nfs: fix nfs4d readlink truncated packet
XDR requires 4-byte alignment; nfs4d READLINK reply writes out the padding,
but truncates the packet to the padding-less size.
Fix by taking the padding into consideration when truncating the packet.
Symptoms:
# ll /mnt/
ls: cannot read symbolic link /mnt/test: Input/output error
total 4
-rw-r--r--. 1 root root 0 Jun 14 01:21 123456
lrwxrwxrwx. 1 root root 6 Jul 2 03:33 test
drwxr-xr-x. 1 root root 0 Jul 2 23:50 tmp
drwxr-xr-x. 1 root root 60 Jul 2 23:44 tree
Signed-off-by: Avi Kivity <avi@cloudius-systems.com>
Fixes: 476a7b1f4b2c (nfsd4: don't treat readlink like a zero-copy operation)
Reviewed-by: Kinglong Mee <kinglongmee@gmail.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index 5b4fef5..2fc7abe 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -3278,7 +3278,7 @@
wire_count = htonl(maxcount);
write_bytes_to_xdr_buf(xdr->buf, length_offset, &wire_count, 4);
- xdr_truncate_encode(xdr, length_offset + 4 + maxcount);
+ xdr_truncate_encode(xdr, length_offset + 4 + ALIGN(maxcount, 4));
if (maxcount & 3)
write_bytes_to_xdr_buf(xdr->buf, length_offset + 4 + maxcount,
&zero, 4 - (maxcount&3));