fs/logfs/file.c - kernel/lockdown - Git at Google

 /*
  * fs/logfs/file.c	- prepare_write, commit_write and friends
  *
  * As should be obvious for Linux kernel code, license is GPLv2
  *
  * Copyright (c) 2005-2008 Joern Engel <joern@logfs.org>
  */
 #include "logfs.h"
 #include <linux/sched.h>
 #include <linux/writeback.h>

 static int logfs_write_begin(struct file *file, struct address_space *mapping,
 		loff_t pos, unsigned len, unsigned flags,
 		struct page **pagep, void **fsdata)
 {
 	struct inode *inode = mapping->host;
 	struct page *page;
 	pgoff_t index = pos >> PAGE_CACHE_SHIFT;

 	page = grab_cache_page_write_begin(mapping, index, flags);
 	if (!page)
 		return -ENOMEM;
 	*pagep = page;

 	if ((len == PAGE_CACHE_SIZE) || PageUptodate(page))
 		return 0;
 	if ((pos & PAGE_CACHE_MASK) >= i_size_read(inode)) {
 		unsigned start = pos & (PAGE_CACHE_SIZE - 1);
 		unsigned end = start + len;

 		/* Reading beyond i_size is simple: memset to zero */
 		zero_user_segments(page, 0, start, end, PAGE_CACHE_SIZE);
 		return 0;
 	}
 	return logfs_readpage_nolock(page);
 }

 static int logfs_write_end(struct file *file, struct address_space *mapping,
 		loff_t pos, unsigned len, unsigned copied, struct page *page,
 		void *fsdata)
 {
 	struct inode *inode = mapping->host;
 	pgoff_t index = page->index;
 	unsigned start = pos & (PAGE_CACHE_SIZE - 1);
 	unsigned end = start + copied;
 	int ret = 0;

 	BUG_ON(PAGE_CACHE_SIZE != inode->i_sb->s_blocksize);
 	BUG_ON(page->index > I3_BLOCKS);

 	if (copied < len) {
 		/*
 		 * Short write of a non-initialized paged.  Just tell userspace
 		 * to retry the entire page.
 		 */
 		if (!PageUptodate(page)) {
 			copied = 0;
 			goto out;
 		}
 	}
 	if (copied == 0)
 		goto out; /* FIXME: do we need to update inode? */

 	if (i_size_read(inode) < (index << PAGE_CACHE_SHIFT) + end) {
 		i_size_write(inode, (index << PAGE_CACHE_SHIFT) + end);
 		mark_inode_dirty_sync(inode);
 	}

 	SetPageUptodate(page);
 	if (!PageDirty(page)) {
 		if (!get_page_reserve(inode, page))
 			__set_page_dirty_nobuffers(page);
 		else
 			ret = logfs_write_buf(inode, page, WF_LOCK);
 	}
 out:
 	unlock_page(page);
 	page_cache_release(page);
 	return ret ? ret : copied;
 }

 int logfs_readpage(struct file *file, struct page *page)
 {
 	int ret;

 	ret = logfs_readpage_nolock(page);
 	unlock_page(page);
 	return ret;
 }

 /* Clear the page's dirty flag in the radix tree. */
 /* TODO: mucking with PageWriteback is silly.  Add a generic function to clear
  * the dirty bit from the radix tree for filesystems that don't have to wait
  * for page writeback to finish (i.e. any compressing filesystem).
  */
 static void clear_radix_tree_dirty(struct page *page)
 {
 	BUG_ON(PagePrivate(page) || page->private);
 	set_page_writeback(page);
 	end_page_writeback(page);
 }

 static int __logfs_writepage(struct page *page)
 {
 	struct inode *inode = page->mapping->host;
 	int err;

 	err = logfs_write_buf(inode, page, WF_LOCK);
 	if (err)
 		set_page_dirty(page);
 	else
 		clear_radix_tree_dirty(page);
 	unlock_page(page);
 	return err;
 }

 static int logfs_writepage(struct page *page, struct writeback_control *wbc)
 {
 	struct inode *inode = page->mapping->host;
 	loff_t i_size = i_size_read(inode);
 	pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
 	unsigned offset;
 	u64 bix;
 	level_t level;

 	log_file("logfs_writepage(%lx, %lx, %p)\n", inode->i_ino, page->index,
 			page);

 	logfs_unpack_index(page->index, &bix, &level);

 	/* Indirect blocks are never truncated */
 	if (level != 0)
 		return __logfs_writepage(page);

 	/*
 	 * TODO: everything below is a near-verbatim copy of nobh_writepage().
 	 * The relevant bits should be factored out after logfs is merged.
 	 */

