From: Miklos Szeredi <mszeredi@redhat.com>
To: linux-unionfs@vger.kernel.org
Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH v2 11/35] ovl: stack file ops
Date: Mon, 7 May 2018 10:37:43 +0200 [thread overview]
Message-ID: <20180507083807.28792-12-mszeredi@redhat.com> (raw)
In-Reply-To: <20180507083807.28792-1-mszeredi@redhat.com>
Implement file operations on a regular overlay file. The underlying file
is opened separately and cached in ->private_data.
It might be worth making an exception for such files when accounting in
nr_file to confirm to userspace expectations. We are only adding a small
overhead (248bytes for the struct file) since the real inode and dentry are
pinned by overlayfs anyway.
This patch doesn't have any effect, since the vfs will use d_real() to find
the real underlying file to open. The patch at the end of the series will
actually enable this functionality.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
---
fs/overlayfs/Makefile | 4 +--
fs/overlayfs/file.c | 76 ++++++++++++++++++++++++++++++++++++++++++++++++
fs/overlayfs/inode.c | 1 +
fs/overlayfs/overlayfs.h | 3 ++
4 files changed, 82 insertions(+), 2 deletions(-)
create mode 100644 fs/overlayfs/file.c
diff --git a/fs/overlayfs/Makefile b/fs/overlayfs/Makefile
index 30802347a020..46e1ff8ac056 100644
--- a/fs/overlayfs/Makefile
+++ b/fs/overlayfs/Makefile
@@ -4,5 +4,5 @@
obj-$(CONFIG_OVERLAY_FS) += overlay.o
-overlay-objs := super.o namei.o util.o inode.o dir.o readdir.o copy_up.o \
- export.o
+overlay-objs := super.o namei.o util.o inode.o file.o dir.o readdir.o \
+ copy_up.o export.o
diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c
new file mode 100644
index 000000000000..a0b606885c41
--- /dev/null
+++ b/fs/overlayfs/file.c
@@ -0,0 +1,76 @@
+/*
+ * Copyright (C) 2017 Red Hat, Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ */
+
+#include <linux/cred.h>
+#include <linux/file.h>
+#include <linux/xattr.h>
+#include "overlayfs.h"
+
+static struct file *ovl_open_realfile(const struct file *file)
+{
+ struct inode *inode = file_inode(file);
+ struct inode *upperinode = ovl_inode_upper(inode);
+ struct inode *realinode = upperinode ?: ovl_inode_lower(inode);
+ struct file *realfile;
+ const struct cred *old_cred;
+
+ old_cred = ovl_override_creds(inode->i_sb);
+ realfile = path_open(&file->f_path, file->f_flags | O_NOATIME,
+ realinode, current_cred(), false);
+ revert_creds(old_cred);
+
+ pr_debug("open(%p[%pD2/%c], 0%o) -> (%p, 0%o)\n",
+ file, file, upperinode ? 'u' : 'l', file->f_flags,
+ realfile, IS_ERR(realfile) ? 0 : realfile->f_flags);
+
+ return realfile;
+}
+
+static int ovl_open(struct inode *inode, struct file *file)
+{
+ struct dentry *dentry = file_dentry(file);
+ struct file *realfile;
+ int err;
+
+ err = ovl_open_maybe_copy_up(dentry, file->f_flags);
+ if (err)
+ return err;
+
+ /* No longer need these flags, so don't pass them on to underlying fs */
+ file->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);
+
+ realfile = ovl_open_realfile(file);
+ if (IS_ERR(realfile))
+ return PTR_ERR(realfile);
+
+ file->private_data = realfile;
+
+ return 0;
+}
+
+static int ovl_release(struct inode *inode, struct file *file)
+{
+ fput(file->private_data);
+
+ return 0;
+}
+
+static loff_t ovl_llseek(struct file *file, loff_t offset, int whence)
+{
+ struct inode *realinode = ovl_inode_real(file_inode(file));
+
+ return generic_file_llseek_size(file, offset, whence,
+ realinode->i_sb->s_maxbytes,
+ i_size_read(realinode));
+}
+
+const struct file_operations ovl_file_operations = {
+ .open = ovl_open,
+ .release = ovl_release,
+ .llseek = ovl_llseek,
+};
diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
index ba3f832cc39a..a228eda66ad8 100644
--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -535,6 +535,7 @@ static void ovl_fill_inode(struct inode *inode, umode_t mode, dev_t rdev,
switch (mode & S_IFMT) {
case S_IFREG:
inode->i_op = &ovl_file_inode_operations;
+ inode->i_fop = &ovl_file_operations;
break;
case S_IFDIR:
diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
index b9f7c632ab9c..edbf69c8f45d 100644
--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -374,6 +374,9 @@ int ovl_create_real(struct inode *dir, struct dentry *newdentry,
