376 lines
12 KiB
C
376 lines
12 KiB
C
/* This file is the counterpart of "read.c". It contains the code for writing
|
|
* insofar as this is not contained in fs_readwrite().
|
|
*
|
|
* The entry points into this file are
|
|
* write_map: write a new block into an inode
|
|
* new_block: acquire a new block
|
|
* zero_block: overwrite a block with zeroes
|
|
*
|
|
* Created (MFS based):
|
|
* February 2010 (Evgeniy Ivanov)
|
|
*/
|
|
|
|
#include "fs.h"
|
|
#include <string.h>
|
|
#include "buf.h"
|
|
#include "inode.h"
|
|
#include "super.h"
|
|
|
|
FORWARD _PROTOTYPE( void wr_indir, (struct buf *bp, int index, block_t block) );
|
|
FORWARD _PROTOTYPE( int empty_indir, (struct buf *, struct super_block *) );
|
|
|
|
/*===========================================================================*
|
|
* write_map *
|
|
*===========================================================================*/
|
|
PUBLIC int write_map(rip, position, new_block, op)
|
|
struct inode *rip; /* pointer to inode to be changed */
|
|
off_t position; /* file address to be mapped */
|
|
block_t new_block; /* block # to be inserted */
|
|
int op; /* special actions */
|
|
{
|
|
/* Write a new block into an inode.
|
|
*
|
|
* If op includes WMAP_FREE, free the block corresponding to that position
|
|
* in the inode ('new_block' is ignored then). Also free the indirect block
|
|
* if that was the last entry in the indirect block.
|
|
* Also free the double/triple indirect block if that was the last entry in
|
|
* the double/triple indirect block.
|
|
* It's the only function which should take care about rip->i_blocks counter.
|
|
*/
|
|
int index1, index2, index3; /* indexes in single..triple indirect blocks */
|
|
long excess, block_pos;
|
|
char new_ind = 0, new_dbl = 0, new_triple = 0;
|
|
int single = 0, triple = 0;
|
|
register block_t old_block, b1, b2, b3;
|
|
struct buf *bp = NULL,
|
|
*bp_dindir = NULL,
|
|
*bp_tindir = NULL;
|
|
static char first_time = TRUE;
|
|
static long addr_in_block;
|
|
static long addr_in_block2;
|
|
static long doub_ind_s;
|
|
static long triple_ind_s;
|
|
static long out_range_s;
|
|
|
|
if (first_time) {
|
|
addr_in_block = rip->i_sp->s_block_size / BLOCK_ADDRESS_BYTES;
|
|
addr_in_block2 = addr_in_block * addr_in_block;
|
|
doub_ind_s = EXT2_NDIR_BLOCKS + addr_in_block;
|
|
triple_ind_s = doub_ind_s + addr_in_block2;
|
|
out_range_s = triple_ind_s + addr_in_block2 * addr_in_block;
|
|
first_time = FALSE;
|
|
}
|
|
|
|
block_pos = position / rip->i_sp->s_block_size; /* relative blk # in file */
|
|
rip->i_dirt = DIRTY; /* inode will be changed */
|
|
|
|
/* Is 'position' to be found in the inode itself? */
|
|
if (block_pos < EXT2_NDIR_BLOCKS) {
|
|
if (rip->i_block[block_pos] != NO_BLOCK && (op & WMAP_FREE)) {
|
|
free_block(rip->i_sp, rip->i_block[block_pos]);
|
|
rip->i_block[block_pos] = NO_BLOCK;
|
|
rip->i_blocks -= rip->i_sp->s_sectors_in_block;
|
|
} else {
|
|
rip->i_block[block_pos] = new_block;
|
|
rip->i_blocks += rip->i_sp->s_sectors_in_block;
|
|
}
|
|
return(OK);
|
|
}
|
|
|
|
/* It is not in the inode, so it must be single, double or triple indirect */
|
|
if (block_pos < doub_ind_s) {
|
|
b1 = rip->i_block[EXT2_NDIR_BLOCKS]; /* addr of single indirect block */
|
|
index1 = block_pos - EXT2_NDIR_BLOCKS;
|
|
single = TRUE;
|
|
} else if (block_pos >= out_range_s) { /* TODO: do we need it? */
|
|
return(EFBIG);
|
|
} else {
|
|
/* double or triple indirect block. At first if it's triple,
|
|
* find double indirect block.
