[PATCH 3.16 130/328] fs/9p/xattr.c: catch the error of p9_client_clunk when setting xattr failed

From: Ben Hutchings
Date: Sun Dec 09 2018 - 17:15:17 EST

3.16.62-rc1 review patch. If anyone has any objections, please let me know.


From: piaojun <piaojun@xxxxxxxxxx>

commit 3111784bee81591ea2815011688d28b65df03627 upstream.

In my testing, v9fs_fid_xattr_set will return successfully even if the
backend ext4 filesystem has no space to store xattr key-value. That will
cause inconsistent behavior between front end and back end. The reason is
that lsetxattr will be triggered by p9_client_clunk, and unfortunately we
did not catch the error. This patch will catch the error to notify upper

p9_client_clunk (in 9p)
p9_client_rpc(clnt, P9_TCLUNK, "d", fid->fid);
v9fs_clunk (in qemu)
ext4_xattr_user_set (in host ext4 filesystem)

Link: http://lkml.kernel.org/r/5B57EACC.2060900@xxxxxxxxxx
Signed-off-by: Jun Piao <piaojun@xxxxxxxxxx>
Cc: Eric Van Hensbergen <ericvh@xxxxxxxxx>
Cc: Ron Minnich <rminnich@xxxxxxxxxx>
Cc: Latchesar Ionkov <lucho@xxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Dominique Martinet <dominique.martinet@xxxxxx>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
fs/9p/xattr.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

--- a/fs/9p/xattr.c
+++ b/fs/9p/xattr.c
@@ -121,7 +121,7 @@ int v9fs_fid_xattr_set(struct p9_fid *fi
const void *value, size_t value_len, int flags)
u64 offset = 0;
- int retval, msize, write_count;
+ int retval, err, msize, write_count;

p9_debug(P9_DEBUG_VFS, "name = %s value_len = %zu flags = %d\n",
name, value_len, flags);
@@ -158,7 +158,9 @@ int v9fs_fid_xattr_set(struct p9_fid *fi
retval = 0;
- p9_client_clunk(fid);
+ err = p9_client_clunk(fid);
+ if (!retval && err)
+ retval = err;
return retval;