/*
 * file.c
 *
 * PURPOSE
 *  File handling routines for the OSTA-UDF(tm) filesystem.
 *
 * COPYRIGHT
 *  This file is distributed under the terms of the GNU General Public
 *  License (GPL). Copies of the GPL can be obtained from:
 *    ftp://prep.ai.mit.edu/pub/gnu/GPL
 *  Each contributing author retains all rights to their own work.
 *
 *  (C) 1998-1999 Dave Boynton
 *  (C) 1998-2004 Ben Fennema
 *  (C) 1999-2000 Stelias Computing Inc
 *
 * HISTORY
 *
 *  10/02/98 dgb  Attempt to integrate into udf.o
 *  10/07/98      Switched to using generic_readpage, etc., like isofs
 *                And it works!
 *  12/06/98 blf  Added udf_file_read. uses generic_file_read for all cases but
 *                ICBTAG_FLAG_AD_IN_ICB.
 *  04/06/99      64 bit file handling on 32 bit systems taken from ext2 file.c
 *  05/12/99      Preliminary file write support
 */

#include "udfdecl.h"
#include <linux/fs.h>
#include <linux/uaccess.h>
#include <linux/kernel.h>
#include <linux/string.h> /* memset */
#include <linux/capability.h>
#include <linux/errno.h>
#include <linux/pagemap.h>
#include <linux/uio.h>

#include "udf_i.h"
#include "udf_sb.h"

static void __udf_adinicb_readpage(struct page *page)
{
        struct inode *inode = page->mapping->host;
        char *kaddr;
        struct udf_inode_info *iinfo = UDF_I(inode);
        loff_t isize = i_size_read(inode);

        /*
         * We have to be careful here as truncate can change i_size under us.
         * So just sample it once and use the same value everywhere.
         */
        kaddr = kmap_atomic(page);
        memcpy(kaddr, iinfo->i_ext.i_data + iinfo->i_lenEAttr, isize);
        memset(kaddr + isize, 0, PAGE_SIZE - isize);
        flush_dcache_page(page);
        SetPageUptodate(page);
        kunmap_atomic(kaddr);
}

static int udf_adinicb_readpage(struct file *file, struct page *page)
{
        BUG_ON(!PageLocked(page));
        __udf_adinicb_readpage(page);
        unlock_page(page);

        return 0;
}

static int udf_adinicb_writepage(struct page *page,
                                 struct writeback_control *wbc)
{
        struct inode *inode = page->mapping->host;
        char *kaddr;
        struct udf_inode_info *iinfo = UDF_I(inode);

        BUG_ON(!PageLocked(page));

        kaddr = kmap_atomic(page);
        memcpy(iinfo->i_ext.i_data + iinfo->i_lenEAttr, kaddr,
                i_size_read(inode));
        SetPageUptodate(page);
        kunmap_atomic(kaddr);
        mark_inode_dirty(inode);
        unlock_page(page);

        return 0;
}

static int udf_adinicb_write_begin(struct file *file,
                        struct address_space *mapping, loff_t pos,
                        unsigned len, unsigned flags, struct page **pagep,
                        void **fsdata)
{
        struct page *page;

        if (WARN_ON_ONCE(pos >= PAGE_SIZE))
                return -EIO;
        page = grab_cache_page_write_begin(mapping, 0, flags);
        if (!page)
                return -ENOMEM;
        *pagep = page;

        if (!PageUptodate(page))
                __udf_adinicb_readpage(page);
        return 0;
}

static ssize_t udf_adinicb_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
{
        /* Fallback to buffered I/O. */
        return 0;
}

static int udf_adinicb_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;
        if (last_pos > inode->i_size)
                i_size_write(inode, last_pos);
        set_page_dirty(page);
        unlock_page(page);
        put_page(page);
        return copied;
}

const struct address_space_operations udf_adinicb_aops = {
        .readpage       = udf_adinicb_readpage,
        .writepage      = udf_adinicb_writepage,
        .write_begin    = udf_adinicb_write_begin,
        .write_end      = udf_adinicb_write_end,
        .direct_IO      = udf_adinicb_direct_IO,
};

static ssize_t udf_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
{
        ssize_t retval;
        struct file *file = iocb->ki_filp;
        struct inode *inode = file_inode(file);
        struct udf_inode_info *iinfo = UDF_I(inode);
        int err;

