On Thu, 11 Sep 2014 16:19:37 +1000 NeilBrown <neilb@xxxxxxx> wrote: > > > commit 4fa2c54b5198d09607a534e2fd436581064587ed > NFS: nfs4_do_open should add negative results to the dcache. > > used "d_drop(); d_add();" to ensure that a dentry was hashed > as a negative cached entry. > This is not safe if the dentry has an non-NULL ->d_inode. > It will trigger a BUG_ON in d_instantiate(). > In that case, d_delete() is needed. > > Also, only d_add if the dentry is currently unhashed, it seems > pointless removed and re-adding it unchanged. > > Reported-by: Christoph Hellwig <hch@xxxxxxxxxxxxx> > Fixes: 4fa2c54b5198d09607a534e2fd436581064587ed > Cc: Jeff Layton <jeff.layton@xxxxxxxxxxxxxxx> > Link: http://lkml.kernel.org/r/20140908144525.GB19811@xxxxxxxxxxxxx > Signed-off-by: NeilBrown <neilb@xxxxxxx> > > diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c > index 7dd8aca31c29..ac2dd953fc18 100644 > --- a/fs/nfs/nfs4proc.c > +++ b/fs/nfs/nfs4proc.c > @@ -2226,9 +2226,13 @@ static int _nfs4_open_and_get_state(struct nfs4_opendata *opendata, > ret = _nfs4_proc_open(opendata); > if (ret != 0) { > if (ret == -ENOENT) { > - d_drop(opendata->dentry); > - d_add(opendata->dentry, NULL); > - nfs_set_verifier(opendata->dentry, > + dentry = opendata->dentry; > + if (dentry->d_inode) > + d_delete(dentry); > + else if (d_unhashed(dentry)) > + d_add(dentry, NULL); > + > + nfs_set_verifier(dentry, > nfs_save_change_attribute(opendata->dir->d_inode)); > } > goto out; Acked-by: Jeff Layton <jlayton@xxxxxxxxxxxxxxx>
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