[PATCH 6.1 108/127] btrfs: remove BUG_ON()s in add_new_free_space()

Greg Kroah-Hartman
2023-08-09T10:57:27Z

From: Filipe Manana <fdmanana@suse.com>

commit d8ccbd21918fd7fa6ce3226cffc22c444228e8ad upstream.

At add_new_free_space() we have these BUG_ON()'s that are there to deal
with any failure to add free space to the in memory free space cache.
Such failures are mostly -ENOMEM that should be very rare. However there's
no need to have these BUG_ON()'s, we can just return any error to the
caller and all callers and their upper call chain are already dealing with
errors.

So just make add_new_free_space() return any errors, while removing the
BUG_ON()'s, and returning the total amount of added free space to an
optional u64 pointer argument.

Reported-by: syzbot+3ba856e07b7127889d8c@syzkaller.appspotmail.com
Link: https://lore.kernel.org/linux-btrfs/000000000000e9cb8305ff4e8327@google.com/
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/btrfs/block-group.c | 51 ++++++++++++++++++++++++++++++---------------
fs/btrfs/block-group.h | 4 +--
fs/btrfs/free-space-tree.c | 24 +++++++++++++++------
3 files changed, 53 insertions(+), 26 deletions(-)

--- a/fs/btrfs/block-group.c
+++ b/fs/btrfs/block-group.c
@@ -494,12 +494,16 @@ static void fragment_free_space(struct b
* used yet since their free space will be released as soon as the transaction
* commits.
*/
-u64 add_new_free_space(struct btrfs_block_group *block_group, u64 start, u64 end)
+int add_new_free_space(struct btrfs_block_group *block_group, u64 start, u64 end,
+ u64 *total_added_ret)
{
struct btrfs_fs_info *info = block_group->fs_info;
- u64 extent_start, extent_end, size, total_added = 0;
+ u64 extent_start, extent_end, size;
int ret;

+ if (total_added_ret)
+ *total_added_ret = 0;
+
while (start < end) {
ret = find_first_extent_bit(&info->excluded_extents, start,
&extent_start, &extent_end,
@@ -512,10 +516,12 @@ u64 add_new_free_space(struct btrfs_bloc
start = extent_end + 1;
} else if (extent_start > start && extent_start < end) {
size = extent_start - start;
- total_added += size;
ret = btrfs_add_free_space_async_trimmed(block_group,
start, size);
- BUG_ON(ret); /* -ENOMEM or logic error */
+ if (ret)
+ return ret;
+ if (total_added_ret)
+ *total_added_ret += size;
start = extent_end + 1;
} else {
break;
@@ -524,13 +530,15 @@ u64 add_new_free_space(struct btrfs_bloc

if (start < end) {
size = end - start;
- total_added += size;
ret = btrfs_add_free_space_async_trimmed(block_group, start,
size);
- BUG_ON(ret); /* -ENOMEM or logic error */
+ if (ret)
+ return ret;
+ if (total_added_ret)
+ *total_added_ret += size;
}

- return total_added;
+ return 0;
}

static int load_extent_tree_free(struct btrfs_caching_control *caching_ctl)
@@ -637,8 +645,13 @@ next:

if (key.type == BTRFS_EXTENT_ITEM_KEY ||
key.type == BTRFS_METADATA_ITEM_KEY) {
- total_found += add_new_free_space(block_group, last,
- key.objectid);
+ u64 space_added;
+
+ ret = add_new_free_space(block_group, last, key.objectid,
+ &space_added);
+ if (ret)
+ goto out;
+ total_found += space_added;
if (key.type == BTRFS_METADATA_ITEM_KEY)
last = key.objectid +
fs_info->nodesize;
@@ -653,11 +666,10 @@ next:
}
path->slots[0]++;
}
- ret = 0;
-
- total_found += add_new_free_space(block_group, last,
- block_group->start + block_group->length);

