/* * dir.c - Operations for sysfs directories. */ #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 <asm/semaphore.h> #include "sysfs.h" DEFINE_MUTEX(sysfs_mutex); spinlock_t sysfs_assoc_lock = SPIN_LOCK_UNLOCKED; static spinlock_t sysfs_ino_lock = SPIN_LOCK_UNLOCKED; 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_children. * * Locking: * mutex_lock(sysfs_mutex) */ void sysfs_link_sibling(struct sysfs_dirent *sd) { struct sysfs_dirent *parent_sd = sd->s_parent; BUG_ON(sd->s_sibling); sd->s_sibling = parent_sd->s_children; parent_sd->s_children = 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_children. * * Locking: * mutex_lock(sysfs_mutex) */ void sysfs_unlink_sibling(struct sysfs_dirent *sd) { struct sysfs_dirent **pos; for (pos = &sd->s_parent->s_children; *pos; pos = &(*pos)->s_sibling) { if (*pos == sd) { *pos = sd->s_sibling; sd->s_sibling = NULL; break; } } } /** * sysfs_get_dentry - get dentry for the given sysfs_dirent * @sd: sysfs_dirent of interest * * Get dentry for @sd. Dentry is looked up if currently not * present. This function climbs sysfs_dirent tree till it * reaches a sysfs_dirent with valid dentry attached and descends * down from there looking up dentry for each step. * * LOCKING: * Kernel thread context (may sleep) * * RETURNS: * Pointer to found dentry on success, ERR_PTR() value on error. */ struct dentry *sysfs_get_dentry(struct sysfs_dirent *sd) { struct sysfs_dirent *cur; struct dentry *parent_dentry, *dentry; int i, depth; /* Find the first parent which has valid s_dentry and get the * dentry. */ mutex_lock(&sysfs_mutex); restart0: spin_lock(&sysfs_assoc_lock); restart1: spin_lock(&dcache_lock); dentry = NULL; depth = 0; cur = sd; while (!cur->s_dentry || !cur->s_dentry->d_inode) { if (cur->s_flags & SYSFS_FLAG_REMOVED) { dentry = ERR_PTR(-ENOENT); depth = 0; break; } cur = cur->s_parent; depth++; } if (!IS_ERR(dentry)) dentry = dget_locked(cur->s_dentry); spin_unlock(&dcache_lock); spin_unlock(&sysfs_assoc_lock); /* from the found dentry, look up depth times */ while (depth--) { /* find and get depth'th ancestor */ for (cur = sd, i = 0; cur && i < depth; i++) cur = cur->s_parent; /* This can happen if tree structure was modified due * to move/rename. Restart. */ if (i != depth) { dput(dentry); goto restart0; } sysfs_get(cur); mutex_unlock(&sysfs_mutex); /* look it up */ parent_dentry = dentry; dentry = lookup_one_len_kern(cur->s_name, parent_dentry, strlen(cur->s_name)); dput(parent_dentry); if (IS_ERR(dentry)) { sysfs_put(cur); return dentry; } mutex_lock(&sysfs_mutex); spin_lock(&sysfs_assoc_lock); /* This, again, can happen if tree structure has * changed and we looked up the wrong thing. Restart. */ if (cur->s_dentry != dentry) { dput(dentry); sysfs_put(cur); goto restart1; } spin_unlock(&sysfs_assoc_lock); sysfs_put(cur); } mutex_unlock(&sysfs_mutex); return dentry; } /** * 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)) 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; 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_get_active_two - get active references to sysfs_dirent and parent * @sd: sysfs_dirent of interest * * Get active reference to @sd and its parent. Parent's active * reference is grabbed first. This function is noop if @sd is * NULL. * * RETURNS: * Pointer to @sd on success, NULL on failure. */ struct sysfs_dirent *sysfs_get_active_two(struct sysfs_dirent *sd) { if (sd) { if (sd->s_parent && unlikely(!sysfs_get_active(sd->s_parent))) return NULL; if (unlikely(!sysfs_get_active(sd))) { sysfs_put_active(sd->s_parent); return NULL; } } return sd; } /** * sysfs_put_active_two - put active references to