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-rw-r--r--fs/libfs.c549
1 files changed, 549 insertions, 0 deletions
diff --git a/fs/libfs.c b/fs/libfs.c
new file mode 100644
index 00000000000..f90b2959592
--- /dev/null
+++ b/fs/libfs.c
@@ -0,0 +1,549 @@
+/*
+ * fs/libfs.c
+ * Library for filesystems writers.
+ */
+
+#include <linux/module.h>
+#include <linux/pagemap.h>
+#include <linux/mount.h>
+#include <linux/vfs.h>
+#include <asm/uaccess.h>
+
+int simple_getattr(struct vfsmount *mnt, struct dentry *dentry,
+ struct kstat *stat)
+{
+ struct inode *inode = dentry->d_inode;
+ generic_fillattr(inode, stat);
+ stat->blocks = inode->i_mapping->nrpages << (PAGE_CACHE_SHIFT - 9);
+ return 0;
+}
+
+int simple_statfs(struct super_block *sb, struct kstatfs *buf)
+{
+ buf->f_type = sb->s_magic;
+ buf->f_bsize = PAGE_CACHE_SIZE;
+ buf->f_namelen = NAME_MAX;
+ return 0;
+}
+
+/*
+ * Retaining negative dentries for an in-memory filesystem just wastes
+ * memory and lookup time: arrange for them to be deleted immediately.
+ */
+static int simple_delete_dentry(struct dentry *dentry)
+{
+ return 1;
+}
+
+/*
+ * 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, struct nameidata *nd)
+{
+ static struct dentry_operations simple_dentry_operations = {
+ .d_delete = simple_delete_dentry,
+ };
+
+ if (dentry->d_name.len > NAME_MAX)
+ return ERR_PTR(-ENAMETOOLONG);
+ dentry->d_op = &simple_dentry_operations;
+ d_add(dentry, NULL);
+ return NULL;
+}
+
+int simple_sync_file(struct file * file, struct dentry *dentry, int datasync)
+{
+ return 0;
+}
+
+int dcache_dir_open(struct inode *inode, struct file *file)
+{
+ static struct qstr cursor_name = {.len = 1, .name = "."};
+
+ file->private_data = d_alloc(file->f_dentry, &cursor_name);
+
+ return file->private_data ? 0 : -ENOMEM;
+}
+
+int dcache_dir_close(struct inode *inode, struct file *file)
+{
+ dput(file->private_data);
+ return 0;
+}
+
+loff_t dcache_dir_lseek(struct file *file, loff_t offset, int origin)
+{
+ down(&file->f_dentry->d_inode->i_sem);
+ switch (origin) {
+ case 1:
+ offset += file->f_pos;
+ case 0:
+ if (offset >= 0)
+ break;
+ default:
+ up(&file->f_dentry->d_inode->i_sem);
+ return -EINVAL;
+ }
+ if (offset != file->f_pos) {
+ file->f_pos = offset;
+ if (file->f_pos >= 2) {
+ struct list_head *p;
+ struct dentry *cursor = file->private_data;
+ loff_t n = file->f_pos - 2;
+
+ spin_lock(&dcache_lock);
+ list_del(&cursor->d_child);
+ p = file->f_dentry->d_subdirs.next;
+ while (n && p != &file->f_dentry->d_subdirs) {
+ struct dentry *next;
+ next = list_entry(p, struct dentry, d_child);
+ if (!d_unhashed(next) && next->d_inode)
+ n--;
+ p = p->next;
+ }
+ list_add_tail(&cursor->d_child, p);
+ spin_unlock(&dcache_lock);
+ }
+ }
+ up(&file->f_dentry->d_inode->i_sem);
+ return offset;
+}
+
