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btrfs: do not BUG_ON() when freeing tree block after error

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When freeing a tree block, at btrfs_free_tree_block(), if we fail to
create a delayed reference we don't deal with the error and just do a
BUG_ON(). The error most likely to happen is -ENOMEM, and we have a
comment mentioning that only -ENOMEM can happen, but that is not true,
because in case qgroups are enabled any error returned from
btrfs_qgroup_trace_extent_post() (can be -EUCLEAN or anything returned
from btrfs_search_slot() for example) can be propagated back to
btrfs_free_tree_block().

So stop doing a BUG_ON() and return the error to the callers and make
them abort the transaction to prevent leaking space. Syzbot was
triggering this, likely due to memory allocation failure injection.

Reported-by: syzbot+a306f914b4d01b3958fe@syzkaller.appspotmail.com
Link: https://lore.kernel.org/linux-btrfs/000000000000fcba1e05e998263c@google.com/
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Filipe Manana 2024-06-14 14:50:47 +01:00 committed by David Sterba
parent b751915765
commit bb3868033a
6 changed files with 76 additions and 31 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

53
fs/btrfs/ctree.c
View File

@ -620,10 +620,16 @@ int btrfs_force_cow_block(struct btrfs_trans_handle *trans,
atomic_inc(&cow->refs);
rcu_assign_pointer(root->node, cow);
btrfs_free_tree_block(trans, btrfs_root_id(root), buf,
parent_start, last_ref);
ret = btrfs_free_tree_block(trans, btrfs_root_id(root), buf,
parent_start, last_ref);
free_extent_buffer(buf);
add_root_to_dirty_list(root);
if (ret < 0) {
btrfs_tree_unlock(cow);
free_extent_buffer(cow);
btrfs_abort_transaction(trans, ret);
return ret;
}
} else {
WARN_ON(trans->transid != btrfs_header_generation(parent));
ret = btrfs_tree_mod_log_insert_key(parent, parent_slot,
@ -648,8 +654,14 @@ int btrfs_force_cow_block(struct btrfs_trans_handle *trans,
return ret;
}
}
btrfs_free_tree_block(trans, btrfs_root_id(root), buf,
parent_start, last_ref);
ret = btrfs_free_tree_block(trans, btrfs_root_id(root), buf,
parent_start, last_ref);
if (ret < 0) {
btrfs_tree_unlock(cow);
free_extent_buffer(cow);
btrfs_abort_transaction(trans, ret);
return ret;
}
}
if (unlock_orig)
btrfs_tree_unlock(buf);
@ -983,9 +995,13 @@ static noinline int balance_level(struct btrfs_trans_handle *trans,
free_extent_buffer(mid);
root_sub_used_bytes(root);
btrfs_free_tree_block(trans, btrfs_root_id(root), mid, 0, 1);
ret = btrfs_free_tree_block(trans, btrfs_root_id(root), mid, 0, 1);
/* once for the root ptr */
free_extent_buffer_stale(mid);
if (ret < 0) {
btrfs_abort_transaction(trans, ret);
goto out;
}
return 0;
}
if (btrfs_header_nritems(mid) >
@ -1053,10 +1069,14 @@ static noinline int balance_level(struct btrfs_trans_handle *trans,
goto out;
}
root_sub_used_bytes(root);
btrfs_free_tree_block(trans, btrfs_root_id(root), right,
0, 1);
ret = btrfs_free_tree_block(trans, btrfs_root_id(root),
right, 0, 1);
free_extent_buffer_stale(right);
right = NULL;
if (ret < 0) {
btrfs_abort_transaction(trans, ret);
goto out;
}
} else {
struct btrfs_disk_key right_key;
btrfs_node_key(right, &right_key, 0);
@ -1111,9 +1131,13 @@ static noinline int balance_level(struct btrfs_trans_handle *trans,
goto out;
}
root_sub_used_bytes(root);
btrfs_free_tree_block(trans, btrfs_root_id(root), mid, 0, 1);
ret = btrfs_free_tree_block(trans, btrfs_root_id(root), mid, 0, 1);
free_extent_buffer_stale(mid);
mid = NULL;
if (ret < 0) {
btrfs_abort_transaction(trans, ret);
goto out;
}
} else {
/* update the parent key to reflect our changes */
struct btrfs_disk_key mid_key;
@ -2878,7 +2902,11 @@ static noinline int insert_new_root(struct btrfs_trans_handle *trans,
old = root->node;
ret = btrfs_tree_mod_log_insert_root(root->node, c, false);
if (ret < 0) {
btrfs_free_tree_block(trans, btrfs_root_id(root), c, 0, 1);
int ret2;
ret2 = btrfs_free_tree_block(trans, btrfs_root_id(root), c, 0, 1);
if (ret2 < 0)
btrfs_abort_transaction(trans, ret2);
btrfs_tree_unlock(c);
free_extent_buffer(c);
return ret;
@ -4447,9 +4475,12 @@ static noinline int btrfs_del_leaf(struct btrfs_trans_handle *trans,
root_sub_used_bytes(root);
atomic_inc(&leaf->refs);
btrfs_free_tree_block(trans, btrfs_root_id(root), leaf, 0, 1);
ret = btrfs_free_tree_block(trans, btrfs_root_id(root), leaf, 0, 1);
free_extent_buffer_stale(leaf);
return 0;
if (ret < 0)
btrfs_abort_transaction(trans, ret);
return ret;
}
/*
* delete the item at the leaf level in path. If that empties

