If device tree has hole, find_free_dev_extent() cannot find available
address properly.
The problem can be reproduce by following script.
mntpath=/btrfs
loopdev=/dev/loop0
filepath=/home/forrest/image
umount $mntpath
losetup -d $loopdev
truncate --size 100g $filepath
losetup $loopdev $filepath
mkfs.btrfs -f $loopdev
mount $loopdev $mntpath
# make device tree with one big hole
for i in `seq 1 1 100`; do
fallocate -l 1g $mntpath/$i
done
sync
for i in `seq 1 1 95`; do
rm $mntpath/$i
done
sync
# wait cleaner thread remove unused block group
sleep 300
fallocate -l 1g $mntpath/aaa
# failed to allocate new chunk
fallocate -l 1g $mntpath/bbb
Above script will make device tree with one big hole, and can only allocate
just one chunk in a transaction, so failed to allocate new chunk for
$mntpath/bbb
item 8 key (1 DEV_EXTENT 2185232384) itemoff 15859 itemsize 48
dev extent chunk_tree 3
chunk objectid 256 chunk offset 106292051968 length 1073741824
item 9 key (1 DEV_EXTENT 104190705664) itemoff 15811 itemsize 48
dev extent chunk_tree 3
chunk objectid 256 chunk offset 103108575232 length 1073741824
Signed-off-by: Forrest Liu <forre...@synology.com>
Reviewed-by: Liu Bo <bo.li....@oracle.com>
---
V2: fix typo key_offset
replace WARN_ON with WARN_ON_ONCE
V3: add missing {} to stick to kernel coding style
add reprducing step in commit message
fs/btrfs/volumes.c | 15 +++++++++++----
1 file changed, 11 insertions(+), 4 deletions(-)
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 50c5a87..ddda8a0 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -1060,6 +1060,7 @@ static int contains_pending_extent(struct
btrfs_trans_handle *trans,
struct extent_map *em;
struct list_head *search_list = &trans->transaction->pending_chunks;
int ret = 0;
+ u64 physical_start = *start;
again:
list_for_each_entry(em, search_list, list) {
@@ -1070,9 +1071,9 @@ again:
for (i = 0; i < map->num_stripes; i++) {
if (map->stripes[i].dev != device)
continue;
- if (map->stripes[i].physical >= *start + len ||
+ if (map->stripes[i].physical >= physical_start + len ||
map->stripes[i].physical + em->orig_block_len <=
- *start)
+ physical_start)
continue;
*start = map->stripes[i].physical +
em->orig_block_len;
@@ -1195,8 +1196,14 @@ again:
*/
if (contains_pending_extent(trans, device,
&search_start,
- hole_size))
- hole_size = 0;
+ hole_size)) {
+ if (key.offset >= search_start) {
+ hole_size = key.offset - search_start;
+ } else {
+ WARN_ON_ONCE(1);
+ hole_size = 0;
+ }
+ }
if (hole_size > max_hole_size) {
max_hole_start = search_start;
--
1.9.1
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