4.18-stable review patch. If anyone has any objections, please let me know.
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From: Mike Snitzer snitzer@redhat.com
commit beb9caac211c1be1bc118bb62d5cf09c4107e6a5 upstream.
It is best to avoid any extra overhead associated with bio completion. DM core will indirectly call a DM target's .end_io if it is defined. In the case of DM linear, there is no need to do so (for every bio that completes) if CONFIG_DM_ZONED is not enabled.
Avoiding an extra indirect call for every bio completion is very important for ensuring DM linear doesn't incur more overhead that further widens the performance gap between dm-linear and raw block devices.
Fixes: 0be12c1c7fce7 ("dm linear: add support for zoned block devices") Cc: stable@vger.kernel.org Signed-off-by: Mike Snitzer snitzer@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/md/dm-linear.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)
--- a/drivers/md/dm-linear.c +++ b/drivers/md/dm-linear.c @@ -102,6 +102,7 @@ static int linear_map(struct dm_target * return DM_MAPIO_REMAPPED; }
+#ifdef CONFIG_DM_ZONED static int linear_end_io(struct dm_target *ti, struct bio *bio, blk_status_t *error) { @@ -112,6 +113,7 @@ static int linear_end_io(struct dm_targe
return DM_ENDIO_DONE; } +#endif
static void linear_status(struct dm_target *ti, status_type_t type, unsigned status_flags, char *result, unsigned maxlen) @@ -208,12 +210,16 @@ static size_t linear_dax_copy_to_iter(st static struct target_type linear_target = { .name = "linear", .version = {1, 4, 0}, +#ifdef CONFIG_DM_ZONED + .end_io = linear_end_io, .features = DM_TARGET_PASSES_INTEGRITY | DM_TARGET_ZONED_HM, +#else + .features = DM_TARGET_PASSES_INTEGRITY, +#endif .module = THIS_MODULE, .ctr = linear_ctr, .dtr = linear_dtr, .map = linear_map, - .end_io = linear_end_io, .status = linear_status, .prepare_ioctl = linear_prepare_ioctl, .iterate_devices = linear_iterate_devices,