[LU-3273] mdt_mfd_open() may call mdt_handle2mfd() w/o holding med_open_lock

• Type: Bug
• Resolution: Fixed
• Priority: Minor
• Fix Version/s: Lustre 2.5.0, Lustre 2.4.2
• Affects Version/s: Lustre 2.4.0
• Labels: mdt patch
• Severity: 3
• Assignee: John Hammond
• Reporter: John Hammond

Description

During replay mdt_mfd_open() calls mdt_handle2mfd() with out holding the med_open_lock. This seems like an potentially unsafe walk of the med_open_head list. It later takes the lock to unlink mfd, but it does not seem to check that it has won the possible race to unlink this mfd.