diff options
Diffstat (limited to 'fs/kernfs')
| -rw-r--r-- | fs/kernfs/Makefile | 5 | ||||
| -rw-r--r-- | fs/kernfs/dir.c | 1073 | ||||
| -rw-r--r-- | fs/kernfs/file.c | 867 | ||||
| -rw-r--r-- | fs/kernfs/inode.c | 377 | ||||
| -rw-r--r-- | fs/kernfs/kernfs-internal.h | 122 | ||||
| -rw-r--r-- | fs/kernfs/mount.c | 165 | ||||
| -rw-r--r-- | fs/kernfs/symlink.c | 151 |
7 files changed, 2760 insertions, 0 deletions
diff --git a/fs/kernfs/Makefile b/fs/kernfs/Makefile new file mode 100644 index 0000000..674337c --- /dev/null +++ b/fs/kernfs/Makefile @@ -0,0 +1,5 @@ +# +# Makefile for the kernfs pseudo filesystem +# + +obj-y := mount.o inode.o dir.o file.o symlink.o diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c new file mode 100644 index 0000000..5104cf5 --- /dev/null +++ b/fs/kernfs/dir.c @@ -0,0 +1,1073 @@ +/* + * fs/kernfs/dir.c - kernfs directory implementation + * + * Copyright (c) 2001-3 Patrick Mochel + * Copyright (c) 2007 SUSE Linux Products GmbH + * Copyright (c) 2007, 2013 Tejun Heo <tj@kernel.org> + * + * This file is released under the GPLv2. + */ + +#include <linux/fs.h> +#include <linux/namei.h> +#include <linux/idr.h> +#include <linux/slab.h> +#include <linux/security.h> +#include <linux/hash.h> + +#include "kernfs-internal.h" + +DEFINE_MUTEX(kernfs_mutex); + +#define rb_to_kn(X) rb_entry((X), struct kernfs_node, rb) + +/** + * kernfs_name_hash + * @name: Null terminated string to hash + * @ns: Namespace tag to hash + * + * Returns 31 bit hash of ns + name (so it fits in an off_t ) + */ +static unsigned int kernfs_name_hash(const char *name, const void *ns) +{ + unsigned long hash = init_name_hash(); + unsigned int len = strlen(name); + while (len--) + hash = partial_name_hash(*name++, hash); + hash = (end_name_hash(hash) ^ hash_ptr((void *)ns, 31)); + hash &= 0x7fffffffU; + /* Reserve hash numbers 0, 1 and INT_MAX for magic directory entries */ + if (hash < 1) + hash += 2; + if (hash >= INT_MAX) + hash = INT_MAX - 1; + return hash; +} + +static int kernfs_name_compare(unsigned int hash, const char *name, + const void *ns, const struct kernfs_node *kn) +{ + if (hash != kn->hash) + return hash - kn->hash; + if (ns != kn->ns) + return ns - kn->ns; + return strcmp(name, kn->name); +} + +static int kernfs_sd_compare(const struct kernfs_node *left, + const struct kernfs_node *right) +{ + return kernfs_name_compare(left->hash, left->name, left->ns, right); +} + +/** + * kernfs_link_sibling - link kernfs_node into sibling rbtree + * @kn: kernfs_node of interest + * + * Link @kn into its sibling rbtree which starts from + * @kn->parent->dir.children. + * + * Locking: + * mutex_lock(kernfs_mutex) + * + * RETURNS: + * 0 on susccess -EEXIST on failure. + */ +static int kernfs_link_sibling(struct kernfs_node *kn) +{ + struct rb_node **node = &kn->parent->dir.children.rb_node; + struct rb_node *parent = NULL; + + if (kernfs_type(kn) == KERNFS_DIR) + kn->parent->dir.subdirs++; + + while (*node) { + struct kernfs_node *pos; + int result; + + pos = rb_to_kn(*node); + parent = *node; + result = kernfs_sd_compare(kn, pos); + if (result < 0) + node = &pos->rb.rb_left; + else if (result > 0) + node = &pos->rb.rb_right; + else + return -EEXIST; + } + /* add new node and rebalance the tree */ + rb_link_node(&kn->rb, parent, node); + rb_insert_color(&kn->rb, &kn->parent->dir.children); + return 0; +} + +/** + * kernfs_unlink_sibling - unlink kernfs_node from sibling rbtree + * @kn: kernfs_node of interest + * + * Unlink @kn from its sibling rbtree which starts from + * kn->parent->dir.children. + * + * Locking: + * mutex_lock(kernfs_mutex) + */ +static void kernfs_unlink_sibling(struct kernfs_node *kn) +{ + if (kernfs_type(kn) == KERNFS_DIR) + kn->parent->dir.subdirs--; + + rb_erase(&kn->rb, &kn->parent->dir.children); +} + +/** + * kernfs_get_active - get an active reference to kernfs_node + * @kn: kernfs_node to get an active reference to + * + * Get an active reference of @kn. This function is noop if @kn + * is NULL. + * + * RETURNS: + * Pointer to @kn on success, NULL on failure. + */ +struct kernfs_node *kernfs_get_active(struct kernfs_node *kn) +{ + if (unlikely(!kn)) + return NULL; + + if (!atomic_inc_unless_negative(&kn->active)) + return NULL; + + if (kn->flags & KERNFS_LOCKDEP) + rwsem_acquire_read(&kn->dep_map, 0, 1, _RET_IP_); + return kn; +} + +/** + * kernfs_put_active - put an active reference to kernfs_node + * @kn: kernfs_node to put an active reference to + * + * Put an active reference to @kn. This function is noop if @kn + * is NULL. + */ +void kernfs_put_active(struct kernfs_node *kn) +{ + int v; + + if (unlikely(!kn)) + return; + + if (kn->flags & KERNFS_LOCKDEP) + rwsem_release(&kn->dep_map, 1, _RET_IP_); + v = atomic_dec_return(&kn->active); + if (likely(v != KN_DEACTIVATED_BIAS)) + return; + + /* + * atomic_dec_return() is a mb(), we'll always see the updated + * kn->u.completion. + */ + complete(kn->u.completion); +} + +/** + * kernfs_deactivate - deactivate kernfs_node + * @kn: kernfs_node to deactivate + * + * Deny new active references and drain existing ones. + */ +static void kernfs_deactivate(struct kernfs_node *kn) +{ + DECLARE_COMPLETION_ONSTACK(wait); + int v; + + BUG_ON(!(kn->flags & KERNFS_REMOVED)); + + if (!(kernfs_type(kn) & KERNFS_ACTIVE_REF)) + return; + + kn->u.completion = (void *)&wait; + + rwsem_acquire(&kn->dep_map, 0, 0, _RET_IP_); + /* atomic_add_return() is a mb(), put_active() will always see + * the updated kn->u.completion. + */ + v = atomic_add_return(KN_DEACTIVATED_BIAS, &kn->active); + + if (v != KN_DEACTIVATED_BIAS) { + lock_contended(&kn->dep_map, _RET_IP_); + wait_for_completion(&wait); + } + + lock_acquired(&kn->dep_map, _RET_IP_); + rwsem_release(&kn->dep_map, 1, _RET_IP_); +} + +/** + * kernfs_get - get a reference count on a kernfs_node + * @kn: the target kernfs_node + */ +void kernfs_get(struct kernfs_node *kn) +{ + if (kn) { + WARN_ON(!atomic_read(&kn->count)); + atomic_inc(&kn->count); + } +} +EXPORT_SYMBOL_GPL(kernfs_get); + +/** + * kernfs_put - put a reference count on a kernfs_node + * @kn: the target kernfs_node + * + * Put a reference count of @kn and destroy it if it reached zero. + */ +void kernfs_put(struct kernfs_node *kn) +{ + struct kernfs_node *parent; + struct kernfs_root *root; + + if (!kn || !atomic_dec_and_test(&kn->count)) + return; + root = kernfs_root(kn); + repeat: + /* Moving/renaming is always done while holding reference. + * kn->parent won't change beneath us. + */ + parent = kn->parent; + + WARN(!(kn->flags & KERNFS_REMOVED), "kernfs: free using entry: %s/%s\n", + parent ? parent->name : "", kn->name); + + if (kernfs_type(kn) == KERNFS_LINK) + kernfs_put(kn->symlink.target_kn); + if (!(kn->flags & KERNFS_STATIC_NAME)) + kfree(kn->name); + if (kn->iattr) { + if (kn->iattr->ia_secdata) + security_release_secctx(kn->iattr->ia_secdata, + kn->iattr->ia_secdata_len); + simple_xattrs_free(&kn->iattr->xattrs); + } + kfree(kn->iattr); + ida_simple_remove(&root->ino_ida, kn->ino); + kmem_cache_free(kernfs_node_cache, kn); + + kn = parent; + if (kn) { + if (atomic_dec_and_test(&kn->count)) + goto repeat; + } else { + /* just released the root kn, free @root too */ + ida_destroy(&root->ino_ida); + kfree(root); + } +} +EXPORT_SYMBOL_GPL(kernfs_put); + +static int kernfs_dop_revalidate(struct dentry *dentry, unsigned int flags) +{ + struct kernfs_node *kn; + + if (flags & LOOKUP_RCU) + return -ECHILD; + + /* Always perform fresh lookup for negatives */ + if (!dentry->d_inode) + goto out_bad_unlocked; + + kn = dentry->d_fsdata; + mutex_lock(&kernfs_mutex); + + /* The kernfs node has been deleted */ + if (kn->flags & KERNFS_REMOVED) + goto out_bad; + + /* The kernfs node has been moved? */ + if (dentry->d_parent->d_fsdata != kn->parent) + goto out_bad; + + /* The kernfs node has been renamed */ + if (strcmp(dentry->d_name.name, kn->name) != 0) + goto out_bad; + + /* The kernfs node has been moved to a different namespace */ + if (kn->parent && kernfs_ns_enabled(kn->parent) && + kernfs_info(dentry->d_sb)->ns != kn->ns) + goto out_bad; + + mutex_unlock(&kernfs_mutex); +out_valid: + return 1; +out_bad: + mutex_unlock(&kernfs_mutex); +out_bad_unlocked: + /* + * @dentry doesn't match the underlying kernfs node, drop the + * dentry and force lookup. 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, so use check_submounts_and_drop() + * instead of d_drop(). + */ + if (check_submounts_and_drop(dentry) != 0) + goto out_valid; + + return 0; +} + +static void kernfs_dop_release(struct dentry *dentry) +{ + kernfs_put(dentry->d_fsdata); +} + +const struct dentry_operations kernfs_dops = { + .d_revalidate = kernfs_dop_revalidate, + .d_release = kernfs_dop_release, +}; + +static struct kernfs_node *__kernfs_new_node(struct kernfs_root *root, + const char *name, umode_t mode, + unsigned flags) +{ + char *dup_name = NULL; + struct kernfs_node *kn; + int ret; + + if (!