[PATCH] VFS: d_obtain_alias needs to use "/" as default name.

From: NeilBrown
Date: Wed Aug 08 2012 - 21:57:21 EST



NFS appears to use d_obtain_alias() to create the root dentry rather
than d_make_root. This can cause 'prepend_path()' to complain that the
root has a weird name if an NFS filesystem is lazily unmounted.
e.g. if "/mnt" is an NFS mount then

{ cd /mnt; umount -l /mnt ; ls -l /proc/self/cwd; }

will cause a WARN message like
WARNING: at /home/git/linux/fs/dcache.c:2624 prepend_path+0x1d7/0x1e0()
...
Root dentry has weird name <>

to appear in kernel logs.

So change d_obtain_alias() to use "/" rather than "" as the anonymous
name.

Signed-off-by: NeilBrown <neilb@xxxxxxx>

diff --git a/fs/dcache.c b/fs/dcache.c
index 8086636..c959e41 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -1579,7 +1579,7 @@ EXPORT_SYMBOL(d_find_any_alias);
*/
struct dentry *d_obtain_alias(struct inode *inode)
{
- static const struct qstr anonstring = { .name = "" };
+ static const struct qstr anonstring = QSTR_INIT("/", 1);
struct dentry *tmp;
struct dentry *res;

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