/* * fs/sysfs/dir.c - sysfs core and dir operation implementation * * Copyright (c) 2001-3 Patrick Mochel * Copyright (c) 2007 SUSE Linux Products GmbH * Copyright (c) 2007 Tejun Heo <teheo@suse.de> * * This file is released under the GPLv2. * * Please see Documentation/filesystems/sysfs.txt for more information. */ #undef DEBUG #include <linux/fs.h> #include <linux/mount.h> #include <linux/module.h> #include <linux/kobject.h> #include <linux/namei.h> #include <linux/idr.h> #include <linux/completion.h> #include <linux/mutex.h> #include <linux/slab.h> #include <linux/security.h> #include "sysfs.h" DEFINE_MUTEX(sysfs_mutex); DEFINE_SPINLOCK(sysfs_assoc_lock); static DEFINE_SPINLOCK(sysfs_ino_lock); static DEFINE_IDA(sysfs_ino_ida); /** * sysfs_link_sibling - link sysfs_dirent into sibling list * @sd: sysfs_dirent of interest * * Link @sd into its sibling list which starts from * sd->s_parent->s_dir.children. * * Locking: * mutex_lock(sysfs_mutex) */ static void sysfs_link_sibling(struct sysfs_dirent *sd) { struct sysfs_dirent *parent_sd = sd->s_parent; struct sysfs_dirent **pos; BUG_ON(sd->s_sibling); /* Store directory entries in order by ino. This allows * readdir to properly restart without having to add a * cursor into the s_dir.children list. */ for (pos = &parent_sd->s_dir.children; *pos; pos = &(*pos)->s_sibling) { if (sd->s_ino < (*pos)->s_ino) break; } sd->s_sibling = *pos; *pos = sd; } /** * sysfs_unlink_sibling - unlink sysfs_dirent from sibling list * @sd: sysfs_dirent of interest * * Unlink @sd from its sibling list which starts from * sd->s_parent->s_dir.children. * * Locking: * mutex_lock(sysfs_mutex) */ static void sysfs_unlink_sibling(struct sysfs_dirent *sd) { struct sysfs_dirent **pos; for (pos = &sd->s_parent->s_dir.children; *pos; pos = &(*pos)->s_sibling) { if (*pos == sd) { *pos = sd->s_sibling; sd->s_sibling = NULL; break; } } } /** * sysfs_get_active - get an active reference to sysfs_dirent * @sd: sysfs_dirent to get an active reference to * * Get an active reference of @sd. This function is noop if @sd * is NULL. * * RETURNS: * Pointer to @sd on success, NULL on failure. */ struct sysfs_dirent *sysfs_get_active(struct sysfs_dirent *sd) { if (unlikely(!sd)) return NULL; while (1) { int v, t; v = atomic_read(&sd->s_active); if (unlikely(v < 0)) return NULL; t = atomic_cmpxchg(&sd->s_active, v, v + 1); if (likely(t == v)) { rwsem_acquire_read(&sd->dep_map, 0, 1, _RET_IP_); return sd; } if (t < 0) return NULL; cpu_relax(); } } /** * sysfs_put_active - put an active reference to sysfs_dirent * @sd: sysfs_dirent to put an active reference to * * Put an active reference to @sd. This function is noop if @sd * is NULL. */ void sysfs_put_active(struct sysfs_dirent *sd) { struct completion *cmpl; int v; if (unlikely(!sd)) return; rwsem_release(&sd->dep_map, 1, _RET_IP_); v = atomic_dec_return(&sd->s_active); if (likely(v != SD_DEACTIVATED_BIAS)) return; /* atomic_dec_return() is a mb(), we'll always see the updated * sd->s_sibling. */ cmpl = (void *)sd->s_sibling; complete(cmpl); } /** * sysfs_deactivate - deactivate sysfs_dirent * @sd: sysfs_dirent to deactivate * * Deny new active references and drain existing ones. */ static void sysfs_deactivate(struct sysfs_dirent *sd) { DECLARE_COMPLETION_ONSTACK(wait); int v; BUG_ON(sd->s_sibling || !