From: Huaisheng Ye <[email protected]>
This series patches are used to realize the dax_operations for dm-snapshot
with persistent memory device.
Here are the steps about how to verify the function.
1. Configure the persistent memory to fs-dax mode and create namespace with ndctl;
2. find them in /dev;
# ndctl list
{
"dev":"namespace0.0",
"mode":"fsdax",
"map":"dev",
"size":132118478848,
"sector_size":512,
"blockdev":"pmem0",
"name":"yhs_pmem0",
"numa_node":0
},
3. create lv_pmem (here is 4G size) for testing;
# pvcreate /dev/pmem0
# vgcreate vg_pmem /dev/pmem0
# lvcreate -L 4G -n lv_pmem vg_pmem
4. create filesystem (ext2 or ext4) to /dev/pmem0
# mkfs.ext2 -b 4096 /dev/vg_pmem/lv_pmem
5. mount pmem with DAX way;
# mkdir /mnt/lv_pmem
# mount -o dax /dev/vg_pmem/lv_pmem /mnt/lv_pmem/
6. cp some files to /mnt/lv_pmem;
# cp linear_table03.log /mnt/lv_pmem/
# cp test0.log /mnt/lv_pmem/
7. create snapshot for test (here I limit it to 1G size);
# lvcreate -L 1G -n snap_pmem -s /dev/vg_pmem/lv_pmem
8. modify the files copied with vim or copy more other new files;
# vim /mnt/lv_pmem/test0.log
9. umount the pmem device;
# umount /mnt/lv_pmem/
10.merge the snapshot back to origin;
# lvconvert --merge /dev/vg_pmem/snap_pmem
11.mount pmem device again for checking the content of files;
# mount -o dax /dev/vg_pmem/lv_pmem /mnt/lv_pmem/
Huaisheng Ye (3):
dm: enable dax_operations for dm-snapshot
dm: expand hc_map in mapped_device for lack of map
dm: expand valid types for dm-ioctl
drivers/md/dm-core.h | 1 +
drivers/md/dm-ioctl.c | 4 +++-
drivers/md/dm-snap.c | 44 ++++++++++++++++++++++++++++++++++++++++++--
drivers/md/dm.c | 15 +++++++++++++++
4 files changed, 61 insertions(+), 3 deletions(-)
--
1.8.3.1
From: Huaisheng Ye <[email protected]>
If use DAX way to mount the origin device of dm_snapshot, when
merging back snapshot to origin, system call table_load during the
construction of snapshot-merge will try to detect new dm_table's type
equals to the existed md's type or not.
The existed type equals to DM_TYPE_DAX_BIO_BASED, but the new created
type belongs to DM_TYPE_BIO_BASED. So, we need to expand valid_type in
function is_valid_type.
Signed-off-by: Huaisheng Ye <[email protected]>
---
drivers/md/dm-ioctl.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c
index a27016e..158d657 100644
--- a/drivers/md/dm-ioctl.c
+++ b/drivers/md/dm-ioctl.c
@@ -1295,7 +1295,8 @@ static int populate_table(struct dm_table *table,
static bool is_valid_type(enum dm_queue_mode cur, enum dm_queue_mode new)
{
if (cur == new ||
- (cur == DM_TYPE_BIO_BASED && new == DM_TYPE_DAX_BIO_BASED))
+ (cur == DM_TYPE_BIO_BASED && new == DM_TYPE_DAX_BIO_BASED) ||
+ (cur == DM_TYPE_DAX_BIO_BASED && new == DM_TYPE_BIO_BASED))
return true;
return false;
--
1.8.3.1
From: Huaisheng Ye <[email protected]>
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 <[email protected]>
---
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
From: Huaisheng Ye <[email protected]>
Sometimes dm_swap_table couldn't be used in time.
For example, during the origin construction of
dm-snapshot, the sys_ioctl table_load will try to
detect the lower device origin-real whether support
direct access or not. But origin-real md's struct
dm-table pointer has not yet been assigned real address
in time by dev_suspend.
So I expand hc_map for get the address from struct
hash_cell directly in this case.
Here is the call trace, dm_dax_direct_access will call
dm_dax_get_live_target for get the struct dm_table pointer.
[ 213.975827] Call Trace:
[ 213.975832] dump_stack+0x5a/0x73
[ 213.975840] dm_dax_direct_access+0x12b/0x1b0 [dm_mod]
[ 213.975845] dax_direct_access+0x2d/0x60
[ 213.975848] __bdev_dax_supported+0x162/0x2a0
[ 213.975851] ? dump_stack+0x5a/0x73
[ 213.975859] device_supports_dax+0x15/0x20 [dm_mod]
[ 213.975867] dm_table_supports_dax.isra.13+0x7d/0xa0 [dm_mod]
[ 213.975875] dm_table_complete+0x3fb/0x750 [dm_mod]
[ 213.975883] table_load+0x19a/0x390 [dm_mod]
[ 213.975891] ? retrieve_status+0x1c0/0x1c0 [dm_mod]
[ 213.975898] ctl_ioctl+0x1d8/0x450 [dm_mod]
[ 213.975909] dm_ctl_ioctl+0xa/0x10 [dm_mod]
[ 213.975913] do_vfs_ioctl+0xa9/0x620
[ 213.975918] ? syscall_trace_enter+0x1c9/0x2b0
[ 213.975923] ksys_ioctl+0x60/0x90
[ 213.975927] __x64_sys_ioctl+0x16/0x20
[ 213.975931] do_syscall_64+0x5b/0x180
[ 213.975936] entry_SYSCALL_64_after_hwframe+0x44/0xa9
Signed-off-by: Huaisheng Ye <[email protected]>
---
drivers/md/dm-core.h | 1 +
drivers/md/dm-ioctl.c | 1 +
drivers/md/dm.c | 15 +++++++++++++++
3 files changed, 17 insertions(+)
diff --git a/drivers/md/dm-core.h b/drivers/md/dm-core.h
index 224d445..5577d90 100644
--- a/drivers/md/dm-core.h
+++ b/drivers/md/dm-core.h
@@ -40,6 +40,7 @@ struct mapped_device {
* dereference.
*/
void __rcu *map;
+ struct dm_table *hc_map;
unsigned long flags;
diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c
index f666778..a27016e 100644
--- a/drivers/md/dm-ioctl.c
+++ b/drivers/md/dm-ioctl.c
@@ -1365,6 +1365,7 @@ static int table_load(struct file *filp, struct dm_ioctl *param, size_t param_si
if (hc->new_map)
old_map = hc->new_map;
hc->new_map = t;
+ hc->md->hc_map = hc->new_map;
up_write(&_hash_lock);
param->flags |= DM_INACTIVE_PRESENT_FLAG;
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index c510179..19b48bb 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1080,6 +1080,21 @@ static struct dm_target *dm_dax_get_live_target(struct mapped_device *md,
struct dm_target *ti;
map = dm_get_live_table(md, srcu_idx);
+ if (!map) {
+ /* Sometimes dm_swap_table couldn't be used in time.
+ *
+ * For example, during the origin construction of
+ * dm-snapshot, the sys_ioctl table_load will try to
+ * detect the lower device origin-real whether support
+ * direct access or not. But origin-real device md's struct
+ * dm-table pointer has not yet been assigned real address.
+ * So hc_map has been used for get the address from
+ * struct hash_cell directly.
+ */
+ DMINFO("failed to get map, use hc_map insteadly");
+ map = md->hc_map;
+ }
+
if (!map)
return NULL;
--
1.8.3.1