Example #1
0
static ssize_t unionfs_write(struct file *file, const char __user *buf,
			     size_t count, loff_t *ppos)
{
	int err = 0;
	struct file *lower_file;
	struct dentry *dentry = file->f_path.dentry;
	struct dentry *parent;

	unionfs_read_lock(dentry->d_sb, UNIONFS_SMUTEX_PARENT);
	parent = unionfs_lock_parent(dentry, UNIONFS_DMUTEX_PARENT);
	unionfs_lock_dentry(dentry, UNIONFS_DMUTEX_CHILD);

	err = unionfs_file_revalidate(file, parent, true);
	if (unlikely(err))
		goto out;

	lower_file = unionfs_lower_file(file);
	err = vfs_write(lower_file, buf, count, ppos);
	/* update our inode times+sizes upon a successful lower write */
	if (err >= 0) {
		fsstack_copy_inode_size(dentry->d_inode,
					lower_file->f_path.dentry->d_inode);
		fsstack_copy_attr_times(dentry->d_inode,
					lower_file->f_path.dentry->d_inode);
		UNIONFS_F(file)->wrote_to_file = true; /* for delayed copyup */
		unionfs_check_file(file);
	}

out:
	unionfs_unlock_dentry(dentry);
	unionfs_unlock_parent(dentry, parent);
	unionfs_read_unlock(dentry->d_sb);
	return err;
}
Example #2
0
static int unionfs_page_mkwrite(struct vm_area_struct *vma,
				struct vm_fault *vmf)
{
	int err = 0;
	struct file *file, *lower_file;
	const struct vm_operations_struct *lower_vm_ops;
	struct vm_area_struct lower_vma;

	BUG_ON(!vma);
	memcpy(&lower_vma, vma, sizeof(struct vm_area_struct));
	file = lower_vma.vm_file;
	lower_vm_ops = UNIONFS_F(file)->lower_vm_ops;
	BUG_ON(!lower_vm_ops);
	if (!lower_vm_ops->page_mkwrite)
		goto out;

	lower_file = unionfs_lower_file(file);
	BUG_ON(!lower_file);
	/*
	 * XXX: vm_ops->page_mkwrite may be called in parallel.
	 * Because we have to resort to temporarily changing the
	 * vma->vm_file to point to the lower file, a concurrent
	 * invocation of unionfs_page_mkwrite could see a different
	 * value.  In this workaround, we keep a different copy of the
	 * vma structure in our stack, so we never expose a different
	 * value of the vma->vm_file called to us, even temporarily.
	 * A better fix would be to change the calling semantics of
	 * ->page_mkwrite to take an explicit file pointer.
	 */
	lower_vma.vm_file = lower_file;
	err = lower_vm_ops->page_mkwrite(&lower_vma, vmf);
out:
	return err;
}
Example #3
0
static ssize_t unionfs_splice_write(struct pipe_inode_info *pipe,
				    struct file *file, loff_t *ppos,
				    size_t len, unsigned int flags)
{
	ssize_t err = 0;
	struct file *lower_file;
	struct dentry *dentry = file->f_path.dentry;
	struct dentry *parent;

	unionfs_read_lock(dentry->d_sb, UNIONFS_SMUTEX_PARENT);
	parent = unionfs_lock_parent(dentry, UNIONFS_DMUTEX_PARENT);
	unionfs_lock_dentry(dentry, UNIONFS_DMUTEX_CHILD);

	err = unionfs_file_revalidate(file, parent, true);
	if (unlikely(err))
		goto out;

	lower_file = unionfs_lower_file(file);
	err = vfs_splice_from(pipe, lower_file, ppos, len, flags);
	/* update our inode times+sizes upon a successful lower write */
	if (err >= 0) {
		fsstack_copy_inode_size(dentry->d_inode,
					lower_file->f_path.dentry->d_inode);
		fsstack_copy_attr_times(dentry->d_inode,
					lower_file->f_path.dentry->d_inode);
		unionfs_check_file(file);
	}

out:
	unionfs_unlock_dentry(dentry);
	unionfs_unlock_parent(dentry, parent);
	unionfs_read_unlock(dentry->d_sb);
	return err;
}
Example #4
0
static ssize_t unionfs_read(struct file *file, char __user *buf,
			    size_t count, loff_t *ppos)
{
	int err;
	struct file *lower_file;
	struct dentry *dentry = file->f_path.dentry;
	struct dentry *parent;

	unionfs_read_lock(dentry->d_sb, UNIONFS_SMUTEX_PARENT);
	parent = unionfs_lock_parent(dentry, UNIONFS_DMUTEX_PARENT);
	unionfs_lock_dentry(dentry, UNIONFS_DMUTEX_CHILD);

