From ace9429bb58fd418f0c81d4c2835699bddf6bde6 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Thu, 11 Apr 2024 10:27:49 +0200 Subject: Adding upstream version 6.6.15. Signed-off-by: Daniel Baumann --- fs/kernfs/mount.c | 434 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 434 insertions(+) create mode 100644 fs/kernfs/mount.c (limited to 'fs/kernfs/mount.c') diff --git a/fs/kernfs/mount.c b/fs/kernfs/mount.c new file mode 100644 index 0000000000..c4bf26142e --- /dev/null +++ b/fs/kernfs/mount.c @@ -0,0 +1,434 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * 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 + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include "kernfs-internal.h" + +struct kmem_cache *kernfs_node_cache, *kernfs_iattrs_cache; +struct kernfs_global_locks *kernfs_locks; + +static int kernfs_sop_show_options(struct seq_file *sf, struct dentry *dentry) +{ + struct kernfs_root *root = kernfs_root(kernfs_dentry_node(dentry)); + struct kernfs_syscall_ops *scops = root->syscall_ops; + + if (scops && scops->show_options) + return scops->show_options(sf, root); + return 0; +} + +static int kernfs_sop_show_path(struct seq_file *sf, struct dentry *dentry) +{ + struct kernfs_node *node = kernfs_dentry_node(dentry); + struct kernfs_root *root = kernfs_root(node); + struct kernfs_syscall_ops *scops = root->syscall_ops; + + if (scops && scops->show_path) + return scops->show_path(sf, node, root); + + seq_dentry(sf, dentry, " \t\n\\"); + return 0; +} + +static int kernfs_statfs(struct dentry *dentry, struct kstatfs *buf) +{ + simple_statfs(dentry, buf); + buf->f_fsid = uuid_to_fsid(dentry->d_sb->s_uuid.b); + return 0; +} + +const struct super_operations kernfs_sops = { + .statfs = kernfs_statfs, + .drop_inode = generic_delete_inode, + .evict_inode = kernfs_evict_inode, + + .show_options = kernfs_sop_show_options, + .show_path = kernfs_sop_show_path, +}; + +static int kernfs_encode_fh(struct inode *inode, __u32 *fh, int *max_len, + struct inode *parent) +{ + struct kernfs_node *kn = inode->i_private; + + if (*max_len < 2) { + *max_len = 2; + return FILEID_INVALID; + } + + *max_len = 2; + *(u64 *)fh = kn->id; + return FILEID_KERNFS; +} + +static struct dentry *__kernfs_fh_to_dentry(struct super_block *sb, + struct fid *fid, int fh_len, + int fh_type, bool get_parent) +{ + struct kernfs_super_info *info = kernfs_info(sb); + struct kernfs_node *kn; + struct inode *inode; + u64 id; + + if (fh_len < 2) + return NULL; + + switch (fh_type) { + case FILEID_KERNFS: + id = *(u64 *)fid; + break; + case FILEID_INO32_GEN: + case FILEID_INO32_GEN_PARENT: + /* + * blk_log_action() exposes "LOW32,HIGH32" pair without + * type and userland can call us with generic fid + * constructed from them. Combine it back to ID. See + * blk_log_action(). + */ + id = ((u64)fid->i32.gen << 32) | fid->i32.ino; + break; + default: + return NULL; + } + + kn = kernfs_find_and_get_node_by_id(info->root, id); + if (!kn) + return ERR_PTR(-ESTALE); + + if (get_parent) { + struct kernfs_node *parent; + + parent = kernfs_get_parent(kn); + kernfs_put(kn); + kn = parent; + if (!kn) + return ERR_PTR(-ESTALE); + } + + inode = kernfs_get_inode(sb, kn); + kernfs_put(kn); + if (!inode) + return ERR_PTR(-ESTALE); + + return d_obtain_alias(inode); +} + +static struct dentry *kernfs_fh_to_dentry(struct super_block *sb, + struct fid *fid, int fh_len, + int