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- // SPDX-License-Identifier: GPL-2.0-only
- /*
- * fs/libfs.c
- * Library for filesystems writers.
- */
- #include <linux/blkdev.h>
- #include <linux/export.h>
- #include <linux/pagemap.h>
- #include <linux/slab.h>
- #include <linux/cred.h>
- #include <linux/mount.h>
- #include <linux/vfs.h>
- #include <linux/quotaops.h>
- #include <linux/mutex.h>
- #include <linux/namei.h>
- #include <linux/exportfs.h>
- #include <linux/writeback.h>
- #include <linux/buffer_head.h> /* sync_mapping_buffers */
- #include <linux/fs_context.h>
- #include <linux/pseudo_fs.h>
- #include <linux/fsnotify.h>
- #include <linux/unicode.h>
- #include <linux/fscrypt.h>
- #include <linux/uaccess.h>
- #include "internal.h"
- int simple_getattr(const struct path *path, struct kstat *stat,
- u32 request_mask, unsigned int query_flags)
- {
- struct inode *inode = d_inode(path->dentry);
- generic_fillattr(inode, stat);
- stat->blocks = inode->i_mapping->nrpages << (PAGE_SHIFT - 9);
- return 0;
- }
- EXPORT_SYMBOL(simple_getattr);
- int simple_statfs(struct dentry *dentry, struct kstatfs *buf)
- {
- buf->f_type = dentry->d_sb->s_magic;
- buf->f_bsize = PAGE_SIZE;
- buf->f_namelen = NAME_MAX;
- return 0;
- }
- EXPORT_SYMBOL(simple_statfs);
- /*
- * Retaining negative dentries for an in-memory filesystem just wastes
- * memory and lookup time: arrange for them to be deleted immediately.
- */
- int always_delete_dentry(const struct dentry *dentry)
- {
- return 1;
- }
- EXPORT_SYMBOL(always_delete_dentry);
- const struct dentry_operations simple_dentry_operations = {
- .d_delete = always_delete_dentry,
- };
- EXPORT_SYMBOL(simple_dentry_operations);
- /*
- * Lookup the data. This is trivial - if the dentry didn't already
- * exist, we know it is negative. Set d_op to delete negative dentries.
- */
- struct dentry *simple_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
- {
- if (dentry->d_name.len > NAME_MAX)
- return ERR_PTR(-ENAMETOOLONG);
- if (!dentry->d_sb->s_d_op)
- d_set_d_op(dentry, &simple_dentry_operations);
- d_add(dentry, NULL);
- return NULL;
- }
- EXPORT_SYMBOL(simple_lookup);
- int dcache_dir_open(struct inode *inode, struct file *file)
- {
- file->private_data = d_alloc_cursor(file->f_path.dentry);
- return file->private_data ? 0 : -ENOMEM;
- }
- EXPORT_SYMBOL(dcache_dir_open);
- int dcache_dir_close(struct inode *inode, struct file *file)
- {
- dput(file->private_data);
- return 0;
- }
- EXPORT_SYMBOL(dcache_dir_close);
- /* parent is locked at least shared */
- /*
- * Returns an element of siblings' list.
- * We are looking for <count>th positive after <p>; if
- * found, dentry is grabbed and returned to caller.
- * If no such element exists, NULL is returned.
- */
- static struct dentry *scan_positives(struct dentry *cursor,
- struct list_head *p,
- loff_t count,
- struct dentry *last)
- {
- struct dentry *dentry = cursor->d_parent, *found = NULL;
- spin_lock(&dentry->d_lock);
- while ((p = p->next) != &dentry->d_subdirs) {
- struct dentry *d = list_entry(p, struct dentry, d_child);
- // we must at least skip cursors, to avoid livelocks
- if (d->d_flags & DCACHE_DENTRY_CURSOR)
- continue;
- if (simple_positive(d) && !--count) {
- spin_lock_nested(&d->d_lock, DENTRY_D_LOCK_NESTED);
- if (simple_positive(d))
- found = dget_dlock(d);
- spin_unlock(&d->d_lock);
- if (likely(found))
- break;
- count = 1;
- }
- if (need_resched()) {
- list_move(&cursor->d_child, p);
- p = &cursor->d_child;
- spin_unlock(&dentry->d_lock);
- cond_resched();
- spin_lock(&dentry->d_lock);
- }
- }
- spin_unlock(&dentry->d_lock);
- dput(last);
- return found;
- }
- loff_t dcache_dir_lseek(struct file *file, loff_t offset, int whence)
- {
- struct dentry *dentry = file->f_path.dentry;
- switch (whence) {
- case 1:
- offset += file->f_pos;
- fallthrough;
- case 0:
- if (offset >= 0)
- break;
- fallthrough;
- default:
- return -EINVAL;
- }
- if (offset != file->f_pos) {
- struct dentry *cursor = file->private_data;
- struct dentry *to = NULL;
- inode_lock_shared(dentry->d_inode);
- if (offset > 2)
- to = scan_positives(cursor, &dentry->d_subdirs,
- offset - 2, NULL);
- spin_lock(&dentry->d_lock);
- if (to)
- list_move(&cursor->d_child, &to->d_child);
- else
- list_del_init(&cursor->d_child);
- spin_unlock(&dentry->d_lock);
- dput(to);
- file->f_pos = offset;
- inode_unlock_shared(dentry->d_inode);
- }
- return offset;
- }
- EXPORT_SYMBOL(dcache_dir_lseek);
- /* Relationship between i_mode and the DT_xxx types */
- static inline unsigned char dt_type(struct inode *inode)
- {
- return (inode->i_mode >> 12) & 15;
- }
- /*
- * Directory is locked and all positive dentries in it are safe, since
- * for ramfs-type trees they can't go away without unlink() or rmdir(),
- * both impossible due to the lock on directory.