	err = unionfs_file_revalidate(file, parent, false);
	if (unlikely(err))
		goto out;

	lower_file = unionfs_lower_file(file);
	err = vfs_read(lower_file, buf, count, ppos);
	/* update our inode atime upon a successful lower read */
	if (err >= 0) {
		fsstack_copy_attr_atime(dentry->d_inode,
					lower_file->f_path.dentry->d_inode);
		unionfs_check_file(file);
	}

out:
	unionfs_unlock_dentry(dentry);
	unionfs_unlock_parent(dentry, parent);
	unionfs_read_unlock(dentry->d_sb);
	return err;
}
Example #5
0
/* pass the ioctl to the lower fs */
static long do_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
	struct file *lower_file;
	int err;

	lower_file = unionfs_lower_file(file);

	err = -ENOTTY;
	if (!lower_file || !lower_file->f_op)
		goto out;
	if (lower_file->f_op->unlocked_ioctl) {
		err = lower_file->f_op->unlocked_ioctl(lower_file, cmd, arg);
	} else if (lower_file->f_op->ioctl) {
		lock_kernel();
		err = lower_file->f_op->ioctl(
			lower_file->f_path.dentry->d_inode,
			lower_file, cmd, arg);
		unlock_kernel();
	}

out:
	return err;
}
Example #6
0
static int unionfs_setattr(struct dentry *dentry, struct iattr *ia)
{
	int err = 0;
	struct dentry *lower_dentry;
	struct dentry *parent;
	struct inode *inode;
	struct inode *lower_inode;
	int bstart, bend, bindex;
	loff_t size;
	struct iattr lower_ia;

	/* check if user has permission to change inode */
	err = inode_change_ok(dentry->d_inode, ia);
	if (err)
		goto out_err;

	unionfs_read_lock(dentry->d_sb, UNIONFS_SMUTEX_CHILD);
	parent = unionfs_lock_parent(dentry, UNIONFS_DMUTEX_PARENT);
	unionfs_lock_dentry(dentry, UNIONFS_DMUTEX_CHILD);

	if (unlikely(!__unionfs_d_revalidate(dentry, parent, false, 0))) {
		err = -ESTALE;
		goto out;
	}

	bstart = dbstart(dentry);
	bend = dbend(dentry);
	inode = dentry->d_inode;

	/*
	 * mode change is for clearing setuid/setgid. Allow lower filesystem
	 * to reinterpret it in its own way.
	 */
	if (ia->ia_valid & (ATTR_KILL_SUID | ATTR_KILL_SGID))
		ia->ia_valid &= ~ATTR_MODE;

	lower_dentry = unionfs_lower_dentry(dentry);
	if (!lower_dentry) { /* should never happen after above revalidate */
		err = -EINVAL;
		goto out;
	}

	/*
	 * Get the lower inode directly from lower dentry, in case ibstart
	 * is -1 (which happens when the file is open but unlinked.
	 */
	lower_inode = lower_dentry->d_inode;

	/* check if user has permission to change lower inode */
	err = inode_change_ok(lower_inode, ia);
	if (err)
		goto out;

	/* copyup if the file is on a read only branch */
	if (is_robranch_super(dentry->d_sb, bstart)
	    || __is_rdonly(lower_inode)) {
		/* check if we have a branch to copy up to */
		if (bstart <= 0) {
			err = -EACCES;
			goto out;
		}

		if (ia->ia_valid & ATTR_SIZE)
			size = ia->ia_size;
		else
			size = i_size_read(inode);
		/* copyup to next available branch */
		for (bindex = bstart - 1; bindex >= 0; bindex--) {
			err = copyup_dentry(parent->d_inode,
					    dentry, bstart, bindex,
					    dentry->d_name.name,
					    dentry->d_name.len,
					    NULL, size);
			if (!err)
				break;
		}
		if (err)
			goto out;
		/* get updated lower_dentry/inode after copyup */
		lower_dentry = unionfs_lower_dentry(dentry);
		lower_inode = unionfs_lower_inode(inode);
		/*
		 * check for whiteouts in writeable branch, and remove them
		 * if necessary.
		 */
		if (lower_dentry) {
			err = check_unlink_whiteout(dentry, lower_dentry,
						    bindex);
			if (err > 0) /* ignore if whiteout found and removed */
				err = 0;
		}
	}

