Add fields needed for the copy-on-write ext4 development work.
The h_cowing flag is used by ext4 snapshots code to mark the task in
COWING state.
The h_XXX_credits fields are used to track buffer credits usage
(accounted by COW and non-COW operations).
The h_cow_XXX fields are used as per task debugging counters.
Merging this commit into mainline will allow users to test ext4
snapshots as a standalone module, without the need to patch and
install a development kernel.
Signed-off-by: Amir Goldstein <amir73il@users.sf.net>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
93737456d6