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>
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5 changed files with 40 additions and 5 deletions
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@ -67,6 +67,7 @@ prototypes:
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struct file *, unsigned open_flag,
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umode_t create_mode, int *opened);
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int (*tmpfile) (struct inode *, struct dentry *, umode_t);
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int (*dentry_open)(struct dentry *, struct file *, const struct cred *);
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locking rules:
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all may block
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@ -96,6 +97,7 @@ fiemap: no
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update_time: no
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atomic_open: yes
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tmpfile: no
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dentry_open: no
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Additionally, ->rmdir(), ->unlink() and ->rename() have ->i_mutex on
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victim.
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@ -364,6 +364,7 @@ struct inode_operations {
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int (*atomic_open)(struct inode *, struct dentry *, struct file *,
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unsigned open_flag, umode_t create_mode, int *opened);
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int (*tmpfile) (struct inode *, struct dentry *, umode_t);
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int (*dentry_open)(struct dentry *, struct file *, const struct cred *);
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};
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Again, all methods are called without any locks being held, unless
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@ -696,6 +697,12 @@ struct address_space_operations {
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but instead uses bmap to find out where the blocks in the file
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are and uses those addresses directly.
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dentry_open: *WARNING: probably going away soon, do not use!* This is an
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alternative to f_op->open(), the difference is that this method may open
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a file not necessarily originating from the same filesystem as the one
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i_op->open() was called on. It may be useful for stacking filesystems
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which want to allow native I/O directly on underlying files.
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invalidatepage: If a page has PagePrivate set, then invalidatepage
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will be called when part or all of the page is to be removed
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@ -3064,9 +3064,12 @@ finish_open_created:
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error = may_open(&nd->path, acc_mode, open_flag);
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if (error)
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goto out;
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file->f_path.mnt = nd->path.mnt;
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error = finish_open(file, nd->path.dentry, NULL, opened);
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if (error) {
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BUG_ON(*opened & FILE_OPENED); /* once it's opened, it's opened */
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error = vfs_open(&nd->path, file, current_cred());
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if (!error) {
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*opened |= FILE_OPENED;
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} else {
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if (error == -EOPENSTALE)
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goto stale_open;
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goto out;
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23
fs/open.c
23
fs/open.c
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@ -823,8 +823,7 @@ struct file *dentry_open(const struct path *path, int flags,
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f = get_empty_filp();
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if (!IS_ERR(f)) {
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f->f_flags = flags;
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f->f_path = *path;
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error = do_dentry_open(f, NULL, cred);
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error = vfs_open(path, f, cred);
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if (!error) {
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/* from now on we need fput() to dispose of f */
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error = open_check_o_direct(f);
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@ -841,6 +840,26 @@ struct file *dentry_open(const struct path *path, int flags,
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}
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EXPORT_SYMBOL(dentry_open);
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/**
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* vfs_open - open the file at the given path
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* @path: path to open
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* @filp: newly allocated file with f_flag initialized
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* @cred: credentials to use
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*/
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int vfs_open(const struct path *path, struct file *filp,
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const struct cred *cred)
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{
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struct inode *inode = path->dentry->d_inode;
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if (inode->i_op->dentry_open)
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return inode->i_op->dentry_open(path->dentry, filp, cred);
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else {
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filp->f_path = *path;
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return do_dentry_open(filp, NULL, cred);
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}
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}
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EXPORT_SYMBOL(vfs_open);
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static inline int build_open_flags(int flags, umode_t mode, struct open_flags *op)
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{
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int lookup_flags = 0;
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@ -1528,6 +1528,9 @@ struct inode_operations {
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umode_t create_mode, int *opened);
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int (*tmpfile) (struct inode *, struct dentry *, umode_t);
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int (*set_acl)(struct inode *, struct posix_acl *, int);
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/* WARNING: probably going away soon, do not use! */
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int (*dentry_open)(struct dentry *, struct file *, const struct cred *);
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} ____cacheline_aligned;
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ssize_t rw_copy_check_uvector(int type, const struct iovec __user * uvector,
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@ -2040,6 +2043,7 @@ extern struct file *file_open_name(struct filename *, int, umode_t);
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extern struct file *filp_open(const char *, int, umode_t);
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extern struct file *file_open_root(struct dentry *, struct vfsmount *,
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const char *, int);
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extern int vfs_open(const struct path *, struct file *, const struct cred *);
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extern struct file * dentry_open(const struct path *, int, const struct cred *);
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extern int filp_close(struct file *, fl_owner_t id);
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