 	/* Is the page fully inside i_size? */
 	if (bix < end_index)
 		return __logfs_writepage(page);

 	 /* Is the page fully outside i_size? (truncate in progress) */
 	offset = i_size & (PAGE_CACHE_SIZE-1);
 	if (bix > end_index || offset == 0) {
 		unlock_page(page);
 		return 0; /* don't care */
 	}

 	/*
 	 * The page straddles i_size.  It must be zeroed out on each and every
 	 * writepage invokation because it may be mmapped.  "A file is mapped
 	 * in multiples of the page size.  For a file that is not a multiple of
 	 * the  page size, the remaining memory is zeroed when mapped, and
 	 * writes to that region are not written out to the file."
 	 */
 	zero_user_segment(page, offset, PAGE_CACHE_SIZE);
 	return __logfs_writepage(page);
 }

 static void logfs_invalidatepage(struct page *page, unsigned int offset,
 				 unsigned int length)
 {
 	struct logfs_block *block = logfs_block(page);

 	if (block->reserved_bytes) {
 		struct super_block *sb = page->mapping->host->i_sb;
 		struct logfs_super *super = logfs_super(sb);

 		super->s_dirty_pages -= block->reserved_bytes;
 		block->ops->free_block(sb, block);
 		BUG_ON(bitmap_weight(block->alias_map, LOGFS_BLOCK_FACTOR));
 	} else
 		move_page_to_btree(page);
 	BUG_ON(PagePrivate(page) || page->private);
 }

 static int logfs_releasepage(struct page *page, gfp_t only_xfs_uses_this)
 {
 	return 0; /* None of these are easy to release */
 }


 long logfs_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 {
 	struct inode *inode = file_inode(file);
 	struct logfs_inode *li = logfs_inode(inode);
 	unsigned int oldflags, flags;
 	int err;

 	switch (cmd) {
 	case FS_IOC_GETFLAGS:
 		flags = li->li_flags & LOGFS_FL_USER_VISIBLE;
 		return put_user(flags, (int __user *)arg);
 	case FS_IOC_SETFLAGS:
 		if (IS_RDONLY(inode))
 			return -EROFS;

 		if (!inode_owner_or_capable(inode))
 			return -EACCES;

 		err = get_user(flags, (int __user *)arg);
 		if (err)
 			return err;

 		mutex_lock(&inode->i_mutex);
 		oldflags = li->li_flags;
 		flags &= LOGFS_FL_USER_MODIFIABLE;
 		flags |= oldflags & ~LOGFS_FL_USER_MODIFIABLE;
 		li->li_flags = flags;
 		mutex_unlock(&inode->i_mutex);

 		inode->i_ctime = CURRENT_TIME;
 		mark_inode_dirty_sync(inode);
 		return 0;

 	default:
 		return -ENOTTY;
 	}
 }

 int logfs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
 {
 	struct super_block *sb = file->f_mapping->host->i_sb;
 	struct inode *inode = file->f_mapping->host;
 	int ret;

 	ret = filemap_write_and_wait_range(inode->i_mapping, start, end);
 	if (ret)
 		return ret;

 	mutex_lock(&inode->i_mutex);
 	logfs_get_wblocks(sb, NULL, WF_LOCK);
 	logfs_write_anchor(sb);
 	logfs_put_wblocks(sb, NULL, WF_LOCK);
 	mutex_unlock(&inode->i_mutex);

 	return 0;
 }

 static int logfs_setattr(struct dentry *dentry, struct iattr *attr)
 {
 	struct inode *inode = dentry->d_inode;
 	int err = 0;

 	err = inode_change_ok(inode, attr);
 	if (err)
 		return err;

 	if (attr->ia_valid & ATTR_SIZE) {
 		err = logfs_truncate(inode, attr->ia_size);
 		if (err)
 			return err;
 	}

 	setattr_copy(inode, attr);
 	mark_inode_dirty(inode);
 	return 0;
 }

 const struct inode_operations logfs_reg_iops = {
 	.setattr	= logfs_setattr,
 };

 const struct file_operations logfs_reg_fops = {
 	.aio_read	= generic_file_aio_read,
 	.aio_write	= generic_file_aio_write,
 	.fsync		= logfs_fsync,
 	.unlocked_ioctl	= logfs_ioctl,
 	.llseek		= generic_file_llseek,
 	.mmap		= generic_file_readonly_mmap,
 	.open		= generic_file_open,
 	.read		= do_sync_read,
 	.write		= do_sync_write,
 };