sysfs_dirent and parent * @sd: sysfs_dirent of interest * * Put active references to @sd and its parent. This function is * noop if @sd is NULL. */ void sysfs_put_active_two(struct sysfs_dirent *sd) { if (sd) { sysfs_put_active(sd); sysfs_put_active(sd->s_parent); } } /** * 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)); sd->s_sibling = (void *)&wait; /* 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) wait_for_completion(&wait); sd->s_sibling = NULL; } 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_elem.symlink.target_sd); if (sysfs_type(sd) & SYSFS_COPY_NAME) kfree(sd->s_name); 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 void sysfs_d_iput(struct dentry * dentry, struct inode * inode) { struct sysfs_dirent * sd = dentry->d_fsdata; if (sd) { /* sd->s_dentry is protected with sysfs_assoc_lock. * This allows sysfs_drop_dentry() to dereference it. */ spin_lock(&sysfs_assoc_lock); /* The dentry might have been deleted or another * lookup could have happened updating sd->s_dentry to * point the new dentry. Ignore if it isn't pointing * to this dentry. */ if (sd->s_dentry == dentry) sd->s_dentry = NULL; spin_unlock(&sysfs_assoc_lock); sysfs_put(sd); } iput(inode); } static struct dentry_operations sysfs_dentry_ops = { .d_iput = sysfs_d_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); atomic_set(&sd->s_event, 1); 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_attach_dentry - associate sysfs_dirent with dentry * @sd: target sysfs_dirent * @dentry: dentry to associate * * Associate @sd with @dentry. This is protected by * sysfs_assoc_lock to avoid race with sysfs_d_iput(). * * LOCKING: * mutex_lock(sysfs_mutex) */ static void sysfs_attach_dentry(struct sysfs_dirent *sd, struct dentry *dentry) { dentry->d_op = &sysfs_dentry_ops; dentry->d_fsdata = sysfs_get(sd); /* protect sd->s_dentry against sysfs_d_iput */ spin_lock(&sysfs_assoc_lock); sd->s_dentry = dentry; spin_unlock(&sysfs_assoc_lock); d_rehash(dentry); } static int sysfs_ilookup_test(struct inode *inode, void *arg) { struct sysfs_dirent *sd = arg; return inode->i_ino == sd->s_ino; } /** * 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, grabs inode for @parent_sd if available and lock * i_mutex of it. @acxt is used to keep and pass context to * other addrm functions. * * LOCKING: * Kernel thread context (may sleep). sysfs_mutex is locked on * return. i_mutex of parent inode is locked on return if * available. */ void sysfs_addrm_start(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *parent_sd) { struct inode *inode; memset(acxt, 0, sizeof(*acxt)); acxt->parent_sd = parent_sd; /* Lookup parent inode. inode initialization and I_NEW * clearing are protected by sysfs_mutex. By grabbing it and * looking up with _nowait variant, inode state can be * determined reliably. */ mutex_lock(&sysfs_mutex); inode = ilookup5_nowait(sysfs_sb, parent_sd->s_ino, sysfs_ilookup_test, parent_sd); if (inode && !(inode->i_state & I_NEW)) { /* parent inode available */ acxt->parent_inode = inode; /* sysfs_mutex is below i_mutex in lock hierarchy. * First, trylock i_mutex. If fails, unlock * sysfs_mutex and lock them in order. */ if (!mutex_trylock(&inode->i_mutex)) { mutex_unlock(&sysfs_mutex); mutex_lock(&inode->i_mutex); mutex_lock(&sysfs_mutex); } } else iput(inode); } /** * 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. @sd is NOT * linked into the children list of the parent. The caller * should invoke sysfs_link_sibling() after this function * completes if @sd needs to be on 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_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd) { sd->s_parent = sysfs_get(acxt->parent_sd); if (sysfs_type(sd) == SYSFS_DIR && acxt->parent_inode) inc_nlink(acxt->parent_inode); acxt->cnt++; } /** * sysfs_remove_one - remove sysfs_dirent from parent * @acxt: addrm context to use * @sd: sysfs_dirent to be added * * Mark @sd removed and drop nlink of parent inode if @sd is a * directory. @sd is NOT unlinked from the children list of the * parent. The caller is repsonsible for removing @sd from the * children list before calling this function. * * 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) { BUG_ON(sd->s_sibling || (sd->s_flags & SYSFS_FLAG_REMOVED)); sd->s_flags |= SYSFS_FLAG_REMOVED; sd->s_sibling = acxt->removed; acxt->removed = sd; if (sysfs_type(sd) == SYSFS_DIR && acxt->parent_inode) drop_nlink(acxt->parent_inode); acxt->cnt++; } /** * sysfs_drop_dentry - drop dentry for the specified sysfs_dirent * @sd: target sysfs_dirent * * Drop dentry for @sd. @sd must have been unlinked from its * parent on entry to this function such that it can't be looked * up anymore. * * @sd->s_dentry which is protected with sysfs_assoc_lock points * to the currently associated dentry but we're not holding a * reference to it and racing with dput(). Grab dcache_lock and * verify dentry before dropping it. If @sd->s_dentry is NULL or * dput() beats us, no need to bother. */ static void sysfs_drop_dentry(struct sysfs_dirent *sd) { struct dentry *dentry = NULL; struct inode *inode; /* We're not holding a reference to ->s_dentry dentry but the * field will stay valid as long as sysfs_assoc_lock is held. */ spin_lock(&sysfs_assoc_lock); spin_lock(&dcache_lock); /* drop dentry if it's there and dput() didn't kill it yet */ if (sd->s_dentry && sd->s_dentry->d_inode) { dentry = dget_locked(sd->s_dentry); spin_lock(&dentry->d_lock); __d_drop(dentry); spin_unlock(&dentry->d_lock); } spin_unlock(&dcache_lock); spin_unlock(&sysfs_assoc_lock); /* dentries for shadowed inodes are pinned, unpin */ if (dentry && sysfs_is_shadowed_inode(dentry->d_inode)) dput(dentry); dput(dentry); /* adjust nlink and update timestamp */ inode = ilookup(sysfs_sb, sd->s_ino); if (inode) { mutex_lock(&inode->i_mutex); inode->i_ctime = CURRENT_TIME; drop_nlink(inode); if (sysfs_type(sd) == SYSFS_DIR) drop_nlink(inode); mutex_unlock(&inode->i_mutex); iput(inode); } } /** * 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. Timestamps on the parent inode are updated. * * LOCKING: * All mutexes acquired by sysfs_addrm_start() are released. * * RETURNS: * Number of added/removed sysfs_dirents since sysfs_addrm_start(). */ int sysfs_addrm_finish(struct sysfs_addrm_cxt *acxt) { /* release resources acquired by sysfs_addrm_start() */ mutex_unlock(&sysfs_mutex); if (acxt->parent_inode) { struct inode *inode = acxt->parent_inode; /* if added/removed, update timestamps on the parent */ if (acxt->cnt) inode->i_ctime = inode->i_mtime = CURRENT_TIME; mutex_unlock(&inode->i_mutex); iput(inode); } /* kill removed sysfs_dirents */ while (acxt->removed) { struct sysfs_dirent *sd = acxt->removed; acxt->removed = sd->s_sibling; sd->s_sibling = NULL; sysfs_drop_dentry(sd); sysfs_deactivate(sd); sysfs_put(sd); } return acxt->cnt; } /** * 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_children; sd; sd = sd->s_sibling) if (sysfs_type(sd) && !