	/*
	 * If shrinking, first truncate upper level to cancel writing dirty
	 * pages beyond the new eof; and also if its' maxbytes is more
	 * limiting (fail with -EFBIG before making any change to the lower
	 * level).  There is no need to vmtruncate the upper level
	 * afterwards in the other cases: we fsstack_copy_inode_size from
	 * the lower level.
	 */
	if (ia->ia_valid & ATTR_SIZE) {
		err = inode_newsize_ok(inode, ia->ia_size);
		if (err)
			goto out;
		truncate_setsize(inode, ia->ia_size);
	}

	/* notify the (possibly copied-up) lower inode */
	/*
	 * Note: we use lower_dentry->d_inode, because lower_inode may be
	 * unlinked (no inode->i_sb and i_ino==0.  This happens if someone
	 * tries to open(), unlink(), then ftruncate() a file.
	 */
	/* prepare our own lower struct iattr (with our own lower file) */
	memcpy(&lower_ia, ia, sizeof(lower_ia));
	if (ia->ia_valid & ATTR_FILE) {
		lower_ia.ia_file = unionfs_lower_file(ia->ia_file);
		BUG_ON(!lower_ia.ia_file); // XXX?
	}

	mutex_lock(&lower_dentry->d_inode->i_mutex);
	err = notify_change(lower_dentry, &lower_ia);
	mutex_unlock(&lower_dentry->d_inode->i_mutex);
	if (err)
		goto out;

	/* get attributes from the first lower inode */
	if (ibstart(inode) >= 0)
		unionfs_copy_attr_all(inode, lower_inode);
	/*
	 * unionfs_copy_attr_all will copy the lower times to our inode if
	 * the lower ones are newer (useful for cache coherency).  However,
	 * ->setattr is the only place in which we may have to copy the
	 * lower inode times absolutely, to support utimes(2).
	 */
	if (ia->ia_valid & ATTR_MTIME_SET)
		inode->i_mtime = lower_inode->i_mtime;
	if (ia->ia_valid & ATTR_CTIME)
		inode->i_ctime = lower_inode->i_ctime;
	if (ia->ia_valid & ATTR_ATIME_SET)
		inode->i_atime = lower_inode->i_atime;
	fsstack_copy_inode_size(inode, lower_inode);

out:
	if (!err)
		unionfs_check_dentry(dentry);
	unionfs_unlock_dentry(dentry);
	unionfs_unlock_parent(dentry, parent);
	unionfs_read_unlock(dentry->d_sb);
out_err:
	return err;
}
Example #7
0
/*
 * Helper function for unionfs_file_revalidate/locked.
 * Expects dentry/parent to be locked already, and revalidated.
 */
static int __unionfs_file_revalidate(struct file *file, struct dentry *dentry,
				     struct dentry *parent,
				     struct super_block *sb, int sbgen,
				     int dgen, bool willwrite)
{
	int fgen;
	int bstart, bend, orig_brid;
	int size;
	int err = 0;

	fgen = atomic_read(&UNIONFS_F(file)->generation);

	/*
	 * There are two cases we are interested in.  The first is if the
	 * generation is lower than the super-block.  The second is if
	 * someone has copied up this file from underneath us, we also need
	 * to refresh things.
	 */
	if (d_deleted(dentry) ||
	    (sbgen <= fgen &&
	     dbstart(dentry) == fbstart(file) &&
	     unionfs_lower_file(file)))
		goto out_may_copyup;

	/* save orig branch ID */
	orig_brid = UNIONFS_F(file)->saved_branch_ids[fbstart(file)];

	/* First we throw out the existing files. */
	cleanup_file(file);

	/* Now we reopen the file(s) as in unionfs_open. */
	bstart = fbstart(file) = dbstart(dentry);
	bend = fbend(file) = dbend(dentry);

	size = sizeof(struct file *) * sbmax(sb);
	UNIONFS_F(file)->lower_files = kzalloc(size, GFP_KERNEL);
	if (unlikely(!UNIONFS_F(file)->lower_files)) {
		err = -ENOMEM;
		goto out;
	}
	size = sizeof(int) * sbmax(sb);
	UNIONFS_F(file)->saved_branch_ids = kzalloc(size, GFP_KERNEL);
	if (unlikely(!UNIONFS_F(file)->saved_branch_ids)) {
		err = -ENOMEM;
		goto out;
	}

