343 lines
11 KiB
C
343 lines
11 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 zone into an inode
|
|
* clear_zone: erase a zone in the middle of a file
|
|
* new_block: acquire a new block
|
|
* zero_block: overwrite a block with zeroes
|
|
*
|
|
*/
|
|
|
|
#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, zone_t zone) );
|
|
FORWARD _PROTOTYPE( int empty_indir, (struct buf *, struct super_block *) );
|
|
|
|
|
|
/*===========================================================================*
|
|
* write_map *
|
|
*===========================================================================*/
|
|
PUBLIC int write_map(rip, position, new_zone, op)
|
|
struct inode *rip; /* pointer to inode to be changed */
|
|
off_t position; /* file address to be mapped */
|
|
zone_t new_zone; /* zone # to be inserted */
|
|
int op; /* special actions */
|
|
{
|
|
/* Write a new zone into an inode.
|
|
*
|
|
* If op includes WMAP_FREE, free the data zone corresponding to that position
|
|
* in the inode ('new_zone' is ignored then). Also free the indirect block
|
|
* if that was the last entry in the indirect block.
|
|
* Also free the double indirect block if that was the last entry in the
|
|
* double indirect block.
|
|
*/
|
|
int scale, ind_ex = 0, new_ind, new_dbl,
|
|
zones, nr_indirects, single, zindex, ex;
|
|
zone_t z, z1, z2 = NO_ZONE, old_zone;
|
|
register block_t b;
|
|
long excess, zone;
|
|
struct buf *bp_dindir = NULL, *bp = NULL;
|
|
|
|
rip->i_dirt = DIRTY; /* inode will be changed */
|
|
scale = rip->i_sp->s_log_zone_size; /* for zone-block conversion */
|
|
/* relative zone # to insert */
|
|
zone = (position/rip->i_sp->s_block_size) >> scale;
|
|
zones = rip->i_ndzones; /* # direct zones in the inode */
|
|
nr_indirects = rip->i_nindirs;/* # indirect zones per indirect block */
|
|
|
|
/* Is 'position' to be found in the inode itself? */
|
|
if (zone < zones) {
|
|
zindex = (int) zone; /* we need an integer here */
|
|
if(rip->i_zone[zindex] != NO_ZONE && (op & WMAP_FREE)) {
|
|
free_zone(rip->i_dev, rip->i_zone[zindex]);
|
|
rip->i_zone[zindex] = NO_ZONE;
|
|
} else {
|
|
rip->i_zone[zindex] = new_zone;
|
|
}
|
|
return(OK);
|
|
}
|
|
|
|
/* It is not in the inode, so it must be single or double indirect. */
|
|
excess = zone - zones; /* first Vx_NR_DZONES don't count */
|
|
new_ind = FALSE;
|
|
new_dbl = FALSE;
|
|
|
|
if (excess < nr_indirects) {
|
|
/* 'position' can be located via the single indirect block. */
|
|
z1 = rip->i_zone[zones]; /* single indirect zone */
|
|
single = TRUE;
|
|
} else {
|
|
/* 'position' can be located via the double indirect block. */
|
|
if ( (z2 = z = rip->i_zone[zones+1]) == NO_ZONE &&
|
|
!(op & WMAP_FREE)) {
|
|
/* Create the double indirect block. */
|
|
if ( (z = alloc_zone(rip->i_dev, rip->i_zone[0])) == NO_ZONE)
|
|
return(err_code);
|
|
rip->i_zone[zones+1] = z;
|
|
new_dbl = TRUE; /* set flag for later */
|
|
}
|
|
|
|
/* 'z' is zone number for double indirect block, either old
|
|
* or newly created.
|
|
* If there wasn't one and WMAP_FREE is set, 'z' is NO_ZONE.
|
|
*/
|
|
excess -= nr_indirects; /* single indirect doesn't count */
|
|
ind_ex = (int) (excess / nr_indirects);
|
|
excess = excess % nr_indirects;
|
|
if (ind_ex >= nr_indirects) return(EFBIG);
|
|
|
|
if(z == NO_ZONE) {
|
|
/* WMAP_FREE and no double indirect block - then no
|
|
* single indirect block either.
|
|
*/
|
|
z1 = NO_ZONE;
|
|
} else {
|
|
b = (block_t) z << scale;
|
|
bp_dindir = get_block(rip->i_dev, b, (new_dbl?NO_READ:NORMAL));
|
|
if (new_dbl) zero_block(bp_dindir);
|
|
z1 = rd_indir(bp_dindir, ind_ex);
|
|
}
|
|
single = FALSE;
|
|
}
|
|
|
|
/* z1 is now single indirect zone, or NO_ZONE; 'excess' is index.
