From d20cb71dbf3487f24549ede1a8e2d67579b4632e Mon Sep 17 00:00:00 2001 From: Al Viro Date: Mon, 20 Jun 2016 13:14:36 -0400 Subject: [PATCH] make nfs_atomic_open() call d_drop() on all ->open_context() errors. In "NFSv4: Move dentry instantiation into the NFSv4-specific atomic open code" unconditional d_drop() after the ->open_context() had been removed. It had been correct for success cases (there ->open_context() itself had been doing dcache manipulations), but not for error ones. Only one of those (ENOENT) got a compensatory d_drop() added in that commit, but in fact it should've been done for all errors. As it is, the case of O_CREAT non-exclusive open on a hashed negative dentry racing with e.g. symlink creation from another client ended up with ->open_context() getting an error and proceeding to call nfs_lookup(). On a hashed dentry, which would've instantly triggered BUG_ON() in d_materialise_unique() (or, these days, its equivalent in d_splice_alias()). Cc: stable@vger.kernel.org # v3.10+ Tested-by: Oleg Drokin Signed-off-by: Al Viro Signed-off-by: Trond Myklebust Signed-off-by: Anna Schumaker --- fs/nfs/dir.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c index 2817cce7a9f4..d8015a03db4c 100644 --- a/fs/nfs/dir.c +++ b/fs/nfs/dir.c @@ -1539,9 +1539,9 @@ int nfs_atomic_open(struct inode *dir, struct dentry *dentry, err = PTR_ERR(inode); trace_nfs_atomic_open_exit(dir, ctx, open_flags, err); put_nfs_open_context(ctx); + d_drop(dentry); switch (err) { case -ENOENT: - d_drop(dentry); d_add(dentry, NULL); nfs_set_verifier(dentry, nfs_save_change_attribute(dir)); break;