LU-11109 mdt: handle zero length xattr values correctly

[fs/lustre-release.git] / lustre / llite / xattr26.c

diff --git a/lustre/llite/xattr26.c b/lustre/llite/xattr26.c
index c6c3396..d3e18a5 100644 (file)
--- a/lustre/llite/xattr26.c
+++ b/lustre/llite/xattr26.c
@@ -414,8 +414,13 @@ getxattr_nocache:
                LASSERT(body);
 
                /* only detect the xattr size */
-               if (size == 0)
+               if (size == 0) {
+                       /* LU-11109: Older MDTs do not distinguish
+                        * between nonexistent xattrs and zero length
+                        * values in this case. Newer MDTs will return
+                        * -ENODATA or set OBD_MD_FLXATTR. */
                        GOTO(out, rc = body->mbo_eadatasize);
+               }
 
                if (size < body->mbo_eadatasize) {
                        CERROR("server bug: replied size %u > %u\n",
@@ -423,8 +428,23 @@ getxattr_nocache:
                        GOTO(out, rc = -ERANGE);
                }
 
-               if (body->mbo_eadatasize == 0)
-                       GOTO(out, rc = -ENODATA);
+               if (body->mbo_eadatasize == 0) {
+                       /* LU-11109: Newer MDTs set OBD_MD_FLXATTR on
+                        * success so that we can distinguish between
+                        * zero length value and nonexistent xattr.
+                        *
+                        * If OBD_MD_FLXATTR is not set then we keep
+                        * the old behavior and return -ENODATA for
+                        * getxattr() when mbo_eadatasize is 0. But
+                        * -ENODATA only makes sense for getxattr()
+                        * and not for listxattr(). */
+                       if (body->mbo_valid & OBD_MD_FLXATTR)
+                               GOTO(out, rc = 0);
+                       else if (valid == OBD_MD_FLXATTR)
+                               GOTO(out, rc = -ENODATA);
+                       else
+                               GOTO(out, rc = 0);
+               }
 
                /* do not need swab xattr data */
                xdata = req_capsule_server_sized_get(&req->rq_pill, &RMF_EADATA,