Hello,
I am not sure how to better summarize this but I'll give a more
detailed description.
I am using btrfs tools v4.4, I setup up a btrfs partition on an
external USB2 drive and I started to play with it.
The partition was about HALF full when I decided to run duperemove on
it. This took a while but it eventually hung.
the logs around the hung say something like:
usb 1-1.1: USB disconnect, device number 3
usb 1-1.5: USB disconnect, device number 5
...
BTRFS error (device sdg2): bdev /dev/sdg2 errs: wr 0, rd 1, flush
0, corrupt 0, gen 0
...
Call Trace:
[<ffffffffc03d031f>] btrfs_ioctl+0x25bf/0x28b0 [btrfs]
[<ffffffff814fbf53>] ? tty_insert_flip_string_fixed_flag+0x83/0xe0
[<ffffffff810c3bd4>] ? __wake_up+0x44/0x50
[<ffffffff814f0db1>] ? tty_write_unlock+0x31/0x40
[<ffffffff814fae16>] ? tty_ldisc_deref+0x16/0x20
[<ffffffff81222caf>] do_vfs_ioctl+0x29f/0x490
[<ffffffff8120f099>] ? vfs_write+0x149/0x1a0
[<ffffffff8120df8f>] ? do_sys_open+0x1bf/0x2a0
[<ffffffff81222f19>] SyS_ioctl+0x79/0x90
[<ffffffff8183c672>] entry_SYSCALL_64_fastpath+0x16/0x71
...
usb-storage 1-1.5:1.0: USB Mass Storage device detected
...
sd 7:0:0:0: [sdh] Attached SCSI disk
EXT4-fs (sdh1): recovery complete
EXT4-fs (sdh1): mounted filesystem with ordered data mode. Opts: (null)
BTRFS error (device sdg2): bdev /dev/sdh2 errs: wr 0, rd 5, flush
0, corrupt 0, gen 0
...
BTRFS warning (device sdg2): error -5 while searching for
dev_stats item for device /dev/sdh2
BTRFS warning (device sdg2): Skipping commit of aborted transaction.
...
BTRFS: error (device sdg2) in cleanup_transaction:1746: errno=-5 IO failure
BTRFS info (device sdg2): forced readonly
More complete logs at:
pastebin.com/LqyWQamy
Basically the device can only be mounted as read-only, but no files
are accessible.
- Doing an `ls` on a folder gives "Input/output error".
- doing a `btrfs check` without --repair gives:
Checking filesystem on /dev/sdh2
UUID: 227fbb6c-ae72-4b81-8e65-942a0ddc6ef7
checking extents
checking free space cache
checking fs roots
checking csums
checking root refs
found 247566471406 bytes used err is 0
total csum bytes: 241513756
total tree bytes: 366084096
total fs tree bytes: 90259456
total extent tree bytes: 10010624
btree space waste bytes: 35406538
file data blocks allocated: 23837459185664
referenced 252963553280
So I guess no errors.
I can only mount it as read-only, and when I do a SCRUB it finishes in
0 seconds saying it was ABORTED.
I have no issue accessing the other EXT4 partition or dd-ing the btrfs
partition to /dev/null, so I doubt it is a disk issue.
I have not tried btrfs-zero-log because I do not see those kernel errors.
All I see when I mount it is lots of messages such as:
bdev /dev/sdh2 errs: wr 20, rd 28049, flush 0, corrupt 0, gen 0
I have not tried btrfs check --repair because I do not fully
understand the output of btrfs check.
Now, I have backups of the data, but I was wondering if and how can
BTRFS recover from this type of failure that can be quite common
(pulled plug).
Thanks.
- Alex.
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