diff options
Diffstat (limited to 'kernel/fs/libfs.c')
| -rw-r--r-- | kernel/fs/libfs.c | 1191 |
1 files changed, 1191 insertions, 0 deletions
diff --git a/kernel/fs/libfs.c b/kernel/fs/libfs.c new file mode 100644 index 000000000..02813592e --- /dev/null +++ b/kernel/fs/libfs.c @@ -0,0 +1,1191 @@ +/* + * 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/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 <asm/uaccess.h> + +#include "internal.h" + +static inline int simple_positive(struct dentry *dentry) +{ + return d_really_is_positive(dentry) && !d_unhashed(dentry); +} + +int simple_getattr(struct vfsmount *mnt, struct dentry *dentry, + struct kstat *stat) +{ + struct inode *inode = d_inode(dentry); + generic_fillattr(inode, stat); + stat->blocks = inode->i_mapping->nrpages << (PAGE_CACHE_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_CACHE_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) +{ + static struct qstr cursor_name = QSTR_INIT(".", 1); + + file->private_data = d_alloc(file->f_path.dentry, &cursor_name); + + 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); + +loff_t dcache_dir_lseek(struct file *file, loff_t offset, int whence) +{ + struct dentry *dentry = file->f_path.dentry; + mutex_lock(&d_inode(dentry)->i_mutex); + switch (whence) { + case 1: + offset += file->f_pos; + case 0: + if (offset >= 0) + break; + default: + mutex_unlock(&d_inode(dentry)->i_mutex); + 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(&dentry->d_lock); + /* d_lock not required for cursor */ + list_del(&cursor->d_child); + p = dentry->d_subdirs.next; + while (n && p != &dentry->d_subdirs) { + struct dentry *next; + next = list_entry(p, struct dentry, d_child); + spin_lock_nested(&next->d_lock, DENTRY_D_LOCK_NESTED); + if (simple_positive(next)) + n--; + spin_unlock(&next->d_lock); + p = p->next; + } + list_add_tail(&cursor->d_child, p); + spin_unlock(&dentry->d_lock); + } + } + mutex_unlock(&d_inode(dentry)->i_mutex); + 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 *p, *q = &cursor->d_child; + + if (!dir_emit_dots(file, ctx)) + return 0; + spin_lock(&dentry->d_lock); + if (ctx->pos == 2) + list_move(q, &dentry->d_subdirs); + + for (p = q->next; p != &dentry->d_subdirs; p = p->next) { + struct dentry *next = list_entry(p, struct dentry, d_child); + spin_lock_nested(&next->d_lock, DENTRY_D_LOCK_NESTED); + if (!simple_positive(next)) { + spin_unlock(&next->d_lock); + continue; + } + + spin_unlock(&next->d_lock); + spin_unlock(&dentry->d_lock); + if (!dir_emit(ctx, next->d_name.name, next->d_name.len, + d_inode(next)->i_ino, dt_type(d_inode(next)))) + return 0; + spin_lock(&dentry->d_lock); + spin_lock_nested(&next->d_lock, DENTRY_D_LOCK_NESTED); + /* next is still alive */ + list_move(q, p); + spin_unlock(&next->d_lock); + p = q; + ctx->pos++; + } + spin_unlock(&dentry->d_lock); + 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(generic_read_dir); + +const struct file_operations simple_dir_operations = { + .open = dcache_dir_open, + .release = dcache_dir_close, + .llseek = dcache_dir_lseek, + .read = generic_read_dir, + .iterate = 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 const struct super_operations simple_super_operations = { + .statfs = simple_statfs, +}; + +/* + * Common helper for pseudo-filesystems (sockfs, pipefs, bdev - stuff that + * will never be mountable) + */ +struct dentry *mount_pseudo(struct file_system_type *fs_type, char *name, + const struct super_operations *ops, + const struct dentry_operations *dops, unsigned long magic) +{ + struct super_block *s; + struct dentry *dentry; + struct inode *root; + struct qstr d_name = QSTR_INIT(name, strlen(name)); + + s = sget(fs_type, NULL, set_anon_super, MS_NOUSER, NULL); + if (IS_ERR(s)) + return ERR_CAST(s); + + s->s_maxbytes = MAX_LFS_FILESIZE; + s->s_blocksize = PAGE_SIZE; + s->s_blocksize_bits = PAGE_SHIFT; + s->s_magic = magic; + s->s_op = ops ? ops : &simple_super_operations; + s->s_time_gran = 1; + root = new_inode(s); + if (!root) + goto 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; + dentry = __d_alloc(s, &d_name); + if (!dentry) { + iput(root); + goto Enomem; + } + d_instantiate(dentry, root); + s->s_root = dentry; + s->s_d_op = dops; + s->s_flags |= MS_ACTIVE; + return