From: Keith Busch <[email protected]> Direct I/O user pages are forwarded to the backing files unchanged, so the backing's DMA alignment requirement applies to them. Track the backing file's dio_mem_align and advertise it as the zloop device's dma_alignment if it is larger than the default so we advertise proper limits and misaligned I/O is rejected early instead of being dispatched to the backend.
Signed-off-by: Keith Busch <[email protected]> --- drivers/block/zloop.c | 35 +++++++++++++++++++++++++---------- 1 file changed, 25 insertions(+), 10 deletions(-) diff --git a/drivers/block/zloop.c b/drivers/block/zloop.c index 55eeb6aac0ea3..f97a20cfdb7ce 100644 --- a/drivers/block/zloop.c +++ b/drivers/block/zloop.c @@ -144,6 +144,7 @@ struct zloop_device { unsigned int nr_conv_zones; unsigned int max_open_zones; unsigned int block_size; + unsigned int dio_mem_align; spinlock_t open_zones_lock; struct list_head open_zones_lru_list; @@ -1037,20 +1038,30 @@ static int zloop_get_block_size(struct zloop_device *zlo, struct kstat st; /* - * If the FS block size is lower than or equal to 4K, use that as the - * device block size. Otherwise, fallback to the FS direct IO alignment - * constraint if that is provided, and to the FS underlying device - * physical block size if the direct IO alignment is unknown. + * Use the dio alignment of the file system if provided. The incoming + * request's bio_vec is forwarded to the backing file unchanged, so its + * required memory alignment becomes the device's dma_alignment when + * used for direct-io. */ - if (file_inode(zone->file)->i_sb->s_blocksize <= SZ_4K) - zlo->block_size = file_inode(zone->file)->i_sb->s_blocksize; - else if (!vfs_getattr(&zone->file->f_path, &st, STATX_DIOALIGN, 0) && - (st.result_mask & STATX_DIOALIGN)) + if (!vfs_getattr(&zone->file->f_path, &st, STATX_DIOALIGN, 0) && + (st.result_mask & STATX_DIOALIGN)) { zlo->block_size = st.dio_offset_align; - else if (sb_bdev) + zlo->dio_mem_align = st.dio_mem_align - 1; + } else if (sb_bdev) { zlo->block_size = bdev_physical_block_size(sb_bdev); - else + zlo->dio_mem_align = bdev_dma_alignment(sb_bdev); + } else { zlo->block_size = SECTOR_SIZE; + zlo->dio_mem_align = SECTOR_SIZE - 1; + } + + /* + * Prefer the FS block size for the device block size when it is no + * larger than 4K; otherwise keep the direct I/O / physical block size + * selected above. + */ + if (file_inode(zone->file)->i_sb->s_blocksize <= SZ_4K) + zlo->block_size = file_inode(zone->file)->i_sb->s_blocksize; if (zlo->zone_capacity & ((zlo->block_size >> SECTOR_SHIFT) - 1)) { pr_err("Zone capacity is not aligned to block size %u\n", @@ -1279,6 +1290,10 @@ static int zloop_ctl_add(struct zloop_options *opts) lim.physical_block_size = zlo->block_size; lim.logical_block_size = zlo->block_size; + /* Direct I/O forwards the request pages to the backing files as-is. */ + if (!opts->buffered_io) + lim.dma_alignment = max_t(unsigned int, zlo->dio_mem_align, + SECTOR_SIZE - 1); if (zlo->zone_append) lim.max_hw_zone_append_sectors = lim.max_hw_sectors; lim.max_open_zones = zlo->max_open_zones; -- 2.53.0-Meta
