Josef Bacik
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Btrfs: changes to live filesystem are also written to replacement disk 



During a running dev replace operation, all write requests to
the live filesystem are duplicated to also write to the target
drive. Therefore btrfs_map_block() is changed to duplicate
stripes that are written to the source disk of a device replace
procedure to be written to the target disk as well.

Signed-off-by: default avatarStefan Behrens <sbehrens@giantdisaster.de>
Signed-off-by: default avatarChris Mason <chris.mason@fusionio.com>
parent 29a8d9a0

fs/btrfs/volumes.c

+49 −1
Original line number Diff line number Diff line
@@ -4044,6 +4044,9 @@ static int __btrfs_map_block(struct btrfs_fs_info *fs_info, int rw, 
	int num_stripes;

	int max_errors = 0;

	struct btrfs_bio *bbio = NULL;

	struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;

	int dev_replace_is_ongoing = 0;

	int num_alloc_stripes;



	read_lock(&em_tree->lock);

	em = lookup_extent_mapping(em_tree, logical, *length);
@@ -4089,6 +4092,11 @@ static int __btrfs_map_block(struct btrfs_fs_info *fs_info, int rw, 
	if (!bbio_ret)

		goto out;



	btrfs_dev_replace_lock(dev_replace);

	dev_replace_is_ongoing = btrfs_dev_replace_is_ongoing(dev_replace);

	if (!dev_replace_is_ongoing)

		btrfs_dev_replace_unlock(dev_replace);



	num_stripes = 1;

	stripe_index = 0;

	stripe_nr_orig = stripe_nr;
@@ -4155,7 +4163,10 @@ static int __btrfs_map_block(struct btrfs_fs_info *fs_info, int rw, 
	}

	BUG_ON(stripe_index >= map->num_stripes);



	bbio = kzalloc(btrfs_bio_size(num_stripes), GFP_NOFS);

	num_alloc_stripes = num_stripes;

	if (dev_replace_is_ongoing && (rw & (REQ_WRITE | REQ_DISCARD)))

		num_alloc_stripes <<= 1;

	bbio = kzalloc(btrfs_bio_size(num_alloc_stripes), GFP_NOFS);

	if (!bbio) {

		ret = -ENOMEM;

		goto out;
@@ -4250,11 +4261,48 @@ static int __btrfs_map_block(struct btrfs_fs_info *fs_info, int rw, 
		}

	}



	if (dev_replace_is_ongoing && (rw & (REQ_WRITE | REQ_DISCARD)) &&

	    dev_replace->tgtdev != NULL) {

		int index_where_to_add;

		u64 srcdev_devid = dev_replace->srcdev->devid;



		/*

		 * duplicate the write operations while the dev replace

		 * procedure is running. Since the copying of the old disk

		 * to the new disk takes place at run time while the

		 * filesystem is mounted writable, the regular write

		 * operations to the old disk have to be duplicated to go

		 * to the new disk as well.

		 * Note that device->missing is handled by the caller, and

		 * that the write to the old disk is already set up in the

		 * stripes array.

		 */

		index_where_to_add = num_stripes;

		for (i = 0; i < num_stripes; i++) {

			if (bbio->stripes[i].dev->devid == srcdev_devid) {

				/* write to new disk, too */

				struct btrfs_bio_stripe *new =

					bbio->stripes + index_where_to_add;

				struct btrfs_bio_stripe *old =

					bbio->stripes + i;



				new->physical = old->physical;

				new->length = old->length;

				new->dev = dev_replace->tgtdev;

				index_where_to_add++;

				max_errors++;

			}

		}

		num_stripes = index_where_to_add;

	}



	*bbio_ret = bbio;

	bbio->num_stripes = num_stripes;

	bbio->max_errors = max_errors;

	bbio->mirror_num = mirror_num;

out:

	if (dev_replace_is_ongoing)

		btrfs_dev_replace_unlock(dev_replace);

	free_extent_map(em);

	return ret;

}