A bunch of code is duplicated between debugfs and tracefs, unify it to the libfs library.
The code is very similar, except that dentry and inode creation are unified into a single function (unlike start_creating in debugfs and tracefs, which only takes care of dentries). This adds an output parameter to the creation functions, but pushes all error recovery into fs/libfs.c.
Signed-off-by: Emanuele Giuseppe Esposito eesposit@redhat.com --- fs/libfs.c | 226 +++++++++++++++++++++++++++++++++++++++++++++ include/linux/fs.h | 18 ++++ 2 files changed, 244 insertions(+)
diff --git a/fs/libfs.c b/fs/libfs.c index 5c76e4c648dc..90b0c221d9a2 100644 --- a/fs/libfs.c +++ b/fs/libfs.c @@ -751,6 +751,232 @@ struct inode *simple_alloc_anon_inode(struct simple_fs *fs) } EXPORT_SYMBOL(simple_alloc_anon_inode);
+static struct dentry *failed_creating(struct simple_fs *fs, struct dentry *dentry) +{ + inode_unlock(d_inode(dentry->d_parent)); + dput(dentry); + simple_release_fs(fs); + return ERR_PTR(-ENOMEM); +} + +/** + * simplefs_create_dentry - creates a new dentry and inode + * @fs: a pointer to a struct simple_fs containing the reference counter + * and vfs_mount pointer + * @type: the fs type + * @name: dentry name + * @parent: parent dentry. If this parameter is NULL, + * then the dentry will be created in the root of the + * filesystem. + * @inode: pointer that will contain a newly created inode + * + * This function returns a new dentry, or NULL on error. On success, a + * new inode is created and stored into @inode. Also note that the inode + * for the parent directory is locked by simplefs_create_dentry(), + * and will be unlocked by simple_finish_dentry(). + **/ +struct dentry *simplefs_create_dentry(struct simple_fs *fs, struct file_system_type *type, + const char *name, struct dentry *parent, + struct inode **inode) +{ + struct dentry *dentry; + int error; + + pr_debug("creating file '%s'\n", name); + + if (IS_ERR(parent)) + return parent; + + error = simple_pin_fs(fs, type); + if (error) { + pr_err("Unable to pin filesystem for file '%s'\n", name); + return ERR_PTR(error); + } + + /* If the parent is not specified, we create it in the root. + * We need the root dentry to do this, which is in the super + * block. A pointer to that is in the struct vfsmount that we + * have around. + */ + if (!parent) + parent = fs->mount->mnt_root; + + inode_lock(d_inode(parent)); + dentry = lookup_one_len(name, parent, strlen(name)); + if (!IS_ERR(dentry) && d_really_is_positive(dentry)) { + if (d_is_dir(dentry)) + pr_err("Directory '%s' with parent '%s' already present!\n", + name, parent->d_name.name); + else + pr_err("File '%s' in directory '%s' already present!\n", + name, parent->d_name.name); + dput(dentry); + dentry = ERR_PTR(-EEXIST); + } + + if (IS_ERR(dentry)) { + inode_unlock(d_inode(parent)); + simple_release_fs(fs); + } + + + if (IS_ERR(dentry)) + return dentry; + + *inode = new_inode_current_time(fs->mount->mnt_sb); + if (unlikely(!(*inode))) { + pr_err("out of free inodes, can not create file '%s'\n", + name); + return failed_creating(fs, dentry); + } + + return dentry; +} +EXPORT_SYMBOL(simplefs_create_dentry); + +/** + * simplefs_create_file - creates a new file dentry and inode + * @fs: a pointer to a struct simple_fs containing the reference counter + * and vfs_mount pointer + * @type: the fs type + * @name: file name + * @mode: file mode + * @parent: parent dentry. If this parameter is NULL, + * then the file will be created in the root of the + * filesystem. + * @data: what will the file contain + * @inode: pointer that will contain a newly created inode + * + * This function returns a new dentry, or NULL on error. On success, a + * new inode is created and stored into @inode. Also note that the inode + * for the parent directory is locked by simplefs_create_dentry(), + * and will be unlocked by simple_finish_dentry(). + **/ +struct dentry *simplefs_create_file(struct simple_fs *fs, struct file_system_type *type, + const char *name, umode_t mode, + struct dentry *parent, void *data, + struct inode **inode) +{ + struct dentry *dentry; + + WARN_ON((mode & S_IFMT) && !S_ISREG(mode)); + mode |= S_IFREG; + + dentry = simplefs_create_dentry(fs, type, name, parent, inode); + + if (IS_ERR(dentry)) + return dentry; + + (*inode)->i_mode = mode; + (*inode)->i_private = data; + + return dentry; +} +EXPORT_SYMBOL(simplefs_create_file); + + +/** + * simplefs_finish_dentry- complete creation of a new dentry + * @dentry: the dentry being created + * @inode: the inode associated to the dentry + * + * This function completes the creation of a