From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Huaisheng Ye Subject: [RFC PATCH v2 1/3] dm: enable dax_operations for dm-snapshot Date: Wed, 21 Nov 2018 11:27:00 +0800 Message-Id: <20181121032702.3048-2-yehs2007@zoho.com> In-Reply-To: <20181121032702.3048-1-yehs2007@zoho.com> References: <20181121032702.3048-1-yehs2007@zoho.com> Sender: linux-fsdevel-owner@vger.kernel.org To: linux-nvdimm@lists.01.org, agk@redhat.com, snitzer@redhat.com, dm-devel@redhat.com, dan.j.williams@intel.com, willy@infradead.org, zwisler@kernel.org, jack@suse.cz, dave.jiang@intel.com, vishal.l.verma@intel.com Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, chengnt@lenovo.com, Huaisheng Ye List-ID: From: Huaisheng Ye 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 --- drivers/md/dm-snap.c | 51 +++++++++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 49 insertions(+), 2 deletions(-) diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c index ae4b33d..714e26f 100644 --- a/drivers/md/dm-snap.c +++ b/drivers/md/dm-snap.c @@ -19,6 +19,7 @@ #include #include #include +#include #include "dm.h" @@ -2316,13 +2317,57 @@ static int origin_map(struct dm_target *ti, struct bio *bio) return do_origin(o->dev, bio); } +#if IS_ENABLED(CONFIG_DAX_DRIVER) 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); +} + +#else +#define origin_dax_direct_access NULL +#define origin_dax_copy_from_iter NULL +#define origin_dax_copy_to_iter NULL +#endif + /* * Set the target "max_io_len" field to the minimum of all the snapshots' * chunk sizes. @@ -2383,6 +2428,8 @@ 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