(flags & KERNFS_STATIC_NAME)) { + name = dup_name = kstrdup(name, GFP_KERNEL); + if (!name) + return NULL; + } + + kn = kmem_cache_zalloc(kernfs_node_cache, GFP_KERNEL); + if (!kn) + goto err_out1; + + ret = ida_simple_get(&root->ino_ida, 1, 0, GFP_KERNEL); + if (ret < 0) + goto err_out2; + kn->ino = ret; + + atomic_set(&kn->count, 1); + atomic_set(&kn->active, 0); + + kn->name = name; + kn->mode = mode; + kn->flags = flags | KERNFS_REMOVED; + + return kn; + + err_out2: + kmem_cache_free(kernfs_node_cache, kn); + err_out1: + kfree(dup_name); + return NULL; +} + +struct kernfs_node *kernfs_new_node(struct kernfs_node *parent, + const char *name, umode_t mode, + unsigned flags) +{ + struct kernfs_node *kn; + + kn = __kernfs_new_node(kernfs_root(parent), name, mode, flags); + if (kn) { + kernfs_get(parent); + kn->parent = parent; + } + return kn; +} + +/** + * kernfs_addrm_start - prepare for kernfs_node add/remove + * @acxt: pointer to kernfs_addrm_cxt to be used + * + * This function is called when the caller is about to add or remove + * kernfs_node. This function acquires kernfs_mutex. @acxt is used + * to keep and pass context to other addrm functions. + * + * LOCKING: + * Kernel thread context (may sleep). kernfs_mutex is locked on + * return. + */ +void kernfs_addrm_start(struct kernfs_addrm_cxt *acxt) + __acquires(kernfs_mutex) +{ + memset(acxt, 0, sizeof(*acxt)); + + mutex_lock(&kernfs_mutex); +} + +/** + * kernfs_add_one - add kernfs_node to parent without warning + * @acxt: addrm context to use + * @kn: kernfs_node to be added + * + * The caller must already have initialized @kn->parent. This + * function increments nlink of the parent's inode if @kn is a + * directory and link into the children list of the parent. + * + * This function should be called between calls to + * kernfs_addrm_start() and kernfs_addrm_finish() and should be passed + * the same @acxt as passed to kernfs_addrm_start(). + * + * LOCKING: + * Determined by kernfs_addrm_start(). + * + * RETURNS: + * 0 on success, -EEXIST if entry with the given name already + * exists. + */ +int kernfs_add_one(struct kernfs_addrm_cxt *acxt, struct kernfs_node *kn) +{ + struct kernfs_node *parent = kn->parent; + bool has_ns = kernfs_ns_enabled(parent); + struct kernfs_iattrs *ps_iattr; + int ret; + + if (has_ns != (bool)kn->ns) { + WARN(1, KERN_WARNING "kernfs: ns %s in '%s' for '%s'\n", + has_ns ? "required" : "invalid", parent->name, kn->name); + return -EINVAL; + } + + if (kernfs_type(parent) != KERNFS_DIR) + return -EINVAL; + + if (parent->flags & KERNFS_REMOVED) + return -ENOENT; + + kn->hash = kernfs_name_hash(kn->name, kn->ns); + + ret = kernfs_link_sibling(kn); + if (ret) + return ret; + + /* Update timestamps on the parent */ + ps_iattr = parent->iattr; + if (ps_iattr) { + struct iattr *ps_iattrs = &ps_iattr->ia_iattr; + ps_iattrs->ia_ctime = ps_iattrs->ia_mtime = CURRENT_TIME; + } + + /* Mark the entry added into directory tree */ + kn->flags &= ~KERNFS_REMOVED; + + return 0; +} + +/** + * kernfs_remove_one - remove kernfs_node from parent + * @acxt: addrm context to use + * @kn: kernfs_node to be removed + * + * Mark @kn removed and drop nlink of parent inode if @kn is a + * directory. @kn is unlinked from the children list. + * + * This function should be called between calls to + * kernfs_addrm_start() and kernfs_addrm_finish() and should be + * passed the same @acxt as passed to kernfs_addrm_start(). + * + * LOCKING: + * Determined by kernfs_addrm_start(). + */ +static void kernfs_remove_one(struct kernfs_addrm_cxt *acxt, + struct kernfs_node *kn) +{ + struct kernfs_iattrs *ps_iattr; + + /* + * Removal can be called multiple times on the same node. Only the + * first invocation is effective and puts the base ref. + */ + if (kn->flags & KERNFS_REMOVED) + return; + + if (kn->parent) { + kernfs_unlink_sibling(kn); + + /* Update timestamps on the parent */ + ps_iattr = kn->parent->iattr; + if (ps_iattr) { + ps_iattr->ia_iattr.ia_ctime = CURRENT_TIME; + ps_iattr->ia_iattr.ia_mtime = CURRENT_TIME; + } + } + + kn->flags |= KERNFS_REMOVED; + kn->u.removed_list = acxt->removed; + acxt->removed = kn; +} + +/** + * kernfs_addrm_finish - finish up kernfs_node add/remove + * @acxt: addrm context to finish up + * + * Finish up kernfs_node add/remove. Resources acquired by + * kernfs_addrm_start() are released and removed kernfs_nodes are + * cleaned up. + * + * LOCKING: + * kernfs_mutex is released. + */ +void kernfs_addrm_finish(struct kernfs_addrm_cxt *acxt) + __releases(kernfs_mutex) +{ + /* release resources acquired by kernfs_addrm_start() */ + mutex_unlock(&kernfs_mutex); + + /* kill removed kernfs_nodes */ + while (acxt->removed) { + struct kernfs_node *kn = acxt->removed; + + acxt->removed = kn->u.removed_list; + + kernfs_deactivate(kn); + kernfs_unmap_bin_file(kn); + kernfs_put(kn); + } +} + +/** + * kernfs_find_ns - find kernfs_node with the given name + * @parent: kernfs_node to search under + * @name: name to look for + * @ns: the namespace tag to use + * + * Look for kernfs_node with name @name under @parent. Returns pointer to + * the found kernfs_node on success, %NULL on failure. + */ +static struct kernfs_node *kernfs_find_ns(struct kernfs_node *parent, + const unsigned char *name, + const void *ns) +{ + struct rb_node *node = parent->dir.children.rb_node; + bool has_ns = kernfs_ns_enabled(parent); + unsigned int hash; + + lockdep_assert_held(&kernfs_mutex); + + if (has_ns != (bool)ns) { + WARN(1, KERN_WARNING "kernfs: ns %s in '%s' for '%s'\n", + has_ns ? "required" : "invalid", parent->name, name); + return NULL; + } + + hash = kernfs_name_hash(name, ns); + while (node) { + struct kernfs_node *kn; + int result; + + kn = rb_to_kn(node); + result = kernfs_name_compare(hash, name, ns, kn); + if (result < 0) + node = node->rb_left; + else if (result > 0) + node = node->rb_right; + else + return kn; + } + return NULL; +} + +/** + * kernfs_find_and_get_ns - find and get kernfs_node with the given name + * @parent: kernfs_node to search under + * @name: name to look for + * @ns: the namespace tag to use + * + * Look for kernfs_node with name @name under @parent and get a reference + * if found. This function may sleep and returns pointer to the found + * kernfs_node on success, %NULL on failure. + */ +struct kernfs_node *kernfs_find_and_get_ns(struct kernfs_node *parent, + const char *name, const void *ns) +{ + struct kernfs_node *kn; + + mutex_lock(&kernfs_mutex); + kn = kernfs_find_ns(parent, name, ns); + kernfs_get(kn); + mutex_unlock(&kernfs_mutex); + + return kn; +} +EXPORT_SYMBOL_GPL(kernfs_find_and_get_ns); + +/** + * kernfs_create_root - create a new kernfs hierarchy + * @kdops: optional directory syscall operations for the hierarchy + * @priv: opaque data associated with the new directory + * + * Returns the root of the new hierarchy on success, ERR_PTR() value on + * failure. + */ +struct kernfs_root *kernfs_create_root(struct kernfs_dir_ops *kdops, void *priv) +{ + struct kernfs_root *root; + struct kernfs_node *kn; + + root = kzalloc(sizeof(*root), GFP_KERNEL); + if (!root) + return ERR_PTR(-ENOMEM); + + ida_init(&root->ino_ida); + + kn = __kernfs_new_node(root, "", S_IFDIR | S_IRUGO | S_IXUGO, + KERNFS_DIR); + if (!kn) { + ida_destroy(&root->ino_ida); + kfree(root); + return ERR_PTR(-ENOMEM); + } + + kn->flags &= ~KERNFS_REMOVED; + kn->priv = priv; + kn->dir.root = root; + + root->dir_ops = kdops; + root->kn = kn; + + return root; +} + +/** + * kernfs_destroy_root - destroy a kernfs hierarchy + * @root: root of the hierarchy to destroy + * + * Destroy the hierarchy anchored at @root by removing all existing + * directories and destroying @root. + */ +void kernfs_destroy_root(struct kernfs_root *root) +{ + kernfs_remove(root->kn); /* will also free @root */ +} + +/** + * kernfs_create_dir_ns - create a directory + * @parent: parent in which to create a new directory + * @name: name of the new directory + * @mode: mode of the new directory + * @priv: opaque data associated with the new directory + * @ns: optional namespace tag of the directory + * + * Returns the created node on success, ERR_PTR() value on failure. + */ +struct kernfs_node *kernfs_create_dir_ns(struct kernfs_node *parent, + const char *name, umode_t mode, + void *priv, const void *ns) +{ + struct kernfs_addrm_cxt acxt; + struct kernfs_node *kn; + int rc; + + /* allocate */ + kn = kernfs_new_node(parent, name, mode | S_IFDIR, KERNFS_DIR); + if (!kn) + return ERR_PTR(-ENOMEM); + + kn->dir.root = parent->dir.root; + kn->ns = ns; + kn->priv = priv; + + /* link in */ + kernfs_addrm_start(&acxt); + rc = kernfs_add_one(&acxt, kn); + kernfs_addrm_finish(&acxt); + + if (!rc) + return