24
fs/btrfs/extent-tree.c
View File

@ -3419,10 +3419,10 @@ out_delayed_unlock:
return 0;
}
void btrfs_free_tree_block(struct btrfs_trans_handle *trans,
u64 root_id,
struct extent_buffer *buf,
u64 parent, int last_ref)
int btrfs_free_tree_block(struct btrfs_trans_handle *trans,
u64 root_id,
struct extent_buffer *buf,
u64 parent, int last_ref)
{
struct btrfs_fs_info *fs_info = trans->fs_info;
struct btrfs_block_group *bg;
@ -3449,11 +3449,12 @@ void btrfs_free_tree_block(struct btrfs_trans_handle *trans,
btrfs_init_tree_ref(&generic_ref, btrfs_header_level(buf), 0, false);
btrfs_ref_tree_mod(fs_info, &generic_ref);
ret = btrfs_add_delayed_tree_ref(trans, &generic_ref, NULL);
BUG_ON(ret); /* -ENOMEM */
if (ret < 0)
return ret;
}
if (!last_ref)
return;
return 0;
if (btrfs_header_generation(buf) != trans->transid)
goto out;
@ -3510,6 +3511,7 @@ out:
* matter anymore.
*/
clear_bit(EXTENT_BUFFER_CORRUPT, &buf->bflags);
return 0;
}
/* Can return -ENOMEM */
@ -5754,7 +5756,7 @@ static noinline int walk_up_proc(struct btrfs_trans_handle *trans,
struct walk_control *wc)
{
struct btrfs_fs_info *fs_info = root->fs_info;
int ret;
int ret = 0;
int level = wc->level;
struct extent_buffer *eb = path->nodes[level];
u64 parent = 0;
@ -5849,12 +5851,14 @@ static noinline int walk_up_proc(struct btrfs_trans_handle *trans,
goto owner_mismatch;
}
btrfs_free_tree_block(trans, btrfs_root_id(root), eb, parent,
wc->refs[level] == 1);
ret = btrfs_free_tree_block(trans, btrfs_root_id(root), eb, parent,
wc->refs[level] == 1);
if (ret < 0)
btrfs_abort_transaction(trans, ret);
out:
wc->refs[level] = 0;
wc->flags[level] = 0;
return 0;
return ret;
owner_mismatch:
btrfs_err_rl(fs_info, "unexpected tree owner, have %llu expect %llu",

8
fs/btrfs/extent-tree.h
View File

@ -127,10 +127,10 @@ struct extent_buffer *btrfs_alloc_tree_block(struct btrfs_trans_handle *trans,
u64 empty_size,
u64 reloc_src_root,
enum btrfs_lock_nesting nest);
void btrfs_free_tree_block(struct btrfs_trans_handle *trans,
u64 root_id,
struct extent_buffer *buf,
u64 parent, int last_ref);
int btrfs_free_tree_block(struct btrfs_trans_handle *trans,
u64 root_id,
struct extent_buffer *buf,
u64 parent, int last_ref);
int btrfs_alloc_reserved_file_extent(struct btrfs_trans_handle *trans,
struct btrfs_root *root, u64 owner,
u64 offset, u64 ram_bytes,

10
fs/btrfs/free-space-tree.c
View File

@ -1300,10 +1300,14 @@ int btrfs_delete_free_space_tree(struct btrfs_fs_info *fs_info)
btrfs_tree_lock(free_space_root->node);
btrfs_clear_buffer_dirty(trans, free_space_root->node);
btrfs_tree_unlock(free_space_root->node);
btrfs_free_tree_block(trans, btrfs_root_id(free_space_root),
free_space_root->node, 0, 1);
ret = btrfs_free_tree_block(trans, btrfs_root_id(free_space_root),
free_space_root->node, 0, 1);
btrfs_put_root(free_space_root);
if (ret < 0) {
btrfs_abort_transaction(trans, ret);
btrfs_end_transaction(trans);
return ret;
}
return btrfs_commit_transaction(trans);
}

6
fs/btrfs/ioctl.c
View File

@ -714,6 +714,8 @@ static noinline int create_subvol(struct mnt_idmap *idmap,
ret = btrfs_insert_root(trans, fs_info->tree_root, &key,
root_item);
if (ret) {
int ret2;
/*
* Since we don't abort the transaction in this case, free the
* tree block so that we don't leak space and leave the
@ -724,7 +726,9 @@ static noinline int create_subvol(struct mnt_idmap *idmap,
btrfs_tree_lock(leaf);
btrfs_clear_buffer_dirty(trans, leaf);
btrfs_tree_unlock(leaf);
btrfs_free_tree_block(trans, objectid, leaf, 0, 1);
ret2 = btrfs_free_tree_block(trans, objectid, leaf, 0, 1);
if (ret2 < 0)
btrfs_abort_transaction(trans, ret2);
free_extent_buffer(leaf);
goto out;
}

6
fs/btrfs/qgroup.c
View File

@ -1441,9 +1441,11 @@ int btrfs_quota_disable(struct btrfs_fs_info *fs_info)
btrfs_tree_lock(quota_root->node);
btrfs_clear_buffer_dirty(trans, quota_root->node);
btrfs_tree_unlock(quota_root->node);
btrfs_free_tree_block(trans, btrfs_root_id(quota_root),
quota_root->node, 0, 1);
ret = btrfs_free_tree_block(trans, btrfs_root_id(quota_root),
quota_root->node, 0, 1);
if (ret < 0)
btrfs_abort_transaction(trans, ret);
out:
btrfs_put_root(quota_root);