[linux-lvm] [RFC PATCH] lvconvert: fix the size of log device when converting from linear to mirror

[Zhong Lidong <lidong.zhong@suse.com>]

When converting a large linear device to mirror with --stripes parameter

in lvconvert command, it will report the following error:



ioctl/libdm-iface.c:1895    device-mapper: reload ioctl on  (254:0)
failed: Invalid argument



and the related kernel messages:



kernel: [ 2290.698171] device-mapper: dirty region log: log device 254:1
too small: need 7078912 bytes

kernel: [ 2290.698248] device-mapper: table: 254:0: mirror: Error
creating mirror dirty log

kernel: [ 2290.698251] device-mapper: ioctl: error adding target to table



Steps to reproduce this problem

~$:pvs

  PV         VG Fmt  Attr PSize  PFree

  /dev/loop0 vg lvm2 a--  10.00t 10.00t

  /dev/loop1 vg lvm2 a--  10.00t 10.00t

  /dev/loop2 vg lvm2 a--  10.00t 10.00t

  /dev/loop3    lvm2 ---  10.00t 10.00t

  /dev/loop4    lvm2 ---  10.00t 10.00t

  /dev/loop5    lvm2 ---  10.00t 10.00t



~$:lvcreate -nlv  -L27T vg

  Logical volume "lv" created.



~$:vgextend vg /dev/loop[3-5]

  Volume group "vg" successfully extended



~$:lvconvert  --type mirror --mirrors 1 --stripes 3 -I256  /dev/vg/lv
/dev/loop3 /dev/loop4 /dev/loop5

  device-mapper: reload ioctl on  (254:0) failed: Invalid argument

  Failed to lock logical volume vg/lv.

~$: lvs

  WARNING: Reading VG vg from disk because lvmetad metadata is invalid.

  LV      VG Attr       LSize  Pool Origin Data%  Meta%  Move Log
Cpy%Sync Convert

  lv      vg -wi-a----- 27.00t

  lv_mlog vg -wi-a-----  4.00m

~$: pvs

  PV         VG Fmt  Attr PSize  PFree

  /dev/loop0 vg lvm2 a--  10.00t     0

  /dev/loop1 vg lvm2 a--  10.00t     0

  /dev/loop2 vg lvm2 a--  10.00t  3.00t

  /dev/loop3 vg lvm2 a--  10.00t 10.00t

  /dev/loop4 vg lvm2 a--  10.00t 10.00t

  /dev/loop5 vg lvm2 a--  10.00t 10.00t



Analysis: In kernel space the required log size depends on the whole

target device size.But in user space, the log size is calculated from

the whole target devices size divided by allocation area number, which

leads to the mismatch here.



Signed-off-by: Lidong Zhong <lidong.zhong@suse.com>

---

 lib/metadata/lv_manip.c | 3 +--

 1 file changed, 1 insertion(+), 2 deletions(-)



diff --git a/lib/metadata/lv_manip.c b/lib/metadata/lv_manip.c

index 7e66afd9c..e8d67c79b 100644

--- a/lib/metadata/lv_manip.c

+++ b/lib/metadata/lv_manip.c

@@ -3730,8 +3730,7 @@ static struct alloc_handle *_alloc_init(struct
cmd_context *cmd,

 	} else {

 		ah->log_area_count = metadata_area_count;

 		ah->log_len = !metadata_area_count ? 0 :

-			_mirror_log_extents(ah->region_size, extent_size,

-					    (existing_extents + new_extents) / ah->area_multiple);

+			_mirror_log_extents(ah->region_size, extent_size, existing_extents +
new_extents);

 	}



 	if (total_extents || existing_extents)

-- 

2.26.2

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