+/* 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 * filp, void * dirent, filldir_t filldir)
+{
+ struct dentry *dentry = filp->f_dentry;
+ struct dentry *cursor = filp->private_data;
+ struct list_head *p, *q = &cursor->d_child;
+ ino_t ino;
+ int i = filp->f_pos;
+
+ switch (i) {
+ case 0:
+ ino = dentry->d_inode->i_ino;
+ if (filldir(dirent, ".", 1, i, ino, DT_DIR) < 0)
+ break;
+ filp->f_pos++;
+ i++;
+ /* fallthrough */
+ case 1:
+ ino = parent_ino(dentry);
+ if (filldir(dirent, "..", 2, i, ino, DT_DIR) < 0)
+ break;
+ filp->f_pos++;
+ i++;
+ /* fallthrough */
+ default:
+ spin_lock(&dcache_lock);
+ if (filp->f_pos == 2) {
+ list_del(q);
+ list_add(q, &dentry->d_subdirs);
+ }
+ for (p=q->next; p != &dentry->d_subdirs; p=p->next) {
+ struct dentry *next;
+ next = list_entry(p, struct dentry, d_child);
+ if (d_unhashed(next) || !next->d_inode)
+ continue;
+
+ spin_unlock(&dcache_lock);
+ if (filldir(dirent, next->d_name.name, next->d_name.len, filp->f_pos, next->d_inode->i_ino, dt_type(next->d_inode)) < 0)
+ return 0;
+ spin_lock(&dcache_lock);
+ /* next is still alive */
+ list_del(q);
+ list_add(q, p);
+ p = q;
+ filp->f_pos++;
+ }
+ spin_unlock(&dcache_lock);
+ }
+ return 0;
+}
+
+ssize_t generic_read_dir(struct file *filp, char __user *buf, size_t siz, loff_t *ppos)
+{
+ return -EISDIR;
+}
+
+struct file_operations simple_dir_operations = {
+ .open = dcache_dir_open,
+ .release = dcache_dir_close,
+ .llseek = dcache_dir_lseek,
+ .read = generic_read_dir,
+ .readdir = dcache_readdir,
+};
+
+struct inode_operations simple_dir_inode_operations = {
+ .lookup = simple_lookup,
+};
+
+/*
+ * Common helper for pseudo-filesystems (sockfs, pipefs, bdev - stuff that
+ * will never be mountable)
+ */
+struct super_block *
+get_sb_pseudo(struct file_system_type *fs_type, char *name,
+ struct super_operations *ops, unsigned long magic)
+{
+ struct super_block *s = sget(fs_type, NULL, set_anon_super, NULL);
+ static struct super_operations default_ops = {.statfs = simple_statfs};
+ struct dentry *dentry;
+ struct inode *root;
+ struct qstr d_name = {.name = name, .len = strlen(name)};
+
+ if (IS_ERR(s))
+ return s;
+
+ s->s_flags = MS_NOUSER;
+ s->s_maxbytes = ~0ULL;
+ s->s_blocksize = 1024;
+ s->s_blocksize_bits = 10;
+ s->s_magic = magic;
+ s->s_op = ops ? ops : &default_ops;
+ s->s_time_gran = 1;
+ root = new_inode(s);
+ if (!root)
+ goto Enomem;
+ root->i_mode = S_IFDIR | S_IRUSR | S_IWUSR;
+ root->i_uid = root->i_gid = 0;
+ root->i_atime = root->i_mtime = root->i_ctime = CURRENT_TIME;
+ dentry = d_alloc(NULL, &d_name);
+ if (!dentry) {
+ iput(root);
+ goto Enomem;
+ }
+ dentry->d_sb = s;
+ dentry->d_parent = dentry;
+ d_instantiate(dentry, root);
+ s->s_root = dentry;
+ s->s_flags |= MS_ACTIVE;
+ return s;
+
+Enomem:
+ up_write(&s->s_umount);
