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fs: force_reval_path drop rcu-walk before d_invalidate

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d_revalidate can return in rcu-walk mode even when it returns 0.  We can't just
call any old dcache function on rcu-walk dentry (the dentry is unstable, so
even through d_lock can safely be taken, the result may no longer be what we
expect -- careful re-checks would be required). So just drop rcu in this case.

(I missed this conversion when switching to the rcu-walk convention that Linus
suggested)

Signed-off-by: Nick Piggin <npiggin@kernel.dk>
This commit is contained in:
Nick Piggin 2011-01-14 02:35:53 +00:00 committed by Nick Piggin
parent a82416da83
commit bb20c18db6
1 changed files with 10 additions and 0 deletions
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10
fs/namei.c
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@ -583,6 +583,13 @@ void release_open_intent(struct nameidata *nd)
fput(nd->intent.open.file);
}
/*
* Call d_revalidate and handle filesystems that request rcu-walk
* to be dropped. This may be called and return in rcu-walk mode,
* regardless of success or error. If -ECHILD is returned, the caller
* must return -ECHILD back up the path walk stack so path walk may
* be restarted in ref-walk mode.
*/
static int d_revalidate(struct dentry *dentry, struct nameidata *nd)
{
int status;
@ -673,6 +680,9 @@ force_reval_path(struct path *path, struct nameidata *nd)
return 0;
if (!status) {
/* Don't d_invalidate in rcu-walk mode */
if (nameidata_drop_rcu(nd))
return -ECHILD;
d_invalidate(dentry);
status = -ESTALE;
}