- */
- int dcache_readdir(struct file *file, struct dir_context *ctx)
- {
- struct dentry *dentry = file->f_path.dentry;
- struct dentry *cursor = file->private_data;
- struct list_head *anchor = &dentry->d_subdirs;
- struct dentry *next = NULL;
- struct list_head *p;
- if (!dir_emit_dots(file, ctx))
- return 0;
- if (ctx->pos == 2)
- p = anchor;
- else if (!list_empty(&cursor->d_child))
- p = &cursor->d_child;
- else
- return 0;
- while ((next = scan_positives(cursor, p, 1, next)) != NULL) {
- if (!dir_emit(ctx, next->d_name.name, next->d_name.len,
- d_inode(next)->i_ino, dt_type(d_inode(next))))
- break;
- ctx->pos++;
- p = &next->d_child;
- }
- spin_lock(&dentry->d_lock);
- if (next)
- list_move_tail(&cursor->d_child, &next->d_child);
- else
- list_del_init(&cursor->d_child);
- spin_unlock(&dentry->d_lock);
- dput(next);
- return 0;
- }
- EXPORT_SYMBOL(dcache_readdir);
- ssize_t generic_read_dir(struct file *filp, char __user *buf, size_t siz, loff_t *ppos)
- {
- return -EISDIR;
- }
- EXPORT_SYMBOL_NS(generic_read_dir, ANDROID_GKI_VFS_EXPORT_ONLY);
- const struct file_operations simple_dir_operations = {
- .open = dcache_dir_open,
- .release = dcache_dir_close,
- .llseek = dcache_dir_lseek,
- .read = generic_read_dir,
- .iterate_shared = dcache_readdir,
- .fsync = noop_fsync,
- };
- EXPORT_SYMBOL(simple_dir_operations);
- const struct inode_operations simple_dir_inode_operations = {
- .lookup = simple_lookup,
- };
- EXPORT_SYMBOL(simple_dir_inode_operations);
- static struct dentry *find_next_child(struct dentry *parent, struct dentry *prev)
- {
- struct dentry *child = NULL;
- struct list_head *p = prev ? &prev->d_child : &parent->d_subdirs;
- spin_lock(&parent->d_lock);
- while ((p = p->next) != &parent->d_subdirs) {
- struct dentry *d = container_of(p, struct dentry, d_child);
- if (simple_positive(d)) {
- spin_lock_nested(&d->d_lock, DENTRY_D_LOCK_NESTED);
- if (simple_positive(d))
- child = dget_dlock(d);
- spin_unlock(&d->d_lock);
- if (likely(child))
- break;
- }
- }
- spin_unlock(&parent->d_lock);
- dput(prev);
- return child;
- }
- void simple_recursive_removal(struct dentry *dentry,
- void (*callback)(struct dentry *))
- {
- struct dentry *this = dget(dentry);
- while (true) {
- struct dentry *victim = NULL, *child;
- struct inode *inode = this->d_inode;
- inode_lock(inode);
- if (d_is_dir(this))
- inode->i_flags |= S_DEAD;
- while ((child = find_next_child(this, victim)) == NULL) {
- // kill and ascend
- // update metadata while it's still locked
- inode->i_ctime = current_time(inode);
- clear_nlink(inode);
- inode_unlock(inode);
- victim = this;
- this = this->d_parent;
- inode = this->d_inode;
- inode_lock(inode);
- if (simple_positive(victim)) {
- d_invalidate(victim); // avoid lost mounts
- if (d_is_dir(victim))
- fsnotify_rmdir(inode, victim);
- else
- fsnotify_unlink(inode, victim);
- if (callback)
- callback(victim);
- dput(victim); // unpin it
- }
- if (victim == dentry) {
- inode->i_ctime = inode->i_mtime =
- current_time(inode);
- if (d_is_dir(dentry))
- drop_nlink(inode);
- inode_unlock(inode);
- dput(dentry);
- return;
- }
- }
- inode_unlock(inode);
- this = child;
- }
- }
- EXPORT_SYMBOL(simple_recursive_removal);
- static const struct super_operations simple_super_operations = {
- .statfs = simple_statfs,
- };
- static int pseudo_fs_fill_super(struct super_block *s, struct fs_context *fc)
- {
- struct pseudo_fs_context *ctx = fc->fs_private;
- struct inode *root;
- s->s_maxbytes = MAX_LFS_FILESIZE;
- s->s_blocksize = PAGE_SIZE;
- s->s_blocksize_bits = PAGE_SHIFT;
- s->s_magic = ctx->magic;
- s->s_op = ctx->ops ?: &simple_super_operations;
- s->s_xattr = ctx->xattr;
- s->s_time_gran = 1;
- root = new_inode(s);
- if (!root)
- return -ENOMEM;
- /*
- * since this is the first inode, make it number 1. New inodes created
- * after this must take care not to collide with it (by passing
- * max_reserved of 1 to iunique).
