staging: lustre: llite: correct removexattr detection

[ Upstream commit 1b60f6df ]

In ll_xattr_set_common() detect the removexattr() case correctly by
testing for a NULL value as well as XATTR_REPLACE.
Signed-off-by: John L. Hammond <john.hammond@intel.com>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-10787
Reviewed-on: https://review.whamcloud.com/Reviewed-by: Dmitry Eremin <dmitry.eremin@intel.com>
Reviewed-by: James Simmons <uja.ornl@yahoo.com>
Signed-off-by: James Simmons <jsimmons@infradead.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/lustre/lustre/llite/xattr.c

@@ -103,7 +103,11 @@ ll_xattr_set_common(const struct xattr_handler *handler,
 	__u64 valid;
 	int rc;
 
-	if (flags == XATTR_REPLACE) {
+	/* When setxattr() is called with a size of 0 the value is
+	 * unconditionally replaced by "". When removexattr() is
+	 * called we get a NULL value and XATTR_REPLACE for flags.
+	 */
+	if (!value && flags == XATTR_REPLACE) {
 		ll_stats_ops_tally(ll_i2sbi(inode), LPROC_LL_REMOVEXATTR, 1);
 		valid = OBD_MD_FLXATTRRM;
 	} else {