* [PATCH] btrfs: add remap-tree checks to check_block_group_item()
@ 2026-03-23 17:26 Mark Harmstone
2026-03-23 19:43 ` David Sterba
0 siblings, 1 reply; 3+ messages in thread
From: Mark Harmstone @ 2026-03-23 17:26 UTC (permalink / raw)
To: linux-btrfs; +Cc: Mark Harmstone
Add some write-time checks for block group items relating to the remap
tree.
Here we're checking:
* That the REMAPPED or METADATA_REMAP flags aren't set unless the
REMAP_TREE incompat flag is also set
* That `remap_bytes` isn't more than the size of the block group
* That `identity_remap_count` isn't more than the number of sectors in
the block group
Signed-off-by: Mark Harmstone <mark@harmstone.com>
---
fs/btrfs/tree-checker.c | 42 +++++++++++++++++++++++++++++++++++++++++
1 file changed, 42 insertions(+)
diff --git a/fs/btrfs/tree-checker.c b/fs/btrfs/tree-checker.c
index 495d1dd61e66c2..cad23f3fadfd34 100644
--- a/fs/btrfs/tree-checker.c
+++ b/fs/btrfs/tree-checker.c
@@ -777,6 +777,48 @@ static int check_block_group_item(struct extent_buffer *leaf,
BTRFS_BLOCK_GROUP_METADATA | BTRFS_BLOCK_GROUP_DATA);
return -EUCLEAN;
}
+
+ if (unlikely(!btrfs_fs_incompat(fs_info, REMAP_TREE) &&
+ type == BTRFS_BLOCK_GROUP_METADATA_REMAP)) {
+ block_group_err(leaf, slot,
+"invalid type, METADATA_REMAP set but REMAP_TREE incompat flag not set");
+ return -EUCLEAN;
+ }
+
+ if (unlikely(!btrfs_fs_incompat(fs_info, REMAP_TREE) &&
+ flags & BTRFS_BLOCK_GROUP_REMAPPED)) {
+ block_group_err(leaf, slot,
+"invalid flags, REMAPPED set but REMAP_TREE incompat flag not set");
+ return -EUCLEAN;
+ }
+
+ if (item_size == sizeof(struct btrfs_block_group_item_v2)) {
+ struct btrfs_block_group_item_v2 *bgi2;
+ u64 remap_bytes;
+ u32 identity_remap_count;
+
+ bgi2 = btrfs_item_ptr(leaf, slot, struct btrfs_block_group_item_v2);
+
+ remap_bytes = btrfs_block_group_v2_remap_bytes(leaf, bgi2);
+
+ if (unlikely(remap_bytes > key->offset)) {
+ block_group_err(leaf, slot,
+ "invalid remap_bytes, have %llu expect [0, %llu]",
+ remap_bytes, key->offset);
+ return -EUCLEAN;
+ }
+
+ identity_remap_count = btrfs_block_group_v2_identity_remap_count(leaf, bgi2);
+ if (unlikely((u64)identity_remap_count >
+ key->offset / fs_info->sectorsize)) {
+ block_group_err(leaf, slot,
+ "invalid identity_remap_count, have %u expect [0, %llu]",
+ identity_remap_count,
+ key->offset / fs_info->sectorsize);
+ return -EUCLEAN;
+ }
+ }
+
return 0;
}
--
2.52.0
^ permalink raw reply related [flat|nested] 3+ messages in thread* Re: [PATCH] btrfs: add remap-tree checks to check_block_group_item()
2026-03-23 17:26 [PATCH] btrfs: add remap-tree checks to check_block_group_item() Mark Harmstone
@ 2026-03-23 19:43 ` David Sterba
2026-03-25 12:54 ` Mark Harmstone
0 siblings, 1 reply; 3+ messages in thread
From: David Sterba @ 2026-03-23 19:43 UTC (permalink / raw)
To: Mark Harmstone; +Cc: linux-btrfs
On Mon, Mar 23, 2026 at 05:26:13PM +0000, Mark Harmstone wrote:
> Add some write-time checks for block group items relating to the remap
> tree.
>
> Here we're checking:
> * That the REMAPPED or METADATA_REMAP flags aren't set unless the
> REMAP_TREE incompat flag is also set
> * That `remap_bytes` isn't more than the size of the block group
> * That `identity_remap_count` isn't more than the number of sectors in
> the block group
>
> Signed-off-by: Mark Harmstone <mark@harmstone.com>
> ---
> fs/btrfs/tree-checker.c | 42 +++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 42 insertions(+)
>
> diff --git a/fs/btrfs/tree-checker.c b/fs/btrfs/tree-checker.c
> index 495d1dd61e66c2..cad23f3fadfd34 100644
> --- a/fs/btrfs/tree-checker.c
> +++ b/fs/btrfs/tree-checker.c
> @@ -777,6 +777,48 @@ static int check_block_group_item(struct extent_buffer *leaf,
> BTRFS_BLOCK_GROUP_METADATA | BTRFS_BLOCK_GROUP_DATA);
> return -EUCLEAN;
> }
> +
> + if (unlikely(!btrfs_fs_incompat(fs_info, REMAP_TREE) &&
> + type == BTRFS_BLOCK_GROUP_METADATA_REMAP)) {
> + block_group_err(leaf, slot,
> +"invalid type, METADATA_REMAP set but REMAP_TREE incompat flag not set");
> + return -EUCLEAN;
> + }
> +
> + if (unlikely(!btrfs_fs_incompat(fs_info, REMAP_TREE) &&
> + flags & BTRFS_BLOCK_GROUP_REMAPPED)) {
> + block_group_err(leaf, slot,
> +"invalid flags, REMAPPED set but REMAP_TREE incompat flag not set");
> + return -EUCLEAN;
> + }
> +
> + if (item_size == sizeof(struct btrfs_block_group_item_v2)) {
> + struct btrfs_block_group_item_v2 *bgi2;
> + u64 remap_bytes;
> + u32 identity_remap_count;
> +
> + bgi2 = btrfs_item_ptr(leaf, slot, struct btrfs_block_group_item_v2);
> +
> + remap_bytes = btrfs_block_group_v2_remap_bytes(leaf, bgi2);
> +
> + if (unlikely(remap_bytes > key->offset)) {
> + block_group_err(leaf, slot,
> + "invalid remap_bytes, have %llu expect [0, %llu]",
> + remap_bytes, key->offset);
> + return -EUCLEAN;
> + }
> +
> + identity_remap_count = btrfs_block_group_v2_identity_remap_count(leaf, bgi2);
> + if (unlikely((u64)identity_remap_count >
> + key->offset / fs_info->sectorsize)) {
64bit / 32bit may not work on all arches, we have the sectorize_bits to
avoid it.