kn; + + kernfs_put(kn); + return ERR_PTR(rc); +} + +static struct dentry *kernfs_iop_lookup(struct inode *dir, + struct dentry *dentry, + unsigned int flags) +{ + struct dentry *ret; + struct kernfs_node *parent = dentry->d_parent->d_fsdata; + struct kernfs_node *kn; + struct inode *inode; + const void *ns = NULL; + + mutex_lock(&kernfs_mutex); + + if (kernfs_ns_enabled(parent)) + ns = kernfs_info(dir->i_sb)->ns; + + kn = kernfs_find_ns(parent, dentry->d_name.name, ns); + + /* no such entry */ + if (!kn) { + ret = NULL; + goto out_unlock; + } + kernfs_get(kn); + dentry->d_fsdata = kn; + + /* attach dentry and inode */ + inode = kernfs_get_inode(dir->i_sb, kn); + if (!inode) { + ret = ERR_PTR(-ENOMEM); + goto out_unlock; + } + + /* instantiate and hash dentry */ + ret = d_materialise_unique(dentry, inode); + out_unlock: + mutex_unlock(&kernfs_mutex); + return ret; +} + +static int kernfs_iop_mkdir(struct inode *dir, struct dentry *dentry, + umode_t mode) +{ + struct kernfs_node *parent = dir->i_private; + struct kernfs_dir_ops *kdops = kernfs_root(parent)->dir_ops; + + if (!kdops || !kdops->mkdir) + return -EPERM; + + return kdops->mkdir(parent, dentry->d_name.name, mode); +} + +static int kernfs_iop_rmdir(struct inode *dir, struct dentry *dentry) +{ + struct kernfs_node *kn = dentry->d_fsdata; + struct kernfs_dir_ops *kdops = kernfs_root(kn)->dir_ops; + + if (!kdops || !kdops->rmdir) + return -EPERM; + + return kdops->rmdir(kn); +} + +static int kernfs_iop_rename(struct inode *old_dir, struct dentry *old_dentry, + struct inode *new_dir, struct dentry *new_dentry) +{ + struct kernfs_node *kn = old_dentry->d_fsdata; + struct kernfs_node *new_parent = new_dir->i_private; + struct kernfs_dir_ops *kdops = kernfs_root(kn)->dir_ops; + + if (!kdops || !kdops->rename) + return -EPERM; + + return kdops->rename(kn, new_parent, new_dentry->d_name.name); +} + +const struct inode_operations kernfs_dir_iops = { + .lookup = kernfs_iop_lookup, + .permission = kernfs_iop_permission, + .setattr = kernfs_iop_setattr, + .getattr = kernfs_iop_getattr, + .setxattr = kernfs_iop_setxattr, + .removexattr = kernfs_iop_removexattr, + .getxattr = kernfs_iop_getxattr, + .listxattr = kernfs_iop_listxattr, + + .mkdir = kernfs_iop_mkdir, + .rmdir = kernfs_iop_rmdir, + .rename = kernfs_iop_rename, +}; + +static struct kernfs_node *kernfs_leftmost_descendant(struct kernfs_node *pos) +{ + struct kernfs_node *last; + + while (true) { + struct rb_node *rbn; + + last = pos; + + if (kernfs_type(pos) != KERNFS_DIR) + break; + + rbn = rb_first(&pos->dir.children); + if (!rbn) + break; + + pos = rb_to_kn(rbn); + } + + return last; +} + +/** + * kernfs_next_descendant_post - find the next descendant for post-order walk + * @pos: the current position (%NULL to initiate traversal) + * @root: kernfs_node whose descendants to walk + * + * Find the next descendant to visit for post-order traversal of @root's + * descendants. @root is included in the iteration and the last node to be + * visited. + */ +static struct kernfs_node *kernfs_next_descendant_post(struct kernfs_node *pos, + struct kernfs_node *root) +{ + struct rb_node *rbn; + + lockdep_assert_held(&kernfs_mutex); + + /* if first iteration, visit leftmost descendant which may be root */ + if (!pos) + return kernfs_leftmost_descendant(root); + + /* if we visited @root, we're done */ + if (pos == root) + return NULL; + + /* if there's an unvisited sibling, visit its leftmost descendant */ + rbn = rb_next(&pos->rb); + if (rbn) + return kernfs_leftmost_descendant(rb_to_kn(rbn)); + + /* no sibling left, visit parent */ + return pos->parent; +} + +static void __kernfs_remove(struct kernfs_addrm_cxt *acxt, + struct kernfs_node *kn) +{ + struct kernfs_node *pos, *next; + + if (!kn) + return; + + pr_debug("kernfs %s: removing\n", kn->name); + + next = NULL; + do { + pos = next; + next = kernfs_next_descendant_post(pos, kn); + if (pos) + kernfs_remove_one(acxt, pos); + } while (next); +} + +/** + * kernfs_remove - remove a kernfs_node recursively + * @kn: the kernfs_node to remove + * + * Remove @kn along with all its subdirectories and files. + */ +void kernfs_remove(struct kernfs_node *kn) +{ + struct kernfs_addrm_cxt acxt; + + kernfs_addrm_start(&acxt); + __kernfs_remove(&acxt, kn); + kernfs_addrm_finish(&acxt); +} + +/** + * kernfs_remove_by_name_ns - find a kernfs_node by name and remove it + * @parent: parent of the target + * @name: name of the kernfs_node to remove + * @ns: namespace tag of the kernfs_node to remove + * + * Look for the kernfs_node with @name and @ns under @parent and remove it. + * Returns 0 on success, -ENOENT if such entry doesn't exist. + */ +int kernfs_remove_by_name_ns(struct kernfs_node *parent, const char *name, + const void *ns) +{ + struct kernfs_addrm_cxt acxt; + struct kernfs_node *kn; + + if (!parent) { + WARN(1, KERN_WARNING "kernfs: can not remove '%s', no directory\n", + name); + return -ENOENT; + } + + kernfs_addrm_start(&acxt); + + kn = kernfs_find_ns(parent, name, ns); + if (kn) + __kernfs_remove(&acxt, kn); + + kernfs_addrm_finish(&acxt); + + if (kn) + return 0; + else + return -ENOENT; +} + +/** + * kernfs_rename_ns - move and rename a kernfs_node + * @kn: target node + * @new_parent: new parent to put @sd under + * @new_name: new name + * @new_ns: new namespace tag + */ +int kernfs_rename_ns(struct kernfs_node *kn, struct kernfs_node *new_parent, + const char *new_name, const void *new_ns) +{ + int error; + + mutex_lock(&kernfs_mutex); + + error = -ENOENT; + if ((kn->flags | new_parent->flags) & KERNFS_REMOVED) + goto out; + + error = 0; + if ((kn->parent == new_parent) && (kn->ns == new_ns) && + (strcmp(kn->name, new_name) == 0)) + goto out; /* nothing to rename */ + + error = -EEXIST; + if (kernfs_find_ns(new_parent, new_name, new_ns)) + goto out; + + /* rename kernfs_node */ + if (strcmp(kn->name, new_name) != 0) { + error = -ENOMEM; + new_name = kstrdup(new_name, GFP_KERNEL); + if (!new_name) + goto out; + + if (kn->flags & KERNFS_STATIC_NAME) + kn->flags &= ~KERNFS_STATIC_NAME; + else + kfree(kn->name); + + kn->name = new_name; + } + + /* + * Move to the appropriate place in the appropriate directories rbtree. + */ + kernfs_unlink_sibling(kn); + kernfs_get(new_parent); + kernfs_put(kn->parent); + kn->ns = new_ns; + kn->hash = kernfs_name_hash(kn->name, kn->ns); + kn->parent = new_parent; + kernfs_link_sibling(kn); + + error = 0; + out: + mutex_unlock(&kernfs_mutex); + return error; +} + +/* Relationship between s_mode and the DT_xxx types */ +static inline unsigned char dt_type(struct kernfs_node *kn) +{ + return (kn->mode >> 12) & 15; +} + +static int kernfs_dir_fop_release(struct inode *inode, struct file *filp) +{ + kernfs_put(filp->private_data); + return 0; +} + +static struct kernfs_node *kernfs_dir_pos(const void *ns, + struct kernfs_node *parent, loff_t hash, struct kernfs_node *pos) +{ + if (pos) { + int valid = !(pos->flags & KERNFS_REMOVED) && + pos->parent == parent && hash == pos->hash; + kernfs_put(pos); + if (!valid) + pos = NULL; + } + if (!pos && (hash > 1) && (hash < INT_MAX)) { + struct rb_node *node = parent->dir.children.rb_node; + while (node) { + pos = rb_to_kn(node); + + if (hash < pos->hash) + node = node->rb_left; + else if (hash > pos->hash) + node = node->rb_right; + else + break; + } + } + /* Skip over entries in the wrong namespace */ + while (pos && pos->ns != ns) { + struct rb_node *node = rb_next(&pos->rb); + if (!node) + pos = NULL; + else + pos = rb_to_kn(node); + } + return pos; +} + +static struct kernfs_node *kernfs_dir_next_pos(const void *ns, + struct kernfs_node *parent, ino_t ino, struct kernfs_node *pos) +{ + pos = kernfs_dir_pos(ns, parent, ino, pos); + if (pos) + do { + struct rb_node *node = rb_next(&pos->rb); + if (!node) + pos = NULL; + else + pos = rb_to_kn(node); + } while (pos && pos->ns != ns); + return pos; +} + +static int kernfs_fop_readdir(struct file *file, struct dir_context *ctx) +{ + struct dentry *dentry = file->f_path.dentry; + struct kernfs_node *parent = dentry->d_fsdata; + struct kernfs_node *pos = file->private_data; + const void *ns = NULL; + + if (!dir_emit_dots(file, ctx)) + return 0; + mutex_lock(&kernfs_mutex); + + if (kernfs_ns_enabled(parent)) + ns = kernfs_info(dentry->d_sb)->ns; + + for (pos = kernfs_dir_pos(ns, parent, ctx->pos, pos); + pos; + pos = kernfs_dir_next_pos(ns, parent, ctx->pos, pos)) { + const char *name = pos->name; + unsigned int type = dt_type(pos); + int len = strlen(name); + ino_t ino = pos->ino; + + ctx->pos = pos->hash; + file->private_data = pos; + kernfs_get(pos); + + mutex_unlock(&kernfs_mutex); + if (!dir_emit(ctx, name, len, ino, type)) + return 0; + mutex_lock(&kernfs_mutex); + } + mutex_unlock(&kernfs_mutex); + file->private_data = NULL; + ctx->pos = INT_MAX; + return 0; +} + +static loff_t