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NFS/localio: issue commit inline when not in a memory-reclaim context

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Extend the memory-reclaim-context test used for LOCALIO reads and writes to
the commit (fsync) path.  As with data IO, bouncing every commit through the
dedicated !WQ_MEM_RECLAIM nfslocaliod_workqueue is only required when the
submitting context is a memory-reclaim context: nfs_local_run_commit() calls
vfs_fsync_range(), which may flush the underlying filesystem's own
!WQ_MEM_RECLAIM workqueue, and doing so from a WQ_MEM_RECLAIM worker or a
PF_MEMALLOC task trips check_flush_dependency().

The writeback path does exercise this: nfs_write_inode() (the ->write_inode
super_op) runs under wb_workfn on the WQ_MEM_RECLAIM bdi_wq and reaches
nfs_local_commit() via __nfs_commit_inode(), so that case must keep
deferring.  Application-context commits -- fsync (nfs_file_fsync), O_DIRECT
(nfs_direct), and copy/clone (nfs42) -- are not in a reclaim context and now
run the fsync inline via nfs_local_defer_io(), avoiding the per-commit
workqueue hop.

Completion (nfs_commit_release_pages -> nfs_commit_end) then runs
synchronously in the submitting context; higher layers already cope with
this, as __nfs_commit_inode() dispatches the commit async and waits for it
separately via wait_on_commit().

Assisted-by: Claude:claude-opus-4-8
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
This commit is contained in:
Mike Snitzer
2026-08-17 09:02:08 -07:00
committed by Trond Myklebust
parent b10c63dcf2
commit 3e05a62a97
1 changed files with 13 additions and 1 deletions
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fs/nfs/localio.c
+13 -1
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@@ -1132,7 +1132,19 @@ int nfs_local_commit(struct nfsd_file *localio,
}
nfs_local_init_commit(data, call_ops);
queue_work(nfslocaliod_workqueue, &ctx->work);
/*
* Run the commit (fsync) inline when not in a memory-reclaim context,
* rather than bouncing through nfslocaliod_workqueue; see
* nfs_local_defer_io(). Completion (nfs_commit_release_pages ->
* nfs_commit_end) then runs synchronously, which higher layers cope
* with: __nfs_commit_inode() dispatches async and waits via
* wait_on_commit().
*/
if (nfs_local_defer_io())
queue_work(nfslocaliod_workqueue, &ctx->work);
else
nfs_local_fsync_work(&ctx->work);
return 0;
}