[Devel] [PATCH RHEL7 COMMIT] ms/fs: prepend_path() needs to reinitialize dentry/vfsmount/mnt on restarts

[Konstantin Khorenko]

The commit is pushed to "branch-rh7-3.10.0-123.1.2-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-123.1.2.vz7.5.14
------>
commit 4e9955e2ab67bfb8130919312e0d1689d42e6a2c
Author: Pavel Tikhomirov <ptikhomirov at virtuozzo.com>
Date:   Thu Jun 18 16:59:39 2015 +0400

    ms/fs: prepend_path() needs to reinitialize dentry/vfsmount/mnt on restarts
    
    Patchset description:
    
    port fixes from mainstream to fix fails from getcwd04 test,
    now it pass:
    
      ./third/ltp/testcases/kernel/syscalls/getcwd/getcwd04
      getcwd04    1  TPASS  :  Bug is not reproduced!
    
    https://jira.sw.ru/browse/PSBM-34245
    
    Al Viro (2):
      prepend_path() needs to reinitialize dentry/vfsmount/mnt on restarts
      __dentry_path() fixes
    
    Eric W. Biederman (1):
      vfs: Remove second variable named error in __dentry_path
    
    Pavel Tikhomirov (1):
      dcache: reinitialize error for resetart in prepend_path as in ms
    
    ##################################################################
    This patch description:
    
    From: Al Viro <viro at zeniv.linux.org.uk>
    
    Port mainstream commit:
    
      commit ede4cebce16f5643c61aedd6d88d9070a1d23a68
      Author: Al Viro <viro at zeniv.linux.org.uk>
      Date:   Wed Nov 13 07:45:40 2013 -0500
    
          prepend_path() needs to reinitialize dentry/vfsmount/mnt on
    
          ... and equivalent is needed in 3.12; it's broken there as
    
          Signed-off-by: Al Viro <viro at zeniv.linux.org.uk>
    
    Signed-off-by: Pavel Tikhomirov <ptikhomirov at virtuozzo.com>
    Reviewed-by: Vladimir Davydov <vdavydov at parallels.com>
---
 fs/dcache.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/fs/dcache.c b/fs/dcache.c
index 3670260..27c3a3a 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -2875,9 +2875,9 @@ static int prepend_path(const struct path *path,
 			const struct path *root,
 			char **buffer, int *buflen)
 {
-	struct dentry *dentry = path->dentry;
-	struct vfsmount *vfsmnt = path->mnt;
-	struct mount *mnt = real_mount(vfsmnt);
+	struct dentry *dentry;
+	struct vfsmount *vfsmnt;
+	struct mount *mnt;
 	int error = 0;
 	unsigned seq = 0;
 	char *bptr;
@@ -2887,6 +2887,9 @@ static int prepend_path(const struct path *path,
 restart:
 	bptr = *buffer;
 	blen = *buflen;
+	dentry = path->dentry;
+	vfsmnt = path->mnt;
+	mnt = real_mount(vfsmnt);
 	read_seqbegin_or_lock(&rename_lock, &seq);
 	while (dentry != root->dentry || vfsmnt != root->mnt) {
 		struct dentry * parent;