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<span style="font-family: Aptos, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">Hi all<br>
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I'd like feedback on a small client-utility addition before I open an LU.</div>
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Problem statement</div>
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A user (or a job prolog) who wants to know "how much can I actually write</div>
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here before something shuts the door and stops me?" today has to run two commands and reconcile</div>
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them by hand:</div>
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- `lfs df` -> physical free space, but blind to the caller's quota</div>
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- `lfs quota` -> the caller's quota limit, but blind to physical free space</div>
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The information the user or job is looking for is min(filesystem free, quota hard limit - used),</div>
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per filesystem, for both space/bytes and inodes. </div>
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Getting it wrong means jobs that die mid-run on EDQUOT/ENOSPC that a prolog check could have caught.</div>
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Proposal (step1) -- a read-only 'lfs usage' subcommand</div>
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lfs usage [--user|-u ID] [--group|-g ID] [--projid|-p ID]</div>
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[--human-readable|-h] [PATH ...]</div>
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- With no id, reports the process user/context calling euid.</div>
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- Per filesystem, prints used / limit / usable / use% / fs_free for both</div>
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space and inodes, where usable = min(fs_free, hardlimit - used).</div>
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- Bare numeric output by default (1-KiB units for space, like `lfs quota`);</div>
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-h for human-readable. Follows existing lfs conventions.</div>
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Implementation: </div>
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It would reuse existing client interfaces only -- statfs(2) for the</div>
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physical free (the same number df(1) reports) and OBD_IOC_QUOTACTL /</div>
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LUSTRE_Q_GETQUOTA (QC_GENERAL) for the IDs' live usage+limits, which is already aggregated across all OSTs and MDTs (similar if not the same as `lfs quota` does). </div>
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No new RPC, no wire-protocol change, works against any current server.</div>
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Usage is reported even when enforcement is off, since accounting is always-on; at least thats how I understand it.</div>
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Deliberately NOT changing df/statfs</div>
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This is intentionally a *reporting* tool, not a change to what plain `df` or</div>
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statfs() returns. It does not touch or duplicate the existing project-quota</div>
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statfs mechanism (ll_statfs_project / statfs_project, LU-9555) or the in-flight</div>
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projid df work (LU-19034, Gerrit 65511). It complements them from the utility</div>
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side and adds the user/group dimension, for which there is no prior code as of today if I didnt miss anything.</div>
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Known step1 limitation -> motivates step2</div>
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Enforcement on/off state is not currently retrievable by a client (the qsd</div>
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enable mask is never packed into any RPC reply; it's server-side procfs only).</div>
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So when a limit is set but not enforced, step1's "usable might underreport the real</div>
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writable space -- similar to LU-17395.</div>
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As, step2, I'd like to add an enforcement-state bit to the quota</div>
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reply so `lfs usage` (and, if wanted, ll_statfs_project) can distinguish a</div>
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binding limit from a suggesting one. </div>
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That is the only piece that needs a wire</div>
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change, and I'd like to propose it being implemented alongside the existing quota/statfs work rather</div>
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than on its own.</div>
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Questions for the readers here</div>
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1. Is a new `lfs usage` subcommand the right home/place, or would you prefer this</div>
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folded into `lfs quota` (e.g. a --usable / --df column)? I lean toward a</div>
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separate subcommand because the physical-free term doesn't really belong in</div>
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`lfs quota`, and `lfs df -u` is impossible now that -u is output, but thats me.</div>
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2. Any objection to the step1 reporting approach landing first, decoupled from</div>
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the v2 enforcement-signal wire change?</div>
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A strawman patch (utils-only, plus man page and a sanity-quota test) is ready;</div>
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I'll attach it to the LU once there's rough consensus on the interface, and it's not shut down here.</div>
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Thanks,</div>
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Andreas Krause</div>
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