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buf.c
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/******************************************************************************
*******************************************************************************
**
** Copyright (C) Sistina Software, Inc. 1997-2003 All rights reserved.
** Copyright (C) 2004 Red Hat, Inc. All rights reserved.
**
** This copyrighted material is made available to anyone wishing to use,
** modify, copy, or redistribute it subject to the terms and conditions
** of the GNU General Public License v.2.
**
*******************************************************************************
******************************************************************************/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdint.h>
#include <inttypes.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <errno.h>
#include <linux/types.h>
#include "gfs2_mkfs.h"
#define do_lseek(sdp, off) \
do { \
if (lseek((sdp)->device_fd, (off), SEEK_SET) != (off)) \
die("bad seek: %s on line %d of file %s\n", \
strerror(errno), __LINE__, __FILE__); \
} while (0)
#define do_read(sdp, buf, len) \
do { \
if (read((sdp)->device_fd, (buf), (len)) != (len)) \
die("bad read: %s on line %d of file %s\n", \
strerror(errno), __LINE__, __FILE__); \
} while (0)
#define do_write(sdp, buf, len) \
do { \
if (write((sdp)->device_fd, (buf), (len)) != (len)) \
die("bad write: %s on line %d of file %s\n", \
strerror(errno), __LINE__, __FILE__); \
} while (0)
static __inline__ osi_list_t *
blkno2head(struct gfs2_sbd *sdp, uint64_t blkno)
{
return sdp->buf_hash +
(gfs2_disk_hash((char *)&blkno, sizeof(uint64_t)) & BUF_HASH_MASK);
}
static void
write_buffer(struct gfs2_sbd *sdp, struct buffer_head *bh)
{
#if 0
if (!bh->b_uninit) {
struct gfs2_meta_header mh;
gfs2_meta_header_in(&mh, bh->b_data);
if (mh.mh_magic != GFS2_MAGIC)
fprintf(stderr, "gfs2_mkfs: uninitialized block %"PRIu64"\n",
bh->b_blocknr);
}
#endif
osi_list_del(&bh->b_list);
osi_list_del(&bh->b_hash);
sdp->num_bufs--;
do_lseek(sdp, bh->b_blocknr * sdp->bsize);
do_write(sdp, bh->b_data, sdp->bsize);
free(bh);
sdp->writes++;
}
static void
add_buffer(struct gfs2_sbd *sdp, struct buffer_head *bh)
{
osi_list_t *head = blkno2head(sdp, bh->b_blocknr);
osi_list_add(&bh->b_list, &sdp->buf_list);
osi_list_add(&bh->b_hash, head);
sdp->num_bufs++;
while (sdp->num_bufs * sdp->bsize > 128 << 20) {
bh = osi_list_entry(sdp->buf_list.prev, struct buffer_head, b_list);
if (bh->b_count) {
osi_list_del(&bh->b_list);
osi_list_add(&bh->b_list, &sdp->buf_list);
continue;
}
write_buffer(sdp, bh);
sdp->spills++;
}
}
struct buffer_head *
bfind(struct gfs2_sbd *sdp, uint64_t num)
{
osi_list_t *head = blkno2head(sdp, num);
osi_list_t *tmp;
struct buffer_head *bh;
for (tmp = head->next;
tmp != head;
tmp = tmp->next) {
bh = osi_list_entry(tmp, struct buffer_head, b_hash);
if (bh->b_blocknr == num) {
osi_list_del(&bh->b_list);
osi_list_add(&bh->b_list, &sdp->buf_list);
osi_list_del(&bh->b_hash);
osi_list_add(&bh->b_hash, head);
bh->b_count++;
return bh;
}
}
return NULL;
}
struct buffer_head *
bget(struct gfs2_sbd *sdp, uint64_t num)
{
struct buffer_head *bh;
bh = bfind(sdp, num);
if (bh)
return bh;
zalloc(bh, sizeof(struct buffer_head) + sdp->bsize);
bh->b_count = 1;
bh->b_blocknr = num;
bh->b_data = (char *)bh + sizeof(struct buffer_head);
bh->b_size = sdp->bsize;
add_buffer(sdp, bh);
return bh;
}
struct buffer_head *
bread(struct gfs2_sbd *sdp, uint64_t num)
{
struct buffer_head *bh;
bh = bfind(sdp, num);
if (bh)
return bh;
zalloc(bh, sizeof(struct buffer_head) + sdp->bsize);
bh->b_count = 1;
bh->b_blocknr = num;
bh->b_data = (char *)bh + sizeof(struct buffer_head);
bh->b_size = sdp->bsize;
do_lseek(sdp, num * sdp->bsize);
do_read(sdp, bh->b_data, sdp->bsize);
add_buffer(sdp, bh);
return bh;
}
struct buffer_head *
bhold(struct buffer_head *bh)
{
if (!bh->b_count)
die("buffer hold error\n");
bh->b_count++;
return bh;
}
void
brelse(struct buffer_head *bh)
{
if (!bh->b_count)
die("buffer count underflow\n");
bh->b_count--;
}
void
bsync(struct gfs2_sbd *sdp)
{
struct buffer_head *bh;
while (!osi_list_empty(&sdp->buf_list)) {
bh = osi_list_entry(sdp->buf_list.prev, struct buffer_head, b_list);
if (bh->b_count)
die("buffer still held: %"PRIu64"\n",
bh->b_blocknr);
write_buffer(sdp, bh);
}
}

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