	if (S_ISDIR(dentry->d_inode->i_mode)) {
		/* We need to open all the files. */
		err = open_all_files(file);
		if (err)
			goto out;
	} else {
		int new_brid;
		/* We only open the highest priority branch. */
		err = open_highest_file(file, willwrite);
		if (err)
			goto out;
		new_brid = UNIONFS_F(file)->saved_branch_ids[fbstart(file)];
		if (unlikely(new_brid != orig_brid && sbgen > fgen)) {
			/*
			 * If we re-opened the file on a different branch
			 * than the original one, and this was due to a new
			 * branch inserted, then update the mnt counts of
			 * the old and new branches accordingly.
			 */
			unionfs_mntget(dentry, bstart);
			unionfs_mntput(sb->s_root,
				       branch_id_to_idx(sb, orig_brid));
		}
		/* regular files have only one open lower file */
		fbend(file) = fbstart(file);
	}
	atomic_set(&UNIONFS_F(file)->generation,
		   atomic_read(&UNIONFS_I(dentry->d_inode)->generation));

out_may_copyup:
	/* Copyup on the first write to a file on a readonly branch. */
	if (willwrite && IS_WRITE_FLAG(file->f_flags) &&
	    !IS_WRITE_FLAG(unionfs_lower_file(file)->f_flags) &&
	    is_robranch(dentry)) {
		pr_debug("unionfs: do delay copyup of \"%s\"\n",
			 dentry->d_name.name);
		err = do_delayed_copyup(file, parent);
		/* regular files have only one open lower file */
		if (!err && !S_ISDIR(dentry->d_inode->i_mode))
			fbend(file) = fbstart(file);
	}

out:
	if (err) {
		kfree(UNIONFS_F(file)->lower_files);
		kfree(UNIONFS_F(file)->saved_branch_ids);
	}
	return err;
}
Example #8
0
static int unionfs_mmap(struct file *file, struct vm_area_struct *vma)
{
	int err = 0;
	bool willwrite;
	struct file *lower_file;
	struct dentry *dentry = file->f_path.dentry;
	struct dentry *parent;
	struct vm_operations_struct *saved_vm_ops = NULL;

	unionfs_read_lock(dentry->d_sb, UNIONFS_SMUTEX_PARENT);
	parent = unionfs_lock_parent(dentry, UNIONFS_DMUTEX_PARENT);
	unionfs_lock_dentry(dentry, UNIONFS_DMUTEX_CHILD);

	/* This might be deferred to mmap's writepage */
	willwrite = ((vma->vm_flags | VM_SHARED | VM_WRITE) == vma->vm_flags);
	err = unionfs_file_revalidate(file, parent, willwrite);
	if (unlikely(err))
		goto out;
	unionfs_check_file(file);

	/*
	 * File systems which do not implement ->writepage may use
	 * generic_file_readonly_mmap as their ->mmap op.  If you call
	 * generic_file_readonly_mmap with VM_WRITE, you'd get an -EINVAL.
	 * But we cannot call the lower ->mmap op, so we can't tell that
	 * writeable mappings won't work.  Therefore, our only choice is to
	 * check if the lower file system supports the ->writepage, and if
	 * not, return EINVAL (the same error that
	 * generic_file_readonly_mmap returns in that case).
	 */
	lower_file = unionfs_lower_file(file);
	if (willwrite && !lower_file->f_mapping->a_ops->writepage) {
		err = -EINVAL;
		printk(KERN_ERR "unionfs: branch %d file system does not "
		       "support writeable mmap\n", fbstart(file));
		goto out;
	}

	/*
	 * find and save lower vm_ops.
	 *
	 * XXX: the VFS should have a cleaner way of finding the lower vm_ops
	 */
	if (!UNIONFS_F(file)->lower_vm_ops) {
		err = lower_file->f_op->mmap(lower_file, vma);
		if (err) {
			printk(KERN_ERR "unionfs: lower mmap failed %d\n", err);
			goto out;
		}
		saved_vm_ops = vma->vm_ops;
		err = do_munmap(current->mm, vma->vm_start,
				vma->vm_end - vma->vm_start);
		if (err) {
			printk(KERN_ERR "unionfs: do_munmap failed %d\n", err);
			goto out;
		}
	}

	file->f_mapping->a_ops = &unionfs_dummy_aops;
	err = generic_file_mmap(file, vma);
	file->f_mapping->a_ops = &unionfs_aops;
	if (err) {
		printk(KERN_ERR "unionfs: generic_file_mmap failed %d\n", err);
		goto out;
	}
	vma->vm_ops = &unionfs_vm_ops;
	if (!UNIONFS_F(file)->lower_vm_ops)
		UNIONFS_F(file)->lower_vm_ops = saved_vm_ops;

out:
	if (!err) {
		/* copyup could cause parent dir times to change */
		unionfs_copy_attr_times(parent->d_inode);
		unionfs_check_file(file);
	}
	unionfs_unlock_dentry(dentry);
	unionfs_unlock_parent(dentry, parent);
	unionfs_read_unlock(dentry->d_sb);
	return err;
}