@@ -455,11 +455,10 @@ struct async_chunk {
struct list_head extents;
struct cgroup_subsys_state *blkcg_css;
struct btrfs_work work;
- atomic_t *pending;
+ struct async_cow *async_cow;
};
struct async_cow {
- /* Number of chunks in flight; must be first in the structure */
atomic_t num_chunks;
struct async_chunk chunks[];
};
@@ -1324,18 +1323,17 @@ static noinline void async_cow_submit(struct btrfs_work *work)
static noinline void async_cow_free(struct btrfs_work *work)
{
struct async_chunk *async_chunk;
+ struct async_cow *async_cow;
async_chunk = container_of(work, struct async_chunk, work);
if (async_chunk->inode)
btrfs_add_delayed_iput(async_chunk->inode);
if (async_chunk->blkcg_css)
css_put(async_chunk->blkcg_css);
- /*
- * Since the pointer to 'pending' is at the beginning of the array of
- * async_chunk's, freeing it ensures the whole array has been freed.
- */
- if (atomic_dec_and_test(async_chunk->pending))
- kvfree(async_chunk->pending);
+
+ async_cow = async_chunk->async_cow;
+ if (atomic_dec_and_test(&async_cow->num_chunks))
+ kvfree(async_cow);
}
static int cow_file_range_async(struct btrfs_inode *inode,
@@ -1396,7 +1394,7 @@ static int cow_file_range_async(struct btrfs_inode *inode,
* lightweight reference for the callback lifetime
*/
ihold(&inode->vfs_inode);
- async_chunk[i].pending = &ctx->num_chunks;
+ async_chunk[i].async_cow = ctx;
async_chunk[i].inode = &inode->vfs_inode;
async_chunk[i].start = start;
async_chunk[i].end = cur_end;
For structure async_chunk, we use a very strange member layout to grab structure async_cow who owns this async_chunk. At initialization, it goes like this: async_chunk[i].pending = &ctx->num_chunks; Then at async_cow_free() we do a super weird freeing: /* * Since the pointer to 'pending' is at the beginning of the array of * async_chunk's, freeing it ensures the whole array has been freed. */ if (atomic_dec_and_test(async_chunk->pending)) kvfree(async_chunk->pending); This is absolutely an abuse of kvfree(). Replace async_chunk::pending with async_chunk::async_cow, so that we can grab the async_cow structure directly, without this strange dancing. And with this change, there is no requirement for any specific member location. Signed-off-by: Qu Wenruo <wqu@suse.com> --- fs/btrfs/inode.c | 16 +++++++--------- 1 file changed, 7 insertions(+), 9 deletions(-)