Re: linux-next: Tree for Jan 20 -- Kernel panic - Unable to mount root fs
On Wed, Jan 21, 2015 at 11:06:27AM -0800, Guenter Roeck wrote:
On 01/21/2015 10:29 AM, Al Viro wrote:
>On Wed, Jan 21, 2015 at 05:32:13AM -0800, Guenter Roeck wrote:
>>Another data point (though I have no idea if it is useful or what it means):
>>
>>In the working case, path_init sets nd->flags to 0x50 or 0x51.
>>In the non-working case (ie for all files with a '/' in the name),
>>it sets nd->flags to 0x10 or 0x11, even though it is always called
>>with the LOOKUP_RCU bit set in flags.
>
>Umm... Are those path_init() succeeding or failing? Note that path_init()
>includes "walk everything except for the last component", so your
non-working
>case is "have it walk anything at all". What's failing there?
path_init()
>or handling the remaining component?
>
path_init() returns -2. Guess that explains the unexpected flags ;-).
The failuere is from
link_path_walk()
walk_component()
Which is to say, lookup gave it a negative dentry. OK, let's just make
vfs_mkdir() and walk_component() print what they are doing; on top of
linux-next
diff --git a/fs/namei.c b/fs/namei.c
index 323957f..8a4e22f 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1586,8 +1586,11 @@ static inline int walk_component(struct nameidata *nd, struct path
*path,
inode = path->dentry->d_inode;
}
err = -ENOENT;
- if (!inode || d_is_negative(path->dentry))
+ if (!inode || d_is_negative(path->dentry)) {
+ printk(KERN_ERR "walk_component[%p,%pd4] -> negative\n",
+ path->dentry, path->dentry);
goto out_path_put;
+ }
if (should_follow_link(path->dentry, follow)) {
if (nd->flags & LOOKUP_RCU) {
@@ -3521,6 +3524,7 @@ int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t
mode)
error = dir->i_op->mkdir(dir, dentry, mode);
if (!error)
fsnotify_mkdir(dir, dentry);
+ printk(KERN_ERR "mkdir[%p,%pd4] => %d\n", dentry, dentry, error);
return error;
}
EXPORT_SYMBOL(vfs_mkdir);