[LU-12852] growing a PFL file with last stripe as -1 fails

• Type: Bug
• Resolution: Fixed
• Priority: Critical
• Fix Version/s: Lustre 2.14.0, Lustre 2.12.5
• Affects Version/s: Lustre 2.10.8
• Severity: 2
• Assignee: Emoly Liu
• Reporter: Mahmoud Hanafi

Description

If a file/dir is striped with last stripe count set to -1 growing the file fails.

$  lfs setstripe -E 256M -c 1 -E 16G -c 4 -E -1 -S 4M -c -1 pfldir
$  echo hello > pfldir/test
$ echo helpo >> pfldir/test 
-bash: echo: write error: No space left on device

$  lfs getstripe pfldir/test
pfldir/test
  lcm_layout_gen:    3
  lcm_mirror_count:  1
  lcm_entry_count:   3
    lcme_id:             1
    lcme_mirror_id:      0
    lcme_flags:          init
    lcme_extent.e_start: 0
    lcme_extent.e_end:   268435456
      lmm_stripe_count:  1
      lmm_stripe_size:   1048576
      lmm_pattern:       raid0
      lmm_layout_gen:    0
      lmm_stripe_offset: 313
      lmm_objects:
      - 0: { l_ost_idx: 313, l_fid: [0x101390000:0x110967ab:0x0] }

    lcme_id:             2
    lcme_mirror_id:      0
    lcme_flags:          0
    lcme_extent.e_start: 268435456
    lcme_extent.e_end:   17179869184
      lmm_stripe_count:  4
      lmm_stripe_size:   1048576
      lmm_pattern:       raid0
      lmm_layout_gen:    0
      lmm_stripe_offset: -1

    lcme_id:             3
    lcme_mirror_id:      0
    lcme_flags:          0
    lcme_extent.e_start: 17179869184
    lcme_extent.e_end:   EOF
      lmm_stripe_count:  -1
      lmm_stripe_size:   4194304
      lmm_pattern:       raid0
      lmm_layout_gen:    0
      lmm_stripe_offset: -1

$  lfs setstripe -E 256M -c 1 -E 16G -c 4 -E -1 -S 4M -c 10 pfldir
$  echo hello > pfldir/test
$  echo helpo >> pfldir/test 

This worked.

Comments

[Gerrit Updater]

Oleg Drokin ([e-mail]) merged in patch https://review.whamcloud.com/37512/
Subject: LU-12852 pfl: restrict the stripe count correctly
Project: fs/lustre-release
Branch: b2_12
Current Patch Set:
Commit: 454771e39c556ac5a4b290d2bbf603dc7f308fdf

[Gerrit Updater]

Minh Diep ([e-mail]) uploaded a new patch: https://review.whamcloud.com/37512
Subject: LU-12852 pfl: restrict the stripe count correctly
Project: fs/lustre-release
Branch: b2_12
Current Patch Set: 1
Commit: 6a95331bcb4d4f0dd9c7c8a152509e1a6652042c

[Peter Jones]

Landed for 2.14

[Gerrit Updater]

Oleg Drokin ([e-mail]) merged in patch https://review.whamcloud.com/36947/
Subject: LU-12852 pfl: restrict the stripe count correctly
Project: fs/lustre-release
Branch: master
Current Patch Set:
Commit: 6dc37759cfb22727ac5d776c38b72e8638563fd8

[Gerrit Updater]

Emoly Liu ([e-mail]) uploaded a new patch: https://review.whamcloud.com/36947
Subject: LU-12852 pfl: restrict the stripe count correctly
Project: fs/lustre-release
Branch: master
Current Patch Set: 1
Commit: 8ab6646313ba7c7391ed19bd705ca5e694b5823d

[Peter Jones]

Could you please create a patch to address this issue?

[Andreas Dilger]

It looks like there is already a function "lod_get_stripe_count()" that is supposed to be checking the maximum xattr size and restricting the stripe count to this limit. It may be that the calculation is slightly incorrect (e.g. not taking into account the xattr overhead), so changing this slightly would work:

-        max_stripes = lov_mds_md_max_stripe_count(easize, LOV_MAGIC_V3);
+        max_stripes = lov_mds_md_max_stripe_count(easize, LOV_MAGIC_V3) - 1;

but I haven't tested this yet.

[Mahmoud Hanafi]

"correct number of stripes" meaning what ever it can fit.  Like the non-PFL case. It shouldn't fail.

 

[Andreas Dilger]

Mahmoud, could you clarify what you mean by "correct number of stripes" in this case? Without the "ea_inode" feature, then PFL will just not have as much space to store stripes as a non-PFL file. Hopefully by "correct number of stripes" you mean "whatever will still fit into the remaining xattr space", which is probably about 150 in your case, but will vary based on the number and size of the previous components. If you enable the "ea_inode" feature then you would actually be able to store the full 342 stripes in the last component.

[Mahmoud Hanafi]

I think this is a bug. PFL should create the correct number of stripes as with the non-PFL file.