        inode_lock(inode);

        retval = generic_write_checks(iocb, from);
        if (retval <= 0)
                goto out;

        down_write(&iinfo->i_data_sem);
        if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_IN_ICB) {
                loff_t end = iocb->ki_pos + iov_iter_count(from);

                if (inode->i_sb->s_blocksize <
                                (udf_file_entry_alloc_offset(inode) + end)) {
                        err = udf_expand_file_adinicb(inode);
                        if (err) {
                                inode_unlock(inode);
                                udf_debug("udf_expand_adinicb: err=%d\n", err);
                                return err;
                        }
                } else {
                        iinfo->i_lenAlloc = max(end, inode->i_size);
                        up_write(&iinfo->i_data_sem);
                }
        } else
                up_write(&iinfo->i_data_sem);

        retval = __generic_file_write_iter(iocb, from);
out:
        inode_unlock(inode);

        if (retval > 0) {
                mark_inode_dirty(inode);
                retval = generic_write_sync(iocb, retval);
        }

        return retval;
}

long udf_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
{
        struct inode *inode = file_inode(filp);
        long old_block, new_block;
        int result;

        if (inode_permission(inode, MAY_READ) != 0) {
                udf_debug("no permission to access inode %lu\n", inode->i_ino);
                return -EPERM;
        }

        if (!arg && ((cmd == UDF_GETVOLIDENT) || (cmd == UDF_GETEASIZE) ||
                     (cmd == UDF_RELOCATE_BLOCKS) || (cmd == UDF_GETEABLOCK))) {
                udf_debug("invalid argument to udf_ioctl\n");
                return -EINVAL;
        }

        switch (cmd) {
        case UDF_GETVOLIDENT:
                if (copy_to_user((char __user *)arg,
                                 UDF_SB(inode->i_sb)->s_volume_ident, 32))
                        return -EFAULT;
                return 0;
        case UDF_RELOCATE_BLOCKS:
                if (!capable(CAP_SYS_ADMIN))
                        return -EPERM;
                if (get_user(old_block, (long __user *)arg))
                        return -EFAULT;
                result = udf_relocate_blocks(inode->i_sb,
                                                old_block, &new_block);
                if (result == 0)
                        result = put_user(new_block, (long __user *)arg);
                return result;
        case UDF_GETEASIZE:
                return put_user(UDF_I(inode)->i_lenEAttr, (int __user *)arg);
        case UDF_GETEABLOCK:
                return copy_to_user((char __user *)arg,
                                    UDF_I(inode)->i_ext.i_data,
                                    UDF_I(inode)->i_lenEAttr) ? -EFAULT : 0;
        default:
                return -ENOIOCTLCMD;
        }

        return 0;
}

static int udf_release_file(struct inode *inode, struct file *filp)
{
        if (filp->f_mode & FMODE_WRITE &&
            atomic_read(&inode->i_writecount) == 1) {
                /*
                 * Grab i_mutex to avoid races with writes changing i_size
                 * while we are running.
                 */
                inode_lock(inode);
                down_write(&UDF_I(inode)->i_data_sem);
                udf_discard_prealloc(inode);
                udf_truncate_tail_extent(inode);
                up_write(&UDF_I(inode)->i_data_sem);
                inode_unlock(inode);
        }
        return 0;
}

const struct file_operations udf_file_operations = {
        .read_iter              = generic_file_read_iter,
        .unlocked_ioctl         = udf_ioctl,
        .open                   = generic_file_open,
        .mmap                   = generic_file_mmap,
        .write_iter             = udf_file_write_iter,
        .release                = udf_release_file,
        .fsync                  = generic_file_fsync,
        .splice_read            = generic_file_splice_read,
        .llseek                 = generic_file_llseek,
};

static int udf_setattr(struct dentry *dentry, struct iattr *attr)
{
        struct inode *inode = d_inode(dentry);
        int error;

        error = setattr_prepare(dentry, attr);
        if (error)
                return error;

        if ((attr->ia_valid & ATTR_SIZE) &&
            attr->ia_size != i_size_read(inode)) {
                error = udf_setsize(inode, attr->ia_size);
                if (error)
                        return error;
        }

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

const struct inode_operations udf_file_inode_operations = {
        .setattr                = udf_setattr,
};