|
|
*/
|
|
excess = block_pos - doub_ind_s;
|
|
b2 = rip->i_block[EXT2_DIND_BLOCK];
|
|
if (block_pos >= triple_ind_s) {
|
|
b3 = rip->i_block[EXT2_TIND_BLOCK];
|
|
if (b3 == NO_BLOCK && !(op & WMAP_FREE)) {
|
|
/* Create triple indirect block. */
|
|
if ( (b3 = alloc_block(rip, rip->i_bsearch) ) == NO_BLOCK) {
|
|
ext2_debug("failed to allocate tblock near %d\n", rip->i_block[0]);
|
|
return(ENOSPC);
|
|
}
|
|
rip->i_block[EXT2_TIND_BLOCK] = b3;
|
|
rip->i_blocks += rip->i_sp->s_sectors_in_block;
|
|
new_triple = TRUE;
|
|
}
|
|
/* 'b3' is block number for triple indirect block, either old
|
|
* or newly created.
|
|
* If there wasn't one and WMAP_FREE is set, 'b3' is NO_BLOCK.
|
|
*/
|
|
if (b3 == NO_BLOCK) {
|
|
/* WMAP_FREE and no triple indirect block - then no
|
|
* double and single indirect blocks either.
|
|
*/
|
|
b1 = b2 = NO_BLOCK;
|
|
} else {
|
|
bp_tindir = get_block(rip->i_dev, b3, (new_triple ? NO_READ : NORMAL));
|
|
if (new_triple) {
|
|
zero_block(bp_tindir);
|
|
bp_tindir->b_dirt = DIRTY;
|
|
}
|
|
excess = block_pos - triple_ind_s;
|
|
index3 = excess / addr_in_block2;
|
|
b2 = rd_indir(bp_tindir, index3);
|
|
excess = excess % addr_in_block2;
|
|
}
|
|
triple = TRUE;
|
|
}
|
|
|
|
if (b2 == NO_BLOCK && !(op & WMAP_FREE)) {
|
|
/* Create the double indirect block. */
|
|
if ( (b2 = alloc_block(rip, rip->i_bsearch) ) == NO_BLOCK) {
|
|
/* Release triple ind blk. */
|
|
put_block(bp_tindir, INDIRECT_BLOCK);
|
|
ext2_debug("failed to allocate dblock near %d\n", rip->i_block[0]);
|
|
return(ENOSPC);
|
|
}
|
|
if (triple) {
|
|
wr_indir(bp_tindir, index3, b2); /* update triple indir */
|
|
bp_tindir->b_dirt = DIRTY;
|
|
} else {
|
|
rip->i_block[EXT2_DIND_BLOCK] = b2;
|
|
}
|
|
rip->i_blocks += rip->i_sp->s_sectors_in_block;
|
|
new_dbl = TRUE; /* set flag for later */
|
|
}
|
|
|
|
/* 'b2' is block number for double indirect block, either old
|
|
* or newly created.
|
|
* If there wasn't one and WMAP_FREE is set, 'b2' is NO_BLOCK.
|
|
*/
|
|
if (b2 == NO_BLOCK) {
|
|
/* WMAP_FREE and no double indirect block - then no
|
|
* single indirect block either.
|
|
*/
|
|
b1 = NO_BLOCK;
|
|
} else {
|
|
bp_dindir = get_block(rip->i_dev, b2, (new_dbl ? NO_READ : NORMAL));
|
|
if (new_dbl) {
|
|
zero_block(bp_dindir);
|
|
bp_dindir->b_dirt = DIRTY;
|
|
}
|
|
index2 = excess / addr_in_block;
|
|
b1 = rd_indir(bp_dindir, index2);
|
|
index1 = excess % addr_in_block;
|
|
}
|
|
single = FALSE;
|
|
}
|
|
|
|
/* b1 is now single indirect block or NO_BLOCK; 'index' is index.
|
|
* We have to create the indirect block if it's NO_BLOCK. Unless
|
|
* we're freing (WMAP_FREE).