kernfs_dir_fop_llseek(struct file *file, loff_t offset, + int whence) +{ + struct inode *inode = file_inode(file); + loff_t ret; + + mutex_lock(&inode->i_mutex); + ret = generic_file_llseek(file, offset, whence); + mutex_unlock(&inode->i_mutex); + + return ret; +} + +const struct file_operations kernfs_dir_fops = { + .read = generic_read_dir, + .iterate = kernfs_fop_readdir, + .release = kernfs_dir_fop_release, + .llseek = kernfs_dir_fop_llseek, +}; diff --git a/fs/kernfs/file.c b/fs/kernfs/file.c new file mode 100644 index 0000000..dbf397b --- /dev/null +++ b/fs/kernfs/file.c @@ -0,0 +1,867 @@ +/* + * fs/kernfs/file.c - kernfs file implementation + * + * Copyright (c) 2001-3 Patrick Mochel + * Copyright (c) 2007 SUSE Linux Products GmbH + * Copyright (c) 2007, 2013 Tejun Heo <tj@kernel.org> + * + * This file is released under the GPLv2. + */ + +#include <linux/fs.h> +#include <linux/seq_file.h> +#include <linux/slab.h> +#include <linux/poll.h> +#include <linux/pagemap.h> +#include <linux/sched.h> + +#include "kernfs-internal.h" + +/* + * There's one kernfs_open_file for each open file and one kernfs_open_node + * for each kernfs_node with one or more open files. + * + * kernfs_node->attr.open points to kernfs_open_node. attr.open is + * protected by kernfs_open_node_lock. + * + * filp->private_data points to seq_file whose ->private points to + * kernfs_open_file. kernfs_open_files are chained at + * kernfs_open_node->files, which is protected by kernfs_open_file_mutex. + */ +static DEFINE_SPINLOCK(kernfs_open_node_lock); +static DEFINE_MUTEX(kernfs_open_file_mutex); + +struct kernfs_open_node { + atomic_t refcnt; + atomic_t event; + wait_queue_head_t poll; + struct list_head files; /* goes through kernfs_open_file.list */ +}; + +static struct kernfs_open_file *kernfs_of(struct file *file) +{ + return ((struct seq_file *)file->private_data)->private; +} + +/* + * Determine the kernfs_ops for the given kernfs_node. This function must + * be called while holding an active reference. + */ +static const struct kernfs_ops *kernfs_ops(struct kernfs_node *kn) +{ + if (kn->flags & KERNFS_LOCKDEP) + lockdep_assert_held(kn); + return kn->attr.ops; +} + +/* + * As kernfs_seq_stop() is also called after kernfs_seq_start() or + * kernfs_seq_next() failure, it needs to distinguish whether it's stopping + * a seq_file iteration which is fully initialized with an active reference + * or an aborted kernfs_seq_start() due to get_active failure. The + * position pointer is the only context for each seq_file iteration and + * thus the stop condition should be encoded in it. As the return value is + * directly visible to userland, ERR_PTR(-ENODEV) is the only acceptable + * choice to indicate get_active failure. + * + * Unfortunately, this is complicated due to the optional custom seq_file + * operations which may return ERR_PTR(-ENODEV) too. kernfs_seq_stop() + * can't distinguish whether ERR_PTR(-ENODEV) is from get_active failure or + * custom seq_file operations and thus can't decide whether put_active + * should be performed or not only on ERR_PTR(-ENODEV). + * + * This is worked around by factoring out the custom seq_stop() and + * put_active part into kernfs_seq_stop_active(), skipping it from + * kernfs_seq_stop() if ERR_PTR(-ENODEV) while invoking it directly after + * custom seq_file operations fail with ERR_PTR(-ENODEV) - this ensures + * that kernfs_seq_stop_active() is skipped only after get_active failure. + */ +static void kernfs_seq_stop_active(struct seq_file *sf, void *v) +{ + struct kernfs_open_file *of = sf->private; + const struct kernfs_ops *ops = kernfs_ops(of->kn); + + if (ops->seq_stop) + ops->seq_stop(sf, v); + kernfs_put_active(of->kn); +} + +static void *kernfs_seq_start(struct seq_file *sf, loff_t *ppos) +{ + struct kernfs_open_file *of = sf->private; + const struct kernfs_ops *ops; + + /* + * @of->mutex nests outside active ref and is just to ensure that + * the ops aren't called concurrently for the same open file. + */ + mutex_lock(&of->mutex); + if (!kernfs_get_active(of->kn)) + return ERR_PTR(-ENODEV); + + ops = kernfs_ops(of->kn); + if (ops->seq_start) { + void *next = ops->seq_start(sf, ppos); + /* see the comment above kernfs_seq_stop_active() */ + if (next == ERR_PTR(-ENODEV)) + kernfs_seq_stop_active(sf, next); + return next; + } else { + /* + * The same behavior and code as single_open(). Returns + * !NULL if pos is at the beginning; otherwise, NULL. + */ + return NULL + !*ppos; + } +} + +static void *kernfs_seq_next(struct seq_file *sf, void *v, loff_t *ppos) +{ + struct kernfs_open_file *of = sf->private; + const struct kernfs_ops *ops = kernfs_ops(of->kn); + + if (ops->seq_next) { + void *next = ops->seq_next(sf, v, ppos); + /* see the comment above kernfs_seq_stop_active() */ + if (next == ERR_PTR(-ENODEV)) + kernfs_seq_stop_active(sf, next); + return next; + } else { + /* + * The same behavior and code as single_open(), always + * terminate after the initial read. + */ + ++*ppos; + return NULL; + } +} + +static void kernfs_seq_stop(struct seq_file *sf, void *v) +{ + struct kernfs_open_file *of = sf->private; + + if (v != ERR_PTR(-ENODEV)) + kernfs_seq_stop_active(sf, v); + mutex_unlock(&of->mutex); +} + +static int kernfs_seq_show(struct seq_file *sf, void *v) +{ + struct kernfs_open_file *of = sf->private; + + of->event = atomic_read(&of->kn->attr.open->event); + + return of->kn->attr.ops->seq_show(sf, v); +} + +static const struct seq_operations kernfs_seq_ops = { + .start = kernfs_seq_start, + .next = kernfs_seq_next, + .stop = kernfs_seq_stop, + .show = kernfs_seq_show, +}; + +/* + * As reading a bin file can have side-effects, the exact offset and bytes + * specified in read(2) call should be passed to the read callback making + * it difficult to use seq_file. Implement simplistic custom buffering for + * bin files. + */ +static ssize_t kernfs_file_direct_read(struct kernfs_open_file *of, + char __user *user_buf, size_t count, + loff_t *ppos) +{ + ssize_t len = min_t(size_t, count, PAGE_SIZE); + const struct kernfs_ops *ops; + char *buf; + + buf = kmalloc(len, GFP_KERNEL); + if (!buf) + return -ENOMEM; + + /* + * @of->mutex nests outside active ref and is just to ensure that + * the ops aren't called concurrently for the same open file. + */ + mutex_lock(&of->mutex); + if (!kernfs_get_active(of->kn)) { + len = -ENODEV; + mutex_unlock(&of->mutex); + goto out_free; + } + + ops = kernfs_ops(of->kn); + if (ops->read) + len = ops->read(of, buf, len, *ppos); + else + len = -EINVAL; + + kernfs_put_active(of->kn); + mutex_unlock(&of->mutex); + + if (len < 0) + goto out_free; + + if (copy_to_user(user_buf, buf, len)) { + len = -EFAULT; + goto out_free; + } + + *ppos += len; + + out_free: + kfree(buf); + return len; +} + +/** + * kernfs_fop_read - kernfs vfs read callback + * @file: file pointer + * @user_buf: data to write + * @count: number of bytes + * @ppos: starting offset + */ +static ssize_t kernfs_fop_read(struct file *file, char __user *user_buf, + size_t count, loff_t *ppos) +{ + struct kernfs_open_file *of = kernfs_of(file); + + if (of->kn->flags & KERNFS_HAS_SEQ_SHOW) + return seq_read(file, user_buf, count, ppos); + else + return kernfs_file_direct_read(of, user_buf, count, ppos); +} + +/** + * kernfs_fop_write - kernfs vfs write callback + * @file: file pointer + * @user_buf: data to write + * @count: number of bytes + * @ppos: starting offset + * + * Copy data in from userland and pass it to the matching kernfs write + * operation. + * + * There is no easy way for us to know if userspace is only doing a partial + * write, so we don't support them. We expect the entire buffer to come on + * the first write. Hint: if you're writing a value, first read the file, + * modify only the the value you're changing, then write entire buffer + * back. + */ +static ssize_t kernfs_fop_write(struct file *file, const char __user *user_buf, + size_t count, loff_t *ppos) +{ + struct kernfs_open_file *of = kernfs_of(file); + ssize_t len = min_t(size_t, count, PAGE_SIZE); + const struct kernfs_ops *ops; + char *buf; + + buf = kmalloc(len + 1, GFP_KERNEL); + if (!buf) + return -ENOMEM; + + if (copy_from_user(buf, user_buf, len)) { + len = -EFAULT; + goto out_free; + } + buf[len] = '\0'; /* guarantee string termination */ + + /* + * @of->mutex nests outside active ref and is just to ensure that + * the ops aren't called concurrently for the same open file. + */ + mutex_lock(&of->mutex); + if (!kernfs_get_active(of->kn)) { + mutex_unlock(&of->mutex); + len = -ENODEV; + goto out_free; + } + + ops = kernfs_ops(of->kn); + if (ops->write) + len = ops->write(of, buf, len, *ppos); + else + len = -EINVAL; + + kernfs_put_active(of->kn); + mutex_unlock(&of->mutex); + + if (len > 0) + *ppos += len; +out_free: + kfree(buf); + return