linux/fs/bfs/file.c
Arjan van de Ven 754661f143 [PATCH] mark struct inode_operations const 1
Many struct inode_operations in the kernel can be "const".  Marking them const
moves these to the .rodata section, which avoids false sharing with potential
dirty data.  In addition it'll catch accidental writes at compile time to
these shared resources.

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-02-12 09:48:46 -08:00

168 lines
4.4 KiB
C

/*
* 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,
.sendfile = generic_file_sendfile,
};
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;