|
|
*/
|
|
if (b1 == NO_BLOCK && !(op & WMAP_FREE)) {
|
|
if ( (b1 = alloc_block(rip, rip->i_bsearch) ) == NO_BLOCK) {
|
|
/* Release dbl and triple indirect blks. */
|
|
put_block(bp_dindir, INDIRECT_BLOCK);
|
|
put_block(bp_tindir, INDIRECT_BLOCK);
|
|
ext2_debug("failed to allocate dblock near %d\n", rip->i_block[0]);
|
|
return(ENOSPC);
|
|
}
|
|
if (single) {
|
|
rip->i_block[EXT2_NDIR_BLOCKS] = b1; /* update inode single indirect */
|
|
} else {
|
|
wr_indir(bp_dindir, index2, b1); /* update dbl indir */
|
|
bp_dindir->b_dirt = DIRTY;
|
|
}
|
|
rip->i_blocks += rip->i_sp->s_sectors_in_block;
|
|
new_ind = TRUE;
|
|
}
|
|
|
|
/* b1 is indirect block's number (unless it's NO_BLOCK when we're
|
|
* freeing).
|
|
*/
|
|
if (b1 != NO_BLOCK) {
|
|
bp = get_block(rip->i_dev, b1, (new_ind ? NO_READ : NORMAL) );
|
|
if (new_ind)
|
|
zero_block(bp);
|
|
if (op & WMAP_FREE) {
|
|
if ((old_block = rd_indir(bp, index1)) != NO_BLOCK) {
|
|
free_block(rip->i_sp, old_block);
|
|
rip->i_blocks -= rip->i_sp->s_sectors_in_block;
|
|
wr_indir(bp, index1, NO_BLOCK);
|
|
}
|
|
|
|
/* Last reference in the indirect block gone? Then
|
|
* free the indirect block.
|
|
*/
|
|
if (empty_indir(bp, rip->i_sp)) {
|
|
free_block(rip->i_sp, b1);
|
|
rip->i_blocks -= rip->i_sp->s_sectors_in_block;
|
|
b1 = NO_BLOCK;
|
|
/* Update the reference to the indirect block to
|
|
* NO_BLOCK - in the double indirect block if there
|
|
* is one, otherwise in the inode directly.
|
|
*/
|
|
if (single) {
|
|
rip->i_block[EXT2_NDIR_BLOCKS] = b1;
|
|
} else {
|
|
wr_indir(bp_dindir, index2, b1);
|
|
bp_dindir->b_dirt = DIRTY;
|
|
}
|
|
}
|
|
} else {
|
|
wr_indir(bp, index1, new_block);
|
|
rip->i_blocks += rip->i_sp->s_sectors_in_block;
|
|
}
|
|
/* b1 equals NO_BLOCK only when we are freeing up the indirect block. */
|
|
bp->b_dirt = (b1 == NO_BLOCK) ? CLEAN : DIRTY;;
|
|
put_block(bp, INDIRECT_BLOCK);
|
|
}
|
|
|
|
/* If the single indirect block isn't there (or was just freed),
|
|
* see if we have to keep the double indirect block, if any.
|
|
* If we don't have to keep it, don't bother writing it out.
|
|
*/
|
|
if (b1 == NO_BLOCK && !single && b2 != NO_BLOCK &&
|
|
empty_indir(bp_dindir, rip->i_sp)) {
|
|
bp_dindir->b_dirt = CLEAN;
|
|
free_block(rip->i_sp, b2);
|
|
rip->i_blocks -= rip->i_sp->s_sectors_in_block;
|
|
b2 = NO_BLOCK;
|
|
if (triple) {
|
|
wr_indir(bp_tindir, index3, b2); /* update triple indir */
|
|
bp_tindir->b_dirt = DIRTY;
|
|
} else {
|
|
rip->i_block[EXT2_DIND_BLOCK] = b2;
|
|
}
|
|
}
|
|
/* If the double indirect block isn't there (or was just freed),
|
|
* see if we have to keep the triple indirect block, if any.
|
|
* If we don't have to keep it, don't bother writing it out.