|
|
* We have to create the indirect zone if it's NO_ZONE. Unless
|
|
* we're freeing (WMAP_FREE).
|
|
*/
|
|
if (z1 == NO_ZONE && !(op & WMAP_FREE)) {
|
|
z1 = alloc_zone(rip->i_dev, rip->i_zone[0]);
|
|
if (single)
|
|
rip->i_zone[zones] = z1; /* update inode w. single indirect */
|
|
else
|
|
wr_indir(bp_dindir, ind_ex, z1); /* update dbl indir */
|
|
|
|
new_ind = TRUE;
|
|
/* If double ind, it is dirty. */
|
|
if (bp_dindir != NULL) bp_dindir->b_dirt = DIRTY;
|
|
if (z1 == NO_ZONE) {
|
|
/* Release dbl indirect blk. */
|
|
put_block(bp_dindir, INDIRECT_BLOCK);
|
|
return(err_code); /* couldn't create single ind */
|
|
}
|
|
}
|
|
|
|
/* z1 is indirect block's zone number (unless it's NO_ZONE when we're
|
|
* freeing).
|
|
*/
|
|
if(z1 != NO_ZONE) {
|
|
ex = (int) excess; /* we need an int here */
|
|
b = (block_t) z1 << scale;
|
|
bp = get_block(rip->i_dev, b, (new_ind ? NO_READ : NORMAL) );
|
|
if (new_ind) zero_block(bp);
|
|
if(op & WMAP_FREE) {
|
|
if((old_zone = rd_indir(bp, ex)) != NO_ZONE) {
|
|
free_zone(rip->i_dev, old_zone);
|
|
wr_indir(bp, ex, NO_ZONE);
|
|
}
|
|
|
|
/* Last reference in the indirect block gone? Then
|
|
* free the indirect block.
|
|
*/
|
|
if(empty_indir(bp, rip->i_sp)) {
|
|
free_zone(rip->i_dev, z1);
|
|
z1 = NO_ZONE;
|
|
/* Update the reference to the indirect block to
|
|
* NO_ZONE - in the double indirect block if there
|
|
* is one, otherwise in the inode directly.
|
|
*/
|
|
if(single) {
|
|
rip->i_zone[zones] = z1;
|
|
} else {
|
|
wr_indir(bp_dindir, ind_ex, z1);
|
|
bp_dindir->b_dirt = DIRTY;
|
|
}
|
|
}
|
|
} else {
|
|
wr_indir(bp, ex, new_zone);
|
|
}
|
|
/* z1 equals NO_ZONE only when we are freeing up the indirect block. */
|
|
bp->b_dirt = (z1 == NO_ZONE) ? 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(z1 == NO_ZONE && !single && z2 != NO_ZONE &&
|
|
empty_indir(bp_dindir, rip->i_sp)) {
|
|
bp_dindir->b_dirt = CLEAN;
|
|
free_zone(rip->i_dev, z2);
|
|
rip->i_zone[zones+1] = NO_ZONE;
|
|
}
|
|
|
|
put_block(bp_dindir, INDIRECT_BLOCK); /* release double indirect blk */
|
|
|
|
return(OK);
|
|
}
|
|
|
|
|
|
/*===========================================================================*
|
|
* wr_indir *
|
|
*===========================================================================*/
|
|
PRIVATE void wr_indir(bp, index, zone)
|
|
struct buf *bp; /* pointer to indirect block */
|
|
int index; /* index into *bp */
|
|
zone_t zone; /* zone to write */
|
|
{
|
|
/* Given a pointer to an indirect block, write one entry. */
|
|
|
|
struct super_block *sp;
|
|
|
|
if(bp == NULL)
|
|
panic("wr_indir() on NULL");
|
|
|
|
sp = get_super(bp->b_dev); /* need super block to find file sys type */
|
|
|
|
/* write a zone into an indirect block */
|
|
if (sp->s_version == V1)
|
|
bp->b_v1_ind[index] = (zone1_t) conv2(sp->s_native, (int) zone);
|
|
else
|
|
bp->b_v2_ind[index] = (zone_t) conv4(sp->s_native, (long) zone);
|
|
}
|
|
|
|
|
|
/*===========================================================================*
|
|
* 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_ZONE entries.