- */
- root->i_ino = 1;
- root->i_mode = S_IFDIR | S_IRUSR | S_IWUSR;
- root->i_atime = root->i_mtime = root->i_ctime = current_time(root);
- s->s_root = d_make_root(root);
- if (!s->s_root)
- return -ENOMEM;
- s->s_d_op = ctx->dops;
- return 0;
- }
- static int pseudo_fs_get_tree(struct fs_context *fc)
- {
- return get_tree_nodev(fc, pseudo_fs_fill_super);
- }
- static void pseudo_fs_free(struct fs_context *fc)
- {
- kfree(fc->fs_private);
- }
- static const struct fs_context_operations pseudo_fs_context_ops = {
- .free = pseudo_fs_free,
- .get_tree = pseudo_fs_get_tree,
- };
- /*
- * Common helper for pseudo-filesystems (sockfs, pipefs, bdev - stuff that
- * will never be mountable)
- */
- struct pseudo_fs_context *init_pseudo(struct fs_context *fc,
- unsigned long magic)
- {
- struct pseudo_fs_context *ctx;
- ctx = kzalloc(sizeof(struct pseudo_fs_context), GFP_KERNEL);
- if (likely(ctx)) {
- ctx->magic = magic;
- fc->fs_private = ctx;
- fc->ops = &pseudo_fs_context_ops;
- fc->sb_flags |= SB_NOUSER;
- fc->global = true;
- }
- return ctx;
- }
- EXPORT_SYMBOL(init_pseudo);
- int simple_open(struct inode *inode, struct file *file)
- {
- if (inode->i_private)
- file->private_data = inode->i_private;
- return 0;
- }
- EXPORT_SYMBOL(simple_open);
- int simple_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
- {
- struct inode *inode = d_inode(old_dentry);
- inode->i_ctime = dir->i_ctime = dir->i_mtime = current_time(inode);
- inc_nlink(inode);
- ihold(inode);
- dget(dentry);
- d_instantiate(dentry, inode);
- return 0;
- }
- EXPORT_SYMBOL(simple_link);
- int simple_empty(struct dentry *dentry)
- {
- struct dentry *child;
- int ret = 0;
- spin_lock(&dentry->d_lock);
- list_for_each_entry(child, &dentry->d_subdirs, d_child) {
- spin_lock_nested(&child->d_lock, DENTRY_D_LOCK_NESTED);
- if (simple_positive(child)) {
- spin_unlock(&child->d_lock);
- goto out;
- }
- spin_unlock(&child->d_lock);
- }
- ret = 1;
- out:
- spin_unlock(&dentry->d_lock);
- return ret;
- }
- EXPORT_SYMBOL(simple_empty);
- int simple_unlink(struct inode *dir, struct dentry *dentry)
- {
- struct inode *inode = d_inode(dentry);
- inode->i_ctime = dir->i_ctime = dir->i_mtime = current_time(inode);
- drop_nlink(inode);
- dput(dentry);
- return 0;
- }
- EXPORT_SYMBOL(simple_unlink);
- int simple_rmdir(struct inode *dir, struct dentry *dentry)
- {
- if (!simple_empty(dentry))
- return -ENOTEMPTY;
- drop_nlink(d_inode(dentry));
- simple_unlink(dir, dentry);
- drop_nlink(dir);
- return 0;
- }
- EXPORT_SYMBOL(simple_rmdir);
- int simple_rename(struct inode *old_dir, struct dentry *old_dentry,
- struct inode *new_dir, struct dentry *new_dentry,
- unsigned int flags)
- {
- struct inode *inode = d_inode(old_dentry);
- int they_are_dirs = d_is_dir(old_dentry);
- if (flags & ~RENAME_NOREPLACE)
- return -EINVAL;
- if (!simple_empty(new_dentry))
- return -ENOTEMPTY;
- if (d_really_is_positive(new_dentry)) {
- simple_unlink(new_dir, new_dentry);
- if (they_are_dirs) {
- drop_nlink(d_inode(new_dentry));
- drop_nlink(old_dir);
- }
- } else if (they_are_dirs) {
- drop_nlink(old_dir);
- inc_nlink(new_dir);
- }
- old_dir->i_ctime = old_dir->i_mtime = new_dir->i_ctime =
- new_dir->i_mtime = inode->i_ctime = current_time(old_dir);
- return 0;
- }
- EXPORT_SYMBOL(simple_rename);
- /**
- * simple_setattr - setattr for simple filesystem
- * @dentry: dentry
- * @iattr: iattr structure
- *
- * Returns 0 on success, -error on failure.
- *
- * simple_setattr is a simple ->setattr implementation without a proper
- * implementation of size changes.
- *
- * It can either be used for in-memory filesystems or special files
- * on simple regular filesystems. Anything that needs to change on-disk
- * or wire state on size changes needs its own setattr method.
- */
- int simple_setattr(struct dentry *dentry, struct iattr *iattr)
- {
- struct inode *inode = d_inode(dentry);
- int error;
- error = setattr_prepare(dentry, iattr);
- if (error)
- return error;
- if (iattr->ia_valid & ATTR_SIZE)
- truncate_setsize(inode, iattr->ia_size);
- setattr_copy(inode, iattr);
- mark_inode_dirty(inode);
- return 0;
- }
- EXPORT_SYMBOL(simple_setattr);
- int simple_readpage(struct file *file, struct page *page)
- {
- clear_highpage(page);
- flush_dcache_page(page);
- SetPageUptodate(page);
- unlock_page(page);
- return 0;
- }
- EXPORT_SYMBOL(simple_readpage);
- int simple_write_begin(struct file *file, struct address_space *mapping,
- loff_t pos, unsigned len, unsigned flags,
- struct page **pagep, void **fsdata)
- {
- struct page *page;
- pgoff_t index;
- index = pos >> PAGE_SHIFT;
- page = grab_cache_page_write_begin(mapping, index, flags);
- if (!page)
- return -ENOMEM;
- *pagep = page;
- if (!PageUptodate(page) && (len != PAGE_SIZE)) {
- unsigned from = pos & (PAGE_SIZE - 1);
- zero_user_segments(page, 0, from, from + len, PAGE_SIZE);
- }
- return 0;
- }
- EXPORT_SYMBOL(simple_write_begin);
- /**
- * simple_write_end - .write_end helper for non-block-device FSes
- * @file: See .write_end of address_space_operations
- * @mapping: "
- * @pos: "
- * @len: "
- * @copied: "
- * @page: "
- * @fsdata: "
- *
- * simple_write_end does the minimum needed for updating a page after writing is
- * done. It has the same API signature as the .write_end of
- * address_space_operations vector. So it can just be set onto .write_end for
- * FSes that don't need any other processing. i_mutex is assumed to be held.
- * Block based filesystems should use generic_write_end().
- * NOTE: Even though i_size might get updated by this function, mark_inode_dirty
- * is not called, so a filesystem that actually does store data in .write_inode
- * should extend on what's done here with a call to mark_inode_dirty() in the
- * case that i_size has changed.
- *
- * Use *ONLY* with simple_readpage()
- */
- int simple_write_end(struct file *file, struct address_space *mapping,
- loff_t pos, unsigned len, unsigned copied,
- struct page *page, void *fsdata)
- {
- struct inode *inode = page->mapping->host;
- loff_t last_pos = pos + copied;
- /* zero the stale part of the page if we did a short copy */
- if (!PageUptodate(page)) {
- if (copied < len) {
- unsigned from = pos & (PAGE_SIZE - 1);
- zero_user(page, from + copied, len - copied);
- }
- SetPageUptodate(page);
- }
- /*
- * No need to use i_size_read() here, the i_size
- * cannot change under us because we hold the i_mutex.
