From: Maneesh Soni => changes in version 0.6 o Re-diffed for 2.6.6-mm3 o Provided protection against vulneribility of parent going before the sysfs file being removed in sysfs_remove_dir(). There os less chance happening this here, but still it will have some code clarity. Now it uses s_dentry field to check if the file dentry is vaild instead of doing a lookup. A new routine sysfs_drop_dentry() is introduced for this purpose. => changes in version 0.5 o Changed ->read_dir & ->lseek logic. The ->read_dir and ->lseek logic is now based on the sysfs_dirent tree instead of dentry based tree. Now we don't have to dget/dput children while opening a dir. The earlier logic was wrong in the sense as we might end up in doing dput() for dentrys which were not opened by us. o Code changes to accomodate latest sysfs changes like in sysfs_rename_dir, sysfs_remove_dir and symlinks handling. o BUG_ON in sysfs_d_iput() to check if there are any cases of mismatch in dentry and ((struct sysfs_dirent *) dentry->d_fsdata)->s_dentry => changes in version 0.4 o Do not take reference to kobject while creating a dir dentry for it as it can lead to rmmod hang or certain modules due to current limitation of module/kobject refcounting code. => changes in version 0.3a o call sysfs_close_dir_entries() when filldir() returns error in sysfs_readdir(). => changes in version 0.3 o corrected dentry ref counting for sysfs_remove_subdir() => changes in version 0.2 o sysfs_rename_dir() used to call d_move() with unhashed new_dentry causing panic in d_move(). Added d_add() call for new_dentry before calling d_move. o corrected error checking after sysfs_get_dentry() in sysfs_open_dir_entries(). => changes in version 0.1 o re-diffed for 2.6.3 => Changes in last version o added support for symlink o changed logic for sysfs_remove_dir o dir dentries now take a ref on the corresponding kobject so as to have kobject alive during the lifetime of the dentry. ===================================================================== o This patch provides the inode operations ->lookup(), ->readdir() and ->llseek() for sysfs directories. o while sysfs_create_dir() we attach a sysfs_dirent structure to the d_fsdata filed of dentry corresponding to the kobject's direcotry. o sysfs_lookup does not hash the dentry and we hash the dentry when we have attached the sysfs_dirent to it. This was done to cover up a race when we attach a negative dentry and instantiate it before updating the d_fsdata field. As after instantiating we can get a successfull lookup for the dentry but a NULL d_fsdata field. As a result we do not create negative dentries. o sysfs_readdir() or sysfs_dir_lseek() will bring in the dentries corresponding to the attribute files if the offset is more than 2. These are released when we are done with filldir(). o sysfs_d_iput() releases the ref. to the sysfs_dirent() which was taken at the time of dentry allocation. Signed-off-by: Andrew Morton --- 25-akpm/fs/sysfs/dir.c | 351 ++++++++++++++++++++++++++++++++++++++++++------- 1 files changed, 306 insertions(+), 45 deletions(-) diff -puN fs/sysfs/dir.c~sysfs-leaves-dir fs/sysfs/dir.c --- 25/fs/sysfs/dir.c~sysfs-leaves-dir Fri Jun 18 14:57:20 2004 +++ 25-akpm/fs/sysfs/dir.c Fri Jun 18 14:57:20 2004 @@ -12,31 +12,181 @@ DECLARE_RWSEM(sysfs_rename_sem); +struct