fh_type) +{ + return __kernfs_fh_to_dentry(sb, fid, fh_len, fh_type, false); +} + +static struct dentry *kernfs_fh_to_parent(struct super_block *sb, + struct fid *fid, int fh_len, + int fh_type) +{ + return __kernfs_fh_to_dentry(sb, fid, fh_len, fh_type, true); +} + +static struct dentry *kernfs_get_parent_dentry(struct dentry *child) +{ + struct kernfs_node *kn = kernfs_dentry_node(child); + + return d_obtain_alias(kernfs_get_inode(child->d_sb, kn->parent)); +} + +static const struct export_operations kernfs_export_ops = { + .encode_fh = kernfs_encode_fh, + .fh_to_dentry = kernfs_fh_to_dentry, + .fh_to_parent = kernfs_fh_to_parent, + .get_parent = kernfs_get_parent_dentry, +}; + +/** + * kernfs_root_from_sb - determine kernfs_root associated with a super_block + * @sb: the super_block in question + * + * Return: the kernfs_root associated with @sb. If @sb is not a kernfs one, + * %NULL is returned. + */ +struct kernfs_root *kernfs_root_from_sb(struct super_block *sb) +{ + if (sb->s_op == &kernfs_sops) + return kernfs_info(sb)->root; + return NULL; +} + +/* + * find the next ancestor in the path down to @child, where @parent was the + * ancestor whose descendant we want to find. + * + * Say the path is /a/b/c/d. @child is d, @parent is %NULL. We return the root + * node. If @parent is b, then we return the node for c. + * Passing in d as @parent is not ok. + */ +static struct kernfs_node *find_next_ancestor(struct kernfs_node *child, + struct kernfs_node *parent) +{ + if (child == parent) { + pr_crit_once("BUG in find_next_ancestor: called with parent == child"); + return NULL; + } + + while (child->parent != parent) { + if (!child->parent) + return NULL; + child = child->parent; + } + + return child; +} + +/** + * kernfs_node_dentry - get a dentry for the given kernfs_node + * @kn: kernfs_node for which a dentry is needed + * @sb: the kernfs super_block + * + * Return: the dentry pointer + */ +struct dentry *kernfs_node_dentry(struct kernfs_node *kn, + struct super_block *sb) +{ + struct dentry *dentry; + struct kernfs_node *knparent = NULL; + + BUG_ON(sb->s_op != &kernfs_sops); + + dentry = dget(sb->s_root); + + /* Check if this is the root kernfs_node */ + if (!kn->parent) + return dentry; + + knparent = find_next_ancestor(kn, NULL); + if (WARN_ON(!knparent)) { + dput(dentry); + return ERR_PTR(-EINVAL); + } + + do { + struct dentry *dtmp; + struct kernfs_node *kntmp; + + if (kn == knparent) + return dentry; + kntmp = find_next_ancestor(kn, knparent); + if (WARN_ON(!kntmp)) { + dput(dentry); + return ERR_PTR(-EINVAL); + } + dtmp = lookup_positive_unlocked(kntmp->name, dentry, + strlen(kntmp->name)); + dput(dentry); + if (IS_ERR(dtmp)) + return dtmp; + knparent = kntmp; + dentry = dtmp; + } while (true); +} + +static int kernfs_fill_super(struct super_block *sb, struct kernfs_fs_context *kfc) +{ + struct kernfs_super_info *info = kernfs_info(sb); + struct kernfs_root *kf_root = kfc->root; + struct inode *inode; + struct dentry *root; + + info->sb = sb; + /* Userspace would break if executables or devices appear on sysfs */ + sb->s_iflags |= SB_I_NOEXEC | SB_I_NODEV; + sb->s_blocksize = PAGE_SIZE; + sb->s_blocksize_bits = PAGE_SHIFT; + sb->s_magic = kfc->magic; + sb->s_op = &kernfs_sops; + sb->s_xattr = kernfs_xattr_handlers; + if (info->root->flags & KERNFS_ROOT_SUPPORT_EXPORTOP) + sb->s_export_op = &kernfs_export_ops; + sb->s_time_gran = 