[PATCH V4 2/3] md: propagate BLK_FEAT_PCI_P2PDMA from member devices to RAID device
Chaitanya Kulkarni <[email protected]>
| Newsgroups | gmane.linux.raid,gmane.linux.block |
|---|---|
| Message-ID | <[email protected]> |
From: Kiran Kumar Modukuri <[email protected]> MD RAID does not propagate BLK_FEAT_PCI_P2PDMA from member devices to the RAID device, preventing peer-to-peer DMA through the RAID layer even when all underlying devices support it. Enable BLK_FEAT_PCI_P2PDMA unconditionally in raid0, raid1 and raid10 personalities during queue limits setup. blk_stack_limits() clears it automatically if any member device lacks support, consistent with how BLK_FEAT_NOWAIT and BLK_FEAT_POLL are handled in the block core. Parity RAID personalities (raid4/5/6) are excluded because they require CPU access to data pages for parity computation, which is incompatible with P2P mappings. Tested with RAID0/1/10 arrays containing multiple NVMe devices with P2PDMA support, confirming that peer-to-peer transfers work correctly through the RAID layer. Tested-by: Pranjal Shrivastava<[email protected]> Reviewed-by: Christoph Hellwig <[email protected]> Reviewed-by: Sagi Grimberg <[email protected]> Reviewed-by: Xiao Ni <[email protected]> Signed-off-by: Kiran Kumar Modukuri <[email protected]> Signed-off-by: Chaitanya Kulkarni <[email protected]> --- drivers/md/raid0.c | 1 + drivers/md/raid1.c | 1 + drivers/md/raid10.c | 1 + 3 files changed, 3 insertions(+) diff --git a/drivers/md/raid0.c b/drivers/md/raid0.c index 5e38a51e349a..2cdaf7495d92 100644 --- a/drivers/md/raid0.c +++ b/drivers/md/raid0.c @@ -392,6 +392,7 @@ static int raid0_set_limits(struct mddev *mddev) lim.io_opt = lim.io_min * mddev->raid_disks; lim.chunk_sectors = mddev->chunk_sectors; lim.features |= BLK_FEAT_ATOMIC_WRITES; + lim.features |= BLK_FEAT_PCI_P2PDMA; err = mddev_stack_rdev_limits(mddev, &lim, MDDEV_STACK_INTEGRITY); if (err) return err; diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c index 64d970e2ef50..cc628a1be52c 100644 --- a/drivers/md/raid1.c +++ b/drivers/md/raid1.c @@ -3208,6 +3208,7 @@ static int raid1_set_limits(struct mddev *mddev) lim.max_hw_wzeroes_unmap_sectors = 0; lim.logical_block_size = mddev->logical_block_size; lim.features |= BLK_FEAT_ATOMIC_WRITES; + lim.features |= BLK_FEAT_PCI_P2PDMA; err = mddev_stack_rdev_limits(mddev, &lim, MDDEV_STACK_INTEGRITY); if (err) return err; diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c index 39085e7dd6d2..f905dc391b74 100644 --- a/drivers/md/raid10.c +++ b/drivers/md/raid10.c @@ -3941,6 +3941,7 @@ static int raid10_set_queue_limits(struct mddev *mddev) lim.chunk_sectors = mddev->chunk_sectors; lim.io_opt = lim.io_min * raid10_nr_stripes(conf); lim.features |= BLK_FEAT_ATOMIC_WRITES; + lim.features |= BLK_FEAT_PCI_P2PDMA; err = mddev_stack_rdev_limits(mddev, &lim, MDDEV_STACK_INTEGRITY); if (err) return err; -- 2.39.5