ext4: get ext4_group_desc in ext4_mb_prefetch only when necessary

Getting ext4_group_desc structure can contribute to the cost of
ext4_mb_prefetch() without any need, as most groups fail the
!EXT4_MB_GRP_TEST_AND_SET_READ check.

Optimize ext4_mb_prefetch by getting the group description only when
necessary.

The result is further increase in performance of fallocate() system call
path that triggers ext4_mb_prefetch() via a linear group scan.

Signed-off-by: Bohdan Trach <bohdan.trach@huaweicloud.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Link: https://patch.msgid.link/20260615100331.163997-3-bohdan.trach@huaweicloud.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

0 files changed, 0 insertions, 0 deletions