btrfsck out of memory for big fs

[litaibaich...@gmail.com]

Hi Guys,

I had a big btrfs on a md device,  it be mounted , but after a while it will 
become ready only:
# btrfs fi df /data/
Data, single: total=24.46TiB, used=24.46TiB
System, DUP: total=8.00MiB, used=2.59MiB
System, single: total=4.00MiB, used=0.00B
Metadata, DUP: total=81.00GiB, used=79.71GiB
Metadata, single: total=8.00MiB, used=0.00B
GlobalReserve, single: total=512.00MiB, used=264.28MiB

# dmesg -T
[Thu Aug 16 18:16:31 2018] BTRFS error (device md127): parent transid verify 
failed on 26603622694912 wanted 185320 found 207817
[Thu Aug 16 18:16:31 2018] BTRFS error (device md127): parent transid verify 
failed on 26603622694912 wanted 185320 found 207817
[Thu Aug 16 18:16:31 2018] BTRFS warning (device md127): Skipping commit of 
aborted transaction.
[Thu Aug 16 18:16:31 2018] BTRFS: error (device md127) in 
cleanup_transaction:1864: errno=-5 IO failure
[Thu Aug 16 18:16:31 2018] BTRFS info (device md127): forced readonly
[Thu Aug 16 18:16:31 2018] BTRFS info (device md127): delayed_refs has NO entry

I want to use btrfsck to check it,  but it will OOM :
# btrfsck /dev/md127
Checking filesystem on /dev/md127
UUID: 6b87a52f-9a5f-4d03-b345-9d954c2ce259
checking extents
Killed

I am trying to use lowmem mode,  but as I tried before, it may OOM too,    any 
ideas ?

Thanks.

can I change NAME_MAX limit

[litaibaich...@gmail.com]

Hi Guys,

I am running btrfs on a 4.4.178 kernel,  I want to support a longer file name, 
now the NAME_MAX is 255,  can I just increase the NAME_MAX macro and recompile 
the kernel to support longer file name ?  I guess I will break sth,  but I am 
not sure what part will be broken.

Thanks.