len; +} + +static void kernfs_vma_open(struct vm_area_struct *vma) +{ + struct file *file = vma->vm_file; + struct kernfs_open_file *of = kernfs_of(file); + + if (!of->vm_ops) + return; + + if (!kernfs_get_active(of->kn)) + return; + + if (of->vm_ops->open) + of->vm_ops->open(vma); + + kernfs_put_active(of->kn); +} + +static int kernfs_vma_fault(struct vm_area_struct *vma, struct vm_fault *vmf) +{ + struct file *file = vma->vm_file; + struct kernfs_open_file *of = kernfs_of(file); + int ret; + + if (!of->vm_ops) + return VM_FAULT_SIGBUS; + + if (!kernfs_get_active(of->kn)) + return VM_FAULT_SIGBUS; + + ret = VM_FAULT_SIGBUS; + if (of->vm_ops->fault) + ret = of->vm_ops->fault(vma, vmf); + + kernfs_put_active(of->kn); + return ret; +} + +static int kernfs_vma_page_mkwrite(struct vm_area_struct *vma, + struct vm_fault *vmf) +{ + struct file *file = vma->vm_file; + struct kernfs_open_file *of = kernfs_of(file); + int ret; + + if (!of->vm_ops) + return VM_FAULT_SIGBUS; + + if (!kernfs_get_active(of->kn)) + return VM_FAULT_SIGBUS; + + ret = 0; + if (of->vm_ops->page_mkwrite) + ret = of->vm_ops->page_mkwrite(vma, vmf); + else + file_update_time(file); + + kernfs_put_active(of->kn); + return ret; +} + +static int kernfs_vma_access(struct vm_area_struct *vma, unsigned long addr, + void *buf, int len, int write) +{ + struct file *file = vma->vm_file; + struct kernfs_open_file *of = kernfs_of(file); + int ret; + + if (!of->vm_ops) + return -EINVAL; + + if (!kernfs_get_active(of->kn)) + return -EINVAL; + + ret = -EINVAL; + if (of->vm_ops->access) + ret = of->vm_ops->access(vma, addr, buf, len, write); + + kernfs_put_active(of->kn); + return ret; +} + +#ifdef CONFIG_NUMA +static int kernfs_vma_set_policy(struct vm_area_struct *vma, + struct mempolicy *new) +{ + struct file *file = vma->vm_file; + struct kernfs_open_file *of = kernfs_of(file); + int ret; + + if (!of->vm_ops) + return 0; + + if (!kernfs_get_active(of->kn)) + return -EINVAL; + + ret = 0; + if (of->vm_ops->set_policy) + ret = of->vm_ops->set_policy(vma, new); + + kernfs_put_active(of->kn); + return ret; +} + +static struct mempolicy *kernfs_vma_get_policy(struct vm_area_struct *vma, + unsigned long addr) +{ + struct file *file = vma->vm_file; + struct kernfs_open_file *of = kernfs_of(file); + struct mempolicy *pol; + + if (!of->vm_ops) + return vma->vm_policy; + + if (!kernfs_get_active(of->kn)) + return vma->vm_policy; + + pol = vma->vm_policy; + if (of->vm_ops->get_policy) + pol = of->vm_ops->get_policy(vma, addr); + + kernfs_put_active(of->kn); + return pol; +} + +static int kernfs_vma_migrate(struct vm_area_struct *vma, + const nodemask_t *from, const nodemask_t *to, + unsigned long flags) +{ + struct file *file = vma->vm_file; + struct kernfs_open_file *of = kernfs_of(file); + int ret; + + if (!of->vm_ops) + return 0; + + if (!kernfs_get_active(of->kn)) + return 0; + + ret = 0; + if (of->vm_ops->migrate) + ret = of->vm_ops->migrate(vma, from, to, flags); + + kernfs_put_active(of->kn); + return ret; +} +#endif + +static const struct vm_operations_struct kernfs_vm_ops = { + .open = kernfs_vma_open, + .fault = kernfs_vma_fault, + .page_mkwrite = kernfs_vma_page_mkwrite, + .access = kernfs_vma_access, +#ifdef CONFIG_NUMA + .set_policy = kernfs_vma_set_policy, + .get_policy = kernfs_vma_get_policy, + .migrate = kernfs_vma_migrate, +#endif +}; + +static int kernfs_fop_mmap(struct file *file, struct vm_area_struct *vma) +{ + struct kernfs_open_file *of = kernfs_of(file); + const struct kernfs_ops *ops; + int rc; + + /* + * mmap path and of->mutex are prone to triggering spurious lockdep + * warnings and we don't want to add spurious locking dependency + * between the two. Check whether mmap is actually implemented + * without grabbing @of->mutex by testing HAS_MMAP flag. See the + * comment in kernfs_file_open() for more details. + */ + if (!(of->kn->flags & KERNFS_HAS_MMAP)) + return -ENODEV; + + mutex_lock(&of->mutex); + + rc = -ENODEV; + if (!kernfs_get_active(of->kn)) + goto out_unlock; + + ops = kernfs_ops(of->kn); + rc = ops->mmap(of, vma); + + /* + * PowerPC's pci_mmap of legacy_mem uses shmem_zero_setup() + * to satisfy versions of X which crash if the mmap fails: that + * substitutes a new vm_file, and we don't then want bin_vm_ops. + */ + if (vma->vm_file != file) + goto out_put; + + rc = -EINVAL; + if (of->mmapped && of->vm_ops != vma->vm_ops) + goto out_put; + + /* + * It is not possible to successfully wrap close. + * So error if someone is trying to use close. + */ + rc = -EINVAL; + if (vma->vm_ops && vma->vm_ops->close) + goto out_put; + + rc = 0; + of->mmapped = 1; + of->vm_ops = vma->vm_ops; + vma->vm_ops = &kernfs_vm_ops; +out_put: + kernfs_put_active(of->kn); +out_unlock: + mutex_unlock(&of->mutex); + + return rc; +} + +/** + * kernfs_get_open_node - get or create kernfs_open_node + * @kn: target kernfs_node + * @of: kernfs_open_file for this instance of open + * + * If @kn->attr.open exists, increment its reference count; otherwise, + * create one. @of is chained to the files list. + * + * LOCKING: + * Kernel thread context (may sleep). + * + * RETURNS: + * 0 on success, -errno on failure. + */ +static int kernfs_get_open_node(struct kernfs_node *kn, + struct kernfs_open_file *of) +{ + struct kernfs_open_node *on, *new_on = NULL; + + retry: + mutex_lock(&kernfs_open_file_mutex); + spin_lock_irq(&kernfs_open_node_lock); + + if (!kn->attr.open && new_on) { + kn->attr.open = new_on; + new_on = NULL; + } + + on = kn->attr.open; + if (on) { + atomic_inc(&on->refcnt); + list_add_tail(&of->list, &on->files); + } + + spin_unlock_irq(&kernfs_open_node_lock); + mutex_unlock(&kernfs_open_file_mutex); + + if (on) { + kfree(new_on); + return 0; + } + + /* not there, initialize a new one and retry */ + new_on = kmalloc(sizeof(*new_on), GFP_KERNEL); + if (!new_on) + return -ENOMEM; + + atomic_set(&new_on->refcnt, 0); + atomic_set(&new_on->event, 1); + init_waitqueue_head(&new_on->poll); + INIT_LIST_HEAD(&new_on->files); + goto retry; +} + +/** + * kernfs_put_open_node - put kernfs_open_node + * @kn: target kernfs_nodet + * @of: associated kernfs_open_file + * + * Put @kn->attr.open and unlink @of from the files list. If + * reference count reaches zero, disassociate and free it. + * + * LOCKING: + * None. + */ +static void kernfs_put_open_node(struct kernfs_node *kn, + struct kernfs_open_file *of) +{ + struct kernfs_open_node *on = kn->attr.open; + unsigned long flags; + + mutex_lock(&kernfs_open_file_mutex); + spin_lock_irqsave(&kernfs_open_node_lock, flags); + + if (of) + list_del(&of->list); + + if (atomic_dec_and_test(&on->refcnt)) + kn->attr.open = NULL; + else + on = NULL; + + spin_unlock_irqrestore(&kernfs_open_node_lock, flags); + mutex_unlock(&kernfs_open_file_mutex); + + kfree(on); +} + +static int kernfs_fop_open(struct inode *inode, struct file *file) +{ + struct kernfs_node *kn = file->f_path.dentry->d_fsdata; + const struct kernfs_ops *ops; + struct kernfs_open_file *of; + bool has_read, has_write, has_mmap; + int error = -EACCES; + + if (!kernfs_get_active(kn)) + return -ENODEV; + + ops = kernfs_ops(kn); + + has_read = ops->seq_show || ops->read || ops->mmap; + has_write = ops->write || ops->mmap; + has_mmap = ops->mmap; + + /* check perms and supported operations */ + if ((file->f_mode & FMODE_WRITE) && + (!(inode->i_mode & S_IWUGO) || !has_write)) + goto err_out; + + if ((file->f_mode & FMODE_READ) && + (!(inode->i_mode & S_IRUGO) || !has_read)) + goto err_out; + + /* allocate a kernfs_open_file for the file */ + error = -ENOMEM; + of = kzalloc(sizeof(struct kernfs_open_file), GFP_KERNEL); + if (!of) + goto err_out; + + /* + * The following is done to give a different lockdep key to + * @of->mutex for files which implement mmap. This is a rather + * crude way to avoid false positive lockdep warning around + * mm->mmap_sem - mmap nests @of->mutex under mm->mmap_sem and + * reading /sys/block/sda/trace/act_mask grabs sr_mutex, under + * which mm->mmap_sem nests, while holding @of->mutex. As each + * open file has a separate mutex, it's okay as long as those don't + * happen on the same file. At this point, we can't easily give + * each file a separate locking class. Let's differentiate on + * whether the file has mmap or not for now. + * + * Both paths of the branch look the same. They're supposed to + * look that way and give @of->mutex different static lockdep keys. + */ + if (has_mmap) + mutex_init(&of->mutex); + else + mutex_init(&of->mutex); + + of->kn = kn; + of->file = file; + + /* + * Always instantiate seq_file even if read access doesn't use + * seq_file or is not requested. This unifies private data access + * and readable regular files are the vast majority anyway. + */ + if (ops->seq_show) + error = seq_open(file, &kernfs_seq_ops); + else + error = seq_open(file, NULL); + if (error) + goto err_free; + + ((struct seq_file *)file->private_data)->private = of; + + /* seq_file clears PWRITE unconditionally, restore it if WRITE */ + if (file->f_mode & FMODE_WRITE) + file->f_mode |= FMODE_PWRITE; + + /* make sure we have open node struct */ + error = kernfs_get_open_node(kn, of); + if (error) + goto err_close; + + /* open succeeded, put active references */ + kernfs_put_active(kn); + return 0; + +err_close: + seq_release(inode, file); +err_free: + kfree(of); +err_out: + kernfs_put_active(kn); + return error; +} + +static int kernfs_fop_release(struct inode *inode, struct file *filp) +{ + struct kernfs_node *kn = filp->f_path.dentry->d_fsdata; + struct kernfs_open_file *of = kernfs_of(filp); + + kernfs_put_open_node(kn, of); + seq_release(inode, filp); + kfree(of); + + return 0; +} + +void kernfs_unmap_bin_file(struct kernfs_node *kn) +{ + struct kernfs_open_node *on; + struct kernfs_open_file *of; + + if (!