- */
- if (last_pos > inode->i_size)
- i_size_write(inode, last_pos);
- set_page_dirty(page);
- unlock_page(page);
- put_page(page);
- return copied;
- }
- EXPORT_SYMBOL(simple_write_end);
- /*
- * the inodes created here are not hashed. If you use iunique to generate
- * unique inode values later for this filesystem, then you must take care
- * to pass it an appropriate max_reserved value to avoid collisions.
- */
- int simple_fill_super(struct super_block *s, unsigned long magic,
- const struct tree_descr *files)
- {
- struct inode *inode;
- struct dentry *root;
- struct dentry *dentry;
- int i;
- s->s_blocksize = PAGE_SIZE;
- s->s_blocksize_bits = PAGE_SHIFT;
- s->s_magic = magic;
- s->s_op = &simple_super_operations;
- s->s_time_gran = 1;
- inode = new_inode(s);
- if (!inode)
- return -ENOMEM;
- /*
- * because the root inode is 1, the files array must not contain an
- * entry at index 1
- */
- inode->i_ino = 1;
- inode->i_mode = S_IFDIR | 0755;
- inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
- inode->i_op = &simple_dir_inode_operations;
- inode->i_fop = &simple_dir_operations;
- set_nlink(inode, 2);
- root = d_make_root(inode);
- if (!root)
- return -ENOMEM;
- for (i = 0; !files->name || files->name[0]; i++, files++) {
- if (!files->name)
- continue;
- /* warn if it tries to conflict with the root inode */
- if (unlikely(i == 1))
- printk(KERN_WARNING "%s: %s passed in a files array"
- "with an index of 1!\n", __func__,
- s->s_type->name);
- dentry = d_alloc_name(root, files->name);
- if (!dentry)
- goto out;
- inode = new_inode(s);
- if (!inode) {
- dput(dentry);
- goto out;
- }
- inode->i_mode = S_IFREG | files->mode;
- inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
- inode->i_fop = files->ops;
- inode->i_ino = i;
- d_add(dentry, inode);
- }
- s->s_root = root;
- return 0;
- out:
- d_genocide(root);
- shrink_dcache_parent(root);
- dput(root);
- return -ENOMEM;
- }
- EXPORT_SYMBOL(simple_fill_super);
- static DEFINE_SPINLOCK(pin_fs_lock);
- int simple_pin_fs(struct file_system_type *type, struct vfsmount **mount, int *count)
- {
- struct vfsmount *mnt = NULL;
- spin_lock(&pin_fs_lock);
- if (unlikely(!*mount)) {
- spin_unlock(&pin_fs_lock);
- mnt = vfs_kern_mount(type, SB_KERNMOUNT, type->name, NULL);
- if (IS_ERR(mnt))
- return PTR_ERR(mnt);
- spin_lock(&pin_fs_lock);
- if (!*mount)
- *mount = mnt;
- }
- mntget(*mount);
- ++*count;
- spin_unlock(&pin_fs_lock);
- mntput(mnt);
- return 0;
- }
- EXPORT_SYMBOL(simple_pin_fs);
- void simple_release_fs(struct vfsmount **mount, int *count)
- {
- struct vfsmount *mnt;
- spin_lock(&pin_fs_lock);
- mnt = *mount;
- if (!--*count)
- *mount = NULL;
- spin_unlock(&pin_fs_lock);
- mntput(mnt);
- }
- EXPORT_SYMBOL(simple_release_fs);
- /**
- * simple_read_from_buffer - copy data from the buffer to user space
- * @to: the user space buffer to read to
- * @count: the maximum number of bytes to read
- * @ppos: the current position in the buffer
- * @from: the buffer to read from
- * @available: the size of the buffer
- *
- * The simple_read_from_buffer() function reads up to @count bytes from the
- * buffer @from at offset @ppos into the user space address starting at @to.
- *
- * On success, the number of bytes read is returned and the offset @ppos is
- * advanced by this number, or negative value is returned on error.
- **/
- ssize_t simple_read_from_buffer(void __user *to, size_t count, loff_t *ppos,
- const void *from, size_t available)
- {
- loff_t pos = *ppos;
- size_t ret;
- if (pos < 0)
- return -EINVAL;
- if (pos >= available || !count)
- return 0;
- if (count > available - pos)
- count = available - pos;
- ret = copy_to_user(to, from + pos, count);
- if (ret == count)
- return -EFAULT;
- count -= ret;
- *ppos = pos + count;
- return count;
- }
- EXPORT_SYMBOL(simple_read_from_buffer);
- /**
- * simple_write_to_buffer - copy data from user space to the buffer
- * @to: the buffer to write to
- * @available: the size of the buffer
- * @ppos: the current position in the buffer
- * @from: the user space buffer to read from
- * @count: the maximum number of bytes to read
- *
- * The simple_write_to_buffer() function reads up to @count bytes from the user
- * space address starting at @from into the buffer @to at offset @ppos.
- *
- * On success, the number of bytes written is returned and the offset @ppos is
- * advanced by this number, or negative value is returned on error.
- **/
- ssize_t simple_write_to_buffer(void *to, size_t available, loff_t *ppos,
- const void __user *from, size_t count)
- {
- loff_t pos = *ppos;
- size_t res;
- if (pos < 0)
- return -EINVAL;
- if (pos >= available || !count)
- return 0;
- if (count > available - pos)
- count = available - pos;
- res = copy_from_user(to + pos, from, count);
- if (res == count)
- return -EFAULT;
- count -= res;
- *ppos = pos + count;
- return count;
- }
- EXPORT_SYMBOL(simple_write_to_buffer);
- /**
- * memory_read_from_buffer - copy data from the buffer
- * @to: the kernel space buffer to read to
- * @count: the maximum number of bytes to read
- * @ppos: the current position in the buffer
- * @from: the buffer to read from
- * @available: the size of the buffer
- *
- * The memory_read_from_buffer() function reads up to @count bytes from the
- * buffer @from at offset @ppos into the kernel space address starting at @to.