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; } 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; /* allocate */ sd = sysfs_new_dirent(name, mode, SYSFS_DIR); if (!sd) return -ENOMEM; sd->s_elem.dir.kobj = kobj; /* link in */ sysfs_addrm_start(&acxt, parent_sd); if (!sysfs_find_dirent(parent_sd, name)) { sysfs_add_one(&acxt, sd); sysfs_link_sibling(sd); } if (!sysfs_addrm_finish(&acxt)) { sysfs_put(sd); return -EEXIST; } *p_sd = sd; return 0; } 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. * @shadow_parent: parent object. */ int sysfs_create_dir(struct kobject *kobj, struct sysfs_dirent *shadow_parent_sd) { struct sysfs_dirent *parent_sd, *sd; int error = 0; BUG_ON(!kobj); if (shadow_parent_sd) parent_sd = shadow_parent_sd; else if (kobj->parent) parent_sd = kobj->parent->sd; else if (sysfs_mount && sysfs_mount->mnt_sb) parent_sd = sysfs_mount->mnt_sb->s_root->d_fsdata; else return -EFAULT; error = create_dir(kobj, parent_sd, kobject_name(kobj), &sd); if (!error) kobj->sd = sd; return error; } static int sysfs_count_nlink(struct sysfs_dirent *sd) { struct sysfs_dirent *child; int nr = 0; for (child = sd->s_children; child; child = child->s_sibling) if (sysfs_type(child) == SYSFS_DIR) nr++; return nr + 2; } 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 bin_attribute *bin_attr; struct inode *inode; int found = 0; mutex_lock(&sysfs_mutex); for (sd = parent_sd->s_children; sd; sd = sd->s_sibling) { if (sysfs_type(sd) && !strcmp(sd->s_name, dentry->d_name.name)) { found = 1; break; } } /* no such entry */ if (!found) goto out_unlock; /* attach dentry and inode */ inode = sysfs_get_inode(sd); if (!inode) { ret = ERR_PTR(-ENOMEM); goto out_unlock; } if (inode->i_state & I_NEW) { /* initialize inode according to type */ switch (sysfs_type(sd)) { case SYSFS_DIR: inode->i_op = &sysfs_dir_inode_operations; inode->i_fop = &sysfs_dir_operations; inode->i_nlink = sysfs_count_nlink(sd); break; case SYSFS_KOBJ_ATTR: inode->i_size = PAGE_SIZE; inode->i_fop = &sysfs_file_operations; break; case SYSFS_KOBJ_BIN_ATTR: bin_attr = sd->s_elem.bin_attr.bin_attr; inode->i_size = bin_attr->size; inode->i_fop = &bin_fops; break; case SYSFS_KOBJ_LINK: inode->i_op = &sysfs_symlink_inode_operations; break; default: BUG(); } } sysfs_instantiate(dentry, inode); sysfs_attach_dentry(sd, dentry); out_unlock: mutex_unlock(&sysfs_mutex); return ret; } const struct inode_operations sysfs_dir_inode_operations = { .lookup = sysfs_lookup, .setattr = sysfs_setattr, }; static void remove_dir(struct sysfs_dirent *sd) { struct sysfs_addrm_cxt acxt; sysfs_addrm_start(&acxt, sd->s_parent); sysfs_unlink_sibling(sd); 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_children; while (*pos) { struct sysfs_dirent *sd = *pos; if (sysfs_type(sd) && sysfs_type(sd) != SYSFS_DIR) { *pos = sd->s_sibling; sd->s_sibling = NULL; 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_dir(struct kobject *kobj, struct sysfs_dirent *new_parent_sd, const char *new_name) { struct sysfs_dirent *sd = kobj->sd; struct dentry *new_parent = NULL; struct dentry *old_dentry = NULL, *new_dentry = NULL; const char *dup_name = NULL; int error; /* get dentries */ old_dentry = sysfs_get_dentry(sd); if (IS_ERR(old_dentry)) { error = PTR_ERR(old_dentry); goto out_dput; } new_parent = sysfs_get_dentry(new_parent_sd); if (IS_ERR(new_parent)) { error = PTR_ERR(new_parent); goto out_dput; } /* lock new_parent and get dentry for new name */ mutex_lock(&new_parent->d_inode->i_mutex); new_dentry = lookup_one_len(new_name, new_parent, strlen(new_name)); if (IS_ERR(new_dentry)) { error = PTR_ERR(new_dentry); goto out_unlock; } /* By allowing two different directories with the same * d_parent we allow this routine to move between different * shadows of the same directory */ error = -EINVAL; if (old_dentry->d_parent->d_inode != new_parent->d_inode || new_dentry->d_parent->d_inode != new_parent->d_inode || old_dentry == new_dentry) goto out_unlock; error = -EEXIST; if (new_dentry->d_inode) goto