Details
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Bug
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Resolution: Unresolved
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Blocker
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None
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Lustre 2.16.1
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None
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Lustre 2.15 / EL7 or Lustre 2.16 / EL9
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2
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9223372036854775807
Description
Hello! I just realized that posix_fallocate() allows users to bypass Lustre quota enforcement. Tested against Lustre 2.15.5 and 2.16.1.
I'm attaching a simple fallocate helper fallocate.c that I used below.
We assume quota enforcement is enabled here (osd-ldiskfs.lustre-OST*.quota_slave_dt.enabled=up):
User quota enforcement:
$ lfs setquota -u sthiell -B 1T /elm
$ ./fallocate bigfalloc-user $(( 2 * 1024 * 1024 * 1024 * 1024 ))
$ stat bigfalloc-user
File: bigfalloc-user
Size: 2199023255552 Blocks: 4294968080 IO Block: 4194304 regular file
Device: 899af214h/2308633108d Inode: 144115441093058211 Links: 1
Access: (0644/-rw-r--r--) Uid: (282232/ sthiell) Gid: ( 100/ users)
Access: 2025-05-14 15:39:29.000000000 -0700
Modify: 2025-05-14 15:39:29.000000000 -0700
Change: 2025-05-14 15:39:29.000000000 -0700
Birth: 2025-05-14 15:39:29.000000000 -0700
$ lfs quota -u sthiell -h /elm/
Disk quotas for usr sthiell (uid 282232):
Filesystem used quota limit grace files quota limit grace
/elm/ 2T* 0k 1T - 5 0 0 -
On another system, I was able to bypass project quotas in the same way.
$ ./fallocate /scratch/users/sthiell/bigfalloc $(( 10 * 1024 * 1024 * 1024 * 1024 ))
Successfully allocated 10995116277760 bytes for file /scratch/users/sthiell/bigfalloc
$ lfs quota -p 282232 -h /scratch/
Disk quotas for prj 282232 (pid 282232):
Filesystem used quota limit grace files quota limit grace
/scratch/ 112T* 0k 100T - 4849 0 104857600 -
pid 282232 is using default block quota setting
Originally discovered with dtar which makes use of posix_fallocate() to preallocate the resulting tar file. It seems pretty important to fix this ASAP.