(kn->flags & KERNFS_HAS_MMAP)) + return; + + spin_lock_irq(&kernfs_open_node_lock); + on = kn->attr.open; + if (on) + atomic_inc(&on->refcnt); + spin_unlock_irq(&kernfs_open_node_lock); + if (!on) + return; + + mutex_lock(&kernfs_open_file_mutex); + list_for_each_entry(of, &on->files, list) { + struct inode *inode = file_inode(of->file); + unmap_mapping_range(inode->i_mapping, 0, 0, 1); + } + mutex_unlock(&kernfs_open_file_mutex); + + kernfs_put_open_node(kn, NULL); +} + +/* + * Kernfs attribute files are pollable. The idea is that you read + * the content and then you use 'poll' or 'select' to wait for + * the content to change. When the content changes (assuming the + * manager for the kobject supports notification), poll will + * return POLLERR|POLLPRI, and select will return the fd whether + * it is waiting for read, write, or exceptions. + * Once poll/select indicates that the value has changed, you + * need to close and re-open the file, or seek to 0 and read again. + * Reminder: this only works for attributes which actively support + * it, and it is not possible to test an attribute from userspace + * to see if it supports poll (Neither 'poll' nor 'select' return + * an appropriate error code). When in doubt, set a suitable timeout value. + */ +static unsigned int kernfs_fop_poll(struct file *filp, poll_table *wait) +{ + struct kernfs_open_file *of = kernfs_of(filp); + struct kernfs_node *kn = filp->f_path.dentry->d_fsdata; + struct kernfs_open_node *on = kn->attr.open; + + /* need parent for the kobj, grab both */ + if (!kernfs_get_active(kn)) + goto trigger; + + poll_wait(filp, &on->poll, wait); + + kernfs_put_active(kn); + + if (of->event != atomic_read(&on->event)) + goto trigger; + + return DEFAULT_POLLMASK; + + trigger: + return DEFAULT_POLLMASK|POLLERR|POLLPRI; +} + +/** + * kernfs_notify - notify a kernfs file + * @kn: file to notify + * + * Notify @kn such that poll(2) on @kn wakes up. + */ +void kernfs_notify(struct kernfs_node *kn) +{ + struct kernfs_open_node *on; + unsigned long flags; + + spin_lock_irqsave(&kernfs_open_node_lock, flags); + + if (!WARN_ON(kernfs_type(kn) != KERNFS_FILE)) { + on = kn->attr.open; + if (on) { + atomic_inc(&on->event); + wake_up_interruptible(&on->poll); + } + } + + spin_unlock_irqrestore(&kernfs_open_node_lock, flags); +} +EXPORT_SYMBOL_GPL(kernfs_notify); + +const struct file_operations kernfs_file_fops = { + .read = kernfs_fop_read, + .write = kernfs_fop_write, + .llseek = generic_file_llseek, + .mmap = kernfs_fop_mmap, + .open = kernfs_fop_open, + .release = kernfs_fop_release, + .poll = kernfs_fop_poll, +}; + +/** + * __kernfs_create_file - kernfs internal function to create a file + * @parent: directory to create the file in + * @name: name of the file + * @mode: mode of the file + * @size: size of the file + * @ops: kernfs operations for the file + * @priv: private data for the file + * @ns: optional namespace tag of the file + * @static_name: don't copy file name + * @key: lockdep key for the file's active_ref, %NULL to disable lockdep + * + * Returns the created node on success, ERR_PTR() value on error. + */ +struct kernfs_node *__kernfs_create_file(struct kernfs_node *parent, + const char *name, + umode_t mode, loff_t size, + const struct kernfs_ops *ops, + void *priv, const void *ns, + bool name_is_static, + struct lock_class_key *key) +{ + struct kernfs_addrm_cxt acxt; + struct kernfs_node *kn; + unsigned flags; + int rc; + + flags = KERNFS_FILE; + if (name_is_static) + flags |= KERNFS_STATIC_NAME; + + kn = kernfs_new_node(parent, name, (mode & S_IALLUGO) | S_IFREG, flags); + if (!kn) + return ERR_PTR(-ENOMEM); + + kn->attr.ops = ops; + kn->attr.size = size; + kn->ns = ns; + kn->priv = priv; + +#ifdef CONFIG_DEBUG_LOCK_ALLOC + if (key) { + lockdep_init_map(&kn->dep_map, "s_active", key, 0); + kn->flags |= KERNFS_LOCKDEP; + } +#endif + + /* + * kn->attr.ops is accesible only while holding active ref. We + * need to know whether some ops are implemented outside active + * ref. Cache their existence in flags. + */ + if (ops->seq_show) + kn->flags |= KERNFS_HAS_SEQ_SHOW; + if (ops->mmap) + kn->flags |= KERNFS_HAS_MMAP; + + kernfs_addrm_start(&acxt); + rc = kernfs_add_one(&acxt, kn); + kernfs_addrm_finish(&acxt); + + if (rc) { + kernfs_put(kn); + return ERR_PTR(rc); + } + return kn; +} diff --git a/fs/kernfs/inode.c b/fs/kernfs/inode.c new file mode 100644 index 0000000..e55126f --- /dev/null +++ b/fs/kernfs/inode.c @@ -0,0 +1,377 @@ +/* + * fs/kernfs/inode.c - kernfs inode implementation + * + * Copyright (c) 2001-3 Patrick Mochel + * Copyright (c) 2007 SUSE Linux Products GmbH + * Copyright (c) 2007, 2013 Tejun Heo <tj@kernel.org> + * + * This file is released under the GPLv2. + */ + +#include <linux/pagemap.h> +#include <linux/backing-dev.h> +#include <linux/capability.h> +#include <linux/errno.h> +#include <linux/slab.h> +#include <linux/xattr.h> +#include <linux/security.h> + +#include "kernfs-internal.h" + +static const struct address_space_operations kernfs_aops = { + .readpage = simple_readpage, + .write_begin = simple_write_begin, + .write_end = simple_write_end, +}; + +static struct backing_dev_info kernfs_bdi = { + .name = "kernfs", + .ra_pages = 0, /* No readahead */ + .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK, +}; + +static const struct inode_operations kernfs_iops = { + .permission = kernfs_iop_permission, + .setattr = kernfs_iop_setattr, + .getattr = kernfs_iop_getattr, + .setxattr = kernfs_iop_setxattr, + .removexattr = kernfs_iop_removexattr, + .getxattr = kernfs_iop_getxattr, + .listxattr = kernfs_iop_listxattr, +}; + +void __init kernfs_inode_init(void) +{ + if (bdi_init(&kernfs_bdi)) + panic("failed to init kernfs_bdi"); +} + +static struct kernfs_iattrs *kernfs_iattrs(struct kernfs_node *kn) +{ + struct iattr *iattrs; + + if (kn->iattr) + return kn->iattr; + + kn->iattr = kzalloc(sizeof(struct kernfs_iattrs), GFP_KERNEL); + if (!kn->iattr) + return NULL; + iattrs = &kn->iattr->ia_iattr; + + /* assign default attributes */ + iattrs->ia_mode = kn->mode; + iattrs->ia_uid = GLOBAL_ROOT_UID; + iattrs->ia_gid = GLOBAL_ROOT_GID; + iattrs->ia_atime = iattrs->ia_mtime = iattrs->ia_ctime = CURRENT_TIME; + + simple_xattrs_init(&kn->iattr->xattrs); + + return kn->iattr; +} + +static int __kernfs_setattr(struct kernfs_node *kn, const struct iattr *iattr) +{ + struct kernfs_iattrs *attrs; + struct iattr *iattrs; + unsigned int ia_valid = iattr->ia_valid; + + attrs = kernfs_iattrs(kn); + if (!attrs) + return -ENOMEM; + + iattrs = &attrs->ia_iattr; + + if (ia_valid & ATTR_UID) + iattrs->ia_uid = iattr->ia_uid; + if (ia_valid & ATTR_GID) + iattrs->ia_gid = iattr->ia_gid; + if (ia_valid & ATTR_ATIME) + iattrs->ia_atime = iattr->ia_atime; + if (ia_valid & ATTR_MTIME) + iattrs->ia_mtime = iattr->ia_mtime; + if (ia_valid & ATTR_CTIME) + iattrs->ia_ctime = iattr->ia_ctime; + if (ia_valid & ATTR_MODE) { + umode_t mode = iattr->ia_mode; + iattrs->ia_mode = kn->mode = mode; + } + return 0; +} + +/** + * kernfs_setattr - set iattr on a node + * @kn: target node + * @iattr: iattr to set + * + * Returns 0 on success, -errno on failure. + */ +int kernfs_setattr(struct kernfs_node *kn, const struct iattr *iattr) +{ + int ret; + + mutex_lock(&kernfs_mutex); + ret = __kernfs_setattr(kn, iattr); + mutex_unlock(&kernfs_mutex); + return ret; +} + +int kernfs_iop_setattr(struct dentry *dentry, struct iattr *iattr) +{ + struct inode *inode = dentry->d_inode; + struct kernfs_node *kn = dentry->d_fsdata; + int error; + + if (!kn) + return -EINVAL; + + mutex_lock(&kernfs_mutex); + error = inode_change_ok(inode, iattr); + if (error) + goto out; + + error = __kernfs_setattr(kn, iattr); + if (error) + goto out; + + /* this ignores size changes */ + setattr_copy(inode, iattr); + +out: + mutex_unlock(&kernfs_mutex); + return error; +} + +static