From mboxrd@z Thu Jan 1 00:00:00 1970 From: Al Viro Subject: Re: linux-next: Tree for Jan 20 -- Kernel panic - Unable to mount root fs Date: Wed, 21 Jan 2015 20:06:26 +0000 Message-ID: <20150121200626.GR29656@ZenIV.linux.org.uk> References: <1528536.jyty2pu4Mz@sifl> <20150121004117.GM29656@ZenIV.linux.org.uk> <54BF1292.2080902@roeck-us.net> <20150121033600.GN29656@ZenIV.linux.org.uk> <54BF2496.4000807@roeck-us.net> <20150121043637.GO29656@ZenIV.linux.org.uk> <20150121110539.GA8924@kria> <54BFAA5D.4040108@roeck-us.net> <20150121182905.GQ29656@ZenIV.linux.org.uk> <54BFF8B3.6060802@roeck-us.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Sabrina Dubroca , Paul Moore , Stephen Rothwell , linux-next@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-audit@redhat.com, Richard Guy Briggs To: Guenter Roeck Return-path: Content-Disposition: inline In-Reply-To: <54BFF8B3.6060802@roeck-us.net> Sender: linux-next-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org 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);