inode_operations sysfs_dir_inode_operations = { + .lookup = sysfs_lookup, +}; + +struct file_operations sysfs_dir_operations = { + .open = sysfs_dir_open, + .release = sysfs_dir_close, + .llseek = sysfs_dir_lseek, + .read = generic_read_dir, + .readdir = sysfs_readdir, +}; + +static void sysfs_d_iput(struct dentry * dentry, struct inode * inode) +{ + struct sysfs_dirent * sd = dentry->d_fsdata; + + if (sd) { + BUG_ON(sd->s_dentry != dentry); + sd->s_dentry = NULL; + sysfs_put(sd); + } + iput(inode); +} + +static struct dentry_operations sysfs_dentry_ops = { + .d_iput = sysfs_d_iput, +}; + +const unsigned char * sysfs_get_name(struct sysfs_dirent *sd) +{ + struct attribute * attr; + struct bin_attribute * bin_attr; + struct sysfs_symlink * sl; + + if (!sd || !sd->s_element) + BUG(); + + switch (sd->s_type) { + case SYSFS_KOBJECT: + case SYSFS_KOBJ_ATTR_GROUP: + /* Always have a dentry so use that */ + return sd->s_dentry->d_name.name; + + case SYSFS_KOBJ_ATTR: + attr = sd->s_element; + return attr->name; + + case SYSFS_KOBJ_BIN_ATTR: + bin_attr = sd->s_element; + return bin_attr->attr.name; + + case SYSFS_KOBJ_LINK: + sl = sd->s_element; + return sl->link_name; + } + return NULL; +} + +static int init_file(struct inode * inode) +{ + inode->i_size = PAGE_SIZE; + inode->i_fop = &sysfs_file_operations; + return 0; +} + static int init_dir(struct inode * inode) { - inode->i_op = &simple_dir_inode_operations; - inode->i_fop = &simple_dir_operations; + inode->i_op = &sysfs_dir_inode_operations; + inode->i_fop = &sysfs_dir_operations; /* directory inodes start off with i_nlink == 2 (for "." entry) */ inode->i_nlink++; return 0; } +/* attaches attribute's sysfs_dirent to the dentry corresponding to the + * attribute file + */ +static int sysfs_attach_attr(struct sysfs_dirent * sd, struct dentry * dentry) +{ + struct attribute * attr = NULL; + struct bin_attribute * bin_attr = NULL; + int (* init) (struct inode *) = NULL; + int error = 0; + + if (sd->s_type & SYSFS_KOBJ_BIN_ATTR) { + bin_attr = sd->s_element; + attr = &bin_attr->attr; + } else { + attr = sd->s_element; + init = init_file; + } + + error = sysfs_create(dentry, (attr->mode & S_IALLUGO) | S_IFREG, init); + if (error) + return error; + + if (bin_attr) { + dentry->d_inode->i_size = bin_attr->size; + dentry->d_inode->i_fop = &bin_fops; + } + dentry->d_op = &sysfs_dentry_ops; + dentry->d_fsdata = sysfs_get(sd); + sd->s_dentry = dentry; + d_rehash(dentry); + + return 0; +} + +static int sysfs_attach_link(struct sysfs_dirent * sd, struct dentry * dentry) +{ + int err = 0; + + err = sysfs_create(dentry, S_IFLNK|S_IRWXUGO, init_symlink); + if (!err) { + dentry->d_op = &sysfs_dentry_ops; + dentry->d_fsdata = sysfs_get(sd); + sd->s_dentry = dentry; + d_rehash(dentry); + } + return err; +} + +struct dentry * sysfs_lookup(struct inode *dir, struct dentry *dentry, + struct nameidata *nd) +{ + struct sysfs_dirent * parent_sd = dentry->d_parent->d_fsdata; + struct sysfs_dirent * sd; + int err = 0; + + list_for_each_entry(sd, &parent_sd->s_children, s_sibling) { + if (sd->s_type & SYSFS_NOT_PINNED) { + const unsigned char * name = sysfs_get_name(sd); + + if (strcmp(name, dentry->d_name.name)) + continue; + + if (sd->s_type & SYSFS_KOBJ_LINK) + err = sysfs_attach_link(sd, dentry); + else + err = sysfs_attach_attr(sd, dentry); + break; + } + } + + return ERR_PTR(err); +} static int create_dir(struct kobject * k, struct dentry * p, const char * n, struct dentry ** d) { int error; + umode_t mode = S_IFDIR| S_IRWXU | S_IRUGO | S_IXUGO; down(&p->d_inode->i_sem); *d = sysfs_get_dentry(p,n); if (!IS_ERR(*d)) { - error = sysfs_create(*d, - S_IFDIR| S_IRWXU | S_IRUGO | S_IXUGO, - init_dir); + error = sysfs_create(*d, mode, init_dir); if (!error) { - (*d)->d_fsdata = k; - p->d_inode->i_nlink++; + struct sysfs_dirent * sd, * parent_sd; + parent_sd = p->d_fsdata; + sd = sysfs_new_dirent(parent_sd, k, + (parent_sd->s_element == k) ? + SYSFS_KOBJ_ATTR_GROUP : + SYSFS_KOBJECT); + if (sd) { + (*d)->d_fsdata = sysfs_get(sd); + (*d)->d_op = &sysfs_dentry_ops; + p->d_inode->i_nlink++; + sd->s_element = k; + sd->s_dentry = *d; + sd->s_mode = mode; + d_rehash(*d); + } else + error = -ENOMEM; } dput(*d); } else @@ -45,7 +195,6 @@ static int create_dir(struct kobject * k return error; } - int sysfs_create_subdir(struct kobject * k, const char * n, struct dentry ** d) { return create_dir(k,k->dentry,n,d); @@ -79,12 +228,16 @@ int sysfs_create_dir(struct kobject * ko return error; } - static void remove_dir(struct dentry * d) { struct dentry * parent = dget(d->d_parent); + struct sysfs_dirent * sd; + down(&parent->d_inode->i_sem); d_delete(d); + sd = d->d_fsdata; + list_del_init(&sd->s_sibling); + sysfs_put(d->d_fsdata); if (d->d_inode) simple_rmdir(parent->d_inode,d); @@ -106,14 +259,14 @@ void sysfs_remove_subdir(struct dentry * * @kobj: object. * * The only thing special about this is that we remove any files in - * the directory before we remove the directory, and we've inlined - * what used to be sysfs_rmdir() below, instead of calling separately. + * the directory before we remove the directory */ void sysfs_remove_dir(struct kobject * kobj) { - struct list_head * node; struct dentry * dentry = dget(kobj->dentry); + struct sysfs_dirent * parent_sd = dentry->d_fsdata; + struct sysfs_dirent * sd, * tmp; if (!dentry) return; @@ -121,38 +274,13 @@ void sysfs_remove_dir(struct kobject * k pr_debug("sysfs %s: removing dir\n",dentry->d_name.name); down(&dentry->d_inode->i_sem); - spin_lock(&dcache_lock); -restart: - node = dentry->d_subdirs.next; - while (node != &dentry->d_subdirs) { - struct dentry * d = list_entry(node,struct dentry,d_child); - - node = node->next; - pr_debug(" o %s (%d): ",d->d_name.name,atomic_read(&d->d_count)); - if (!d_unhashed(d) && (d->d_inode)) { - d = dget_locked(d); - pr_debug("removing"); - - /** - * Unlink and unhash. - */ - __d_drop(d); - spin_unlock(&dcache_lock); - /* release the target kobject in case of - * a symlink - */ - if (S_ISLNK(d->d_inode->i_mode)) - kobject_put(d->d_fsdata); - - simple_unlink(dentry->d_inode,d); - dput(d); - pr_debug(" done\n"); - spin_lock(&dcache_lock); - /* re-acquired dcache_lock, need to restart */ - goto restart; - } - } - spin_unlock(&dcache_lock); + list_for_each_entry_safe(sd, tmp, &parent_sd->s_children, s_sibling) { + if (!sd->s_element) + continue; + list_del_init(&sd->s_sibling); + sysfs_drop_dentry(sd, dentry); + sysfs_put(sd); + } up(&dentry->d_inode->i_sem); remove_dir(dentry); @@ -182,8 +310,10 @@ int sysfs_rename_dir(struct kobject * ko if (!IS_ERR(new_dentry)) { if (!new_dentry->d_inode) { error = kobject_set_name(kobj,new_name); - if (!error) + if (!error) { + d_add(new_dentry, NULL); d_move(kobj->dentry, new_dentry); + } } dput(new_dentry); } @@ -193,6 +323,137 @@ int sysfs_rename_dir(struct kobject * ko return error; } +int sysfs_dir_open(struct inode *inode, struct file *file) +{ + struct dentry * dentry = file->f_dentry; + struct sysfs_dirent * parent_sd = dentry->d_fsdata; + + down(&dentry->d_inode->i_sem); + file->private_data = sysfs_new_dirent(parent_sd, NULL, 0); + up(&dentry->d_inode->i_sem); + + return file->private_data ? 0 : -ENOMEM; + +} + +int sysfs_dir_close(struct inode *inode, struct file *file) +{ + struct dentry * dentry = file->f_dentry; + struct sysfs_dirent * cursor = file->private_data; + + down(&dentry->d_inode->i_sem); + list_del_init(&cursor->s_sibling); + up(&dentry->d_inode->i_sem); + sysfs_put(file->private_data); + + return 0; +} + +/* Relationship between s_mode and the DT_xxx types */ +static inline unsigned char dt_type(struct sysfs_dirent *sd) +{ + return (sd->s_mode >> 12) & 15; +} + +int sysfs_readdir(struct file * filp, void * dirent, filldir_t filldir) +{ + struct dentry *dentry = filp->f_dentry; + struct sysfs_dirent * parent_sd = dentry->d_fsdata; + struct sysfs_dirent *cursor = filp->private_data; + struct list_head *p, *q = &cursor->s_sibling; + ino_t ino; + int i = filp->f_pos; + + switch (i) { + case 0: + ino = dentry->d_inode->i_ino; + if (filldir(dirent, ".", 1, i, ino, DT_DIR) < 0) + break; + filp->f_pos++; + i++; + /* fallthrough */ + case 1: + ino = parent_ino(dentry); + if (filldir(dirent, "..", 2, i, ino, DT_DIR) < 0) + break; + filp->f_pos++; + i++; + /* fallthrough */ + default: + if (filp->f_pos == 2) { + list_del(q); + list_add(q, &parent_sd->s_children); + } + for (p=q->next; p!= &parent_sd->s_children; p=p->next) { + struct sysfs_dirent *next; + const char * name; + int len; + + next = list_entry(p, struct sysfs_dirent, + s_sibling); + if (!next->s_element) + continue; + + name = sysfs_get_name(next); + len = strlen(name); + if (next->s_dentry) + ino = next->s_dentry->d_inode->i_ino; + else + ino = iunique(sysfs_sb, 2); + + if (filldir(dirent, name, len, filp->f_pos, ino, + dt_type(next)) < 0) + return 0; + + list_del(q); + list_add(q, p); + p = q; + filp->f_pos++; + } + } + return 0; +} + +loff_t sysfs_dir_lseek(struct file * file, loff_t offset, int origin) +{ + struct dentry * dentry = file->f_dentry; + + down(&dentry->d_inode->i_sem); + switch (origin) { + case 1: + offset += file->f_pos; + case 0: + if (offset >= 0) + break; + default: + up(&file->f_dentry->d_inode->i_sem); + return -EINVAL; + } + if (offset != file->f_pos) { + file->f_pos = offset; + if (file->f_pos >= 2) { + struct sysfs_dirent *sd = dentry->d_fsdata; + struct sysfs_dirent *cursor = file->private_data; + struct list_head *p; + loff_t n = file->f_pos - 2; + + list_del(&cursor->s_sibling); + p = sd->s_children.next; + while (n && p != &sd->s_children) { + struct sysfs_dirent *next; + next = list_entry(p, struct sysfs_dirent, + s_sibling); + if (next->s_element) + n--; + p = p->next; + } + list_add_tail(&cursor->s_sibling, p); + } + } + up(&dentry->d_inode->i_sem); + return offset; +} + EXPORT_SYMBOL(sysfs_create_dir); EXPORT_SYMBOL(sysfs_remove_dir); EXPORT_SYMBOL(sysfs_rename_dir); _