[PATCH 5.10 122/289] NFSv4.2 fix handling of sr_eof in SEEKs reply

From: Greg Kroah-Hartman
Date: Mon May 17 2021 - 11:39:04 EST

From: Olga Kornievskaia <kolga@xxxxxxxxxx>

[ Upstream commit 73f5c88f521a630ea1628beb9c2d48a2e777a419 ]

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@xxxxxxxxxx>
Signed-off-by: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
fs/nfs/nfs42proc.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/fs/nfs/nfs42proc.c b/fs/nfs/nfs42proc.c
index 948a4c69687c..4ebcd9dd1535 100644
--- a/fs/nfs/nfs42proc.c
+++ b/fs/nfs/nfs42proc.c
@@ -665,7 +665,10 @@ static loff_t _nfs42_proc_llseek(struct file *filep,
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)