The patch titled
vfs: fix __d_path for lazy unmounts
has been added to the -mm tree. Its filename is
fix-__d_path-for-lazy-unmounts.patch
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------------------------------------------------------
Subject: vfs: fix __d_path for lazy unmounts
From: John Johansen <john.johansen@xxxxxxxxxxxxx>
When __d_path() hits a lazily unmounted mount point, it tries to prepend
the name of the lazily unmounted dentry to the path name. It gets this
wrong, and also overwrites the slash that separates the name from the
following pathname component. This patch fixes that; if a process was in
directory /foo/bar and /foo got lazily unmounted, the old result was
``foobar'' (note the missing slash), while the new result with this patch
is ``/foo/bar''.
Signed-off-by: John Johansen <john.johansen@xxxxxxxxxxxxx>
Cc: Ram Pai <linuxram@xxxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Miklos Szeredi <mszeredi@xxxxxxx>
Cc: Andreas Gruenbacher <agruen@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/dcache.c | 27 +++++++++++++++++++++++----
1 file changed, 23 insertions(+), 4 deletions(-)
diff -puN fs/dcache.c~fix-__d_path-for-lazy-unmounts fs/dcache.c
--- a/fs/dcache.c~fix-__d_path-for-lazy-unmounts
+++ a/fs/dcache.c
@@ -1941,11 +1941,9 @@ char *__d_path(const struct path *path,
retval = end-1;
*retval = '/';
- for (;;) {
+ while(dentry != root->dentry || vfsmnt != root->mnt) {
struct dentry * parent;
- if (dentry == root->dentry && vfsmnt == root->mnt)
- break;
if (dentry == vfsmnt->mnt_root || IS_ROOT(dentry)) {
/* Global root? */
if (vfsmnt->mnt_parent == vfsmnt) {
@@ -1969,9 +1967,30 @@ out:
return retval;
global_root:
- retval += 1; /* hit the slash */
+ /*
+ * We went past the (vfsmount, dentry) we were looking for and have
+ * either hit a root dentry, a lazily unmounted dentry, an
+ * unconnected dentry, or the file is on a pseudo filesystem.
+ */
+ if ((dentry->d_sb->s_flags & MS_NOUSER) ||
+ (dentry->d_name.len = 1 && *dentry->d_name.name == '/')) {
+ /*
+ * Historically, we also glue together the root dentry and
+ * remaining name for pseudo filesystems like pipefs, which
+ * have the MS_NOUSER flag set. This results in pathnames
+ * like "pipe:[439336]".
+ */
+ retval += 1; /* overwrite the slash */
+ buflen++;
+ }
if (prepend_name(&retval, &buflen, &dentry->d_name) != 0)
goto Elong;
+
+ /* connect lazily unmounted mount point */
+ if (*retval != '/' && !(dentry->d_sb->s_flags & MS_NOUSER) &&
+ prepend(&retval, &buflen, "/", 1) != 0)
+ goto Elong;
+
root->mnt = vfsmnt;
root->dentry = dentry;
goto out;
_
Patches currently in -mm which might be from john.johansen@xxxxxxxxxxxxx are
linux-next.patch
fix-__d_path-for-lazy-unmounts.patch
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