Hi, Filesystems may allocate io buffer from slab, and use this buffer to submit bio. This way may break storage drivers if they have special requirement on DMA alignment. The patch 1 adds one warning if the io buffer isn't aligned to DMA alignment. The 2nd & 3rd patches make DMA alignment as stacked limit. The 4th patch introduces helpers for allocating io buffer from slab, and DMA alignment is respected on this allocation. The 5th patch converts xfs to use the introduced helpers for allocating io buffer from slab. See previous discussion on this topic: https://marc.info/?t=153734857500004&r=1&w=2 Thanks, Ming Ming Lei (5): block: warn on un-aligned DMA IO buffer block: move .dma_alignment into q->limits block: make dma_alignment as stacked limit block: introduce helpers for allocating IO buffers from slab xfs: use block layer helpers to allocate io buffer from slab block/Makefile | 3 +- block/blk-core.c | 2 + block/blk-merge.c | 2 + block/blk-sec-buf.c | 144 ++++++++++++++++++++++++++++++++++++++++++++ block/blk-settings.c | 89 +++++++++++++++------------ fs/xfs/xfs_buf.c | 28 ++++++++- fs/xfs/xfs_super.c | 13 +++- include/linux/blk-sec-buf.h | 43 +++++++++++++ include/linux/blkdev.h | 9 ++- 9 files changed, 287 insertions(+), 46 deletions(-) create mode 100644 block/blk-sec-buf.c create mode 100644 include/linux/blk-sec-buf.h Cc: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx> Cc: Dave Chinner <dchinner@xxxxxxxxxx> Cc: Linux FS Devel <linux-fsdevel@xxxxxxxxxxxxxxx> Cc: Darrick J. Wong <darrick.wong@xxxxxxxxxx> Cc: xfs@xxxxxxxxxxxxxxx Cc: Dave Chinner <dchinner@xxxxxxxxxx> Cc: Christoph Hellwig <hch@xxxxxx> Cc: Bart Van Assche <bvanassche@xxxxxxx> Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx> -- 2.9.5
