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| /openbmc/linux/drivers/md/ |
| H A D | dm-core.h | diff 7dd76d1feec70a23e1de2b55c0c2a9c592fa8423 Tue Apr 12 03:56:13 CDT 2022 Ming Lei <ming.lei@redhat.com> dm: improve bio splitting and associated IO accounting
The current DM code (ab)uses late assignment of dm_io->orig_bio (after
__map_bio() returns and any bio splitting is complete) to indicate the
FS bio has been processed and can be accounted. This results in
awkward waiting until ->orig_bio is set in dm_submit_bio_remap().
Also the bio splitting was implemented using bio_split()+bio_chain()
-- a well-worn pattern but it requires bio cloning purely for the
benefit of more natural IO accounting. The bio_split() result was
stored in ->orig_bio to represent the mapped part of the original FS
bio.
DM has switched to the bdev based IO accounting interface. DM's IO
accounting can be implemented in terms of the original FS bio (now
stored early in ->orig_bio) via access to its sectors/bio_op. And
if/when splitting is needed, set a new DM_IO_WAS_SPLIT flag and use
new dm_io fields of .sector_offset & .sectors to allow IO accounting
for split bios _without_ needing to clone a new bio to store in
->orig_bio.
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Co-developed-by: Mike Snitzer <snitzer@kernel.org>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
|
| H A D | dm.c | diff 7dd76d1feec70a23e1de2b55c0c2a9c592fa8423 Tue Apr 12 03:56:13 CDT 2022 Ming Lei <ming.lei@redhat.com> dm: improve bio splitting and associated IO accounting
The current DM code (ab)uses late assignment of dm_io->orig_bio (after
__map_bio() returns and any bio splitting is complete) to indicate the
FS bio has been processed and can be accounted. This results in
awkward waiting until ->orig_bio is set in dm_submit_bio_remap().
Also the bio splitting was implemented using bio_split()+bio_chain()
-- a well-worn pattern but it requires bio cloning purely for the
benefit of more natural IO accounting. The bio_split() result was
stored in ->orig_bio to represent the mapped part of the original FS
bio.
DM has switched to the bdev based IO accounting interface. DM's IO
accounting can be implemented in terms of the original FS bio (now
stored early in ->orig_bio) via access to its sectors/bio_op. And
if/when splitting is needed, set a new DM_IO_WAS_SPLIT flag and use
new dm_io fields of .sector_offset & .sectors to allow IO accounting
for split bios _without_ needing to clone a new bio to store in
->orig_bio.
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Co-developed-by: Mike Snitzer <snitzer@kernel.org>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
|