out_unlock; /* rename kobject and sysfs_dirent */ error = -ENOMEM; new_name = dup_name = kstrdup(new_name, GFP_KERNEL); if (!new_name) goto out_drop; error = kobject_set_name(kobj, "%s", new_name); if (error) goto out_drop; mutex_lock(&sysfs_mutex); dup_name = sd->s_name; sd->s_name = new_name; /* move under the new parent */ d_add(new_dentry, NULL); d_move(sd->s_dentry, new_dentry); sysfs_unlink_sibling(sd); sysfs_get(new_parent_sd); sysfs_put(sd->s_parent); sd->s_parent = new_parent_sd; sysfs_link_sibling(sd); mutex_unlock(&sysfs_mutex); error = 0; goto out_unlock; out_drop: d_drop(new_dentry); out_unlock: mutex_unlock(&new_parent->d_inode->i_mutex); out_dput: kfree(dup_name); dput(new_parent); dput(old_dentry); dput(new_dentry); return error; } int sysfs_move_dir(struct kobject *kobj, struct kobject *new_parent_kobj) { struct sysfs_dirent *sd = kobj->sd; struct sysfs_dirent *new_parent_sd; struct dentry *old_parent, *new_parent = NULL; struct dentry *old_dentry = NULL, *new_dentry = NULL; int error; BUG_ON(!sd->s_parent); new_parent_sd = new_parent_kobj->sd ? new_parent_kobj->sd : &sysfs_root; /* get dentries */ old_dentry = sysfs_get_dentry(sd); if (IS_ERR(old_dentry)) { error = PTR_ERR(old_dentry); goto out_dput; } old_parent = sd->s_parent->s_dentry; new_parent = sysfs_get_dentry(new_parent_sd); if (IS_ERR(new_parent)) { error = PTR_ERR(new_parent); goto out_dput; } if (old_parent->d_inode == new_parent->d_inode) { error = 0; goto out_dput; /* nothing to move */ } again: mutex_lock(&old_parent->d_inode->i_mutex); if (!mutex_trylock(&new_parent->d_inode->i_mutex)) { mutex_unlock(&old_parent->d_inode->i_mutex); goto again; } new_dentry = lookup_one_len(kobj->name, new_parent, strlen(kobj->name)); if (IS_ERR(new_dentry)) { error = PTR_ERR(new_dentry); goto out_unlock; } else error = 0; d_add(new_dentry, NULL); d_move(sd->s_dentry, new_dentry); dput(new_dentry); /* Remove from old parent's list and insert into new parent's list. */ mutex_lock(&sysfs_mutex); sysfs_unlink_sibling(sd); sysfs_get(new_parent_sd); sysfs_put(sd->s_parent); sd->s_parent = new_parent_sd; sysfs_link_sibling(sd); mutex_unlock(&sysfs_mutex); out_unlock: mutex_unlock(&new_parent->d_inode->i_mutex); mutex_unlock(&old_parent->d_inode->i_mutex); out_dput: dput(new_parent); dput(old_dentry); dput(new_dentry); return error; } static int sysfs_dir_open(struct inode *inode, struct file *file) { struct dentry * dentry = file->f_path.dentry; struct sysfs_dirent * parent_sd = dentry->d_fsdata; struct sysfs_dirent * sd; sd = sysfs_new_dirent("_DIR_", 0, 0); if (sd) { mutex_lock(&sysfs_mutex); sd->s_parent = sysfs_get(parent_sd); sysfs_link_sibling(sd); mutex_unlock(&sysfs_mutex); } file->private_data = sd; return sd ? 0 : -ENOMEM; } static int sysfs_dir_close(struct inode *inode, struct file *file) { struct sysfs_dirent * cursor = file->private_data; mutex_lock(&sysfs_mutex); sysfs_unlink_sibling(cursor); mutex_unlock(&sysfs_mutex); release_sysfs_dirent(cursor); 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; } 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 *cursor = filp->private_data; struct sysfs_dirent **pos; ino_t ino; int i = filp->f_pos; switch (i) { case 0: ino = parent_sd->s_ino; if (filldir(dirent, ".", 1, i, ino, DT_DIR) < 0) break; filp->f_pos++; i++; /* fallthrough */ case 1: if (parent_sd->s_parent) ino = parent_sd->s_parent->s_ino; else ino = parent_sd->s_ino; if (filldir(dirent, "..", 2, i, ino, DT_DIR) < 0) break; filp->f_pos++; i++; /* fallthrough */ default: mutex_lock(&sysfs_mutex); pos = &parent_sd->s_children; while (*pos != cursor) pos = &(*pos)->s_sibling; /* unlink cursor */ *pos = cursor->s_sibling; if (filp->f_pos == 2) pos = &parent_sd->s_children; for ( ; *pos; pos = &(*pos)->s_sibling) { struct sysfs_dirent *next = *pos; const char * name; int len; if (!sysfs_type(next)) continue; name = next->s_name; len = strlen(name); ino = next->s_ino; if (filldir(dirent, name, len, filp->f_pos, ino, dt_type(next)) < 0) break; filp->f_pos++; } /* put cursor back in */ cursor->s_sibling = *pos; *pos = cursor; mutex_unlock(&sysfs_mutex); } return 0; } static loff_t sysfs_dir_lseek(struct file * file, loff_t offset, int origin) { struct dentry * dentry = file->f_path.dentry; switch (origin) { case 1: offset += file->f_pos; case 0: if (offset >= 0) break; default: return -EINVAL; } if (offset != file->f_pos) { mutex_lock(&sysfs_mutex); file->f_pos = offset; if (file->f_pos >= 2) { struct sysfs_dirent *sd = dentry->d_fsdata; struct sysfs_dirent *cursor = file->private_data; struct sysfs_dirent **pos; loff_t n = file->f_pos - 2; sysfs_unlink_sibling(cursor); pos = &sd->s_children; while (n && *pos) { struct sysfs_dirent *next = *pos; if (sysfs_type(next)) n--; pos = &(*pos)->s_sibling; } cursor->s_sibling = *pos; *pos = cursor; } mutex_unlock(&sysfs_mutex); } return offset; } /** * sysfs_make_shadowed_dir - Setup so a directory can be shadowed * @kobj: object we're creating shadow of. */ int sysfs_make_shadowed_dir(struct kobject *kobj, void * (*follow_link)(struct dentry *, struct nameidata *)) { struct dentry *dentry; struct inode *inode; struct inode_operations *i_op; /* get dentry for @kobj->sd, dentry of a shadowed dir is pinned */ dentry = sysfs_get_dentry(kobj->sd); if (IS_ERR(dentry)) return PTR_ERR(dentry); inode = dentry->d_inode; if (inode->i_op != &sysfs_dir_inode_operations) { dput(dentry); return -EINVAL; } i_op = kmalloc(sizeof(*i_op), GFP_KERNEL); if (!i_op) return -ENOMEM; memcpy(i_op, &sysfs_dir_inode_operations, sizeof(*i_op)); i_op->follow_link = follow_link; /* Locking of inode->i_op? * Since setting i_op is a single word write and they * are atomic we should be ok here. */ inode->i_op = i_op; return 0; } /** * sysfs_create_shadow_dir - create a shadow directory for an object. * @kobj: object we're creating directory for. * * sysfs_make_shadowed_dir must already have been called on this * directory. */ struct sysfs_dirent *sysfs_create_shadow_dir(struct kobject *kobj) { struct sysfs_dirent *parent_sd = kobj->sd->s_parent; struct dentry *dir, *parent, *shadow; struct inode *inode; struct sysfs_dirent *sd; struct sysfs_addrm_cxt acxt; dir = sysfs_get_dentry(kobj->sd); if (IS_ERR(dir)) { sd = (void *)dir; goto out; } parent = dir->d_parent; inode = dir->d_inode; sd = ERR_PTR(-EINVAL); if (!sysfs_is_shadowed_inode(inode)) goto out_dput; shadow = d_alloc(parent, &dir->d_name); if (!shadow) goto nomem; sd = sysfs_new_dirent("_SHADOW_", inode->i_mode, SYSFS_DIR); if (!sd) goto nomem; sd->s_elem.dir.kobj = kobj; sysfs_addrm_start(&acxt, parent_sd); /* add but don't link into children list */ sysfs_add_one(&acxt, sd); /* attach and instantiate dentry */ sysfs_attach_dentry(sd, shadow); d_instantiate(shadow, igrab(inode)); inc_nlink(inode); /* tj: synchronization? */ sysfs_addrm_finish(&acxt); dget(shadow); /* Extra count - pin the dentry in core */ goto out_dput; nomem: dput(shadow); sd = ERR_PTR(-ENOMEM); out_dput: dput(dir); out: return sd; } /** * sysfs_remove_shadow_dir - remove an object's directory. * @shadow_sd: sysfs_dirent of shadow directory * * 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_shadow_dir(struct sysfs_dirent *shadow_sd) { __sysfs_remove_dir(shadow_sd); } const 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, };