ext4: using nofail preallocation in ext4_es_remove_extent()

ext4: using nofail preallocation in ext4_es_remove_extent()

[ Upstream commit e9fe2b882bd5b26b987c9ba110c2222796f72af5 ]

If __es_remove_extent() returns an error it means that when splitting
extent, allocating an extent that must be kept failed, where returning
an error directly would cause the extent tree to be inconsistent. So we
use GFP_NOFAIL to pre-allocate an extent_status and pass it to
__es_remove_extent() to avoid this problem.

In addition, since the allocated memory is outside the i_es_lock, the
extent_status tree may change and the pre-allocated extent_status is
no longer needed, so we release the pre-allocated extent_status when
es->es_len is not initialized.

Suggested-by: Jan Kara <jack@suse.cz>
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20230424033846.4732-7-libaokun1@huawei.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Stable-dep-of: 8e387c89e96b ("ext4: make sure allocate pending entry not fail")
Signed-off-by: Sasha Levin <sashal@kernel.org>