Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751443AbcCVGY7 (ORCPT ); Tue, 22 Mar 2016 02:24:59 -0400 Received: from mail-pf0-f194.google.com ([209.85.192.194]:33553 "EHLO mail-pf0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751380AbcCVGYu (ORCPT ); Tue, 22 Mar 2016 02:24:50 -0400 From: Daniel Axtens To: "Theodore Ts'o" , Miklos Szeredi Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, dhowells@redhat.com, viro@zeniv.linux.org.uk, Goldwyn Rodrigues , Trond Myklebust , stable@vger.kernel.org Subject: Re: [PATCH 1/4] vfs: add file_dentry() In-Reply-To: <20160321050215.GD3331@thunk.org> References: <1458205323-25685-1-git-send-email-miklos@szeredi.hu> <20160321050215.GD3331@thunk.org> User-Agent: Notmuch/0.21 (http://notmuchmail.org) Emacs/24.5.1 (x86_64-pc-linux-gnu) Date: Tue, 22 Mar 2016 17:24:44 +1100 Message-ID: <8737rjni6r.fsf@gamma.ozlabs.ibm.com> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4801 Lines: 139 >> From: Miklos Szeredi >> >> This series fixes bugs in nfs and ext4 due to 4bacc9c9234c ("overlayfs: Make >> f_path always point to the overlay and f_inode to the underlay"). >> >> Regular files opened on overlayfs will result in the file being opened on >> the underlying filesystem, while f_path points to the overlayfs >> mount/dentry. >> >> This confuses filesystems which get the dentry from struct file and assume >> it's theirs. >> >> Add a new helper, file_dentry() [*], to get the filesystem's own dentry >> from the file. This simply compares file_inode(file->f_path.dentry) to >> file_inode(file) and if they are equal returns file->f_path.dentry (this is >> the common, non-overlayfs case). >> >> In the uncommon case (regular file on overlayfs) it will call into >> overlayfs's ->d_native_dentry() to get the underlying dentry matching >> file_inode(file). >> >> [*] If possible, it's better simply to use file_inode() instead. Hopefully this is not so late as to be useless! For this entire series: Tested-by: Daniel Axtens Regards, Daniel >> >> Signed-off-by: Miklos Szeredi >> Tested-by: Goldwyn Rodrigues >> Reviewed-by: Trond Myklebust >> Cc: # v4.2 >> Cc: David Howells >> Cc: Al Viro >> Cc: Theodore Ts'o >> Cc: Daniel Axtens >> --- >> fs/open.c | 11 +++++++++++ >> fs/overlayfs/super.c | 16 ++++++++++++++++ >> include/linux/dcache.h | 1 + >> include/linux/fs.h | 2 ++ >> 4 files changed, 30 insertions(+) > > I have this patch in the ext4.git tree, but I'd like to get an > Acked-by from Al before I send a pull request to Linus. > > Al? Any objections to my sending in this change via the ext4 tree? > > - Ted > >> >> diff --git a/fs/open.c b/fs/open.c >> index 55bdc75e2172..6326c11eda78 100644 >> --- a/fs/open.c >> +++ b/fs/open.c >> @@ -831,6 +831,17 @@ char *file_path(struct file *filp, char *buf, int buflen) >> } >> EXPORT_SYMBOL(file_path); >> >> +struct dentry *file_dentry(const struct file *file) >> +{ >> + struct dentry *dentry = file->f_path.dentry; >> + >> + if (likely(d_inode(dentry) == file_inode(file))) >> + return dentry; >> + else >> + return dentry->d_op->d_native_dentry(dentry, file_inode(file)); >> +} >> +EXPORT_SYMBOL(file_dentry); >> + >> /** >> * vfs_open - open the file at the given path >> * @path: path to open >> diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c >> index 619ad4b016d2..5142aa2034c4 100644 >> --- a/fs/overlayfs/super.c >> +++ b/fs/overlayfs/super.c >> @@ -336,14 +336,30 @@ static int ovl_dentry_weak_revalidate(struct dentry *dentry, unsigned int flags) >> return ret; >> } >> >> +static struct dentry *ovl_d_native_dentry(struct dentry *dentry, >> + struct inode *inode) >> +{ >> + struct ovl_entry *oe = dentry->d_fsdata; >> + struct dentry *realentry = ovl_upperdentry_dereference(oe); >> + >> + if (realentry && inode == d_inode(realentry)) >> + return realentry; >> + realentry = __ovl_dentry_lower(oe); >> + if (realentry && inode == d_inode(realentry)) >> + return realentry; >> + BUG(); >> +} >> + >> static const struct dentry_operations ovl_dentry_operations = { >> .d_release = ovl_dentry_release, >> .d_select_inode = ovl_d_select_inode, >> + .d_native_dentry = ovl_d_native_dentry, >> }; >> >> static const struct dentry_operations ovl_reval_dentry_operations = { >> .d_release = ovl_dentry_release, >> .d_select_inode = ovl_d_select_inode, >> + .d_native_dentry = ovl_d_native_dentry, >> .d_revalidate = ovl_dentry_revalidate, >> .d_weak_revalidate = ovl_dentry_weak_revalidate, >> }; >> diff --git a/include/linux/dcache.h b/include/linux/dcache.h >> index c4b5f4b3f8f8..99ecb6de636c 100644 >> --- a/include/linux/dcache.h >> +++ b/include/linux/dcache.h >> @@ -161,6 +161,7 @@ struct dentry_operations { >> struct vfsmount *(*d_automount)(struct path *); >> int (*d_manage)(struct dentry *, bool); >> struct inode *(*d_select_inode)(struct dentry *, unsigned); >> + struct dentry *(*d_native_dentry)(struct dentry *, struct inode *); >> } ____cacheline_aligned; >> >> /* >> diff --git a/include/linux/fs.h b/include/linux/fs.h >> index ae681002100a..1091d9f43271 100644 >> --- a/include/linux/fs.h >> +++ b/include/linux/fs.h >> @@ -1234,6 +1234,8 @@ static inline struct inode *file_inode(const struct file *f) >> return f->f_inode; >> } >> >> +extern struct dentry *file_dentry(const struct file *file); >> + >> static inline int locks_lock_file_wait(struct file *filp, struct file_lock *fl) >> { >> return locks_lock_inode_wait(file_inode(filp), fl); >> -- >> 2.1.4 >>