[LU-3642] make seq_proc_write_common() safer

• Type: Bug
• Resolution: Fixed
• Priority: Critical
• Fix Version/s: Lustre 2.5.0
• Affects Version/s: Lustre 2.1.6, Lustre 2.4.1, Lustre 2.5.0
• Severity: 3
• Assignee: Andreas Dilger
• Reporter: Andreas Dilger

Description

Writing arbitrary values to the /proc/fs/lustre/seq/ctl-*/space tunable is dangerous and could make a filesystem unusable. It should be limited to shrinking the available space, instead of allowing arbitrary resetting of the sequence space, which can corrupt the sequence assignments and allow permanent filesystem corruption (e.g. duplicate sequences/FIDs).

Issue Links

• is related to: LU-3565 HSM: Allow specifying minimum FID sequence at format time