 const struct address_space_operations logfs_reg_aops = {
 	.invalidatepage	= logfs_invalidatepage,
 	.readpage	= logfs_readpage,
 	.releasepage	= logfs_releasepage,
 	.set_page_dirty	= __set_page_dirty_nobuffers,
 	.writepage	= logfs_writepage,
 	.writepages	= generic_writepages,
 	.write_begin	= logfs_write_begin,
 	.write_end	= logfs_write_end,
 };
	/*
	* fs/logfs/file.c - prepare_write, commit_write and friends
	*
	* As should be obvious for Linux kernel code, license is GPLv2
	*
	* Copyright (c) 2005-2008 Joern Engel <joern@logfs.org>
	*/
	#include "logfs.h"
	#include <linux/sched.h>
	#include <linux/writeback.h>

	static int logfs_write_begin(struct file file, struct address_space mapping,
	loff_t pos, unsigned len, unsigned flags,
	struct page pagep, void fsdata)
	{
	struct inode *inode = mapping->host;
	struct page *page;
	pgoff_t index = pos >> PAGE_CACHE_SHIFT;

	page = grab_cache_page_write_begin(mapping, index, flags);
	if (!page)
	return -ENOMEM;
	*pagep = page;

	if ((len == PAGE_CACHE_SIZE) \|\| PageUptodate(page))
	return 0;
	if ((pos & PAGE_CACHE_MASK) >= i_size_read(inode)) {
	unsigned start = pos & (PAGE_CACHE_SIZE - 1);
	unsigned end = start + len;

	/* Reading beyond i_size is simple: memset to zero */
	zero_user_segments(page, 0, start, end, PAGE_CACHE_SIZE);
	return 0;
	}
	return logfs_readpage_nolock(page);
	}

	static int logfs_write_end(struct file file, struct address_space mapping,
	loff_t pos, unsigned len, unsigned copied, struct page *page,
	void *fsdata)
	{
	struct inode *inode = mapping->host;
	pgoff_t index = page->index;
	unsigned start = pos & (PAGE_CACHE_SIZE - 1);
	unsigned end = start + copied;
	int ret = 0;

	BUG_ON(PAGE_CACHE_SIZE != inode->i_sb->s_blocksize);
	BUG_ON(page->index > I3_BLOCKS);

	if (copied < len) {
	/*
	* Short write of a non-initialized paged. Just tell userspace
	* to retry the entire page.
	*/
	if (!PageUptodate(page)) {
	copied = 0;
	goto out;
	}
	}
	if (copied == 0)
	goto out; /* FIXME: do we need to update inode? */

	if (i_size_read(inode) < (index << PAGE_CACHE_SHIFT) + end) {
	i_size_write(inode, (index << PAGE_CACHE_SHIFT) + end);
	mark_inode_dirty_sync(inode);
	}

	SetPageUptodate(page);
	if (!PageDirty(page)) {
	if (!get_page_reserve(inode, page))
	__set_page_dirty_nobuffers(page);
	else
	ret = logfs_write_buf(inode, page, WF_LOCK);
	}
	out:
	unlock_page(page);
	page_cache_release(page);
	return ret ? ret : copied;
	}

	int logfs_readpage(struct file file, struct page page)
	{
	int ret;

	ret = logfs_readpage_nolock(page);
	unlock_page(page);
	return ret;
	}

	/* Clear the page's dirty flag in the radix tree. */
	/* TODO: mucking with PageWriteback is silly. Add a generic function to clear
	* the dirty bit from the radix tree for filesystems that don't have to wait
	* for page writeback to finish (i.e. any compressing filesystem).
	*/
	static void clear_radix_tree_dirty(struct page *page)
	{
	BUG_ON(PagePrivate(page) \|\| page->private);
	set_page_writeback(page);
	end_page_writeback(page);
	}

	static int __logfs_writepage(struct page *page)
	{
	struct inode *inode = page->mapping->host;
	int err;

	err = logfs_write_buf(inode, page, WF_LOCK);
	if (err)
	set_page_dirty(page);
	else
	clear_radix_tree_dirty(page);
	unlock_page(page);
	return err;
	}

	static int logfs_writepage(struct page page, struct writeback_control wbc)
	{
	struct inode *inode = page->mapping->host;
	loff_t i_size = i_size_read(inode);
	pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
	unsigned offset;
	u64 bix;
	level_t level;

	log_file("logfs_writepage(%lx, %lx, %p)\n", inode->i_ino, page->index,
	page);

	logfs_unpack_index(page->index, &bix, &level);

	/* Indirect blocks are never truncated */
	if (level != 0)
	return __logfs_writepage(page);

	/*
	* TODO: everything below is a near-verbatim copy of nobh_writepage().
	* The relevant bits should be factored out after logfs is merged.
	*/