int kernfs_node_setsecdata(struct kernfs_node *kn, void **secdata, + u32 *secdata_len) +{ + struct kernfs_iattrs *attrs; + void *old_secdata; + size_t old_secdata_len; + + attrs = kernfs_iattrs(kn); + if (!attrs) + return -ENOMEM; + + old_secdata = attrs->ia_secdata; + old_secdata_len = attrs->ia_secdata_len; + + attrs->ia_secdata = *secdata; + attrs->ia_secdata_len = *secdata_len; + + *secdata = old_secdata; + *secdata_len = old_secdata_len; + return 0; +} + +int kernfs_iop_setxattr(struct dentry *dentry, const char *name, + const void *value, size_t size, int flags) +{ + struct kernfs_node *kn = dentry->d_fsdata; + struct kernfs_iattrs *attrs; + void *secdata; + int error; + u32 secdata_len = 0; + + attrs = kernfs_iattrs(kn); + if (!attrs) + return -ENOMEM; + + if (!strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN)) { + const char *suffix = name + XATTR_SECURITY_PREFIX_LEN; + error = security_inode_setsecurity(dentry->d_inode, suffix, + value, size, flags); + if (error) + return error; + error = security_inode_getsecctx(dentry->d_inode, + &secdata, &secdata_len); + if (error) + return error; + + mutex_lock(&kernfs_mutex); + error = kernfs_node_setsecdata(kn, &secdata, &secdata_len); + mutex_unlock(&kernfs_mutex); + + if (secdata) + security_release_secctx(secdata, secdata_len); + return error; + } else if (!strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN)) { + return simple_xattr_set(&attrs->xattrs, name, value, size, + flags); + } + + return -EINVAL; +} + +int kernfs_iop_removexattr(struct dentry *dentry, const char *name) +{ + struct kernfs_node *kn = dentry->d_fsdata; + struct kernfs_iattrs *attrs; + + attrs = kernfs_iattrs(kn); + if (!attrs) + return -ENOMEM; + + return simple_xattr_remove(&attrs->xattrs, name); +} + +ssize_t kernfs_iop_getxattr(struct dentry *dentry, const char *name, void *buf, + size_t size) +{ + struct kernfs_node *kn = dentry->d_fsdata; + struct kernfs_iattrs *attrs; + + attrs = kernfs_iattrs(kn); + if (!attrs) + return -ENOMEM; + + return simple_xattr_get(&attrs->xattrs, name, buf, size); +} + +ssize_t kernfs_iop_listxattr(struct dentry *dentry, char *buf, size_t size) +{ + struct kernfs_node *kn = dentry->d_fsdata; + struct kernfs_iattrs *attrs; + + attrs = kernfs_iattrs(kn); + if (!attrs) + return -ENOMEM; + + return simple_xattr_list(&attrs->xattrs, buf, size); +} + +static inline void set_default_inode_attr(struct inode *inode, umode_t mode) +{ + inode->i_mode = mode; + inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; +} + +static inline void set_inode_attr(struct inode *inode, struct iattr *iattr) +{ + inode->i_uid = iattr->ia_uid; + inode->i_gid = iattr->ia_gid; + inode->i_atime = iattr->ia_atime; + inode->i_mtime = iattr->ia_mtime; + inode->i_ctime = iattr->ia_ctime; +} + +static void kernfs_refresh_inode(struct kernfs_node *kn, struct inode *inode) +{ + struct kernfs_iattrs *attrs = kn->iattr; + + inode->i_mode = kn->mode; + if (attrs) { + /* + * kernfs_node has non-default attributes get them from + * persistent copy in kernfs_node. + */ + set_inode_attr(inode, &attrs->ia_iattr); + security_inode_notifysecctx(inode, attrs->ia_secdata, + attrs->ia_secdata_len); + } + + if (kernfs_type(kn) == KERNFS_DIR) + set_nlink(inode, kn->dir.subdirs + 2); +} + +int kernfs_iop_getattr(struct vfsmount *mnt, struct dentry *dentry, + struct kstat *stat) +{ + struct kernfs_node *kn = dentry->d_fsdata; + struct inode *inode = dentry->d_inode; + + mutex_lock(&kernfs_mutex); + kernfs_refresh_inode(kn, inode); + mutex_unlock(&kernfs_mutex); + + generic_fillattr(inode, stat); + return 0; +} + +static void kernfs_init_inode(struct kernfs_node *kn, struct inode *inode) +{ + kernfs_get(kn); + inode->i_private = kn; + inode->i_mapping->a_ops = &kernfs_aops; + inode->i_mapping->backing_dev_info = &kernfs_bdi; + inode->i_op = &kernfs_iops; + + set_default_inode_attr(inode, kn->mode); + kernfs_refresh_inode(kn, inode); + + /* initialize inode according to type */ + switch (kernfs_type(kn)) { + case KERNFS_DIR: + inode->i_op = &kernfs_dir_iops; + inode->i_fop = &kernfs_dir_fops; + break; + case KERNFS_FILE: + inode->i_size = kn->attr.size; + inode->i_fop = &kernfs_file_fops; + break; + case KERNFS_LINK: + inode->i_op = &kernfs_symlink_iops; + break; + default: + BUG(); + } + + unlock_new_inode(inode); +} + +/** + * kernfs_get_inode - get inode for kernfs_node + * @sb: super block + * @kn: kernfs_node to allocate inode for + * + * Get inode for @kn. If such inode doesn't exist, a new inode is + * allocated and basics are initialized. New inode is returned + * locked. + * + * LOCKING: + * Kernel thread context (may sleep). + * + * RETURNS: + * Pointer to allocated inode on success, NULL on failure. + */ +struct inode *kernfs_get_inode(struct super_block *sb, struct kernfs_node *kn) +{ + struct inode *inode; + + inode = iget_locked(sb, kn->ino); + if (inode && (inode->i_state & I_NEW)) + kernfs_init_inode(kn, inode); + + return inode; +} + +/* + * The kernfs_node serves as both an inode and a directory entry for + * kernfs. To prevent the kernfs inode numbers from being freed + * prematurely we take a reference to kernfs_node from the kernfs inode. A + * super_operations.evict_inode() implementation is needed to drop that + * reference upon inode destruction. + */ +void kernfs_evict_inode(struct inode *inode) +{ + struct kernfs_node *kn = inode->i_private; + + truncate_inode_pages(&inode->i_data, 0); + clear_inode(inode); + kernfs_put(kn); +} + +int kernfs_iop_permission(struct inode *inode, int mask) +{ + struct kernfs_node *kn; + + if (mask & MAY_NOT_BLOCK) + return -ECHILD; + + kn = inode->i_private; + + mutex_lock(&kernfs_mutex); + kernfs_refresh_inode(kn, inode); + mutex_unlock(&kernfs_mutex); + + return generic_permission(inode, mask); +} diff --git a/fs/kernfs/kernfs-internal.h b/fs/kernfs/kernfs-internal.h new file mode 100644 index 0000000..eb536b7 --- /dev/null +++ b/fs/kernfs/kernfs-internal.h @@ -0,0 +1,122 @@ +/* + * fs/kernfs/kernfs-internal.h - kernfs internal header file + * + * Copyright (c) 2001-3 Patrick Mochel + * Copyright (c) 2007 SUSE Linux Products GmbH + * Copyright (c) 2007, 2013 Tejun Heo <teheo@suse.de> + * + * This file is released under the GPLv2. + */ + +#ifndef __KERNFS_INTERNAL_H +#define __KERNFS_INTERNAL_H + +#include <linux/lockdep.h> +#include <linux/fs.h> +#include <linux/mutex.h> +#include <linux/xattr.h> + +#include <linux/kernfs.h> + +struct kernfs_iattrs { + struct iattr ia_iattr; + void *ia_secdata; + u32 ia_secdata_len; + + struct simple_xattrs xattrs; +}; + +#define KN_DEACTIVATED_BIAS INT_MIN + +/* KERNFS_TYPE_MASK and types are defined in include/linux/kernfs.h */ + +/** + * kernfs_root - find out the kernfs_root a kernfs_node belongs to + * @kn: kernfs_node of interest + * + * Return the kernfs_root @kn belongs to. + */ +static inline struct kernfs_root *kernfs_root(struct kernfs_node *kn) +{ + /* if parent exists, it's always a dir; otherwise, @sd is a dir */ + if (kn->parent) + kn = kn->parent; + return kn->dir.root; +} + +/* + * Context structure to be used while adding/removing nodes. + */ +struct kernfs_addrm_cxt { + struct kernfs_node *removed; +}; + +/* + * mount.c + */ +struct kernfs_super_info { + /* + * The root associated with this super_block. Each super_block is + * identified by the root and ns it's associated with. + */ + struct kernfs_root *root; + + /* + * Each sb is associated with one namespace tag, currently the + * network namespace of the task which mounted this kernfs + * instance. If multiple tags become necessary, make the following + * an array and compare kernfs_node tag against every entry. + */ + const void *ns; +}; +#define kernfs_info(SB) ((struct kernfs_super_info *)(SB->s_fs_info)) + +extern struct kmem_cache *kernfs_node_cache; + +/* + * inode.c + */ +struct inode *kernfs_get_inode(struct super_block *sb, struct kernfs_node *kn); +void kernfs_evict_inode(struct inode *inode); +int kernfs_iop_permission(struct inode *inode, int mask); +int kernfs_iop_setattr(struct dentry *dentry, struct iattr *iattr); +int kernfs_iop_getattr(struct vfsmount *mnt, struct dentry *dentry, + struct kstat *stat); +int kernfs_iop_setxattr(struct dentry *dentry, const char *name, const void *value, + size_t size, int flags); +int kernfs_iop_removexattr(struct dentry *dentry, const char *name); +ssize_t kernfs_iop_getxattr(struct dentry *dentry, const char *name, void *buf, + size_t size); +ssize_t kernfs_iop_listxattr(struct dentry *dentry, char *buf, size_t size); +void kernfs_inode_init(void); + +/* + * dir.c + */ +extern struct mutex kernfs_mutex; +extern const struct dentry_operations kernfs_dops; +extern const struct file_operations kernfs_dir_fops; +extern const struct inode_operations kernfs_dir_iops; + +struct kernfs_node *kernfs_get_active(struct