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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: Stefan Behrens <sbehrens@giantdisaster.de>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
This commit is contained in:
Stefan Behrens 2012-11-06 14:43:46 +01:00 committed by Josef Bacik
parent 29a8d9a0bc
commit 472262f35a
1 changed files with 49 additions and 1 deletions
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50
fs/btrfs/volumes.c
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@ -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;
}