	/* Is the page fully inside i_size? */
	if (bix < end_index)
	return __logfs_writepage(page);

	/* Is the page fully outside i_size? (truncate in progress) */
	offset = i_size & (PAGE_CACHE_SIZE-1);
	if (bix > end_index \|\| offset == 0) {
	unlock_page(page);
	return 0; /* don't care */
	}

	/*
	* The page straddles i_size. It must be zeroed out on each and every
	* writepage invokation because it may be mmapped. "A file is mapped
	* in multiples of the page size. For a file that is not a multiple of
	* the page size, the remaining memory is zeroed when mapped, and
	* writes to that region are not written out to the file."
	*/
	zero_user_segment(page, offset, PAGE_CACHE_SIZE);
	return __logfs_writepage(page);
	}

	static void logfs_invalidatepage(struct page *page, unsigned int offset,
	unsigned int length)
	{
	struct logfs_block *block = logfs_block(page);

	if (block->reserved_bytes) {
	struct super_block *sb = page->mapping->host->i_sb;
	struct logfs_super *super = logfs_super(sb);

	super->s_dirty_pages -= block->reserved_bytes;
	block->ops->free_block(sb, block);
	BUG_ON(bitmap_weight(block->alias_map, LOGFS_BLOCK_FACTOR));
	} else
	move_page_to_btree(page);
	BUG_ON(PagePrivate(page) \|\| page->private);
	}

	static int logfs_releasepage(struct page *page, gfp_t only_xfs_uses_this)
	{
	return 0; /* None of these are easy to release */
	}


	long logfs_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
	{
	struct inode *inode = file_inode(file);
	struct logfs_inode *li = logfs_inode(inode);
	unsigned int oldflags, flags;
	int err;

	switch (cmd) {
	case FS_IOC_GETFLAGS:
	flags = li->li_flags & LOGFS_FL_USER_VISIBLE;
	return put_user(flags, (int __user *)arg);
	case FS_IOC_SETFLAGS:
	if (IS_RDONLY(inode))
	return -EROFS;

	if (!inode_owner_or_capable(inode))
	return -EACCES;

	err = get_user(flags, (int __user *)arg);
	if (err)
	return err;

	mutex_lock(&inode->i_mutex);
	oldflags = li->li_flags;
	flags &= LOGFS_FL_USER_MODIFIABLE;
	flags \|= oldflags & ~LOGFS_FL_USER_MODIFIABLE;
	li->li_flags = flags;
	mutex_unlock(&inode->i_mutex);

	inode->i_ctime = CURRENT_TIME;
	mark_inode_dirty_sync(inode);
	return 0;

	default:
	return -ENOTTY;
	}
	}

	int logfs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
	{
	struct super_block *sb = file->f_mapping->host->i_sb;
	struct inode *inode = file->f_mapping->host;
	int ret;

	ret = filemap_write_and_wait_range(inode->i_mapping, start, end);
	if (ret)
	return ret;

	mutex_lock(&inode->i_mutex);
	logfs_get_wblocks(sb, NULL, WF_LOCK);
	logfs_write_anchor(sb);
	logfs_put_wblocks(sb, NULL, WF_LOCK);
	mutex_unlock(&inode->i_mutex);

	return 0;
	}

	static int logfs_setattr(struct dentry dentry, struct iattr attr)
	{
	struct inode *inode = dentry->d_inode;
	int err = 0;

	err = inode_change_ok(inode, attr);
	if (err)
	return err;

	if (attr->ia_valid & ATTR_SIZE) {
	err = logfs_truncate(inode, attr->ia_size);
	if (err)
	return err;
	}

	setattr_copy(inode, attr);
	mark_inode_dirty(inode);
	return 0;
	}

	const struct inode_operations logfs_reg_iops = {
	.setattr = logfs_setattr,
	};

	const struct file_operations logfs_reg_fops = {
	.aio_read = generic_file_aio_read,
	.aio_write = generic_file_aio_write,
	.fsync = logfs_fsync,
	.unlocked_ioctl = logfs_ioctl,
	.llseek = generic_file_llseek,
	.mmap = generic_file_readonly_mmap,
	.open = generic_file_open,
	.read = do_sync_read,
	.write = do_sync_write,
	};

	const struct address_space_operations logfs_reg_aops = {
	.invalidatepage = logfs_invalidatepage,
	.readpage = logfs_readpage,
	.releasepage = logfs_releasepage,
	.set_page_dirty = __set_page_dirty_nobuffers,
	.writepage = logfs_writepage,
	.writepages = generic_writepages,
	.write_begin = logfs_write_begin,
	.write_end = logfs_write_end,
	};