+ ret = add_new_free_space(block_group, last,
+ block_group->start + block_group->length,
+ NULL);
out:
btrfs_free_path(path);
return ret;
@@ -2101,9 +2113,11 @@ static int read_one_block_group(struct b
btrfs_free_excluded_extents(cache);
} else if (cache->used == 0) {
cache->cached = BTRFS_CACHE_FINISHED;
- add_new_free_space(cache, cache->start,
- cache->start + cache->length);
+ ret = add_new_free_space(cache, cache->start,
+ cache->start + cache->length, NULL);
btrfs_free_excluded_extents(cache);
+ if (ret)
+ goto error;
}

ret = btrfs_add_block_group_cache(info, cache);
@@ -2529,9 +2543,12 @@ struct btrfs_block_group *btrfs_make_blo
return ERR_PTR(ret);
}

- add_new_free_space(cache, chunk_offset, chunk_offset + size);
-
+ ret = add_new_free_space(cache, chunk_offset, chunk_offset + size, NULL);
btrfs_free_excluded_extents(cache);
+ if (ret) {
+ btrfs_put_block_group(cache);
+ return ERR_PTR(ret);
+ }

/*
* Ensure the corresponding space_info object is created and
--- a/fs/btrfs/block-group.h
+++ b/fs/btrfs/block-group.h
@@ -284,8 +284,8 @@ int btrfs_cache_block_group(struct btrfs
void btrfs_put_caching_control(struct btrfs_caching_control *ctl);
struct btrfs_caching_control *btrfs_get_caching_control(
struct btrfs_block_group *cache);
-u64 add_new_free_space(struct btrfs_block_group *block_group,
- u64 start, u64 end);
+int add_new_free_space(struct btrfs_block_group *block_group,
+ u64 start, u64 end, u64 *total_added_ret);
struct btrfs_trans_handle *btrfs_start_trans_remove_block_group(
struct btrfs_fs_info *fs_info,
const u64 chunk_offset);
--- a/fs/btrfs/free-space-tree.c
+++ b/fs/btrfs/free-space-tree.c
@@ -1510,9 +1510,13 @@ static int load_free_space_bitmaps(struc
if (prev_bit == 0 && bit == 1) {
extent_start = offset;
} else if (prev_bit == 1 && bit == 0) {
- total_found += add_new_free_space(block_group,
- extent_start,
- offset);
+ u64 space_added;
+
+ ret = add_new_free_space(block_group, extent_start,
+ offset, &space_added);
+ if (ret)
+ goto out;
+ total_found += space_added;
if (total_found > CACHING_CTL_WAKE_UP) {
total_found = 0;
wake_up(&caching_ctl->wait);
@@ -1524,8 +1528,9 @@ static int load_free_space_bitmaps(struc
}
}
if (prev_bit == 1) {
- total_found += add_new_free_space(block_group, extent_start,
- end);
+ ret = add_new_free_space(block_group, extent_start, end, NULL);
+ if (ret)
+ goto out;
extent_count++;
}

@@ -1564,6 +1569,8 @@ static int load_free_space_extents(struc
end = block_group->start + block_group->length;

while (1) {
+ u64 space_added;
+
ret = btrfs_next_item(root, path);
if (ret < 0)
goto out;
@@ -1578,8 +1585,11 @@ static int load_free_space_extents(struc
ASSERT(key.type == BTRFS_FREE_SPACE_EXTENT_KEY);
ASSERT(key.objectid < end && key.objectid + key.offset <= end);

- total_found += add_new_free_space(block_group, key.objectid,
- key.objectid + key.offset);
+ ret = add_new_free_space(block_group, key.objectid,
+ key.objectid + key.offset, &space_added);
+ if (ret)
+ goto out;
+ total_found += space_added;
if (total_found > CACHING_CTL_WAKE_UP) {
total_found = 0;
wake_up(&caching_ctl->wait);