On Sat, Mar 31, 2018 at 06:11:55AM +0800, Liu Bo wrote:
> This is running in a typical write path, not inside a critical path
> where we have to abort the running transaction, so it's OK to return
> errors to callers and eventually to userspace.
I'm not sure this is entierly correct, several other places do not abort
after btrfs_drop_extents as there's nothing that would leave the
structres in some half-state.
> Signed-off-by: Liu Bo <bo.liu@xxxxxxxxxxxxxxxxx>
> ---
> fs/btrfs/inode.c | 5 +----
> 1 file changed, 1 insertion(+), 4 deletions(-)
>
> diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
> index c7b75dd..b9310f8 100644
> --- a/fs/btrfs/inode.c
> +++ b/fs/btrfs/inode.c
> @@ -4939,16 +4939,13 @@ static int maybe_insert_hole(struct btrfs_root *root, struct inode *inode,
>
> ret = btrfs_drop_extents(trans, root, inode, offset, offset + len, 1);
> if (ret) {
> - btrfs_abort_transaction(trans, ret);
> btrfs_end_transaction(trans);
> return ret;
> }
>
> ret = btrfs_insert_file_extent(trans, root, btrfs_ino(BTRFS_I(inode)),
> offset, 0, 0, len, 0, len, 0, 0, 0);
But here the extents have been already dropped and missing to insert the
items does not seem to lead to a consistent state.
It's possible that I'm missing something. In a call path that can be
safely rolled back even with a started transaction, we don't need to
abort in all cases. But if the rollback requires some non-trivial
modifications, I don't see options how to avoid the abort.
__btrfs_drop_extents does a lot of state changes and can itself fail
in the middle of dropping the range, aborting looks like the safest
option.
> - if (ret)
> - btrfs_abort_transaction(trans, ret);
> - else
> + if (!ret)
> btrfs_update_inode(trans, root, inode);
> btrfs_end_transaction(trans);
> return ret;
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