struct dentry *hardlink, bool debug);
int ovl_cleanup(struct inode *dir, struct dentry *dentry);
+/* file.c */
+extern const struct file_operations ovl_file_operations;
+
/* copy_up.c */
int ovl_copy_up(struct dentry *dentry);
int ovl_copy_up_flags(struct dentry *dentry, int flags);
--
2.14.3
next prev parent reply other threads:[~2018-05-07 8:38 UTC|newest]
Thread overview: 53+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-07 8:37 [PATCH v2 00/35] overlayfs: stack file operations Miklos Szeredi
2018-05-07 8:37 ` [PATCH v2 01/35] vfs: add path_open() Miklos Szeredi
2018-05-07 8:37 ` [PATCH v2 02/35] vfs: optionally don't account file in nr_files Miklos Szeredi
2018-05-07 8:37 ` [PATCH v2 03/35] vfs: add f_op->pre_mmap() Miklos Szeredi
2018-05-07 8:37 ` [PATCH v2 04/35] vfs: export vfs_ioctl() to modules Miklos Szeredi
2018-05-07 8:37 ` [PATCH v2 05/35] vfs: export vfs_dedupe_file_range_one() " Miklos Szeredi
2018-05-07 8:37 ` [PATCH v2 06/35] ovl: copy up times Miklos Szeredi
2018-05-07 8:37 ` [PATCH v2 07/35] ovl: copy up inode flags Miklos Szeredi
2018-05-07 8:37 ` [PATCH v2 08/35] Revert "Revert "ovl: get_write_access() in truncate"" Miklos Szeredi
2018-05-07 8:37 ` [PATCH v2 09/35] ovl: copy up file size as well Miklos Szeredi
2018-05-07 8:37 ` [PATCH v2 10/35] ovl: deal with overlay files in ovl_d_real() Miklos Szeredi
2018-05-07 13:17 ` Vivek Goyal
2018-05-07 8:37 ` Miklos Szeredi [this message]
2018-05-07 8:37 ` [PATCH v2 12/35] ovl: add helper to return real file Miklos Szeredi
2018-05-07 8:37 ` [PATCH v2 13/35] ovl: add ovl_read_iter() Miklos Szeredi
2018-05-07 8:37 ` [PATCH v2 14/35] ovl: add ovl_write_iter() Miklos Szeredi
2018-05-07 8:37 ` [PATCH v2 15/35] ovl: add ovl_fsync() Miklos Szeredi
2018-05-08 5:14 ` Amir Goldstein
2018-05-08 14:57 ` Miklos Szeredi
2018-05-08 15:02 ` Amir Goldstein
2018-05-07 8:37 ` [PATCH v2 16/35] ovl: add ovl_mmap() Miklos Szeredi
2018-05-07 8:37 ` [PATCH v2 17/35] ovl: add ovl_fallocate() Miklos Szeredi
2018-05-07 8:37 ` [PATCH v2 18/35] ovl: add lsattr/chattr support Miklos Szeredi
2018-05-07 8:37 ` [PATCH v2 19/35] ovl: add ovl_fiemap() Miklos Szeredi
2018-05-07 8:37 ` [PATCH v2 20/35] ovl: add O_DIRECT support Miklos Szeredi
2018-05-07 8:37 ` [PATCH v2 21/35] ovl: add reflink/copyfile/dedup support Miklos Szeredi
2018-05-07 20:43 ` Darrick J. Wong
2018-05-08 14:13 ` Miklos Szeredi
2018-05-08 14:38 ` Darrick J. Wong
2018-05-07 8:37 ` [PATCH v2 22/35] vfs: don't open real Miklos Szeredi
2018-05-07 10:27 ` Amir Goldstein
2018-05-07 10:29 ` Miklos Szeredi
2018-05-11 18:54 ` Vivek Goyal
2018-05-11 19:42 ` Vivek Goyal
2018-05-14 13:58 ` Vivek Goyal
2018-05-15 20:42 ` Vivek Goyal
2018-05-14 14:03 ` Daniel Walsh
2018-05-07 8:37 ` [PATCH v2 23/35] ovl: copy-up on MAP_SHARED Miklos Szeredi
2018-05-07 19:28 ` Randy Dunlap
2018-05-08 15:03 ` Miklos Szeredi
2018-05-07 8:37 ` [PATCH v2 24/35] vfs: simplify dentry_open() Miklos Szeredi
2018-05-07 8:37 ` [PATCH v2 25/35] Revert "ovl: fix may_write_real() for overlayfs directories" Miklos Szeredi
2018-05-07 8:37 ` [PATCH v2 26/35] Revert "ovl: don't allow writing ioctl on lower layer" Miklos Szeredi
2018-05-07 8:37 ` [PATCH v2 27/35] vfs: fix freeze protection in mnt_want_write_file() for overlayfs Miklos Szeredi
2018-05-07 8:38 ` [PATCH v2 28/35] Revert "ovl: fix relatime for directories" Miklos Szeredi
2018-05-07 8:38 ` [PATCH v2 29/35] Revert "vfs: update ovl inode before relatime check" Miklos Szeredi
2018-05-07 8:38 ` [PATCH v2 30/35] Revert "vfs: add flags to d_real()" Miklos Szeredi
2018-05-07 8:38 ` [PATCH v2 31/35] Revert "vfs: do get_write_access() on upper layer of overlayfs" Miklos Szeredi
2018-05-07 8:38 ` [PATCH v2 32/35] Partially revert "locks: fix file locking on overlayfs" Miklos Szeredi
2018-05-08 15:15 ` Jeff Layton
2018-05-07 8:38 ` [PATCH v2 33/35] Revert "fsnotify: support overlayfs" Miklos Szeredi
2018-05-07 8:38 ` [PATCH v2 34/35] vfs: remove open_flags from d_real() Miklos Szeredi
2018-05-07 8:38 ` [PATCH v2 35/35] ovl: fix documentation of non-standard behavior Miklos Szeredi
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