From 1932f94dee59198c44e3d906ffa86d7f6c677c20 Mon Sep 17 00:00:00 2001
From: shadow <shadow>
Date: Fri, 31 Jul 2009 10:28:03 +0000
Subject: [PATCH] correctly handling request reference in error cases.

Branch b1_8
b=20122
i=adilger
i=panda
---
 lustre/ChangeLog             |  6 ++++++
 lustre/include/obd_support.h |  2 +-
 lustre/llite/symlink.c       | 10 +++-------
 lustre/mds/handler.c         |  3 +++
 lustre/tests/sanity.sh       | 11 +++++++++++
 5 files changed, 24 insertions(+), 8 deletions(-)

diff --git a/lustre/ChangeLog b/lustre/ChangeLog
index 1247bec..8567a21 100644
--- a/lustre/ChangeLog
+++ b/lustre/ChangeLog
@@ -14,6 +14,12 @@ tbd Sun Microsystems, Inc.
 	  of Lustre filesystem with 4K stack may cause a stack overflow. For
 	  more information, please refer to bugzilla 17630.
 
+
+Severity   : normal
+Bugzilla   : 20122
+Description: don't panic if EPROTO was hit when reading symlink 
+Details    : correctly handling request reference in error cases.
+
 Severity   : normal
 Bugzilla   : 17545
 Description: open sometimes returns ENOENT instead of EACCES
diff --git a/lustre/include/obd_support.h b/lustre/include/obd_support.h
index b50e3bb..2b0988b 100644
--- a/lustre/include/obd_support.h
+++ b/lustre/include/obd_support.h
@@ -191,6 +191,7 @@ extern unsigned int obd_alloc_fail_rate;
 #define OBD_FAIL_MDS_FAIL_LOV_LOG_ADD    0x140
 #define OBD_FAIL_MDS_LOV_PREP_CREATE     0x141
 #define OBD_FAIL_MDS_SPLIT_OPEN          0x142
+#define OBD_FAIL_MDS_READLINK_EPROTO     0x143
 
 #define OBD_FAIL_OST                     0x200
 #define OBD_FAIL_OST_CONNECT_NET         0x201
@@ -290,7 +291,6 @@ extern unsigned int obd_alloc_fail_rate;
 #define OBD_FAIL_PTLRPC_PAUSE_REQ        0x50a
 #define OBD_FAIL_PTLRPC_PAUSE_REP        0x50c
 #define OBD_FAIL_PTLRPC_IMP_DEACTIVE     0x50d
-
 #define OBD_FAIL_PTLRPC_DUMP_LOG         0x50e
 #define OBD_FAIL_PTLRPC_LONG_REPL_UNLINK 0x50f
 #define OBD_FAIL_PTLRPC_LONG_BULK_UNLINK 0x510
diff --git a/lustre/llite/symlink.c b/lustre/llite/symlink.c
index 351c837..19cd222 100644
--- a/lustre/llite/symlink.c
+++ b/lustre/llite/symlink.c
@@ -102,15 +102,11 @@ static int ll_readlink_internal(struct inode *inode,
         /* do not return an error if we cannot cache the symlink locally */
         if (lli->lli_symlink_name) {
                 memcpy(lli->lli_symlink_name, *symname, symlen);
-                ptlrpc_req_finished (*request);
-                *request = NULL;
                 *symname = lli->lli_symlink_name;
         }
-
         RETURN(0);
 
- failed:
-        ptlrpc_req_finished (*request);
+failed:
         RETURN (rc);
 }
 
@@ -131,8 +127,8 @@ static int ll_readlink(struct dentry *dentry, char *buffer, int buflen)
                 GOTO(out, rc);
 
         rc = vfs_readlink(dentry, buffer, buflen, symname);
-        ptlrpc_req_finished(request);
  out:
+        ptlrpc_req_finished(request);
         up(&lli->lli_size_sem);
         RETURN(rc);
 }
@@ -194,7 +190,7 @@ static LL_FOLLOW_LINK_RETURN_TYPE ll_follow_link(struct dentry *dentry, struct n
            we delay request releasing until ll_put_link then. */
         RETURN(request);
 # else
-        if (request != NULL) {
+        if (lli->lli_symlink_name == NULL) {
                 /* falling back to recursive follow link if the request
                  * needs to be cleaned up still. */
                 rc = vfs_follow_link(nd, symname);
diff --git a/lustre/mds/handler.c b/lustre/mds/handler.c
index 2407e33..b024261 100644
--- a/lustre/mds/handler.c
+++ b/lustre/mds/handler.c
@@ -772,6 +772,9 @@ static int mds_getattr_internal(struct obd_device *obd, struct dentry *dentry,
                                 rc, len - 1);
                         rc = -EINVAL;
                 } else {
+                        if (OBD_FAIL_CHECK(OBD_FAIL_MDS_READLINK_EPROTO))
+                                rc -= 2;
+
                         CDEBUG(D_INODE, "read symlink dest %s\n", symname);
                         body->valid |= OBD_MD_LINKNAME;
                         body->eadatasize = rc + 1;
diff --git a/lustre/tests/sanity.sh b/lustre/tests/sanity.sh
index c0b9136..7a96c7a 100644
--- a/lustre/tests/sanity.sh
+++ b/lustre/tests/sanity.sh
@@ -458,6 +458,17 @@ test_17h() { #bug 17378
 }
 run_test 17h "create objects: lov_free_memmd() doesn't lbug"
 
+test_17i() { #bug 20018
+        mkdir -p $DIR/$tdir
+	local foo=$DIR/$tdir/$tfile
+	ln -s $foo $foo || error "create symlink failed"
+#define OBD_FAIL_MDS_READLINK_EPROTO     0x143
+	do_facet mds lctl set_param fail_loc=0x80000143
+	ls -l $foo && error "error not detected"
+	return 0
+}
+run_test 17i "don't panic on short symlink"
+
 test_18() {
 	touch $DIR/f
 	ls $DIR || error
-- 
1.8.3.1