From: Arik Rinberg <ArikRinberg@google.com>
To: Trond Myklebust <trond.myklebust@hammerspace.com>,
Anna Schumaker <anna@kernel.org>
Cc: linux-nfs@vger.kernel.org, linux-kernel@vger.kernel.org,
Arik Rinberg <ArikRinberg@google.com>
Subject: [PATCH] NFS: flag files as supporting FMODE_NOWAIT
Date: Tue, 21 Apr 2026 06:53:49 +0000 [thread overview]
Message-ID: <20260421065350.2219737-1-ArikRinberg@google.com> (raw)
When opening a file in NFS, set FMODE_NOWAIT in filp->f_mode.
Without this flag, asynchronous I/O frameworks like io_uring assume
that the file system does not support non-blocking I/O. This causes
io_uring to punt all I/O operations to background io-wq worker threads
to avoid blocking the main ring. This results in performance
degredation.
By setting FMODE_NOWAIT, we inform the VFS that NFS supports
asynchronous I/O natively, keeping execution on the fast path and
restoring performance.
Link: https://github.com/axboe/liburing/issues/1499
Signed-off-by: Arik Rinberg <ArikRinberg@google.com>
---
fs/nfs/file.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/nfs/file.c b/fs/nfs/file.c
index 5d08b6409c28..8e2100550f10 100644
--- a/fs/nfs/file.c
+++ b/fs/nfs/file.c
@@ -73,7 +73,7 @@ nfs_file_open(struct inode *inode, struct file *filp)
res = nfs_open(inode, filp);
if (res == 0)
- filp->f_mode |= FMODE_CAN_ODIRECT;
+ filp->f_mode |= FMODE_CAN_ODIRECT | FMODE_NOWAIT;
return res;
}
--
2.54.0.rc1.555.g9c883467ad-goog
reply other threads:[~2026-04-21 6:53 UTC|newest]
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