- *
- * On success, the number of bytes read is returned and the offset @ppos is
- * advanced by this number, or negative value is returned on error.
- **/
- ssize_t memory_read_from_buffer(void *to, size_t count, loff_t *ppos,
- const void *from, size_t available)
- {
- loff_t pos = *ppos;
- if (pos < 0)
- return -EINVAL;
- if (pos >= available)
- return 0;
- if (count > available - pos)
- count = available - pos;
- memcpy(to, from + pos, count);
- *ppos = pos + count;
- return count;
- }
- EXPORT_SYMBOL(memory_read_from_buffer);
- /*
- * Transaction based IO.
- * The file expects a single write which triggers the transaction, and then
- * possibly a read which collects the result - which is stored in a
- * file-local buffer.
- */
- void simple_transaction_set(struct file *file, size_t n)
- {
- struct simple_transaction_argresp *ar = file->private_data;
- BUG_ON(n > SIMPLE_TRANSACTION_LIMIT);
- /*
- * The barrier ensures that ar->size will really remain zero until
- * ar->data is ready for reading.
- */
- smp_mb();
- ar->size = n;
- }
- EXPORT_SYMBOL(simple_transaction_set);
- char *simple_transaction_get(struct file *file, const char __user *buf, size_t size)
- {
- struct simple_transaction_argresp *ar;
- static DEFINE_SPINLOCK(simple_transaction_lock);
- if (size > SIMPLE_TRANSACTION_LIMIT - 1)
- return ERR_PTR(-EFBIG);
- ar = (struct simple_transaction_argresp *)get_zeroed_page(GFP_KERNEL);
- if (!ar)
- return ERR_PTR(-ENOMEM);
- spin_lock(&simple_transaction_lock);
- /* only one write allowed per open */
- if (file->private_data) {
- spin_unlock(&simple_transaction_lock);
- free_page((unsigned long)ar);
- return ERR_PTR(-EBUSY);
- }
- file->private_data = ar;
- spin_unlock(&simple_transaction_lock);
- if (copy_from_user(ar->data, buf, size))
- return ERR_PTR(-EFAULT);
- return ar->data;
- }
- EXPORT_SYMBOL(simple_transaction_get);
- ssize_t simple_transaction_read(struct file *file, char __user *buf, size_t size, loff_t *pos)
- {
- struct simple_transaction_argresp *ar = file->private_data;
- if (!ar)
- return 0;
- return simple_read_from_buffer(buf, size, pos, ar->data, ar->size);
- }
- EXPORT_SYMBOL(simple_transaction_read);
- int simple_transaction_release(struct inode *inode, struct file *file)
- {
- free_page((unsigned long)file->private_data);
- return 0;
- }
- EXPORT_SYMBOL(simple_transaction_release);
- /* Simple attribute files */
- struct simple_attr {
- int (*get)(void *, u64 *);
- int (*set)(void *, u64);
- char get_buf[24]; /* enough to store a u64 and "\n\0" */
- char set_buf[24];
- void *data;
- const char *fmt; /* format for read operation */
- struct mutex mutex; /* protects access to these buffers */
- };
- /* simple_attr_open is called by an actual attribute open file operation
- * to set the attribute specific access operations. */
- int simple_attr_open(struct inode *inode, struct file *file,
- int (*get)(void *, u64 *), int (*set)(void *, u64),
- const char *fmt)
- {
- struct simple_attr *attr;
- attr = kzalloc(sizeof(*attr), GFP_KERNEL);
- if (!attr)
- return -ENOMEM;
- attr->get = get;
- attr->set = set;
- attr->data = inode->i_private;
- attr->fmt = fmt;
- mutex_init(&attr->mutex);
- file->private_data = attr;
- return nonseekable_open(inode, file);
- }
- EXPORT_SYMBOL_GPL(simple_attr_open);
- int simple_attr_release(struct inode *inode, struct file *file)
- {
- kfree(file->private_data);
- return 0;
- }
- EXPORT_SYMBOL_GPL(simple_attr_release); /* GPL-only? This? Really? */
- /* read from the buffer that is filled with the get function */
- ssize_t simple_attr_read(struct file *file, char __user *buf,
- size_t len, loff_t *ppos)
- {
- struct simple_attr *attr;
- size_t size;
- ssize_t ret;
- attr = file->private_data;
- if (!attr->get)
- return -EACCES;
- ret = mutex_lock_interruptible(&attr->mutex);
- if (ret)
- return ret;
- if (*ppos && attr->get_buf[0]) {
- /* continued read */
- size = strlen(attr->get_buf);
- } else {
- /* first read */
- u64 val;
- ret = attr->get(attr->data, &val);
- if (ret)
- goto out;
- size = scnprintf(attr->get_buf, sizeof(attr->get_buf),
- attr->fmt, (unsigned long long)val);
- }
- ret = simple_read_from_buffer(buf, len, ppos, attr->get_buf, size);
- out:
- mutex_unlock(&attr->mutex);
- return ret;
- }
- EXPORT_SYMBOL_GPL(simple_attr_read);
- /* interpret the buffer as a number to call the set function with */
- ssize_t simple_attr_write(struct file *file, const char __user *buf,
- size_t len, loff_t *ppos)
- {
- struct simple_attr *attr;
- unsigned long long val;
- size_t size;
- ssize_t ret;
- attr = file->private_data;
- if (!attr->set)
- return -EACCES;
- ret = mutex_lock_interruptible(&attr->mutex);
- if (ret)
- return ret;
- ret = -EFAULT;
- size = min(sizeof(attr->set_buf) - 1, len);
- if (copy_from_user(attr->set_buf, buf, size))
- goto out;
- attr->set_buf[size] = '\0';
- ret = kstrtoull(attr->set_buf, 0, &val);
- if (ret)
- goto out;
- ret = attr->set(attr->data, val);
- if (ret == 0)
- ret = len; /* on success, claim we got the whole input */
- out:
- mutex_unlock(&attr->mutex);
- return ret;
- }
- EXPORT_SYMBOL_GPL(simple_attr_write);
- /**
- * generic_fh_to_dentry - generic helper for the fh_to_dentry export operation
- * @sb: filesystem to do the file handle conversion on
- * @fid: file handle to convert
- * @fh_len: length of the file handle in bytes
- * @fh_type: type of file handle
- * @get_inode: filesystem callback to retrieve inode
- *
- * This function decodes @fid as long as it has one of the well-known
- * Linux filehandle types and calls @get_inode on it to retrieve the
- * inode for the object specified in the file handle.