|
|
*/
|
|
int i;
|
|
if(sb->s_version == V1) {
|
|
for(i = 0; i < V1_INDIRECTS; i++)
|
|
if(bp->b_v1_ind[i] != NO_ZONE)
|
|
return(0);
|
|
} else {
|
|
for(i = 0; i < V2_INDIRECTS(sb->s_block_size); i++)
|
|
if(bp->b_v2_ind[i] != NO_ZONE)
|
|
return(0);
|
|
}
|
|
|
|
return(1);
|
|
}
|
|
|
|
|
|
/*===========================================================================*
|
|
* clear_zone *
|
|
*===========================================================================*/
|
|
PUBLIC void clear_zone(rip, pos, flag)
|
|
register struct inode *rip; /* inode to clear */
|
|
off_t pos; /* points to block to clear */
|
|
int flag; /* 1 if called by new_block, 0 otherwise */
|
|
{
|
|
/* Zero a zone, possibly starting in the middle. The parameter 'pos' gives
|
|
* a byte in the first block to be zeroed. Clearzone() is called from
|
|
* fs_readwrite(), truncate_inode(), and new_block().
|
|
*/
|
|
|
|
register struct buf *bp;
|
|
register block_t b, blo, bhi;
|
|
register off_t next;
|
|
register int scale;
|
|
register zone_t zone_size;
|
|
|
|
/* If the block size and zone size are the same, clear_zone() not needed. */
|
|
scale = rip->i_sp->s_log_zone_size;
|
|
if (scale == 0) return;
|
|
|
|
zone_size = (zone_t) rip->i_sp->s_block_size << scale;
|
|
if (flag == 1) pos = (pos/zone_size) * zone_size;
|
|
next = pos + rip->i_sp->s_block_size - 1;
|
|
|
|
/* If 'pos' is in the last block of a zone, do not clear the zone. */
|
|
if (next/zone_size != pos/zone_size) return;
|
|
if ( (blo = read_map(rip, next)) == NO_BLOCK) return;
|
|
bhi = ( ((blo>>scale)+1) << scale) - 1;
|
|
|
|
/* Clear all the blocks between 'blo' and 'bhi'. */
|
|
for (b = blo; b <= bhi; b++) {
|
|
bp = get_block(rip->i_dev, b, NO_READ);
|
|
zero_block(bp);
|
|
put_block(bp, FULL_DATA_BLOCK);
|
|
}
|
|
}
|
|
|
|
|
|
/*===========================================================================*
|
|
* 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. Doing so may require
|
|
* allocating a complete zone, and then returning the initial block.
|
|
* On the other hand, the current zone may still have some unused blocks.
|
|
*/
|
|
|
|
register struct buf *bp;
|
|
block_t b, base_block;
|
|
zone_t z;
|
|
zone_t zone_size;
|
|
int scale, r;
|
|
|
|
/* Is another block available in the current zone? */
|
|
if ( (b = read_map(rip, position)) == NO_BLOCK) {
|
|
if (rip->i_zsearch == NO_ZONE) {
|
|
/* First search for this file. Start looking from
|
|
* the file's first data zone to prevent fragmentation
|
|
*/
|
|
if ( (z = rip->i_zone[0]) == NO_ZONE) {
|
|
/* no first zone for file either */
|
|
z = rip->i_sp->s_firstdatazone; /* let alloc_zone decide */
|
|
}
|
|
} else {
|
|
/* searched before, start from last find */
|
|
z = rip->i_zsearch;
|
|
}
|
|
if ( (z = alloc_zone(rip->i_dev, z)) == NO_ZONE) return(NULL);
|
|
rip->i_zsearch = z; /* store for next lookup */
|
|
if ( (r = write_map(rip, position, z, 0)) != OK) {
|
|
free_zone(rip->i_dev, z);
|
|
err_code = r;
|
|
return(NULL);
|
|
}
|
|
|
|
/* If we are not writing at EOF, clear the zone, just to be safe. */
|
|
if ( position != rip->i_size) clear_zone(rip, position, 1);
|
|
scale = rip->i_sp->s_log_zone_size;
|
|
base_block = (block_t) z << scale;
|
|
zone_size = (zone_t) rip->i_sp->s_block_size << scale;
|
|
b = base_block + (block_t)((position % zone_size)/rip->i_sp->s_block_size);
|
|
}
|
|
|
|
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, bp->b_bytes);
|
|
bp->b_dirt = DIRTY;
|
|
}
|
|
|