+ deactivate_super(s);
+ return ERR_PTR(-ENOMEM);
+}
+
+int simple_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
+{
+ struct inode *inode = old_dentry->d_inode;
+
+ inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
+ inode->i_nlink++;
+ atomic_inc(&inode->i_count);
+ dget(dentry);
+ d_instantiate(dentry, inode);
+ return 0;
+}
+
+static inline int simple_positive(struct dentry *dentry)
+{
+ return dentry->d_inode && !d_unhashed(dentry);
+}
+
+int simple_empty(struct dentry *dentry)
+{
+ struct dentry *child;
+ int ret = 0;
+
+ spin_lock(&dcache_lock);
+ list_for_each_entry(child, &dentry->d_subdirs, d_child)
+ if (simple_positive(child))
+ goto out;
+ ret = 1;
+out:
+ spin_unlock(&dcache_lock);
+ return ret;
+}
+
+int simple_unlink(struct inode *dir, struct dentry *dentry)
+{
+ struct inode *inode = dentry->d_inode;
+
+ inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
+ inode->i_nlink--;
+ dput(dentry);
+ return 0;
+}
+
+int simple_rmdir(struct inode *dir, struct dentry *dentry)
+{
+ if (!simple_empty(dentry))
+ return -ENOTEMPTY;
+
+ dentry->d_inode->i_nlink--;
+ simple_unlink(dir, dentry);
+ dir->i_nlink--;
+ return 0;
+}
+
+int simple_rename(struct inode *old_dir, struct dentry *old_dentry,
+ struct inode *new_dir, struct dentry *new_dentry)
+{
+ struct inode *inode = old_dentry->d_inode;
+ int they_are_dirs = S_ISDIR(old_dentry->d_inode->i_mode);
+
+ if (!simple_empty(new_dentry))
+ return -ENOTEMPTY;
+
+ if (new_dentry->d_inode) {
+ simple_unlink(new_dir, new_dentry);
+ if (they_are_dirs)
+ old_dir->i_nlink--;
+ } else if (they_are_dirs) {
+ old_dir->i_nlink--;
+ new_dir->i_nlink++;
+ }
+
+ old_dir->i_ctime = old_dir->i_mtime = new_dir->i_ctime =
+ new_dir->i_mtime = inode->i_ctime = CURRENT_TIME;
+
+ return 0;
+}
+
+int simple_readpage(struct file *file, struct page *page)
+{
+ void *kaddr;
+
+ if (PageUptodate(page))
+ goto out;
+
+ kaddr = kmap_atomic(page, KM_USER0);
+ memset(kaddr, 0, PAGE_CACHE_SIZE);
+ kunmap_atomic(kaddr, KM_USER0);
+ flush_dcache_page(page);
+ SetPageUptodate(page);
+out:
+ unlock_page(page);
+ return 0;
+}
+
+int simple_prepare_write(struct file *file, struct page *page,
+ unsigned from, unsigned to)
+{
+ if (!PageUptodate(page)) {
+ if (to - from != PAGE_CACHE_SIZE) {
+ void *kaddr = kmap_atomic(page, KM_USER0);
+ memset(kaddr, 0, from);
+ memset(kaddr + to, 0, PAGE_CACHE_SIZE - to);
+ flush_dcache_page(page);
+ kunmap_atomic(kaddr, KM_USER0);
+ }
+ SetPageUptodate(page);
+ }
+ return 0;
+}
+
+int simple_commit_write(struct file *file, struct page *page,
+ unsigned offset, unsigned to)
+{
+ struct inode *inode = page->mapping->host;
+ loff_t pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to;
+
+ /*
+ * No need to use i_size_read() here, the i_size
+ * cannot change under us because we hold the i_sem.
