From f39c01047994e66e7f3d89ddb4c6141f23349d8d Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Thu, 11 Sep 2014 16:19:37 +1000 Subject: [PATCH] NFS: remove BUG possibility in nfs4_open_and_get_state 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 Fixes: 4fa2c54b5198d09607a534e2fd436581064587ed Cc: Jeff Layton Link: http://lkml.kernel.org/r/20140908144525.GB19811@infradead.org Signed-off-by: NeilBrown Acked-by: Jeff Layton Signed-off-by: Trond Myklebust --- fs/nfs/nfs4proc.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) 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; -- 2.20.1