(sd->s_flags & SYSFS_FLAG_REMOVED)); if (!(sysfs_type(sd) & SYSFS_ACTIVE_REF)) return; sd->s_sibling = (void *)&wait; rwsem_acquire(&sd->dep_map, 0, 0, _RET_IP_); /* atomic_add_return() is a mb(), put_active() will always see * the updated sd->s_sibling. */ v = atomic_add_return(SD_DEACTIVATED_BIAS, &sd->s_active); if (v != SD_DEACTIVATED_BIAS) { lock_contended(&sd->dep_map, _RET_IP_); wait_for_completion(&wait); } sd->s_sibling = NULL; lock_acquired(&sd->dep_map, _RET_IP_); rwsem_release(&sd->dep_map, 1, _RET_IP_); } static int sysfs_alloc_ino(ino_t *pino) { int ino, rc; retry: spin_lock(&sysfs_ino_lock); rc = ida_get_new_above(&sysfs_ino_ida, 2, &ino); spin_unlock(&sysfs_ino_lock); if (rc == -EAGAIN) { if (ida_pre_get(&sysfs_ino_ida, GFP_KERNEL)) goto retry; rc = -ENOMEM; } *pino = ino; return rc; } static void sysfs_free_ino(ino_t ino) { spin_lock(&sysfs_ino_lock); ida_remove(&sysfs_ino_ida, ino); spin_unlock(&sysfs_ino_lock); } void release_sysfs_dirent(struct sysfs_dirent * sd) { struct sysfs_dirent *parent_sd; repeat: /* Moving/renaming is always done while holding reference. * sd->s_parent won't change beneath us. */ parent_sd = sd->s_parent; if (sysfs_type(sd) == SYSFS_KOBJ_LINK) sysfs_put(sd->s_symlink.target_sd); if (sysfs_type(sd) & SYSFS_COPY_NAME) kfree(sd->s_name); if (sd->s_iattr && sd->s_iattr->ia_secdata) security_release_secctx(sd->s_iattr->ia_secdata, sd->s_iattr->ia_secdata_len); kfree(sd->s_iattr); sysfs_free_ino(sd->s_ino); kmem_cache_free(sysfs_dir_cachep, sd); sd = parent_sd; if (sd && atomic_dec_and_test(&sd->s_count)) goto repeat; } static int sysfs_dentry_delete(struct dentry *dentry) { struct sysfs_dirent *sd = dentry->d_fsdata; return !!(sd->s_flags & SYSFS_FLAG_REMOVED); } static int sysfs_dentry_revalidate(struct dentry *dentry, struct nameidata *nd) { struct sysfs_dirent *sd = dentry->d_fsdata; int is_dir; mutex_lock(&sysfs_mutex); /* The sysfs dirent has been deleted */ if (sd->s_flags & SYSFS_FLAG_REMOVED) goto out_bad; /* The sysfs dirent has been moved? */ if (dentry->d_parent->d_fsdata != sd->s_parent) goto out_bad; /* The sysfs dirent has been renamed */ if (strcmp(dentry->d_name.name, sd->s_name) != 0) goto out_bad; mutex_unlock(&sysfs_mutex); out_valid: return 1; out_bad: /* Remove the dentry from the dcache hashes. * If this is a deleted dentry we use d_drop instead of d_delete * so sysfs doesn't need to cope with negative dentries. * * If this is a dentry that has simply been renamed we * use d_drop to remove it from the dcache lookup on its * old parent. If this dentry persists later when a lookup * is performed at its new name the dentry will be readded * to the dcache hashes. */ is_dir = (sysfs_type(sd) == SYSFS_DIR); mutex_unlock(&sysfs_mutex); if (is_dir) { /* If we have submounts we must allow the vfs caches * to lie about the state of the filesystem to prevent * leaks and other nasty things. */ if (have_submounts(dentry)) goto out_valid; shrink_dcache_parent(dentry); } d_drop(dentry); return 0; } static void sysfs_dentry_iput(struct dentry *dentry, struct inode *inode) { struct sysfs_dirent * sd = dentry->d_fsdata; sysfs_put(sd); iput(inode); } static const struct dentry_operations