- */
- struct dentry *generic_fh_to_dentry(struct super_block *sb, struct fid *fid,
- int fh_len, int fh_type, struct inode *(*get_inode)
- (struct super_block *sb, u64 ino, u32 gen))
- {
- struct inode *inode = NULL;
- if (fh_len < 2)
- return NULL;
- switch (fh_type) {
- case FILEID_INO32_GEN:
- case FILEID_INO32_GEN_PARENT:
- inode = get_inode(sb, fid->i32.ino, fid->i32.gen);
- break;
- }
- return d_obtain_alias(inode);
- }
- EXPORT_SYMBOL_GPL(generic_fh_to_dentry);
- /**
- * generic_fh_to_parent - generic helper for the fh_to_parent export operation
- * @sb: filesystem to do the file handle conversion on
- * @fid: file handle to convert
- * @fh_len: length of the file handle in bytes
- * @fh_type: type of file handle
- * @get_inode: filesystem callback to retrieve inode
- *
- * This function decodes @fid as long as it has one of the well-known
- * Linux filehandle types and calls @get_inode on it to retrieve the
- * inode for the _parent_ object specified in the file handle if it
- * is specified in the file handle, or NULL otherwise.
- */
- struct dentry *generic_fh_to_parent(struct super_block *sb, struct fid *fid,
- int fh_len, int fh_type, struct inode *(*get_inode)
- (struct super_block *sb, u64 ino, u32 gen))
- {
- struct inode *inode = NULL;
- if (fh_len <= 2)
- return NULL;
- switch (fh_type) {
- case FILEID_INO32_GEN_PARENT:
- inode = get_inode(sb, fid->i32.parent_ino,
- (fh_len > 3 ? fid->i32.parent_gen : 0));
- break;
- }
- return d_obtain_alias(inode);
- }
- EXPORT_SYMBOL_GPL(generic_fh_to_parent);
- /**
- * __generic_file_fsync - generic fsync implementation for simple filesystems
- *
- * @file: file to synchronize
- * @start: start offset in bytes
- * @end: end offset in bytes (inclusive)
- * @datasync: only synchronize essential metadata if true
- *
- * This is a generic implementation of the fsync method for simple
- * filesystems which track all non-inode metadata in the buffers list
- * hanging off the address_space structure.
- */
- int __generic_file_fsync(struct file *file, loff_t start, loff_t end,
- int datasync)
- {
- struct inode *inode = file->f_mapping->host;
- int err;
- int ret;
- err = file_write_and_wait_range(file, start, end);
- if (err)
- return err;
- inode_lock(inode);
- ret = sync_mapping_buffers(inode->i_mapping);
- if (!(inode->i_state & I_DIRTY_ALL))
- goto out;
- if (datasync && !(inode->i_state & I_DIRTY_DATASYNC))
- goto out;
- err = sync_inode_metadata(inode, 1);
- if (ret == 0)
- ret = err;
- out:
- inode_unlock(inode);
- /* check and advance again to catch errors after syncing out buffers */
- err = file_check_and_advance_wb_err(file);
- if (ret == 0)
- ret = err;
- return ret;
- }
- EXPORT_SYMBOL(__generic_file_fsync);
- /**
- * generic_file_fsync - generic fsync implementation for simple filesystems
- * with flush
- * @file: file to synchronize
- * @start: start offset in bytes
- * @end: end offset in bytes (inclusive)
- * @datasync: only synchronize essential metadata if true
- *
- */
- int generic_file_fsync(struct file *file, loff_t start, loff_t end,
- int datasync)
- {
- struct inode *inode = file->f_mapping->host;
- int err;
- err = __generic_file_fsync(file, start, end, datasync);
- if (err)
- return err;
- return blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL);
- }
- EXPORT_SYMBOL(generic_file_fsync);
- /**
- * generic_check_addressable - Check addressability of file system
- * @blocksize_bits: log of file system block size
- * @num_blocks: number of blocks in file system
- *
- * Determine whether a file system with @num_blocks blocks (and a
- * block size of 2**@blocksize_bits) is addressable by the sector_t
- * and page cache of the system. Return 0 if so and -EFBIG otherwise.
- */
- int generic_check_addressable(unsigned blocksize_bits, u64 num_blocks)
- {
- u64 last_fs_block = num_blocks - 1;
- u64 last_fs_page =
- last_fs_block >> (PAGE_SHIFT - blocksize_bits);
- if (unlikely(num_blocks == 0))
- return 0;
- if ((blocksize_bits < 9) || (blocksize_bits > PAGE_SHIFT))
- return -EINVAL;
- if ((last_fs_block > (sector_t)(~0ULL) >> (blocksize_bits - 9)) ||
- (last_fs_page > (pgoff_t)(~0ULL))) {
- return -EFBIG;
- }
- return 0;
- }
- EXPORT_SYMBOL(generic_check_addressable);
- /*
- * No-op implementation of ->fsync for in-memory filesystems.
- */
- int noop_fsync(struct file *file, loff_t start, loff_t end, int datasync)
- {
- return 0;
- }
- EXPORT_SYMBOL(noop_fsync);
- int noop_set_page_dirty(struct page *page)
- {
- /*
- * Unlike __set_page_dirty_no_writeback that handles dirty page
- * tracking in the page object, dax does all dirty tracking in
- * the inode address_space in response to mkwrite faults. In the
- * dax case we only need to worry about potentially dirty CPU
- * caches, not dirty page cache pages to write back.