dget(s->s_root); + +Enomem: + deactivate_locked_super(s); + return ERR_PTR(-ENOMEM); +} +EXPORT_SYMBOL(mount_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; + 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; + 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) +{ + struct inode *inode = d_inode(old_dentry); + int they_are_dirs = d_is_dir(old_dentry); + + 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; + + 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 = inode_change_ok(inode, 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_CACHE_SHIFT; + + page = grab_cache_page_write_begin(mapping, index, flags); + if (!page) + return -ENOMEM; + + *pagep = page; + + if (!PageUptodate(page) && (len != PAGE_CACHE_SIZE)) { + unsigned from = pos & (PAGE_CACHE_SIZE - 1); + + zero_user_segments(page, 0, from, from + len, PAGE_CACHE_SIZE); + } + return 0; +} +EXPORT_SYMBOL(simple_write_begin); + +/** + * simple_write_end - .write_end helper for non-block-device FSes + * @available: See .write_end of address_space_operations + * @file: " + * @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. + */ +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 (copied < len) { + unsigned from = pos & (PAGE_CACHE_SIZE - 1); + + zero_user(page, from + copied, len - copied); + } + + if (!PageUptodate(page)) + 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); + page_cache_release(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, + struct tree_descr *files) +{ + 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 = &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->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->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, MS_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 = kmalloc(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) { /* 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; + u64 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'; + val = simple_strtoll(attr->set_buf, NULL, 0); + 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 = filemap_write_and_wait_range(inode->i_mapping, start, end); + if (err) + return err; + + mutex_lock(&inode->i_mutex); + 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: + mutex_unlock(&inode->i_mutex); + 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, NULL); +} +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_CACHE_SHIFT - blocksize_bits); + + if (unlikely(num_blocks == 0)) + return 0; + + if ((blocksize_bits < 9) || (blocksize_bits > PAGE_CACHE_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); + +void kfree_put_link(struct dentry *dentry, struct nameidata *nd, + void *cookie) +{ + char *s = nd_get_link(nd); + if (!IS_ERR(s)) + kfree(s); +} +EXPORT_SYMBOL(kfree_put_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; +}; + +/* + * A single inode exists for all anon_inode files. Contrary to pipes, + * anon_inode inodes have no associated per-instance data, so we need + * only allocate one of them. + */ +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; + 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); + + +/* + * 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(struct vfsmount *mnt, struct dentry *dentry, + struct kstat *stat) +{ + struct inode *inode = d_inode(dentry); + generic_fillattr(inode, stat); + return 0; +} + +static int empty_dir_setattr(struct dentry *dentry, struct iattr *attr) +{ + return -EPERM; +} + +static int empty_dir_setxattr(struct dentry *dentry, const char *name, + const void *value, size_t size, int flags) +{ + return -EOPNOTSUPP; +} + +static ssize_t empty_dir_getxattr(struct dentry *dentry, const char *name, + void *value, size_t size) +{ + return -EOPNOTSUPP; +} + +static int empty_dir_removexattr(struct dentry *dentry, const char *name) +{ + return -EOPNOTSUPP; +} + +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, + .setxattr = empty_dir_setxattr, + .getxattr = empty_dir_getxattr, + .removexattr = empty_dir_removexattr, + .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 = 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 = 2; + inode->i_blkbits = PAGE_SHIFT; + inode->i_blocks = 0; + + inode->i_op = &empty_dir_inode_operations; + 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); +} |