[LU-13832] "lfs migrate -m" leads to inconsistent ldiskfs directories

• Type: Bug
• Resolution: Cannot Reproduce
• Priority: Major
• Affects Version/s: Lustre 2.14.0
• Severity: 3
• Assignee: Lai Siyao
• Reporter: Andreas Dilger

Description

I created a test directory with striped DNE directories as follows:

# export MDSCOUNT=8
# export DIR=/mnt/testfs/allmdt
# lfs mkdir -c -1 $DIR
# for D in $(seq $MDSCOUNT); do
    lfs mkdir -c 2 $DIR/dirstr$D
    rsync -a --exclude "policy.*" /etc/ $DIR/dirstr$D/
done

This created the test directories with a variety of files that can be verified. Then, migrate each directory and verify the contents have not changed (the rsync should not report any files that need to be updated):

# for D in $(seq $MDSCOUNT); do
    echo $DIR/dirstr$D
    lfs migrate -m $((RANDOM % MDSCOUNT)) -c2 $DIR/dirstr$D
    rsync -av --exclude "policy.*" --dry-run /etc/ $DIR/dirstr$D/
done

I ran this a couple of times, then ran e2fsck on the MDTs, and all of them showed the same problem on a lot of remote directories:

e2fsck 1.45.2.wc1 (27-May-2019)
Pass 1: Checking inodes, blocks, and sizes
Pass 2: Checking directory structure
Directory entry for '.' in ... (25191) is big. Split? yes
Missing '..' in directory inode 25191. Fix? yes
Setting filetype for entry '..' in ... (25191) to 2.
:
Pass 3: Checking directory connectivity   [[[ WHEN NOT FIXING ]]]
'..' in /REMOTE_PARENT_DIR/0x200000407:0x6f5:0x0 (26203) is <The NULL inode> (0), should be /REMOTE_PARENT_DIR (25001).
Fix? no
[[[ OR ]]]
Pass 3: Checking directory connectivity  [[[ WHEN FIXING ]]]
Unconnected directory inode 25191 (/???)
Connect to /lost+found? yes
:
Pass 4: Checking reference counts
Inode 2 ref count is 0, should be 11.  Fix? yes

Inode 25191 ref count is 3, should be 2.  Fix? yes

Looking at the directories under REMOTE_PARENT_DIR it appears that the ".." entry is missing from the directory, so "." is a single 4096-byte entry that consumes the whole block. It may be that this hasn't been noticed in the past because these directories are all small and do not need to be split for HTREE, which would add a ".." as part of struct dx_info.

Issue Links

• is related to: LU-14719 "lfs migrate -m" creates broken agent inodes when target MDT full