From 862bee84d77fa01cc8929656ae77781abf917863 Mon Sep 17 00:00:00 2001
From: Chuck Lever <chuck.lever@oracle.com>
Date: Sat, 16 Dec 2023 11:57:43 -0500
Subject: NFSD: Revert 6c41d9a9bd0298002805758216a9c44e38a8500d

For some reason, the wait_on_bit() in nfsd4_deleg_getattr_conflict()
is waiting forever, preventing a clean server shutdown. The
requesting client might also hang waiting for a reply to the
conflicting GETATTR.

Invoking wait_on_bit() in an nfsd thread context is a hazard. The
correct fix is to replace this wait_on_bit() call site with a
mechanism that defers the conflicting GETATTR until the CB_GETATTR
completes or is known to have failed.

That will require some surgery and extended testing and it's late
in the v6.7-rc cycle, so I'm reverting now in favor of trying again
in a subsequent kernel release.

This is my fault: I should have recognized the ramifications of
calling wait_on_bit() in here before accepting this patch.

Thanks to Dai Ngo <dai.ngo@oracle.com> for diagnosing the issue.

Reported-by: Wolfgang Walter <linux-nfs@stwm.de>
Closes: https://lore.kernel.org/linux-nfs/e3d43ecdad554fbdcaa7181833834f78@stwm.de/
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
 fs/nfsd/nfs4xdr.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

(limited to 'fs/nfsd/nfs4xdr.c')

diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index ec4ed6206df1..b499fe9caa32 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -3505,9 +3505,7 @@ nfsd4_encode_fattr4(struct svc_rqst *rqstp, struct xdr_stream *xdr,
 		u32		attrmask[3];
 		unsigned long	mask[2];
 	} u;
-	bool file_modified;
 	unsigned long bit;
-	u64 size = 0;
 
 	WARN_ON_ONCE(bmval[1] & NFSD_WRITEONLY_ATTRS_WORD1);
 	WARN_ON_ONCE(!nfsd_attrs_supported(minorversion, bmval));
@@ -3534,8 +3532,7 @@ nfsd4_encode_fattr4(struct svc_rqst *rqstp, struct xdr_stream *xdr,
 	}
 	args.size = 0;
 	if (u.attrmask[0] & (FATTR4_WORD0_CHANGE | FATTR4_WORD0_SIZE)) {
-		status = nfsd4_deleg_getattr_conflict(rqstp, d_inode(dentry),
-						      &file_modified, &size);
+		status = nfsd4_deleg_getattr_conflict(rqstp, d_inode(dentry));
 		if (status)
 			goto out;
 	}
@@ -3545,7 +3542,7 @@ nfsd4_encode_fattr4(struct svc_rqst *rqstp, struct xdr_stream *xdr,
 			  AT_STATX_SYNC_AS_STAT);
 	if (err)
 		goto out_nfserr;
-	args.size = file_modified ? size : args.stat.size;
+	args.size = args.stat.size;
 
 	if (!(args.stat.result_mask & STATX_BTIME))
 		/* underlying FS does not offer btime so we can't share it */
-- 
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