+ */
+ if (pos > inode->i_size)
+ i_size_write(inode, pos);
+ set_page_dirty(page);
+ return 0;
+}
+
+int simple_fill_super(struct super_block *s, int magic, struct tree_descr *files)
+{
+ static struct super_operations s_ops = {.statfs = simple_statfs};
+ struct inode *inode;
+ struct dentry *root;
+ struct dentry *dentry;
+ int i;
+
+ s->s_blocksize = PAGE_CACHE_SIZE;
+ s->s_blocksize_bits = PAGE_CACHE_SHIFT;
+ s->s_magic = magic;
+ s->s_op = &s_ops;
+ s->s_time_gran = 1;
+
+ inode = new_inode(s);
+ if (!inode)
+ return -ENOMEM;
+ inode->i_mode = S_IFDIR | 0755;
+ inode->i_uid = inode->i_gid = 0;
+ inode->i_blksize = PAGE_CACHE_SIZE;
+ inode->i_blocks = 0;
+ inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
+ inode->i_op = &simple_dir_inode_operations;
+ inode->i_fop = &simple_dir_operations;
+ root = d_alloc_root(inode);
+ if (!root) {
+ iput(inode);
+ return -ENOMEM;
+ }
+ for (i = 0; !files->name || files->name[0]; i++, files++) {
+ if (!files->name)
+ continue;
+ dentry = d_alloc_name(root, files->name);
+ if (!dentry)
+ goto out;
+ inode = new_inode(s);
+ if (!inode)
+ goto out;
+ inode->i_mode = S_IFREG | files->mode;
+ inode->i_uid = inode->i_gid = 0;
+ inode->i_blksize = PAGE_CACHE_SIZE;
+ inode->i_blocks = 0;
+ inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
+ inode->i_fop = files->ops;
+ inode->i_ino = i;
+ d_add(dentry, inode);
+ }
+ s->s_root = root;
+ return 0;
+out:
+ d_genocide(root);
+ dput(root);
+ return -ENOMEM;
+}
+
+static DEFINE_SPINLOCK(pin_fs_lock);
+
+int simple_pin_fs(char *name, struct vfsmount **mount, int *count)
+{
+ struct vfsmount *mnt = NULL;
+ spin_lock(&pin_fs_lock);
+ if (unlikely(!*mount)) {
+ spin_unlock(&pin_fs_lock);
+ mnt = do_kern_mount(name, 0, 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;
+}
+
+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);
+}
+
+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;
+ if (pos < 0)
+ return -EINVAL;
+ if (pos >= available)
+ return 0;
+ if (count > available - pos)
+ count = available - pos;
+ if (copy_to_user(to, from + pos, count))
+ return -EFAULT;
+ *ppos = pos + count;
+ return count;
+}
+
+/*
+ * 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.
+ */
+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;
+}
+
+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);
+}
+
+int simple_transaction_release(struct inode *inode, struct file *file)
+{
+ free_page((unsigned long)file->private_data);
+ return 0;
+}
+
+EXPORT_SYMBOL(dcache_dir_close);
+EXPORT_SYMBOL(dcache_dir_lseek);
+EXPORT_SYMBOL(dcache_dir_open);
+EXPORT_SYMBOL(dcache_readdir);
+EXPORT_SYMBOL(generic_read_dir);
+EXPORT_SYMBOL(get_sb_pseudo);
+EXPORT_SYMBOL(simple_commit_write);
+EXPORT_SYMBOL(simple_dir_inode_operations);
+EXPORT_SYMBOL(simple_dir_operations);
+EXPORT_SYMBOL(simple_empty);
+EXPORT_SYMBOL(d_alloc_name);
+EXPORT_SYMBOL(simple_fill_super);
+EXPORT_SYMBOL(simple_getattr);
+EXPORT_SYMBOL(simple_link);
+EXPORT_SYMBOL(simple_lookup);
+EXPORT_SYMBOL(simple_pin_fs);
+EXPORT_SYMBOL(simple_prepare_write);
+EXPORT_SYMBOL(simple_readpage);
+EXPORT_SYMBOL(simple_release_fs);
+EXPORT_SYMBOL(simple_rename);
+EXPORT_SYMBOL(simple_rmdir);
+EXPORT_SYMBOL(simple_statfs);
+EXPORT_SYMBOL(simple_sync_file);
+EXPORT_SYMBOL(simple_unlink);
+EXPORT_SYMBOL(simple_read_from_buffer);
+EXPORT_SYMBOL(simple_transaction_get);
+EXPORT_SYMBOL(simple_transaction_read);
+EXPORT_SYMBOL(simple_transaction_release);
generated by cgit v1.2.3 (git 2.25.1) at 2024-04-26 22:25:02 +0000