On Tue 29 Dec 2020 at 21:29, Qu Wenruo <w...@suse.com> wrote:
[BUG]
There are several bug reports about recent kernel unable to
relocate
certain data block groups.
Sometimes the error just go away, but there is one reporter who
can
reproduce it reliably.
The dmesg would look like:
[ 438.260483] BTRFS info (device dm-10): balance: start
-dvrange=34625344765952..34625344765953
[ 438.269018] BTRFS info (device dm-10): relocating block group
34625344765952 flags data|raid1
[ 450.439609] BTRFS info (device dm-10): found 167 extents,
stage: move data extents
[ 463.501781] BTRFS info (device dm-10): balance: ended with
status: -2
[CAUSE]
The -ENOENT error is returned from the following chall chain:
add_data_references()
|- delete_v1_space_cache();
|- if (!found)
return -ENOENT;
The variable @found is set to true if we find a data extent
whose
disk bytenr matches parameter @data_bytes.
With extra debug, the offending tree block looks like this:
leaf bytenr = 42676709441536, data_bytenr = 34626327621632
ctime 1567904822.739884119 (2019-09-08 03:07:02)
mtime 0.0 (1970-01-01 01:00:00)
otime 0.0 (1970-01-01 01:00:00)
item 27 key (51933 EXTENT_DATA 0) itemoff 9854 itemsize
53
generation 1517381 type 2 (prealloc)
prealloc data disk byte 34626327621632 nr 262144
<<<
prealloc data offset 0 nr 262144
item 28 key (52262 ROOT_ITEM 0) itemoff 9415 itemsize
439
generation 2618893 root_dirid 256 bytenr
42677048360960 level 3 refs 1
lastsnap 2618893 byte_limit 0 bytes_used
5557338112 flags 0x0(none)
uuid d0d4361f-d231-6d40-8901-fe506e4b2b53
Although item 27 has disk bytenr 34626327621632, which matches
the
data_bytenr, its type is prealloc, not reg.
This makes the existing code skip that item, and return -ENOENT.
[FIX]
The code is modified in commit 19b546d7a1b2 ("btrfs:
relocation: Use
btrfs_find_all_leafs to locate data extent parent tree leaves"),
before
that commit, we use something like
"if (type == BTRFS_FILE_EXTENT_INLINE) continue;".
But in that offending commit, we use (type ==
BTRFS_FILE_EXTENT_REG),
ignoring BTRFS_FILE_EXTENT_PREALLOC.
Fix it by also checking BTRFS_FILE_EXTENT_PREALLOC.
Reported-by: Stéphane Lesimple <stephane_btr...@lesimple.fr>
Fixes: 19b546d7a1b2 ("btrfs: relocation: Use
btrfs_find_all_leafs to locate data extent parent tree leaves")
Signed-off-by: Qu Wenruo <w...@suse.com>
Reviewed-by: Su Yue <l...@damenly.su>
---
fs/btrfs/relocation.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
index 19b7db8b2117..df63ef64c5c0 100644
--- a/fs/btrfs/relocation.c
+++ b/fs/btrfs/relocation.c
@@ -2975,11 +2975,16 @@ static int delete_v1_space_cache(struct
extent_buffer *leaf,
return 0;
for (i = 0; i < btrfs_header_nritems(leaf); i++) {
+ u8 type;
+
btrfs_item_key_to_cpu(leaf, &key, i);
if (key.type != BTRFS_EXTENT_DATA_KEY)
continue;
ei = btrfs_item_ptr(leaf, i, struct
btrfs_file_extent_item);
- if (btrfs_file_extent_type(leaf, ei) ==
BTRFS_FILE_EXTENT_REG &&
+ type = btrfs_file_extent_type(leaf, ei);
+
+ if ((type == BTRFS_FILE_EXTENT_REG ||
+ type == BTRFS_FILE_EXTENT_PREALLOC) &&
btrfs_file_extent_disk_bytenr(leaf, ei) ==
data_bytenr) {
found = true;
space_cache_ino = key.objectid;
