Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754690Ab0GLIGM (ORCPT ); Mon, 12 Jul 2010 04:06:12 -0400 Received: from fxip-0047f.externet.hu ([88.209.222.127]:42439 "EHLO pomaz-ex.szeredi.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752402Ab0GLIGL (ORCPT ); Mon, 12 Jul 2010 04:06:11 -0400 To: "Aneesh Kumar K.V" CC: hch@infradead.org, viro@zeniv.linux.org.uk, adilger@sun.com, corbet@lwn.net, neilb@suse.de, npiggin@suse.de, hooanon05@yahoo.co.jp, bfields@fieldses.org, linux-fsdevel@vger.kernel.org, sfrench@us.ibm.com, philippe.deniel@CEA.FR, linux-kernel@vger.kernel.org, aneesh.kumar@linux.vnet.ibm.com In-reply-to: <1278916545-19751-8-git-send-email-aneesh.kumar@linux.vnet.ibm.com> Subject: Re: [PATCH -V16 07/12] vfs: Support null pathname in linkat References: <1278916545-19751-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com> <1278916545-19751-8-git-send-email-aneesh.kumar@linux.vnet.ibm.com> Message-Id: From: Miklos Szeredi Date: Mon, 12 Jul 2010 10:05:39 +0200 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3174 Lines: 103 On Mon, 12 Jul 2010, Aneesh Kumar K.V wrote: > This enables to use linkat to create hardlinks from a > file descriptor pointing to the file. This can be used > with open_by_handle syscall that returns a file descriptor. This needs more thought, filesystems don't usually tolerate resurrecting a file which has already been unlinked (i_nlink == 0). Thanks, Miklos > > Signed-off-by: Aneesh Kumar K.V > --- > fs/namei.c | 34 +++++++++++++++++++++++++--------- > 1 files changed, 25 insertions(+), 9 deletions(-) > > diff --git a/fs/namei.c b/fs/namei.c > index a6a8093..9a7b71a 100644 > --- a/fs/namei.c > +++ b/fs/namei.c > @@ -2553,16 +2553,28 @@ SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, > { > struct dentry *new_dentry; > struct nameidata nd; > - struct path old_path; > - int error; > + struct path old_path, *old_pathp; > + struct file *file = NULL; > + int error, fput_needed; > char *to; > > if ((flags & ~AT_SYMLINK_FOLLOW) != 0) > return -EINVAL; > > - error = user_path_at(olddfd, oldname, > - flags & AT_SYMLINK_FOLLOW ? LOOKUP_FOLLOW : 0, > - &old_path); > + if (oldname == NULL && olddfd != AT_FDCWD) { > + file = fget_light(olddfd, &fput_needed); > + if (file) { > + old_pathp = &file->f_path; > + error = 0; > + } else > + error = -EBADF; > + } else { > + error = user_path_at(olddfd, oldname, > + flags & AT_SYMLINK_FOLLOW ? > + LOOKUP_FOLLOW : 0, > + &old_path); > + old_pathp = &old_path; > + } > if (error) > return error; > > @@ -2570,7 +2582,7 @@ SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, > if (error) > goto out; > error = -EXDEV; > - if (old_path.mnt != nd.path.mnt) > + if (old_pathp->mnt != nd.path.mnt) > goto out_release; > new_dentry = lookup_create(&nd, 0); > error = PTR_ERR(new_dentry); > @@ -2579,10 +2591,11 @@ SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, > error = mnt_want_write(nd.path.mnt); > if (error) > goto out_dput; > - error = security_path_link(old_path.dentry, &nd.path, new_dentry); > + error = security_path_link(old_pathp->dentry, &nd.path, new_dentry); > if (error) > goto out_drop_write; > - error = vfs_link(old_path.dentry, nd.path.dentry->d_inode, new_dentry); > + error = vfs_link(old_pathp->dentry, > + nd.path.dentry->d_inode, new_dentry); > out_drop_write: > mnt_drop_write(nd.path.mnt); > out_dput: > @@ -2593,7 +2606,10 @@ out_release: > path_put(&nd.path); > putname(to); > out: > - path_put(&old_path); > + if (file) > + fput_light(file, fput_needed); > + else > + path_put(&old_path); > > return error; > } > -- > 1.7.2.rc1 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/