9:20 p.m.
From: Huaisheng Ye <yehs1(a)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 <yehs1(a)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