sysfs_dentry_ops = { .d_revalidate = sysfs_dentry_revalidate, .d_delete = sysfs_dentry_delete, .d_iput = sysfs_dentry_iput, }; struct sysfs_dirent *sysfs_new_dirent(const char *name, umode_t mode, int type) { char *dup_name = NULL; struct sysfs_dirent *sd; if (type & SYSFS_COPY_NAME) { name = dup_name = kstrdup(name, GFP_KERNEL); if (!name) return NULL; } sd = kmem_cache_zalloc(sysfs_dir_cachep, GFP_KERNEL); if (!sd) goto err_out1; if (sysfs_alloc_ino(&sd->s_ino)) goto err_out2; atomic_set(&sd->s_count, 1); atomic_set(&sd->s_active, 0); sd->s_name = name; sd->s_mode = mode; sd->s_flags = type; return sd; err_out2: kmem_cache_free(sysfs_dir_cachep, sd); err_out1: kfree(dup_name); return NULL; } /** * sysfs_addrm_start - prepare for sysfs_dirent add/remove * @acxt: pointer to sysfs_addrm_cxt to be used * @parent_sd: parent sysfs_dirent * * This function is called when the caller is about to add or * remove sysfs_dirent under @parent_sd. This function acquires * sysfs_mutex. @acxt is used to keep and pass context to * other addrm functions. * * LOCKING: * Kernel thread context (may sleep). sysfs_mutex is locked on * return. */ void sysfs_addrm_start(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *parent_sd) { memset(acxt, 0, sizeof(*acxt)); acxt->parent_sd = parent_sd; mutex_lock(&sysfs_mutex); } /** * __sysfs_add_one - add sysfs_dirent to parent without warning * @acxt: addrm context to use * @sd: sysfs_dirent to be added * * Get @acxt->parent_sd and set sd->s_parent to it and increment * nlink of parent inode if @sd is a directory and link into the * children list of the parent. * * This function should be called between calls to * sysfs_addrm_start() and sysfs_addrm_finish() and should be * passed the same @acxt as passed to sysfs_addrm_start(). * * LOCKING: * Determined by sysfs_addrm_start(). * * RETURNS: * 0 on success, -EEXIST if entry with the given name already * exists. */ int __sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd) { struct sysfs_inode_attrs *ps_iattr; if (sysfs_find_dirent(acxt->parent_sd, sd->s_name)) return -EEXIST; sd->s_parent = sysfs_get(acxt->parent_sd); sysfs_link_sibling(sd); /* Update timestamps on the parent */ ps_iattr = acxt->parent_sd->s_iattr; if (ps_iattr) { struct iattr *ps_iattrs = &ps_iattr->ia_iattr; ps_iattrs->ia_ctime = ps_iattrs->ia_mtime = CURRENT_TIME; } return 0; } /** * sysfs_pathname - return full path to sysfs dirent * @sd: sysfs_dirent whose path we want * @path: caller allocated buffer * * Gives the name "/" to the sysfs_root entry; any path returned * is relative to wherever sysfs is mounted. * * XXX: does no error checking on @path size */ static char *sysfs_pathname(struct sysfs_dirent *sd, char *path) { if (sd->s_parent) { sysfs_pathname(sd->s_parent, path); strcat(path, "/"); } strcat(path, sd->s_name); return path; } /** * sysfs_add_one - add sysfs_dirent to parent * @acxt: addrm context to use * @sd: sysfs_dirent to be added * * Get @acxt->parent_sd and set sd->s_parent to it and increment * nlink of parent inode if @sd is a directory and link into the * children list of the parent. * * This function should be called between calls to * sysfs_addrm_start() and sysfs_addrm_finish() and should be * passed the same @acxt as passed