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/*
* fs/bfs/file.c
* BFS file operations.
* Copyright (C) 1999,2000 Tigran Aivazian <tigran@veritas.com>
*/
#include <linux/fs.h>
#include <linux/buffer_head.h>
#include <linux/smp_lock.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 = do_sync_read,
.aio_read = generic_file_aio_read,
.write = do_sync_write,
.aio_write = generic_file_aio_write,
.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);
struct buffer_head *sbh = info->si_sbh;
if (block > info->si_blocks)
return -EIO;
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 (inode->i_size && 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 rest has to be protected against itself */
lock_kernel();
/* 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);
mark_buffer_dirty(sbh);
err = 0;
goto out;
}
/* Ok, we have to move this entire file to the next free block */
phys = info->si_lf_eblk + 1;
if (bi->i_sblock) { /* if data starts on block 0 then there is no data */
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);
mark_buffer_dirty(sbh);
map_bh(bh_result, sb, phys);
out:
unlock_kernel();
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 int bfs_prepare_write(struct file *file, struct page *page, unsigned from, unsigned to)
{
return block_prepare_write(page, from, to, bfs_get_block);
}
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,
.sync_page = block_sync_page,
.prepare_write = bfs_prepare_write,
.commit_write = generic_commit_write,
.bmap = bfs_bmap,
};
const struct inode_operations bfs_file_inops;
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