On 2017年09月20日 12:59, Qu Wenruo wrote:
On 2017年09月20日 12:49, Rich Rauenzahn wrote:
On 9/19/2017 5:31 PM, Qu Wenruo wrote:
On 2017年09月19日 23:56, Rich Rauenzahn wrote:
[ 4.747377] WARNING: CPU: 3 PID: 439 at fs/btrfs/ctree.h:1559
btrfs_update_device+0x1c5/0x1d0 [btrfs]
Is that line the following WARN_ON()?
---
static inline void btrfs_set_device_total_bytes(struct extent_buffer
*eb,
struct btrfs_dev_item *s,
u64 val)
{
BUILD_BUG_ON(sizeof(u64) !=
sizeof(((struct btrfs_dev_item *)0))->total_bytes);
WARN_ON(!IS_ALIGNED(val, eb->fs_info->sectorsize)); <<<
btrfs_set_64(eb, s, offsetof(struct btrfs_dev_item, total_bytes),
val);
}
---
If so, that means your devices size is not aligned to 4K.
Is your block device still using old 512 block size?
AFAIK nowadays most HDDs are using 4K blocksize and it's recommended
to use it.
It's not a big problem and one can easily remove the WARN_ON().
But I think we'd better fix the caller to do round_down() before
calling this function.
That's interesting! I believe I made an effort to align them when I
set it up years ago, but never knew how to verify.
Well, best verifying if that's the line causing the warning, since I
don't have the source of RedHat kernel.
I have three mirrored filesystems:
[snip]
Number Start (sector) End (sector) Size Code Name
1 40 3907029134 1.8 TiB 8300 BTRFS MEDIA
GPT fdisk (gdisk) version 0.8.6
At least this size is not aligned to 4K.
Partition table scan:
[snip]
.....and one is aligned differently!
Could it be /dev/sdd that's the issue? But it's aligned at 4096 -- so
I'm not sure that's the issue after all.
Its start sector is aligned, but end point is not, so the size is not
aligned either.
BTW, is /dev/sdd added to btrfs using "btrfs device add"?
In my test, if making btrfs on a unaligned file, it will round down to
its sectorsize boundary.
Confirmed that "btrfs device add" won't round down the size.
Check the btrfs-debug-tree output:
------
item 0 key (DEV_ITEMS DEV_ITEM 1) itemoff 16185 itemsize 98
devid 1 total_bytes 10737418240 bytes_used 2172649472
io_align 4096 io_width 4096 sector_size 4096 type 0
generation 0 start_offset 0 dev_group 0
seek_speed 0 bandwidth 0
uuid 243a1117-ca31-4d87-8656-81c5630aafb2
fsid 6452cde7-14d5-4541-aa07-b265a400bad0
item 1 key (DEV_ITEMS DEV_ITEM 2) itemoff 16087 itemsize 98
devid 2 total_bytes 1073742336 bytes_used 0
io_align 4096 io_width 4096 sector_size 4096 type 0
generation 0 start_offset 0 dev_group 0
seek_speed 0 bandwidth 0
uuid 6bb07260-d230-4e22-88b1-1eabb46622ed
fsid 6452cde7-14d5-4541-aa07-b265a400bad0
------
Where first device is completely aligned, the 2nd device which is just
1G + 512, definitely not aligned.
So if you're using single device purely created by mkfs.btrfs, you're OK.
But if any new device added, you're not OK and causing the false alert.
Any way, it should not be hard to fix.
Just remove the WARN_ON() and add extra round_down when adding device.
Thanks for the report,
Qu
So I'm wondering if it's caused by added new btrfs device.
Thanks,
Qu
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