[2.5.69] ext3 error: rec_len %% 4 != 0

[Florian Weimer]

Sometimes, our 2.5 test machine (actually, it's a production machine,
please don't ask why we can't use 2.4 *sigh*) stops with an ext3 error
message.  We have now activated proper logging, and that's what we
got:

May 28 03:23:00 kernel: EXT3-fs error (device md0): ext3_readdir: bad entry in directory #16056745: rec_len %% 4 != 0 - offset=52, inode=431743, rec_len=37017, name_len=41 
May 28 03:23:00 kernel: Aborting journal on device md0. 
May 28 03:23:00 kernel: ext3_abort called. 
May 28 03:23:00 kernel: EXT3-fs abort (device md0): ext3_journal_start: Detected aborted journal 
May 28 03:23:00 kernel: Remounting filesystem read-only 
May 28 03:23:00 kernel: EXT3-fs error (device md0) in ext3_commit_write: IO failure 
May 28 03:23:00 kernel: EXT3-fs error (device md0) in start_transaction: Journal has aborted 

What could cause this?  Spurious data transmission errors?  md0 is a
RAID-5, the machine is a Siemens Primergy H450 (Quad Pentium 4/Xeon, 4
GB RAM, two-channel Adaptec aic7899 Ultra160 SCSI adapter).

According to fsck.ext3, the on-disk data structures are clean, and if
I run "find" across the file system after the reboot, it doesn't
complain about bad directory entries, either.