|
|
*/
|
|
if (b2 == NO_BLOCK && triple && b3 != NO_BLOCK &&
|
|
empty_indir(bp_tindir, rip->i_sp)) {
|
|
bp_tindir->b_dirt = CLEAN;
|
|
free_block(rip->i_sp, b3);
|
|
rip->i_blocks -= rip->i_sp->s_sectors_in_block;
|
|
rip->i_block[EXT2_TIND_BLOCK] = NO_BLOCK;
|
|
}
|
|
|
|
put_block(bp_dindir, INDIRECT_BLOCK); /* release double indirect blk */
|
|
put_block(bp_tindir, INDIRECT_BLOCK); /* release triple indirect blk */
|
|
|
|
return(OK);
|
|
}
|
|
|
|
|
|
/*===========================================================================*
|
|
* wr_indir *
|
|
*===========================================================================*/
|
|
PRIVATE void wr_indir(bp, index, block)
|
|
struct buf *bp; /* pointer to indirect block */
|
|
int index; /* index into *bp */
|
|
block_t block; /* block to write */
|
|
{
|
|
/* Given a pointer to an indirect block, write one entry. */
|
|
|
|
if(bp == NULL)
|
|
panic("wr_indir() on NULL");
|
|
|
|
/* write a block into an indirect block */
|
|
bp->b_ind[index] = conv4(le_CPU, block);
|
|
}
|
|
|
|
|
|
/*===========================================================================*
|
|
* empty_indir *
|
|
*===========================================================================*/
|
|
PRIVATE int empty_indir(bp, sb)
|
|
struct buf *bp; /* pointer to indirect block */
|
|
struct super_block *sb; /* superblock of device block resides on */
|
|
{
|
|
/* Return nonzero if the indirect block pointed to by bp contains
|
|
* only NO_BLOCK entries.
|
|
*/
|
|
long addr_in_block = sb->s_block_size/4; /* 4 bytes per addr */
|
|
int i;
|
|
for(i = 0; i < addr_in_block; i++)
|
|
if(bp->b_ind[i] != NO_BLOCK)
|
|
return(0);
|
|
return(1);
|
|
}
|
|
|
|
/*===========================================================================*
|
|
* new_block *
|
|
*===========================================================================*/
|
|
PUBLIC struct buf *new_block(rip, position)
|
|
register struct inode *rip; /* pointer to inode */
|
|
off_t position; /* file pointer */
|
|
{
|
|
/* Acquire a new block and return a pointer to it. */
|
|
register struct buf *bp;
|
|
int r;
|
|
block_t b;
|
|
|
|
/* Is another block available? */
|
|
if ( (b = read_map(rip, position)) == NO_BLOCK) {
|
|
/* Check if this position follows last allocated
|
|
* block.
|
|
*/
|
|
block_t goal = NO_BLOCK;
|
|
if (rip->i_last_pos_bl_alloc != 0) {
|
|
off_t position_diff = position - rip->i_last_pos_bl_alloc;
|
|
if (rip->i_bsearch == 0) {
|
|
/* Should never happen, but not critical */
|
|
ext2_debug("warning, i_bsearch is 0, while\
|
|
i_last_pos_bl_alloc is not!");
|
|
}
|
|
if (position_diff <= rip->i_sp->s_block_size) {
|
|
goal = rip->i_bsearch + 1;
|
|
} else {
|
|
/* Non-sequential write operation,
|
|
* disable preallocation
|
|
* for this inode.
|
|
*/
|
|
rip->i_preallocation = 0;
|
|
discard_preallocated_blocks(rip);
|
|
}
|
|
}
|
|
|
|
if ( (b = alloc_block(rip, goal) ) == NO_BLOCK) {
|
|
err_code = ENOSPC;
|
|
return(NULL);
|
|
}
|
|
if ( (r = write_map(rip, position, b, 0)) != OK) {
|
|
free_block(rip->i_sp, b);
|
|
err_code = r;
|
|
ext2_debug("write_map failed\n");
|
|
return(NULL);
|
|
}
|
|
rip->i_last_pos_bl_alloc = position;
|
|
if (position == 0) {
|
|
/* rip->i_last_pos_bl_alloc points to the block position,
|
|
* and zero indicates first usage, thus just increment.
|
|
*/
|
|
rip->i_last_pos_bl_alloc++;
|
|
}
|
|
}
|
|
|
|
bp = get_block(rip->i_dev, b, NO_READ);
|
|
zero_block(bp);
|
|
return(bp);
|
|
}
|
|
|
|
/*===========================================================================*
|
|
* zero_block *
|
|
*===========================================================================*/
|
|
PUBLIC void zero_block(bp)
|
|
register struct buf *bp; /* pointer to buffer to zero */
|
|
{
|
|
/* Zero a block. */
|
|
ASSERT(bp->b_bytes > 0);
|
|
ASSERT(bp->bp);
|
|
memset(bp->b_data, 0, (size_t) bp->b_bytes);
|
|
bp->b_dirt = DIRTY;
|
|
}
|