147 lines
5.1 KiB
Diff
147 lines
5.1 KiB
Diff
From 241ccca7d4e91d2b9d7249bc0b2758d9470b4c65 Mon Sep 17 00:00:00 2001
|
|
From: Miklos Szeredi <mszeredi@suse.cz>
|
|
Date: Thu, 27 Jun 2013 16:39:49 +0200
|
|
Subject: [PATCH 1/9] vfs: add i_op->dentry_open()
|
|
|
|
Add a new inode operation i_op->dentry_open(). This is for stacked filesystems
|
|
that want to return a struct file from a different filesystem.
|
|
|
|
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
|
|
---
|
|
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 0706d32..4331290 100644
|
|
--- a/Documentation/filesystems/Locking
|
|
+++ b/Documentation/filesystems/Locking
|
|
@@ -66,6 +66,7 @@ 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
|
|
@@ -93,6 +94,7 @@ removexattr: yes
|
|
fiemap: no
|
|
update_time: no
|
|
atomic_open: yes
|
|
+dentry_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 bc4b06b..f64a4d1 100644
|
|
--- a/Documentation/filesystems/vfs.txt
|
|
+++ b/Documentation/filesystems/vfs.txt
|
|
@@ -362,6 +362,7 @@ 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
|
|
@@ -681,6 +682,12 @@ 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 9ed9361..c06e521 100644
|
|
--- a/fs/namei.c
|
|
+++ b/fs/namei.c
|
|
@@ -2867,9 +2867,12 @@ 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 8c74100..ab07bc9 100644
|
|
--- a/fs/open.c
|
|
+++ b/fs/open.c
|
|
@@ -800,8 +800,7 @@ struct file *dentry_open(const struct path *path, int flags,
|
|
f = get_empty_filp();
|
|
if (!IS_ERR(f)) {
|
|
f->f_flags = flags;
|
|
- f->f_path = *path;
|
|
- error = do_dentry_open(f, NULL, cred);
|
|
+ error = vfs_open(path, f, cred);
|
|
if (!error) {
|
|
/* from now on we need fput() to dispose of f */
|
|
error = open_check_o_direct(f);
|
|
@@ -818,6 +817,26 @@ 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 inline int build_open_flags(int flags, umode_t mode, struct open_flags *op)
|
|
{
|
|
int lookup_flags = 0;
|
|
diff --git a/include/linux/fs.h b/include/linux/fs.h
|
|
index 65c2be2..0a87abc 100644
|
|
--- a/include/linux/fs.h
|
|
+++ b/include/linux/fs.h
|
|
@@ -1575,6 +1575,7 @@ 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;
|
|
|
|
ssize_t rw_copy_check_uvector(int type, const struct iovec __user * uvector,
|
|
@@ -2008,6 +2009,7 @@ extern struct file *file_open_name(struct filename *, int, umode_t);
|
|
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);
|
|
|
|
--
|
|
1.8.3.2
|
|
|