Btrfs, replace: write dirty pages into the replace target device
The implementation is simple:
- In order to avoid changing the code logic of btrfs_map_bio and
RAID56, we add the stripes of the replace target devices at the
end of the stripe array in btrfs bio, and we sort those target
device stripes in the array. And we keep the number of the target
device stripes in the btrfs bio.
- Except write operation on RAID56, all the other operation don't
take the target device stripes into account.
- When we do write operation, we read the data from the common devices
and calculate the parity. Then write the dirty data and new parity
out, at this time, we will find the relative replace target stripes
and wirte the relative data into it.
Note: The function that copying old data on the source device to
the target device was implemented in the past, it is similar to
the other RAID type.
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 217c42e..6d8a5e8 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -4881,13 +4881,15 @@
static void sort_parity_stripes(struct btrfs_bio *bbio, u64 *raid_map)
{
struct btrfs_bio_stripe s;
+ int real_stripes = bbio->num_stripes - bbio->num_tgtdevs;
int i;
u64 l;
int again = 1;
+ int m;
while (again) {
again = 0;
- for (i = 0; i < bbio->num_stripes - 1; i++) {
+ for (i = 0; i < real_stripes - 1; i++) {
if (parity_smaller(raid_map[i], raid_map[i+1])) {
s = bbio->stripes[i];
l = raid_map[i];
@@ -4895,6 +4897,14 @@
raid_map[i] = raid_map[i+1];
bbio->stripes[i+1] = s;
raid_map[i+1] = l;
+
+ if (bbio->tgtdev_map) {
+ m = bbio->tgtdev_map[i];
+ bbio->tgtdev_map[i] =
+ bbio->tgtdev_map[i + 1];
+ bbio->tgtdev_map[i + 1] = m;
+ }
+
again = 1;
}
}
@@ -4923,6 +4933,7 @@
int ret = 0;
int num_stripes;
int max_errors = 0;
+ int tgtdev_indexes = 0;
struct btrfs_bio *bbio = NULL;
struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
int dev_replace_is_ongoing = 0;
@@ -5234,14 +5245,19 @@
num_alloc_stripes <<= 1;
if (rw & REQ_GET_READ_MIRRORS)
num_alloc_stripes++;
+ tgtdev_indexes = num_stripes;
}
- bbio = kzalloc(btrfs_bio_size(num_alloc_stripes), GFP_NOFS);
+
+ bbio = kzalloc(btrfs_bio_size(num_alloc_stripes, tgtdev_indexes),
+ GFP_NOFS);
if (!bbio) {
kfree(raid_map);
ret = -ENOMEM;
goto out;
}
atomic_set(&bbio->error, 0);
+ if (dev_replace_is_ongoing)
+ bbio->tgtdev_map = (int *)(bbio->stripes + num_alloc_stripes);
if (rw & REQ_DISCARD) {
int factor = 0;
@@ -5326,6 +5342,7 @@
if (rw & (REQ_WRITE | REQ_GET_READ_MIRRORS))
max_errors = btrfs_chunk_max_errors(map);
+ tgtdev_indexes = 0;
if (dev_replace_is_ongoing && (rw & (REQ_WRITE | REQ_DISCARD)) &&
dev_replace->tgtdev != NULL) {
int index_where_to_add;
@@ -5354,8 +5371,10 @@
new->physical = old->physical;
new->length = old->length;
new->dev = dev_replace->tgtdev;
+ bbio->tgtdev_map[i] = index_where_to_add;
index_where_to_add++;
max_errors++;
+ tgtdev_indexes++;
}
}
num_stripes = index_where_to_add;
@@ -5401,7 +5420,9 @@
tgtdev_stripe->length =
bbio->stripes[index_srcdev].length;
tgtdev_stripe->dev = dev_replace->tgtdev;
+ bbio->tgtdev_map[index_srcdev] = num_stripes;
+ tgtdev_indexes++;
num_stripes++;
}
}
@@ -5411,6 +5432,7 @@
bbio->num_stripes = num_stripes;
bbio->max_errors = max_errors;
bbio->mirror_num = mirror_num;
+ bbio->num_tgtdevs = tgtdev_indexes;
/*
* this is the case that REQ_READ && dev_replace_is_ongoing &&