> + block_group_err(leaf, slot,
> + "invalid identity_remap_count, have %u expect [0, %llu]",
> + identity_remap_count,
> + key->offset / fs_info->sectorsize);
> + return -EUCLEAN;
> + }
> + }
> +
> return 0;
> }
>
> --
> 2.52.0
>
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH] btrfs: add remap-tree checks to check_block_group_item()
2026-03-23 19:43 ` David Sterba
@ 2026-03-25 12:54 ` Mark Harmstone
0 siblings, 0 replies; 3+ messages in thread
From: Mark Harmstone @ 2026-03-25 12:54 UTC (permalink / raw)
To: dsterba; +Cc: linux-btrfs
On 23/03/2026 7.43 pm, David Sterba wrote:
> On Mon, Mar 23, 2026 at 05:26:13PM +0000, Mark Harmstone wrote:
>> Add some write-time checks for block group items relating to the remap
>> tree.
>>
>> Here we're checking:
>> * That the REMAPPED or METADATA_REMAP flags aren't set unless the
>> REMAP_TREE incompat flag is also set
>> * That `remap_bytes` isn't more than the size of the block group
>> * That `identity_remap_count` isn't more than the number of sectors in
>> the block group
>>
>> Signed-off-by: Mark Harmstone <mark@harmstone.com>
>> ---
>> fs/btrfs/tree-checker.c | 42 +++++++++++++++++++++++++++++++++++++++++
>> 1 file changed, 42 insertions(+)
>>
>> diff --git a/fs/btrfs/tree-checker.c b/fs/btrfs/tree-checker.c
>> index 495d1dd61e66c2..cad23f3fadfd34 100644
>> --- a/fs/btrfs/tree-checker.c
>> +++ b/fs/btrfs/tree-checker.c
>> @@ -777,6 +777,48 @@ static int check_block_group_item(struct extent_buffer *leaf,
>> BTRFS_BLOCK_GROUP_METADATA | BTRFS_BLOCK_GROUP_DATA);
>> return -EUCLEAN;
>> }
>> +
>> + if (unlikely(!btrfs_fs_incompat(fs_info, REMAP_TREE) &&
>> + type == BTRFS_BLOCK_GROUP_METADATA_REMAP)) {
>> + block_group_err(leaf, slot,
>> +"invalid type, METADATA_REMAP set but REMAP_TREE incompat flag not set");
>> + return -EUCLEAN;
>> + }
>> +
>> + if (unlikely(!btrfs_fs_incompat(fs_info, REMAP_TREE) &&
>> + flags & BTRFS_BLOCK_GROUP_REMAPPED)) {
>> + block_group_err(leaf, slot,
>> +"invalid flags, REMAPPED set but REMAP_TREE incompat flag not set");
>> + return -EUCLEAN;
>> + }
>> +
>> + if (item_size == sizeof(struct btrfs_block_group_item_v2)) {
>> + struct btrfs_block_group_item_v2 *bgi2;
>> + u64 remap_bytes;
>> + u32 identity_remap_count;
>> +
>> + bgi2 = btrfs_item_ptr(leaf, slot, struct btrfs_block_group_item_v2);
>> +
>> + remap_bytes = btrfs_block_group_v2_remap_bytes(leaf, bgi2);
>> +
>> + if (unlikely(remap_bytes > key->offset)) {
>> + block_group_err(leaf, slot,
>> + "invalid remap_bytes, have %llu expect [0, %llu]",
>> + remap_bytes, key->offset);
>> + return -EUCLEAN;
>> + }
>> +
>> + identity_remap_count = btrfs_block_group_v2_identity_remap_count(leaf, bgi2);
>> + if (unlikely((u64)identity_remap_count >
>> + key->offset / fs_info->sectorsize)) {
>
> 64bit / 32bit may not work on all arches, we have the sectorize_bits to
> avoid it.
Annoying. Thank you, I've sent another patch.
>> + block_group_err(leaf, slot,
>> + "invalid identity_remap_count, have %u expect [0, %llu]",
>> + identity_remap_count,
>> + key->offset / fs_info->sectorsize);
>> + return -EUCLEAN;
>> + }
>> + }
>> +
>> return 0;
>> }
>>
>> --
>> 2.52.0
>>
^ permalink raw reply [flat|nested] 3+ messages in thread
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2026-03-23 17:26 [PATCH] btrfs: add remap-tree checks to check_block_group_item() Mark Harmstone
2026-03-23 19:43 ` David Sterba
2026-03-25 12:54 ` Mark Harmstone
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