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/*
* fs/bfs/file.c
* BFS file operations.
* Copyright (C) 1999,2000 Tigran Aivazian <tigran@veritas.com>
*
* Make the file block allocation algorithm understand the size
* of the underlying block device.
* Copyright (C) 2007 Dmitri Vorobiev <dmitri.vorobiev@gmail.com>
*
*/
#include <linux/fs.h>
#include <linux/buffer_head.h>
#include "bfs.h"
#undef DEBUG
#ifdef DEBUG
#define dprintf(x...) printf(x)
#else
#define dprintf(x...)
#endif
const struct file_operations bfs_file_operations = {
.llseek = generic_file_llseek,
.read_iter = generic_file_read_iter,
.write_iter = generic_file_write_iter,
.mmap = generic_file_mmap,
.splice_read = generic_file_splice_read,
};
static int bfs_move_block(unsigned long from, unsigned long to,
struct super_block *sb)
{
struct buffer_head *bh, *new;
bh = sb_bread(sb, from);
if (!bh)
return -EIO;
new = sb_getblk(sb, to);
memcpy(new->b_data, bh->b_data, bh->b_size);
mark_buffer_dirty(new);
bforget(bh);
brelse(new);
return 0;
}
static int bfs_move_blocks(struct super_block *sb, unsigned long start,
unsigned long end, unsigned long where)
{
unsigned long i;
dprintf("%08lx-%08lx->%08lx\n", start, end, where);
for (i = start; i <= end; i++)
if(bfs_move_block(i, where + i, sb)) {
dprintf("failed to move block %08lx -> %08lx\n", i,
where + i);
return -EIO;
}
return 0;
}
static int bfs_get_block(struct inode *inode, sector_t block,
struct buffer_head *bh_result, int create)
{
unsigned long phys;
int err;
struct super_block *sb = inode->i_sb;
struct bfs_sb_info *info = BFS_SB(sb);
struct bfs_inode_info *bi = BFS_I(inode);
phys = bi->i_sblock + block;
if (!create) {
if (phys <= bi->i_eblock) {
dprintf("c=%d, b=%08lx, phys=%09lx (granted)\n",
create, (unsigned long)block, phys);
map_bh(bh_result, sb, phys);
}
return 0;
}
/*
* If the file is not empty and the requested block is within the
* range of blocks allocated for this file, we can grant it.
*/
if (bi->i_sblock && (phys <= bi->i_eblock)) {
dprintf("c=%d, b=%08lx, phys=%08lx (interim block granted)\n",
create, (unsigned long)block, phys);
map_bh(bh_result, sb, phys);
return 0;
}
/* The file will be extended, so let's see if there is enough space. */
if (phys >= info->si_blocks)
return -ENOSPC;
/* The rest has to be protected against itself. */
mutex_lock(&info->bfs_lock);
/*
* If the last data block for this file is the last allocated
* block, we can extend the file trivially, without moving it
* anywhere.
*/
if (bi->i_eblock == info->si_lf_eblk) {
dprintf("c=%d, b=%08lx, phys=%08lx (simple extension)\n",
create, (unsigned long)block, phys);
map_bh(bh_result, sb, phys);
info->si_freeb -= phys - bi->i_eblock;
info->si_lf_eblk = bi->i_eblock = phys;
mark_inode_dirty(inode);
err = 0;
goto out;
}
/* Ok, we have to move this entire file to the next free block. */
phys = info->si_lf_eblk + 1;
if (phys + block >= info->si_blocks) {
err = -ENOSPC;
goto out;
}
if (bi->i_sblock) {
err = bfs_move_blocks(inode->i_sb, bi->i_sblock,
bi->i_eblock, phys);
if (err) {
dprintf("failed to move ino=%08lx -> fs corruption\n",
inode->i_ino);
goto out;
}
} else
err = 0;
dprintf("c=%d, b=%08lx, phys=%08lx (moved)\n",
create, (unsigned long)block, phys);
bi->i_sblock = phys;
phys += block;
info->si_lf_eblk = bi->i_eblock = phys;
/*
* This assumes nothing can write the inode back while we are here
* and thus update inode->i_blocks! (XXX)
*/
info->si_freeb -= bi->i_eblock - bi->i_sblock + 1 - inode->i_blocks;
mark_inode_dirty(inode);
map_bh(bh_result, sb, phys);
out:
mutex_unlock(&info->bfs_lock);
return err;
}
static int bfs_writepage(struct page *page, struct writeback_control *wbc)
{
return block_write_full_page(page, bfs_get_block, wbc);
}
static int bfs_readpage(struct file *file, struct page *page)
{
return block_read_full_page(page, bfs_get_block);
}
static void bfs_write_failed(struct address_space *mapping, loff_t to)
{
struct inode *inode = mapping->host;
if (to > inode->i_size)
truncate_pagecache(inode, inode->i_size);
}
static int bfs_write_begin(struct file *file, struct address_space *mapping,
loff_t pos, unsigned len, unsigned flags,
struct page **pagep, void **fsdata)
{
int ret;
ret = block_write_begin(mapping, pos, len, flags, pagep,
bfs_get_block);
if (unlikely(ret))
bfs_write_failed(mapping, pos + len);
return ret;
}
static sector_t bfs_bmap(struct address_space *mapping, sector_t block)
{
return generic_block_bmap(mapping, block, bfs_get_block);
}
const struct address_space_operations bfs_aops = {
.readpage = bfs_readpage,
.writepage = bfs_writepage,
.write_begin = bfs_write_begin,
.write_end = generic_write_end,
.bmap = bfs_bmap,
};
const struct inode_operations bfs_file_inops;
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