From: Huaisheng Ye <ye...@lenovo.com> Reconstruct origin_dax_direct_access and expand functions origin_dax_copy_to/from_iter for DAX operations of dm-snapshot.
Here is the call trace of origin_dax_copy_to_iter, origin_dax_copy_to_iter will callin dm-linear (-real) for further dax_operation. [518597.924019] Call Trace: [518597.927320] dump_stack+0x65/0x7e [518597.931592] origin_dax_copy_to_iter+0x51/0x78 [dm_snapshot] [518597.938494] dm_dax_copy_to_iter+0x86/0xc5 [dm_mod] [518597.944519] dax_copy_to_iter+0x27/0x29 [518597.949371] dax_iomap_actor+0x264/0x326 [518597.954308] ? trace_event_raw_event_dax_pmd_load_hole_class+0xd0/0xd0 [518597.962159] iomap_apply+0xc7/0x128 [518597.966609] ? trace_event_raw_event_dax_pmd_load_hole_class+0xd0/0xd0 [518597.974447] dax_iomap_rw+0x66/0xa8 [518597.978893] ? trace_event_raw_event_dax_pmd_load_hole_class+0xd0/0xd0 [518597.986741] ext2_file_read_iter+0x4f/0x83 [ext2] [518597.992552] __vfs_read+0x130/0x168 [518597.997001] vfs_read+0x92/0x146 [518598.001155] ksys_read+0x4f/0xa5 [518598.005308] __x64_sys_read+0x16/0x18 [518598.009942] do_syscall_64+0x88/0x15f [518598.014575] entry_SYSCALL_64_after_hwframe+0x44/0xa9 Signed-off-by: Huaisheng Ye <ye...@lenovo.com> --- drivers/md/dm-snap.c | 44 ++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 42 insertions(+), 2 deletions(-) diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c index ae4b33d..75738b3 100644 --- a/drivers/md/dm-snap.c +++ b/drivers/md/dm-snap.c @@ -19,6 +19,7 @@ #include <linux/vmalloc.h> #include <linux/log2.h> #include <linux/dm-kcopyd.h> +#include <linux/dax.h> #include "dm.h" @@ -2319,8 +2320,45 @@ static int origin_map(struct dm_target *ti, struct bio *bio) static long origin_dax_direct_access(struct dm_target *ti, pgoff_t pgoff, long nr_pages, void **kaddr, pfn_t *pfn) { - DMWARN("device does not support dax."); - return -EIO; + long ret = 0; + struct dm_origin *o = ti->private; + struct block_device *bdev = o->dev->bdev; + struct dax_device *dax_dev = o->dev->dax_dev; + sector_t sector = pgoff * PAGE_SECTORS; + + ret = bdev_dax_pgoff(bdev, sector, nr_pages * PAGE_SIZE, &pgoff); + if (ret) + return ret; + + return dax_direct_access(dax_dev, pgoff, nr_pages, kaddr, pfn); +} + +static size_t origin_dax_copy_from_iter(struct dm_target *ti, pgoff_t pgoff, + void *addr, size_t bytes, struct iov_iter *i) +{ + struct dm_origin *o = ti->private; + struct block_device *bdev = o->dev->bdev; + struct dax_device *dax_dev = o->dev->dax_dev; + sector_t sector = pgoff * PAGE_SECTORS; + + if (bdev_dax_pgoff(bdev, sector, ALIGN(bytes, PAGE_SIZE), &pgoff)) + return 0; + + return dax_copy_from_iter(dax_dev, pgoff, addr, bytes, i); +} + +static size_t origin_dax_copy_to_iter(struct dm_target *ti, pgoff_t pgoff, + void *addr, size_t bytes, struct iov_iter *i) +{ + struct dm_origin *o = ti->private; + struct block_device *bdev = o->dev->bdev; + struct dax_device *dax_dev = o->dev->dax_dev; + sector_t sector = pgoff * PAGE_SECTORS; + + if (bdev_dax_pgoff(bdev, sector, ALIGN(bytes, PAGE_SIZE), &pgoff)) + return 0; + + return dax_copy_to_iter(dax_dev, pgoff, addr, bytes, i); } /* @@ -2383,6 +2421,8 @@ static int origin_iterate_devices(struct dm_target *ti, .status = origin_status, .iterate_devices = origin_iterate_devices, .direct_access = origin_dax_direct_access, + .dax_copy_to_iter = origin_dax_copy_to_iter, + .dax_copy_from_iter = origin_dax_copy_from_iter, }; static struct target_type snapshot_target = { -- 1.8.3.1 _______________________________________________ Linux-nvdimm mailing list Linux-nvdimm@lists.01.org https://lists.01.org/mailman/listinfo/linux-nvdimm