| From d20cb71dbf3487f24549ede1a8e2d67579b4632e Mon Sep 17 00:00:00 2001 |
| From: Al Viro <viro@ZenIV.linux.org.uk> |
| Date: Mon, 20 Jun 2016 13:14:36 -0400 |
| Subject: make nfs_atomic_open() call d_drop() on all ->open_context() errors. |
| |
| From: Al Viro <viro@ZenIV.linux.org.uk> |
| |
| commit d20cb71dbf3487f24549ede1a8e2d67579b4632e upstream. |
| |
| 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()). |
| |
| Tested-by: Oleg Drokin <green@linuxhacker.ru> |
| Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> |
| Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com> |
| Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| fs/nfs/dir.c | 2 +- |
| 1 file changed, 1 insertion(+), 1 deletion(-) |
| |
| --- a/fs/nfs/dir.c |
| +++ b/fs/nfs/dir.c |
| @@ -1531,9 +1531,9 @@ int nfs_atomic_open(struct inode *dir, s |
| 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; |