- *
- * This callback is defined to prevent fallback to
- * __set_page_dirty_buffers() in set_page_dirty().
- */
- return 0;
- }
- EXPORT_SYMBOL_GPL(noop_set_page_dirty);
- void noop_invalidatepage(struct page *page, unsigned int offset,
- unsigned int length)
- {
- /*
- * There is no page cache to invalidate in the dax case, however
- * we need this callback defined to prevent falling back to
- * block_invalidatepage() in do_invalidatepage().
- */
- }
- EXPORT_SYMBOL_GPL(noop_invalidatepage);
- ssize_t noop_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
- {
- /*
- * iomap based filesystems support direct I/O without need for
- * this callback. However, it still needs to be set in
- * inode->a_ops so that open/fcntl know that direct I/O is
- * generally supported.
- */
- return -EINVAL;
- }
- EXPORT_SYMBOL_GPL(noop_direct_IO);
- /* Because kfree isn't assignment-compatible with void(void*) ;-/ */
- void kfree_link(void *p)
- {
- kfree(p);
- }
- EXPORT_SYMBOL(kfree_link);
- /*
- * nop .set_page_dirty method so that people can use .page_mkwrite on
- * anon inodes.
- */
- static int anon_set_page_dirty(struct page *page)
- {
- return 0;
- };
- struct inode *alloc_anon_inode(struct super_block *s)
- {
- static const struct address_space_operations anon_aops = {
- .set_page_dirty = anon_set_page_dirty,
- };
- struct inode *inode = new_inode_pseudo(s);
- if (!inode)
- return ERR_PTR(-ENOMEM);
- inode->i_ino = get_next_ino();
- inode->i_mapping->a_ops = &anon_aops;
- /*
- * Mark the inode dirty from the very beginning,
- * that way it will never be moved to the dirty
- * list because mark_inode_dirty() will think
- * that it already _is_ on the dirty list.
- */
- inode->i_state = I_DIRTY;
- inode->i_mode = S_IRUSR | S_IWUSR;
- inode->i_uid = current_fsuid();
- inode->i_gid = current_fsgid();
- inode->i_flags |= S_PRIVATE;
- inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
- return inode;
- }
- EXPORT_SYMBOL(alloc_anon_inode);
- /**
- * simple_nosetlease - generic helper for prohibiting leases
- * @filp: file pointer
- * @arg: type of lease to obtain
- * @flp: new lease supplied for insertion
- * @priv: private data for lm_setup operation
- *
- * Generic helper for filesystems that do not wish to allow leases to be set.
- * All arguments are ignored and it just returns -EINVAL.
- */
- int
- simple_nosetlease(struct file *filp, long arg, struct file_lock **flp,
- void **priv)
- {
- return -EINVAL;
- }
- EXPORT_SYMBOL(simple_nosetlease);
- /**
- * simple_get_link - generic helper to get the target of "fast" symlinks
- * @dentry: not used here
- * @inode: the symlink inode
- * @done: not used here
- *
- * Generic helper for filesystems to use for symlink inodes where a pointer to
- * the symlink target is stored in ->i_link. NOTE: this isn't normally called,
- * since as an optimization the path lookup code uses any non-NULL ->i_link
- * directly, without calling ->get_link(). But ->get_link() still must be set,
- * to mark the inode_operations as being for a symlink.
- *
- * Return: the symlink target
- */
- const char *simple_get_link(struct dentry *dentry, struct inode *inode,
- struct delayed_call *done)
- {
- return inode->i_link;
- }
- EXPORT_SYMBOL(simple_get_link);
- const struct inode_operations simple_symlink_inode_operations = {
- .get_link = simple_get_link,
- };
- EXPORT_SYMBOL(simple_symlink_inode_operations);
- /*
- * Operations for a permanently empty directory.
- */
- static struct dentry *empty_dir_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
- {
- return ERR_PTR(-ENOENT);
- }
- static int empty_dir_getattr(const struct path *path, struct kstat *stat,
- u32 request_mask, unsigned int query_flags)
- {
- struct inode *inode = d_inode(path->dentry);
- generic_fillattr(inode, stat);
- return 0;
- }
- static int empty_dir_setattr(struct dentry *dentry, struct iattr *attr)
- {
- return -EPERM;
- }
- static ssize_t empty_dir_listxattr(struct dentry *dentry, char *list, size_t size)
- {
- return -EOPNOTSUPP;
- }
- static const struct inode_operations empty_dir_inode_operations = {
- .lookup = empty_dir_lookup,
- .permission = generic_permission,
- .setattr = empty_dir_setattr,
- .getattr = empty_dir_getattr,
- .listxattr = empty_dir_listxattr,
- };
- static loff_t empty_dir_llseek(struct file *file, loff_t offset, int whence)
- {
- /* An empty directory has two entries . and .. at offsets 0 and 1 */
- return generic_file_llseek_size(file, offset, whence, 2, 2);
- }
- static int empty_dir_readdir(struct file *file, struct dir_context *ctx)
- {
- dir_emit_dots(file, ctx);
- return 0;
- }
- static const struct file_operations empty_dir_operations = {
- .llseek = empty_dir_llseek,
- .read = generic_read_dir,
- .iterate_shared = empty_dir_readdir,
- .fsync = noop_fsync,
- };
- void make_empty_dir_inode(struct inode *inode)
- {
- set_nlink(inode, 2);
- inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO;
- inode->i_uid = GLOBAL_ROOT_UID;
- inode->i_gid = GLOBAL_ROOT_GID;
- inode->i_rdev = 0;
- inode->i_size = 0;
- inode->i_blkbits = PAGE_SHIFT;
- inode->i_blocks = 0;
- inode->i_op = &empty_dir_inode_operations;
- inode->i_opflags &= ~IOP_XATTR;
- inode->i_fop = &empty_dir_operations;
- }
- bool is_empty_dir_inode(struct inode *inode)
- {
- return (inode->i_fop == &empty_dir_operations) &&
- (inode->i_op == &empty_dir_inode_operations);
- }
- #ifdef CONFIG_UNICODE
- /*
- * Determine if the name of a dentry should be casefolded.
