From: Kiran Kumar Modukuri Date: Wed, 13 May 2026 18:51:52 +0000 (-0700) Subject: md: propagate BLK_FEAT_PCI_P2PDMA from member devices to RAID device X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=02666132403aec8fc5de315002894f713ef17dbc;p=thirdparty%2Fkernel%2Flinux.git md: propagate BLK_FEAT_PCI_P2PDMA from member devices to RAID device 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 Reviewed-by: Christoph Hellwig Reviewed-by: Sagi Grimberg Reviewed-by: Xiao Ni Signed-off-by: Kiran Kumar Modukuri Signed-off-by: Chaitanya Kulkarni Reviewed-by: Yu Kuai Tested=by: Pranjal Shrivastava Link: https://patch.msgid.link/20260513185153.95552-3-kch@nvidia.com Signed-off-by: Jens Axboe --- diff --git a/drivers/md/raid0.c b/drivers/md/raid0.c index 5e38a51e349ad..2cdaf7495d92e 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 64d970e2ef50f..cc628a1be52c7 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 39085e7dd6d26..f905dc391b745 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;