to sysfs_addrm_start(). * * LOCKING: * Determined by sysfs_addrm_start(). * * RETURNS: * 0 on success, -EEXIST if entry with the given name already * exists. */ int sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd) { int ret; ret = __sysfs_add_one(acxt, sd); if (ret == -EEXIST) { char *path = kzalloc(PATH_MAX, GFP_KERNEL); WARN(1, KERN_WARNING "sysfs: cannot create duplicate filename '%s'\n", (path == NULL) ? sd->s_name : strcat(strcat(sysfs_pathname(acxt->parent_sd, path), "/"), sd->s_name)); kfree(path); } return ret; } /** * sysfs_remove_one - remove sysfs_dirent from parent * @acxt: addrm context to use * @sd: sysfs_dirent to be removed * * Mark @sd removed and drop nlink of parent inode if @sd is a * directory. @sd is unlinked from the children list. * * This function should be called between calls to * sysfs_addrm_start() and sysfs_addrm_finish() and should be * passed the same @acxt as passed to sysfs_addrm_start(). * * LOCKING: * Determined by sysfs_addrm_start(). */ void sysfs_remove_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd) { struct sysfs_inode_attrs *ps_iattr; BUG_ON(sd->s_flags & SYSFS_FLAG_REMOVED); sysfs_unlink_sibling(sd); /* Update timestamps on the parent */ ps_iattr = acxt->parent_sd->s_iattr; if (ps_iattr) { struct iattr *ps_iattrs = &ps_iattr->ia_iattr; ps_iattrs->ia_ctime = ps_iattrs->ia_mtime = CURRENT_TIME; } sd->s_flags |= SYSFS_FLAG_REMOVED; sd->s_sibling = acxt->removed; acxt->removed = sd; } /** * sysfs_addrm_finish - finish up sysfs_dirent add/remove * @acxt: addrm context to finish up * * Finish up sysfs_dirent add/remove. Resources acquired by * sysfs_addrm_start() are released and removed sysfs_dirents are * cleaned up. * * LOCKING: * sysfs_mutex is released. */ void sysfs_addrm_finish(struct sysfs_addrm_cxt *acxt) { /* release resources acquired by sysfs_addrm_start() */ mutex_unlock(&sysfs_mutex); /* kill removed sysfs_dirents */ while (acxt->removed) { struct sysfs_dirent *sd = acxt->removed; acxt->removed = sd->s_sibling; sd->s_sibling = NULL; sysfs_deactivate(sd); unmap_bin_file(sd); sysfs_put(sd); } } /** * sysfs_find_dirent - find sysfs_dirent with the given name * @parent_sd: sysfs_dirent to search under * @name: name to look for * * Look for sysfs_dirent with name @name under @parent_sd. * * LOCKING: * mutex_lock(sysfs_mutex) * * RETURNS: * Pointer to sysfs_dirent if found, NULL if not. */ struct sysfs_dirent *sysfs_find_dirent(struct sysfs_dirent *parent_sd, const unsigned char *name) { struct sysfs_dirent *sd; for (sd = parent_sd->s_dir.children; sd; sd = sd->s_sibling) if (!strcmp(sd->s_name, name)) return sd; return NULL; } /** * sysfs_get_dirent - find and get sysfs_dirent with the given name * @parent_sd: sysfs_dirent to search under * @name: name to look for * * Look for sysfs_dirent with name @name under @parent_sd and get * it if found. * * LOCKING: * Kernel thread context (may sleep). Grabs sysfs_mutex. * * RETURNS: * Pointer to sysfs_dirent if found, NULL if not. */ struct sysfs_dirent *sysfs_get_dirent(struct sysfs_dirent *parent_sd, const unsigned char *name) { struct sysfs_dirent *sd; mutex_lock(&sysfs_mutex); sd = sysfs_find_dirent(parent_sd, name); sysfs_get(sd); mutex_unlock(&sysfs_mutex); return