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btrfs: remove BUG_ON()'s in add_new_free_space()
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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>
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Filipe Manana authored and David Sterba committed Jul 24, 2023
1 parent 8dbfc14 commit d8ccbd2
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Showing 3 changed files with 53 additions and 26 deletions.
51 changes: 34 additions & 17 deletions fs/btrfs/block-group.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -499,12 +499,16 @@ static void fragment_free_space(struct btrfs_block_group *block_group)
* 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,
Expand All @@ -517,10 +521,12 @@ u64 add_new_free_space(struct btrfs_block_group *block_group, u64 start, u64 end
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;
Expand All @@ -529,13 +535,15 @@ u64 add_new_free_space(struct btrfs_block_group *block_group, u64 start, u64 end

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;
}

/*
Expand Down Expand Up @@ -779,8 +787,13 @@ static int load_extent_tree_free(struct btrfs_caching_control *caching_ctl)

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;
Expand All @@ -795,11 +808,10 @@ static int load_extent_tree_free(struct btrfs_caching_control *caching_ctl)
}
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;
Expand Down Expand Up @@ -2294,9 +2306,11 @@ static int read_one_block_group(struct btrfs_fs_info *info,
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);
Expand Down Expand Up @@ -2740,9 +2754,12 @@ struct btrfs_block_group *btrfs_make_block_group(struct btrfs_trans_handle *tran
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
Expand Down
4 changes: 2 additions & 2 deletions fs/btrfs/block-group.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -289,8 +289,8 @@ int btrfs_cache_block_group(struct btrfs_block_group *cache, bool wait);
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);
Expand Down
24 changes: 17 additions & 7 deletions fs/btrfs/free-space-tree.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1515,9 +1515,13 @@ static int load_free_space_bitmaps(struct btrfs_caching_control *caching_ctl,
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);
Expand All @@ -1529,8 +1533,9 @@ static int load_free_space_bitmaps(struct btrfs_caching_control *caching_ctl,
}
}
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++;
}

Expand Down Expand Up @@ -1569,6 +1574,8 @@ static int load_free_space_extents(struct btrfs_caching_control *caching_ctl,
end = block_group->start + block_group->length;

while (1) {
u64 space_added;

ret = btrfs_next_item(root, path);
if (ret < 0)
goto out;
Expand All @@ -1583,8 +1590,11 @@ static int load_free_space_extents(struct btrfs_caching_control *caching_ctl,
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);
Expand Down

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