dentry. + * This includes associating @inode with the dentry, ensuring the link + * counts are consistent and informing fsnotify. + **/ +struct dentry *simplefs_finish_dentry(struct dentry *dentry, struct inode *inode) +{ + d_instantiate(dentry, inode); + if (S_ISDIR(inode->i_mode)) { + inc_nlink(d_inode(dentry->d_parent)); + fsnotify_mkdir(d_inode(dentry->d_parent), dentry); + } else { + fsnotify_create(d_inode(dentry->d_parent), dentry); + } + inode_unlock(d_inode(dentry->d_parent)); + return dentry; +} +EXPORT_SYMBOL(simplefs_finish_dentry); + +/** + * simplefs_create_dir - creates a new directory dentry and inode + * @fs: a pointer to a struct simple_fs containing the reference counter + * and vfs_mount pointer + * @type: the fs type + * @name: dir name + * @mode: dir mode + * @parent: parent dentry. If this parameter is NULL, + * then the directory will be created in the root of the + * filesystem. + * @inode: pointer that will contain a newly created inode + * + * This function returns a new dentry, or NULL on error. On success, a + * new inode is created and stored into @inode. Also note that the inode + * for the parent directory is locked by simplefs_create_dentry(), + * and will be unlocked by simple_finish_dentry(). + **/ +struct dentry *simplefs_create_dir(struct simple_fs *fs, struct file_system_type *type, + const char *name, umode_t mode, struct dentry *parent, + struct inode **inode) +{ + struct dentry *dentry; + + WARN_ON((mode & S_IFMT) && !S_ISDIR(mode)); + mode |= S_IFDIR; + + dentry = simplefs_create_dentry(fs, type, name, parent, inode); + if (IS_ERR(dentry)) + return dentry; + + (*inode)->i_mode = mode; + (*inode)->i_op = &simple_dir_inode_operations; + (*inode)->i_fop = &simple_dir_operations; + + /* directory inodes start off with i_nlink == 2 (for "." entry) */ + inc_nlink(*inode); + return dentry; +} +EXPORT_SYMBOL(simplefs_create_dir); + +/** + * simplefs_create_symlink - creates a new symlink dentry and inode + * @fs: a pointer to a struct simple_fs containing the reference counter + * and vfs_mount pointer + * @type: the fs type + * @name: symlink name + * @parent: parent dentry. If this parameter is NULL, + * then the symbolic link will be created in the root of the + * filesystem. + * @inode: pointer that will contain a newly created inode + * + * This function returns a new dentry, or NULL on error. On success, a + * new inode is created and stored into @inode. Also note that the inode + * for the parent directory is locked by simplefs_create_dentry(), + * and will be unlocked by simple_finish_dentry(). + **/ +struct dentry *simplefs_create_symlink(struct simple_fs *fs, struct file_system_type *type, + const char *name, struct dentry *parent, + const char *target, struct inode **inode) +{ + struct dentry *dentry; + char *link = kstrdup(target, GFP_KERNEL); + + if (!link) + return ERR_PTR(-ENOMEM); + + dentry = simplefs_create_dentry(fs, type, name, parent, inode); + if (IS_ERR(dentry)) { + kfree_link(link); + return dentry; + } + + (*inode)->i_mode = S_IFLNK | S_IRWXUGO; + (*inode)->i_link = link; + (*inode)->i_op = &simple_symlink_inode_operations; + return dentry; +} +EXPORT_SYMBOL(simplefs_create_symlink); + /** * simple_read_from_buffer - copy data from the buffer to user space * @to: the user space buffer to read to diff --git a/include/linux/fs.h b/include/linux/fs.h index 5e93de72118b..0569540fbe61 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -3375,6 +3375,24 @@ extern void simple_release_fs(struct simple_fs *);
extern struct inode *simple_alloc_anon_inode(struct simple_fs *fs);
+extern struct dentry *simplefs_create_dentry(struct simple_fs *fs, + struct file_system_type *type, + const char *name, struct dentry *parent, + struct inode **inode); +struct dentry *simplefs_finish_dentry(struct dentry *dentry, struct inode *inode); + +extern struct dentry *simplefs_create_file(struct simple_fs *fs, + struct file_system_type *type, + const char *name, umode_t mode, + struct dentry *parent, void *data, + struct inode **inode); +extern struct dentry *simplefs_create_dir(struct simple_fs *fs, struct file_system_type *type, + const char *name, umode_t mode, struct dentry *parent, + struct inode **inode); +extern struct dentry *simplefs_create_symlink(struct simple_fs *fs, struct file_system_type *type, + const char *name, struct dentry *parent, + const char *target, struct inode **inode); + extern ssize_t simple_read_from_buffer(void __user *to, size_t count, loff_t *ppos, const void *from, size_t available); extern ssize_t simple_write_to_buffer(void *to, size_t available, loff_t *ppos,