From: Miklos Szeredi Add a new inode operation i_op->open(). This is for stacked filesystems that want to return a struct file from a different filesystem. Signed-off-by: Miklos Szeredi --- fs/open.c | 83 +++++++++++++++++++++++++++++++---------------------- include/linux/fs.h | 2 + 2 files changed, 51 insertions(+), 34 deletions(-) Index: linux-2.6/include/linux/fs.h =================================================================== --- linux-2.6.orig/include/linux/fs.h 2011-03-01 12:18:10.000000000 +0100 +++ linux-2.6/include/linux/fs.h 2011-03-01 12:18:15.000000000 +0100 @@ -1587,6 +1587,7 @@ struct inode_operations { void (*truncate_range)(struct inode *, loff_t, loff_t); int (*fiemap)(struct inode *, struct fiemap_extent_info *, u64 start, u64 len); + struct file *(*open)(struct dentry *, int flags, const struct cred *); } ____cacheline_aligned; struct seq_file; @@ -1990,6 +1991,7 @@ extern int do_fallocate(struct file *fil extern long do_sys_open(int dfd, const char __user *filename, int flags, int mode); extern struct file *filp_open(const char *, int, int); +extern struct file *vfs_open(struct path *, int flags, const struct cred *); extern struct file * dentry_open(struct dentry *, struct vfsmount *, int, const struct cred *); extern int filp_close(struct file *, fl_owner_t id); Index: linux-2.6/fs/open.c =================================================================== --- linux-2.6.orig/fs/open.c 2011-03-01 12:18:10.000000000 +0100 +++ linux-2.6/fs/open.c 2011-03-01 12:18:15.000000000 +0100 @@ -656,19 +656,19 @@ static inline int __get_file_write_acces return error; } -static struct file *__dentry_open(struct dentry *dentry, struct vfsmount *mnt, - struct file *f, +static struct file *__dentry_open(struct path *path, struct file *f, int (*open)(struct inode *, struct file *), const struct cred *cred) { struct inode *inode; int error; + path_get(path); f->f_mode = OPEN_FMODE(f->f_flags) | FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE; - inode = dentry->d_inode; + inode = path->dentry->d_inode; if (f->f_mode & FMODE_WRITE) { - error = __get_file_write_access(inode, mnt); + error = __get_file_write_access(inode, path->mnt); if (error) goto cleanup_file; if (!special_file(inode->i_mode)) @@ -676,8 +676,7 @@ static struct file *__dentry_open(struct } f->f_mapping = inode->i_mapping; - f->f_path.dentry = dentry; - f->f_path.mnt = mnt; + f->f_path = *path; f->f_pos = 0; f->f_op = fops_get(inode->i_fop); file_sb_list_add(f, inode->i_sb); @@ -723,7 +722,7 @@ static struct file *__dentry_open(struct * here, so just reset the state. */ file_reset_write(f); - mnt_drop_write(mnt); + mnt_drop_write(path->mnt); } } file_sb_list_del(f); @@ -731,8 +730,7 @@ static struct file *__dentry_open(struct f->f_path.mnt = NULL; cleanup_file: put_filp(f); - dput(dentry); - mntput(mnt); + path_put(path); return ERR_PTR(error); } @@ -758,14 +756,14 @@ static struct file *__dentry_open(struct struct file *lookup_instantiate_filp(struct nameidata *nd, struct dentry *dentry, int (*open)(struct inode *, struct file *)) { + struct path path = { .dentry = dentry, .mnt = nd->path.mnt }; const struct cred *cred = current_cred(); if (IS_ERR(nd->intent.open.file)) goto out; if (IS_ERR(dentry)) goto out_err; - nd->intent.open.file = __dentry_open(dget(dentry), mntget(nd->path.mnt), - nd->intent.open.file, + nd->intent.open.file = __dentry_open(&path, nd->intent.open.file, open, cred); out: return nd->intent.open.file; @@ -794,10 +792,17 @@ struct file *nameidata_to_filp(struct na /* Has the filesystem initialised the file for us? */ if (filp->f_path.dentry == NULL) { - path_get(&nd->path); - filp = __dentry_open(nd->path.dentry, nd->path.mnt, filp, - NULL, cred); + struct inode *inode = nd->path.dentry->d_inode; + + if (inode->i_op->open) { + int flags = filp->f_flags; + put_filp(filp); + filp = inode->i_op->open(nd->path.dentry, flags, cred); + } else { + filp = __dentry_open(&nd->path, filp, NULL, cred); + } } + return filp; } @@ -808,35 +813,45 @@ struct file *nameidata_to_filp(struct na struct file *dentry_open(struct dentry *dentry, struct vfsmount *mnt, int flags, const struct cred *cred) { - int error; + struct path path = { .dentry = dentry, .mnt = mnt }; + struct file *ret; + + BUG_ON(!mnt); + + ret = vfs_open(&path, flags, cred); + path_put(&path); + + return ret; +} +EXPORT_SYMBOL(dentry_open); + +/** + * vfs_open - open the file at the given path + * @path: path to open + * @flags: open flags + * @cred: credentials to use + * + * Open the file. If successful, the returned file will have acquired + * an additional reference for path. + */ +struct file *vfs_open(struct path *path, int flags, const struct cred *cred) +{ struct file *f; + struct inode *inode = path->dentry->d_inode; validate_creds(cred); - /* - * We must always pass in a valid mount pointer. Historically - * callers got away with not passing it, but we must enforce this at - * the earliest possible point now to avoid strange problems deep in the - * filesystem stack. - */ - if (!mnt) { - printk(KERN_WARNING "%s called with NULL vfsmount\n", __func__); - dump_stack(); - return ERR_PTR(-EINVAL); - } + if (inode->i_op->open) + return inode->i_op->open(path->dentry, flags, cred); - error = -ENFILE; f = get_empty_filp(); - if (f == NULL) { - dput(dentry); - mntput(mnt); - return ERR_PTR(error); - } + if (f == NULL) + return ERR_PTR(-ENFILE); f->f_flags = flags; - return __dentry_open(dentry, mnt, f, NULL, cred); + return __dentry_open(path, f, NULL, cred); } -EXPORT_SYMBOL(dentry_open); +EXPORT_SYMBOL(vfs_open); static void __put_unused_fd(struct files_struct *files, unsigned int fd) { -- -- 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/