From: Olga Kornievskaia <kolga@netapp.com>
Date: Wed, 31 Mar 2021 15:30:25 -0400
Subject: [PATCH] NFSv4.2 fix handling of sr_eof in SEEK's reply
Git-commit: 73f5c88f521a630ea1628beb9c2d48a2e777a419
Patch-mainline: v5.13
References: git-fixes

Currently the client ignores the value of the sr_eof of the SEEK
operation. According to the spec, if the server didn't find the
requested extent and reached the end of the file, the server
would return sr_eof=true. In case the request for DATA and no
data was found (ie in the middle of the hole), then the lseek
expects that ENXIO would be returned.

Fixes: 1c6dcbe5ceff8 ("NFS: Implement SEEK")
Signed-off-by: Olga Kornievskaia <kolga@netapp.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Acked-by: NeilBrown <neilb@suse.com>

---
 fs/nfs/nfs42proc.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

--- a/fs/nfs/nfs42proc.c
+++ b/fs/nfs/nfs42proc.c
@@ -334,7 +334,10 @@ static loff_t _nfs42_proc_llseek(struct
 	if (status)
 		return status;
 
-	return vfs_setpos(filep, res.sr_offset, inode->i_sb->s_maxbytes);
+	if (whence == SEEK_DATA && res.sr_eof)
+		return -NFS4ERR_NXIO;
+	else
+		return vfs_setpos(filep, res.sr_offset, inode->i_sb->s_maxbytes);
 }
 
 loff_t nfs42_proc_llseek(struct file *filep, loff_t offset, int whence)