On 11/30/2011 09:33 PM, Chris Dunlop wrote: > On Wed, Nov 30, 2011 at 08:22:39PM -0600, Dave Kleikamp wrote: >> On 11/30/2011 06:47 PM, Chris Dunlop wrote: >>>> It's also worth printing a message - this *is* a kernel bug of some >>>> description >>>> if it happens. >>> >>> Like the below? This covers the d_revalidate for 9p, afs, coda, >>> hfs, ncpfs, proc, sysfs. >>> >>> Note: jfs isn't susceptible to this problem, but the resolution >>> doesn't look like the other file systems, and from the comment >>> I'm not sure if the problem was really understood and if it's >>> doing the right thing: >> >> This code, as well as the comments, were copied from vfat. It seems >> reasonable for case-insensitive but case-preserving behavior (not jfs's >> default). The safe thing is to drop the negative dentry if we don't know >> the operation. > > In that case, it looks like the thing to do might be to add the > "protection" to the start of jfs_ci_revaliate(), per how the > original has been changed in vfat:
The LOOKUP_RCU check had previously been there, but Al Viro removed it: commit 5c0f360b083fb33d05d1bff4b138b82d715eb419 Author: Al Viro <[email protected]> Date: Sat Jun 25 21:41:09 2011 -0400 jfs_ci_revalidate() is safe from RCU mode I'm not sure what it takes to be "safe", but this is a simple function that doesn't block, take locks, or do much of anything. You shouldn't need to do anything with jfs. Shaggy > > fs/fat/namei_vfat.c: > static int vfat_revalidate_ci(struct dentry *dentry, struct nameidata *nd) > { > if (nd && nd->flags & LOOKUP_RCU) > return -ECHILD; > ... > } > > E.g.: > > ---------------------------------------------------------------------- > Don't oops when abused by broken layered file systems > > Signed-off-by: Chris Dunlop <[email protected]> > --- > fs/jfs/namei.c | 3 +++ > 1 files changed, 3 insertions(+), 0 deletions(-) > > diff --git a/fs/jfs/namei.c b/fs/jfs/namei.c > index e17545e..5504f6e 100644 > --- a/fs/jfs/namei.c > +++ b/fs/jfs/namei.c > @@ -1585,6 +1585,9 @@ out: > > static int jfs_ci_revalidate(struct dentry *dentry, struct nameidata *nd) > { > + if (nd && nd->flags & LOOKUP_RCU) > + return -ECHILD; > + > /* > * This is not negative dentry. Always valid. > * ------------------------------------------------------------------------------ All the data continuously generated in your IT infrastructure contains a definitive record of customers, application performance, security threats, fraudulent activity, and more. Splunk takes this data and makes sense of it. IT sense. And common sense. http://p.sf.net/sfu/splunk-novd2d _______________________________________________ Jfs-discussion mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/jfs-discussion
