Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755910Ab2HORWC (ORCPT ); Wed, 15 Aug 2012 13:22:02 -0400 Received: from fieldses.org ([174.143.236.118]:56708 "EHLO fieldses.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754562Ab2HORWA (ORCPT ); Wed, 15 Aug 2012 13:22:00 -0400 Date: Wed, 15 Aug 2012 13:21:50 -0400 To: Miklos Szeredi Cc: viro@ZenIV.linux.org.uk, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, hch@infradead.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, apw@canonical.com, nbd@openwrt.org, neilb@suse.de, hramrach@centrum.cz, jordipujolp@gmail.com, ezk@fsl.cs.sunysb.edu, ricwheeler@gmail.com, dhowells@redhat.com, hpj@urpla.net, sedat.dilek@googlemail.com, penberg@kernel.org, goran.cetusic@gmail.com, romain@orebokech.com, mszeredi@suse.cz Subject: Re: [PATCH 01/13] vfs: add i_op->open() Message-ID: <20120815172150.GA25062@fieldses.org> References: <1345045700-9062-1-git-send-email-miklos@szeredi.hu> <1345045700-9062-2-git-send-email-miklos@szeredi.hu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1345045700-9062-2-git-send-email-miklos@szeredi.hu> User-Agent: Mutt/1.5.20 (2009-06-14) From: "J. Bruce Fields" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5923 Lines: 160 On Wed, Aug 15, 2012 at 05:48:08PM +0200, Miklos Szeredi wrote: > From: Miklos Szeredi > > Add a new inode operation i_op->open(). This is for stacked Shouldn't that "->open()" be "->dentry_open()" ? --b. > filesystems that want to return a struct file from a different > filesystem. > > Signed-off-by: Miklos Szeredi > --- > Documentation/filesystems/Locking | 2 ++ > Documentation/filesystems/vfs.txt | 7 +++++++ > fs/namei.c | 9 ++++++--- > fs/open.c | 23 +++++++++++++++++++++-- > include/linux/fs.h | 2 ++ > 5 files changed, 38 insertions(+), 5 deletions(-) > > diff --git a/Documentation/filesystems/Locking b/Documentation/filesystems/Locking > index 0f103e3..d222b6a 100644 > --- a/Documentation/filesystems/Locking > +++ b/Documentation/filesystems/Locking > @@ -64,6 +64,7 @@ prototypes: > int (*atomic_open)(struct inode *, struct dentry *, > struct file *, unsigned open_flag, > umode_t create_mode, int *opened); > + int (*dentry_open)(struct dentry *, struct file *, const struct cred *); > > locking rules: > all may block > @@ -92,6 +93,7 @@ removexattr: yes > fiemap: no > update_time: no > atomic_open: yes > +open: no > > Additionally, ->rmdir(), ->unlink() and ->rename() have ->i_mutex on > victim. > diff --git a/Documentation/filesystems/vfs.txt b/Documentation/filesystems/vfs.txt > index 065aa2d..f53d93c 100644 > --- a/Documentation/filesystems/vfs.txt > +++ b/Documentation/filesystems/vfs.txt > @@ -367,6 +367,7 @@ struct inode_operations { > int (*atomic_open)(struct inode *, struct dentry *, > struct file *, unsigned open_flag, > umode_t create_mode, int *opened); > + int (*dentry_open)(struct dentry *, struct file *, const struct cred *); > }; > > Again, all methods are called without any locks being held, unless > @@ -696,6 +697,12 @@ struct address_space_operations { > but instead uses bmap to find out where the blocks in the file > are and uses those addresses directly. > > + dentry_open: this is an alternative to f_op->open(), the difference is that > + this method may open a file not necessarily originating from the same > + filesystem as the one i_op->open() was called on. It may be > + useful for stacking filesystems which want to allow native I/O directly > + on underlying files. > + > > invalidatepage: If a page has PagePrivate set, then invalidatepage > will be called when part or all of the page is to be removed > diff --git a/fs/namei.c b/fs/namei.c > index 1b46439..ac2526d 100644 > --- a/fs/namei.c > +++ b/fs/namei.c > @@ -2816,9 +2816,12 @@ finish_open_created: > error = may_open(&nd->path, acc_mode, open_flag); > if (error) > goto out; > - file->f_path.mnt = nd->path.mnt; > - error = finish_open(file, nd->path.dentry, NULL, opened); > - if (error) { > + > + BUG_ON(*opened & FILE_OPENED); /* once it's opened, it's opened */ > + error = vfs_open(&nd->path, file, current_cred()); > + if (!error) { > + *opened |= FILE_OPENED; > + } else { > if (error == -EOPENSTALE) > goto stale_open; > goto out; > diff --git a/fs/open.c b/fs/open.c > index f3d96e7..c5a8cac 100644 > --- a/fs/open.c > +++ b/fs/open.c > @@ -787,8 +787,7 @@ struct file *dentry_open(const struct path *path, int flags, > return ERR_PTR(error); > > f->f_flags = flags; > - f->f_path = *path; > - error = do_dentry_open(f, NULL, cred); > + error = vfs_open(path, f, cred); > if (!error) { > error = open_check_o_direct(f); > if (error) { > @@ -803,6 +802,26 @@ struct file *dentry_open(const struct path *path, int flags, > } > EXPORT_SYMBOL(dentry_open); > > +/** > + * vfs_open - open the file at the given path > + * @path: path to open > + * @filp: newly allocated file with f_flag initialized > + * @cred: credentials to use > + */ > +int vfs_open(const struct path *path, struct file *filp, > + const struct cred *cred) > +{ > + struct inode *inode = path->dentry->d_inode; > + > + if (inode->i_op->dentry_open) > + return inode->i_op->dentry_open(path->dentry, filp, cred); > + else { > + filp->f_path = *path; > + return do_dentry_open(filp, NULL, cred); > + } > +} > +EXPORT_SYMBOL(vfs_open); > + > static void __put_unused_fd(struct files_struct *files, unsigned int fd) > { > struct fdtable *fdt = files_fdtable(files); > diff --git a/include/linux/fs.h b/include/linux/fs.h > index 38dba16..abc7a53 100644 > --- a/include/linux/fs.h > +++ b/include/linux/fs.h > @@ -1836,6 +1836,7 @@ struct inode_operations { > int (*atomic_open)(struct inode *, struct dentry *, > struct file *, unsigned open_flag, > umode_t create_mode, int *opened); > + int (*dentry_open)(struct dentry *, struct file *, const struct cred *); > } ____cacheline_aligned; > > struct seq_file; > @@ -2201,6 +2202,7 @@ extern long do_sys_open(int dfd, const char __user *filename, int flags, > extern struct file *filp_open(const char *, int, umode_t); > extern struct file *file_open_root(struct dentry *, struct vfsmount *, > const char *, int); > +extern int vfs_open(const struct path *, struct file *, const struct cred *); > extern struct file * dentry_open(const struct path *, int, const struct cred *); > extern int filp_close(struct file *, fl_owner_t id); > extern char * getname(const char __user *); > -- > 1.7.7 > > -- > 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/ -- 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/