- *
- * Return: if names will need casefolding
- */
- static bool needs_casefold(const struct inode *dir)
- {
- return IS_CASEFOLDED(dir) && dir->i_sb->s_encoding;
- }
- /**
- * generic_ci_d_compare - generic d_compare implementation for casefolding filesystems
- * @dentry: dentry whose name we are checking against
- * @len: len of name of dentry
- * @str: str pointer to name of dentry
- * @name: Name to compare against
- *
- * Return: 0 if names match, 1 if mismatch, or -ERRNO
- */
- static int generic_ci_d_compare(const struct dentry *dentry, unsigned int len,
- const char *str, const struct qstr *name)
- {
- const struct dentry *parent = READ_ONCE(dentry->d_parent);
- const struct inode *dir = READ_ONCE(parent->d_inode);
- const struct super_block *sb = dentry->d_sb;
- const struct unicode_map *um = sb->s_encoding;
- struct qstr qstr = QSTR_INIT(str, len);
- char strbuf[DNAME_INLINE_LEN];
- int ret;
- if (!dir || !needs_casefold(dir))
- goto fallback;
- /*
- * If the dentry name is stored in-line, then it may be concurrently
- * modified by a rename. If this happens, the VFS will eventually retry
- * the lookup, so it doesn't matter what ->d_compare() returns.
- * However, it's unsafe to call utf8_strncasecmp() with an unstable
- * string. Therefore, we have to copy the name into a temporary buffer.
- */
- if (len <= DNAME_INLINE_LEN - 1) {
- memcpy(strbuf, str, len);
- strbuf[len] = 0;
- qstr.name = strbuf;
- /* prevent compiler from optimizing out the temporary buffer */
- barrier();
- }
- ret = utf8_strncasecmp(um, name, &qstr);
- if (ret >= 0)
- return ret;
- if (sb_has_strict_encoding(sb))
- return -EINVAL;
- fallback:
- if (len != name->len)
- return 1;
- return !!memcmp(str, name->name, len);
- }
- /**
- * generic_ci_d_hash - generic d_hash implementation for casefolding filesystems
- * @dentry: dentry of the parent directory
- * @str: qstr of name whose hash we should fill in
- *
- * Return: 0 if hash was successful or unchanged, and -EINVAL on error
- */
- static int generic_ci_d_hash(const struct dentry *dentry, struct qstr *str)
- {
- const struct inode *dir = READ_ONCE(dentry->d_inode);
- struct super_block *sb = dentry->d_sb;
- const struct unicode_map *um = sb->s_encoding;
- int ret = 0;
- if (!dir || !needs_casefold(dir))
- return 0;
- ret = utf8_casefold_hash(um, dentry, str);
- if (ret < 0 && sb_has_strict_encoding(sb))
- return -EINVAL;
- return 0;
- }
- static const struct dentry_operations generic_ci_dentry_ops = {
- .d_hash = generic_ci_d_hash,
- .d_compare = generic_ci_d_compare,
- };
- #endif
- #ifdef CONFIG_FS_ENCRYPTION
- static const struct dentry_operations generic_encrypted_dentry_ops = {
- .d_revalidate = fscrypt_d_revalidate,
- };
- #endif
- #if defined(CONFIG_FS_ENCRYPTION) && defined(CONFIG_UNICODE)
- static const struct dentry_operations generic_encrypted_ci_dentry_ops = {
- .d_hash = generic_ci_d_hash,
- .d_compare = generic_ci_d_compare,
- .d_revalidate = fscrypt_d_revalidate,
- };
- #endif
- /**
- * generic_set_encrypted_ci_d_ops - helper for setting d_ops for given dentry
- * @dentry: dentry to set ops on
- *
- * Casefolded directories need d_hash and d_compare set, so that the dentries
- * contained in them are handled case-insensitively. Note that these operations
- * are needed on the parent directory rather than on the dentries in it, and
- * while the casefolding flag can be toggled on and off on an empty directory,
- * dentry_operations can't be changed later. As a result, if the filesystem has
- * casefolding support enabled at all, we have to give all dentries the
- * casefolding operations even if their inode doesn't have the casefolding flag
- * currently (and thus the casefolding ops would be no-ops for now).
- *
- * Encryption works differently in that the only dentry operation it needs is
- * d_revalidate, which it only needs on dentries that have the no-key name flag.
- * The no-key flag can't be set "later", so we don't have to worry about that.
- *
- * Finally, to maximize compatibility with overlayfs (which isn't compatible
- * with certain dentry operations) and to avoid taking an unnecessary
- * performance hit, we use custom dentry_operations for each possible
- * combination rather than always installing all operations.
- */
- void generic_set_encrypted_ci_d_ops(struct dentry *dentry)
- {
- #ifdef CONFIG_FS_ENCRYPTION
- bool needs_encrypt_ops = dentry->d_flags & DCACHE_NOKEY_NAME;
- #endif
- #ifdef CONFIG_UNICODE
- bool needs_ci_ops = dentry->d_sb->s_encoding;
- #endif
- #if defined(CONFIG_FS_ENCRYPTION) && defined(CONFIG_UNICODE)
- if (needs_encrypt_ops && needs_ci_ops) {
- d_set_d_op(dentry, &generic_encrypted_ci_dentry_ops);
- return;
- }
- #endif
- #ifdef CONFIG_FS_ENCRYPTION
- if (needs_encrypt_ops) {
- d_set_d_op(dentry, &generic_encrypted_dentry_ops);
- return;
- }
- #endif
- #ifdef CONFIG_UNICODE
- if (needs_ci_ops) {
- d_set_d_op(dentry, &generic_ci_dentry_ops);
- return;
- }
- #endif
- }
- EXPORT_SYMBOL(generic_set_encrypted_ci_d_ops);
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