kernfs_node *kn); +void kernfs_put_active(struct kernfs_node *kn); +void kernfs_addrm_start(struct kernfs_addrm_cxt *acxt); +int kernfs_add_one(struct kernfs_addrm_cxt *acxt, struct kernfs_node *kn); +void kernfs_addrm_finish(struct kernfs_addrm_cxt *acxt); +struct kernfs_node *kernfs_new_node(struct kernfs_node *parent, + const char *name, umode_t mode, + unsigned flags); + +/* + * file.c + */ +extern const struct file_operations kernfs_file_fops; + +void kernfs_unmap_bin_file(struct kernfs_node *kn); + +/* + * symlink.c + */ +extern const struct inode_operations kernfs_symlink_iops; + +#endif /* __KERNFS_INTERNAL_H */ diff --git a/fs/kernfs/mount.c b/fs/kernfs/mount.c new file mode 100644 index 0000000..0d6ce89 --- /dev/null +++ b/fs/kernfs/mount.c @@ -0,0 +1,165 @@ +/* + * fs/kernfs/mount.c - kernfs mount implementation + * + * Copyright (c) 2001-3 Patrick Mochel + * Copyright (c) 2007 SUSE Linux Products GmbH + * Copyright (c) 2007, 2013 Tejun Heo <tj@kernel.org> + * + * This file is released under the GPLv2. + */ + +#include <linux/fs.h> +#include <linux/mount.h> +#include <linux/init.h> +#include <linux/magic.h> +#include <linux/slab.h> +#include <linux/pagemap.h> + +#include "kernfs-internal.h" + +struct kmem_cache *kernfs_node_cache; + +static const struct super_operations kernfs_sops = { + .statfs = simple_statfs, + .drop_inode = generic_delete_inode, + .evict_inode = kernfs_evict_inode, +}; + +static int kernfs_fill_super(struct super_block *sb) +{ + struct kernfs_super_info *info = kernfs_info(sb); + struct inode *inode; + struct dentry *root; + + sb->s_blocksize = PAGE_CACHE_SIZE; + sb->s_blocksize_bits = PAGE_CACHE_SHIFT; + sb->s_magic = SYSFS_MAGIC; + sb->s_op = &kernfs_sops; + sb->s_time_gran = 1; + + /* get root inode, initialize and unlock it */ + mutex_lock(&kernfs_mutex); + inode = kernfs_get_inode(sb, info->root->kn); + mutex_unlock(&kernfs_mutex); + if (!inode) { + pr_debug("kernfs: could not get root inode\n"); + return -ENOMEM; + } + + /* instantiate and link root dentry */ + root = d_make_root(inode); + if (!root) { + pr_debug("%s: could not get root dentry!\n", __func__); + return -ENOMEM; + } + kernfs_get(info->root->kn); + root->d_fsdata = info->root->kn; + sb->s_root = root; + sb->s_d_op = &kernfs_dops; + return 0; +} + +static int kernfs_test_super(struct super_block *sb, void *data) +{ + struct kernfs_super_info *sb_info = kernfs_info(sb); + struct kernfs_super_info *info = data; + + return sb_info->root == info->root && sb_info->ns == info->ns; +} + +static int kernfs_set_super(struct super_block *sb, void *data) +{ + int error; + error = set_anon_super(sb, data); + if (!error) + sb->s_fs_info = data; + return error; +} + +/** + * kernfs_super_ns - determine the namespace tag of a kernfs super_block + * @sb: super_block of interest + * + * Return the namespace tag associated with kernfs super_block @sb. + */ +const void *kernfs_super_ns(struct super_block *sb) +{ + struct kernfs_super_info *info = kernfs_info(sb); + + return info->ns; +} + +/** + * kernfs_mount_ns - kernfs mount helper + * @fs_type: file_system_type of the fs being mounted + * @flags: mount flags specified for the mount + * @root: kernfs_root of the hierarchy being mounted + * @ns: optional namespace tag of the mount + * + * This is to be called from each kernfs user's file_system_type->mount() + * implementation, which should pass through the specified @fs_type and + * @flags, and specify the hierarchy and namespace tag to mount via @root + * and @ns, respectively. + * + * The return value can be passed to the vfs layer verbatim. + */ +struct dentry *kernfs_mount_ns(struct file_system_type *fs_type, int flags, + struct kernfs_root *root, const void *ns) +{ + struct super_block *sb; + struct kernfs_super_info *info; + int error; + + info = kzalloc(sizeof(*info), GFP_KERNEL); + if (!info) + return ERR_PTR(-ENOMEM); + + info->root = root; + info->ns = ns; + + sb = sget(fs_type, kernfs_test_super, kernfs_set_super, flags, info); + if (IS_ERR(sb) || sb->s_fs_info != info) + kfree(info); + if (IS_ERR(sb)) + return ERR_CAST(sb); + if (!sb->s_root) { + error = kernfs_fill_super(sb); + if (error) { + deactivate_locked_super(sb); + return ERR_PTR(error); + } + sb->s_flags |= MS_ACTIVE; + } + + return dget(sb->s_root); +} + +/** + * kernfs_kill_sb - kill_sb for kernfs + * @sb: super_block being killed + * + * This can be used directly for file_system_type->kill_sb(). If a kernfs + * user needs extra cleanup, it can implement its own kill_sb() and call + * this function at the end. + */ +void kernfs_kill_sb(struct super_block *sb) +{ + struct kernfs_super_info *info = kernfs_info(sb); + struct kernfs_node *root_kn = sb->s_root->d_fsdata; + + /* + * Remove the superblock from fs_supers/s_instances + * so we can't find it, before freeing kernfs_super_info. + */ + kill_anon_super(sb); + kfree(info); + kernfs_put(root_kn); +} + +void __init kernfs_init(void) +{ + kernfs_node_cache = kmem_cache_create("kernfs_node_cache", + sizeof(struct kernfs_node), + 0, SLAB_PANIC, NULL); + kernfs_inode_init(); +} diff --git a/fs/kernfs/symlink.c b/fs/kernfs/symlink.c new file mode 100644 index 0000000..4d45705 --- /dev/null +++ b/fs/kernfs/symlink.c @@ -0,0 +1,151 @@ +/* + * fs/kernfs/symlink.c - kernfs symlink implementation + * + * Copyright (c) 2001-3 Patrick Mochel + * Copyright (c) 2007 SUSE Linux Products GmbH + * Copyright (c) 2007, 2013 Tejun Heo <tj@kernel.org> + * + * This file is released under the GPLv2. + */ + +#include <linux/fs.h> +#include <linux/gfp.h> +#include <linux/namei.h> + +#include "kernfs-internal.h" + +/** + * kernfs_create_link - create a symlink + * @parent: directory to create the symlink in + * @name: name of the symlink + * @target: target node for the symlink to point to + * + * Returns the created node on success, ERR_PTR() value on error. + */ +struct kernfs_node *kernfs_create_link(struct kernfs_node *parent, + const char *name, + struct kernfs_node *target) +{ + struct kernfs_node *kn; + struct kernfs_addrm_cxt acxt; + int error; + + kn = kernfs_new_node(parent, name, S_IFLNK|S_IRWXUGO, KERNFS_LINK); + if (!kn) + return ERR_PTR(-ENOMEM); + + if (kernfs_ns_enabled(parent)) + kn->ns = target->ns; + kn->symlink.target_kn = target; + kernfs_get(target); /* ref owned by symlink */ + + kernfs_addrm_start(&acxt); + error = kernfs_add_one(&acxt, kn); + kernfs_addrm_finish(&acxt); + + if (!error) + return kn; + + kernfs_put(kn); + return ERR_PTR(error); +} + +static int kernfs_get_target_path(struct kernfs_node *parent, + struct kernfs_node *target, char *path) +{ + struct kernfs_node *base, *kn; + char *s = path; + int len = 0; + + /* go up to the root, stop at the base */ + base = parent; + while (base->parent) { + kn = target->parent; + while (kn->parent && base != kn) + kn = kn->parent; + + if (base == kn) + break; + + strcpy(s, "../"); + s += 3; + base = base->parent; + } + + /* determine end of target string for reverse fillup */ + kn = target; + while (kn->parent && kn != base) { + len += strlen(kn->name) + 1; + kn = kn->parent; + } + + /* check limits */ + if (len < 2) + return -EINVAL; + len--; + if ((s - path) + len > PATH_MAX) + return -ENAMETOOLONG; + + /* reverse fillup of target string from target to base */ + kn = target; + while (kn->parent && kn != base) { + int slen = strlen(kn->name); + + len -= slen; + strncpy(s + len, kn->name, slen); + if (len) + s[--len] = '/'; + + kn = kn->parent; + } + + return 0; +} + +static int kernfs_getlink(struct dentry *dentry, char *path) +{ + struct kernfs_node *kn = dentry->d_fsdata; + struct kernfs_node *parent = kn->parent; + struct kernfs_node *target = kn->symlink.target_kn; + int error; + + mutex_lock(&kernfs_mutex); + error = kernfs_get_target_path(parent, target, path); + mutex_unlock(&kernfs_mutex); + + return error; +} + +static void *kernfs_iop_follow_link(struct dentry *dentry, struct nameidata *nd) +{ + int error = -ENOMEM; + unsigned long page = get_zeroed_page(GFP_KERNEL); + if (page) { + error = kernfs_getlink(dentry, (char *) page); + if (error < 0) + free_page((unsigned long)page); + } + nd_set_link(nd, error ? ERR_PTR(error) : (char *)page); + return NULL; +} + +static void kernfs_iop_put_link(struct dentry *dentry, struct nameidata *nd, + void *cookie) +{ + char *page = nd_get_link(nd); + if (!IS_ERR(page)) + free_page((unsigned long)page); +} + +const struct inode_operations kernfs_symlink_iops = { + .setxattr = kernfs_iop_setxattr, + .removexattr = kernfs_iop_removexattr, + .getxattr = kernfs_iop_getxattr, + .listxattr = kernfs_iop_listxattr, + .readlink = generic_readlink, + .follow_link = kernfs_iop_follow_link, + .put_link = kernfs_iop_put_link, + .setattr = kernfs_iop_setattr, + .getattr = kernfs_iop_getattr, + .permission = kernfs_iop_permission, +}; |