1; + + /* sysfs dentries and inodes don't require IO to create */ + sb->s_shrink.seeks = 0; + + /* get root inode, initialize and unlock it */ + down_read(&kf_root->kernfs_rwsem); + inode = kernfs_get_inode(sb, info->root->kn); + up_read(&kf_root->kernfs_rwsem); + 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; + } + sb->s_root = root; + sb->s_d_op = &kernfs_dops; + return 0; +} + +static int kernfs_test_super(struct super_block *sb, struct fs_context *fc) +{ + struct kernfs_super_info *sb_info = kernfs_info(sb); + struct kernfs_super_info *info = fc->s_fs_info; + + return sb_info->root == info->root && sb_info->ns == info->ns; +} + +static int kernfs_set_super(struct super_block *sb, struct fs_context *fc) +{ + struct kernfs_fs_context *kfc = fc->fs_private; + + kfc->ns_tag = NULL; + return set_anon_super_fc(sb, fc); +} + +/** + * 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_get_tree - kernfs filesystem access/retrieval helper + * @fc: The filesystem context. + * + * This is to be called from each kernfs user's fs_context->ops->get_tree() + * implementation, which should set the specified ->@fs_type and ->@flags, and + * specify the hierarchy and namespace tag to mount via ->@root and ->@ns, + * respectively. + * + * Return: %0 on success, -errno on failure. + */ +int kernfs_get_tree(struct fs_context *fc) +{ + struct kernfs_fs_context *kfc = fc->fs_private; + struct super_block *sb; + struct kernfs_super_info *info; + int error; + + info = kzalloc(sizeof(*info), GFP_KERNEL); + if (!info) + return -ENOMEM; + + info->root = kfc->root; + info->ns = kfc->ns_tag; + INIT_LIST_HEAD(&info->node); + + fc->s_fs_info = info; + sb = sget_fc(fc, kernfs_test_super, kernfs_set_super); + if (IS_ERR(sb)) + return PTR_ERR(sb); + + if (!sb->s_root) { + struct kernfs_super_info *info = kernfs_info(sb); + struct kernfs_root *root = kfc->root; + + kfc->new_sb_created = true; + + error = kernfs_fill_super(sb, kfc); + if (error) { + deactivate_locked_super(sb); + return error; + } + sb->s_flags |= SB_ACTIVE; + + uuid_gen(&sb->s_uuid); + + down_write(&root->kernfs_supers_rwsem); + list_add(&info->node, &info->root->supers); + up_write(&root->kernfs_supers_rwsem); + } + + fc->root = dget(sb->s_root); + return 0; +} + +void kernfs_free_fs_context(struct fs_context *fc) +{ + /* Note that we don't deal with kfc->ns_tag here. */ + kfree(fc->s_fs_info); + fc->s_fs_info = NULL; +} + +/** + * 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_root *root = info->root; + + down_write(&root->kernfs_supers_rwsem); + list_del(&info->node); + up_write(&root->kernfs_supers_rwsem); + + /* + * 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); +} + +static void __init kernfs_mutex_init(void) +{ + int count; + + for (count = 0; count < NR_KERNFS_LOCKS; count++) + mutex_init(&kernfs_locks->open_file_mutex[count]); +} + +static void __init kernfs_lock_init(void) +{ + kernfs_locks = kmalloc(sizeof(struct kernfs_global_locks), GFP_KERNEL); + WARN_ON(!kernfs_locks); + + kernfs_mutex_init(); +} + +void __init kernfs_init(void) +{ + kernfs_node_cache = kmem_cache_create("kernfs_node_cache", + sizeof(struct kernfs_node), + 0, SLAB_PANIC, NULL); + + /* Creates slab cache for kernfs inode attributes */ + kernfs_iattrs_cache = kmem_cache_create("kernfs_iattrs_cache", + sizeof(struct kernfs_iattrs), + 0, SLAB_PANIC, NULL); + + kernfs_lock_init(); +} -- cgit v1.2.3