sd; } EXPORT_SYMBOL_GPL(sysfs_get_dirent); static int create_dir(struct kobject *kobj, struct sysfs_dirent *parent_sd, const char *name, struct sysfs_dirent **p_sd) { umode_t mode = S_IFDIR| S_IRWXU | S_IRUGO | S_IXUGO; struct sysfs_addrm_cxt acxt; struct sysfs_dirent *sd; int rc; /* allocate */ sd = sysfs_new_dirent(name, mode, SYSFS_DIR); if (!sd) return -ENOMEM; sd->s_dir.kobj = kobj; /* link in */ sysfs_addrm_start(&acxt, parent_sd); rc = sysfs_add_one(&acxt, sd); sysfs_addrm_finish(&acxt); if (rc == 0) *p_sd = sd; else sysfs_put(sd); return rc; } int sysfs_create_subdir(struct kobject *kobj, const char *name, struct sysfs_dirent **p_sd) { return create_dir(kobj, kobj->sd, name, p_sd); } /** * sysfs_create_dir - create a directory for an object. * @kobj: object we're creating directory for. */ int sysfs_create_dir(struct kobject * kobj) { struct sysfs_dirent *parent_sd, *sd; int error = 0; BUG_ON(!kobj); if (kobj->parent) parent_sd = kobj->parent->sd; else parent_sd = &sysfs_root; error = create_dir(kobj, parent_sd, kobject_name(kobj), &sd); if (!error) kobj->sd = sd; return error; } static struct dentry * sysfs_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd) { struct dentry *ret = NULL; struct sysfs_dirent *parent_sd = dentry->d_parent->d_fsdata; struct sysfs_dirent *sd; struct inode *inode; mutex_lock(&sysfs_mutex); sd = sysfs_find_dirent(parent_sd, dentry->d_name.name); /* no such entry */ if (!sd) { ret = ERR_PTR(-ENOENT); goto out_unlock; } /* attach dentry and inode */ inode = sysfs_get_inode(dir->i_sb, sd); if (!inode) { ret = ERR_PTR(-ENOMEM); goto out_unlock; } /* instantiate and hash dentry */ ret = d_find_alias(inode); if (!ret) { dentry->d_op = &sysfs_dentry_ops; dentry->d_fsdata = sysfs_get(sd); d_add(dentry, inode); } else { d_move(ret, dentry); iput(inode); } out_unlock: mutex_unlock(&sysfs_mutex); return ret; } const struct inode_operations sysfs_dir_inode_operations = { .lookup = sysfs_lookup, .permission = sysfs_permission, .setattr = sysfs_setattr, .getattr = sysfs_getattr, .setxattr = sysfs_setxattr, }; static void remove_dir(struct sysfs_dirent *sd) { struct sysfs_addrm_cxt acxt; sysfs_addrm_start(&acxt, sd->s_parent); sysfs_remove_one(&acxt, sd); sysfs_addrm_finish(&acxt); } void sysfs_remove_subdir(struct sysfs_dirent *sd) { remove_dir(sd); } static void __sysfs_remove_dir(struct sysfs_dirent *dir_sd) { struct sysfs_addrm_cxt acxt; struct sysfs_dirent **pos; if (!dir_sd) return; pr_debug("sysfs %s: removing dir\n", dir_sd->s_name); sysfs_addrm_start(&acxt, dir_sd); pos = &dir_sd->s_dir.children; while (*pos) { struct sysfs_dirent *sd = *pos; if (sysfs_type(sd) != SYSFS_DIR) sysfs_remove_one(&acxt, sd); else pos = &(*pos)->s_sibling; } sysfs_addrm_finish(&acxt); remove_dir(dir_sd); } /** * sysfs_remove_dir - remove an object's directory. * @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. */ void sysfs_remove_dir(struct kobject * kobj) { struct sysfs_dirent *sd = kobj->sd; spin_lock(&sysfs_assoc_lock); kobj->sd = NULL; spin_unlock(&sysfs_assoc_lock); __sysfs_remove_dir(sd); } int sysfs_rename(struct sysfs_dirent *sd, struct sysfs_dirent *new_parent_sd, const char *new_name) { const char *dup_name = NULL; int error; mutex_lock(&sysfs_mutex); error = 0; if ((sd->s_parent == new_parent_sd) && (strcmp(sd->s_name, new_name) == 0)) goto out; /* nothing to rename */ error = -EEXIST; if (sysfs_find_dirent(new_parent_sd, new_name)) goto out; /* rename sysfs_dirent */ if (strcmp(sd->s_name, new_name) != 0) { error = -ENOMEM; new_name = dup_name = kstrdup(new_name, GFP_KERNEL); if (!new_name) goto out; dup_name = sd->s_name; sd->s_name = new_name; } /* Remove from old parent's list and insert into new parent's list. */ if (sd->s_parent != new_parent_sd) { sysfs_unlink_sibling(sd); sysfs_get(new_parent_sd); sysfs_put(sd->s_parent); sd->s_parent = new_parent_sd; sysfs_link_sibling(sd); } error = 0; out: mutex_unlock(&sysfs_mutex); kfree(dup_name); return error; } int sysfs_rename_dir(struct kobject *kobj, const char *new_name) { return sysfs_rename(kobj->sd, kobj->sd->s_parent, new_name); } int sysfs_move_dir(struct kobject *kobj, struct kobject *new_parent_kobj) { struct sysfs_dirent *sd = kobj->sd; struct sysfs_dirent *new_parent_sd; BUG_ON(!sd->s_parent); new_parent_sd = new_parent_kobj && new_parent_kobj->sd ? new_parent_kobj->sd : &sysfs_root; return sysfs_rename(sd, new_parent_sd, sd->s_name); } /* 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; } static int sysfs_dir_release(struct inode *inode, struct file *filp) { sysfs_put(filp->private_data); return 0; } static struct sysfs_dirent *sysfs_dir_pos(struct sysfs_dirent *parent_sd, ino_t ino, struct sysfs_dirent *pos) { if (pos) { int valid = !(pos->s_flags & SYSFS_FLAG_REMOVED) && pos->s_parent == parent_sd && ino == pos->s_ino; sysfs_put(pos); if (valid) return pos; } pos = NULL; if ((ino > 1) && (ino < INT_MAX)) { pos = parent_sd->s_dir.children; while (pos && (ino > pos->s_ino)) pos = pos->s_sibling; } return pos; } static struct sysfs_dirent *sysfs_dir_next_pos(struct sysfs_dirent *parent_sd, ino_t ino, struct sysfs_dirent *pos) { pos = sysfs_dir_pos(parent_sd, ino, pos); if (pos) pos = pos->s_sibling; return pos; } static int sysfs_readdir(struct file * filp, void * dirent, filldir_t filldir) { struct dentry *dentry = filp->f_path.dentry; struct sysfs_dirent * parent_sd = dentry->d_fsdata; struct sysfs_dirent *pos = filp->private_data; ino_t ino; if (filp->f_pos == 0) { ino = parent_sd->s_ino; if (filldir(dirent, ".", 1, filp->f_pos, ino, DT_DIR) == 0) filp->f_pos++; } if (filp->f_pos == 1) { if (parent_sd->s_parent) ino = parent_sd->s_parent->s_ino; else ino = parent_sd->s_ino; if (filldir(dirent, "..", 2, filp->f_pos, ino, DT_DIR) == 0) filp->f_pos++; } mutex_lock(&sysfs_mutex); for (pos = sysfs_dir_pos(parent_sd, filp->f_pos, pos); pos; pos = sysfs_dir_next_pos(parent_sd, filp->f_pos, pos)) { const char * name; unsigned int type; int len, ret; name = pos->s_name; len = strlen(name); ino = pos->s_ino; type = dt_type(pos); filp->f_pos = ino; filp->private_data = sysfs_get(pos); mutex_unlock(&sysfs_mutex); ret = filldir(dirent, name, len, filp->f_pos, ino, type); mutex_lock(&sysfs_mutex); if (ret < 0) break; } mutex_unlock(&sysfs_mutex); if ((filp->f_pos > 1) && !pos) { /* EOF */ filp->f_pos = INT_MAX; filp->private_data = NULL; } return 0; } const struct file_operations sysfs_dir_operations = { .read = generic_read_dir, .readdir = sysfs_readdir, .release = sysfs_dir_release, .llseek = generic_file_llseek, };