hello,
On 08/29/2016 11:52 PM, Ronan Arraes Jardim Chagas wrote:
Hi guys,
I just have the problem again. Now, it happens during the lunch time
when the machine was idle. Only the system processes were running. It
was not the first time that I saw this problem just after lunch when
the machine stayed idle for a long period (+- 1h).
Here is the information requested:
/sys/fs/btrfs/$UUID/allocation/data
./bytes_may_use
0
./bytes_pinned
0
./bytes_reserved
0
./bytes_used
36128374784
./disk_total
37589352448
./disk_used
36128374784
./flags
1
./total_bytes
37589352448
./total_bytes_pinned
20339560448
./single/total_bytes
37589352448
./single/used_bytes
36128374784
/sys/fs/btrfs/$UUID/allocation/metadata
./bytes_may_use
84974452736
./bytes_pinned
0
./bytes_reserved
0
./bytes_used
977354752
./disk_total
4294967296
./disk_used
1954709504
./flags
4
./total_bytes
2147483648
./total_bytes_pinned
-57851904
./dup/total_bytes
2147483648
./dup/used_bytes
977354752
For metadata, "bytes_may_use" is about 80GB, it's very big,
I think this value is very abnormal.
So this explains why you have huge unallocated space, you still
get ENOSPC error. In kernel btrfs, there is a function should_alloc_chunk()
to determine whether to allocate new chunks(new device space)
num_bytes = total_bytes - bytes_readonly; it's 2147483648
num_allocated = bytes_used + bytes_reserved; it's 977354752
if num_allocated < num_bytes * 0.8, it will not allocate new device
space :) even you
have huge unallocated space.
I think the root reason is that bytes_may_use has some computation error and
is not be converted to bytes_used or bytes_reserved.
I just explain why you get ENOSPC error even with huge unallocated space
from
codes :)
# btrfs fi usage /
btrfs_destroy_inode+0x23f/0x2b0 [btrfs]
Ago 29 12:06:07 ronanarraes-osd kernel: [<ffffffff8121f6d1>]
do_unlinkat+0x131/0x310
Ago 29 12:06:07 ronanarraes-osd kernel: [<ffffffff816bb4f6>]
entry_SYSCALL_64_fastpath+0x1e/0xa8
Ago 29 12:06:07 ronanarraes-osd kernel: DWARF2 unwinder stuck at
entry_SYSCALL_64_fastpath+0x1e/0xa8
Ago 29 12:06:07 ronanarraes-osd kernel:
Ago 29 12:06:07 ronanarraes-osd kernel: Leftover inexact backtrace:
Ago 29 12:06:07 ronanarraes-osd kernel: ---[ end trace 5774bd3049f78a63
]---
Yes, I know these WARNINGs, but indeed they are already results,
we don't know the procedures which cause these results.
Can you work out a reproducer for this ENOSPC error, then I can
dig into codes to figure out the true reason.
Regards,
Xiaoguang Wang
Best regards,
Ronan Arraes
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