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buf.c
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buf.c
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#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 "libgfs2.h"
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);
}
void write_buffer(struct gfs2_sbd *sdp, struct gfs2_buffer_head *bh)
{
osi_list_del(&bh->b_list);
osi_list_del(&bh->b_hash);
sdp->num_bufs--;
if (bh->b_changed) {
do_lseek(sdp->device_fd, bh->b_blocknr * sdp->bsize);
do_write(sdp->device_fd, bh->b_data, sdp->bsize);
sdp->writes++;
}
free(bh);
}
static void
add_buffer(struct gfs2_sbd *sdp, struct gfs2_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 gfs2_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 gfs2_buffer_head *bfind(struct gfs2_sbd *sdp, uint64_t num)
{
osi_list_t *head = blkno2head(sdp, num);
osi_list_t *tmp;
struct gfs2_buffer_head *bh;
for (tmp = head->next; tmp != head; tmp = tmp->next) {
bh = osi_list_entry(tmp, struct gfs2_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 gfs2_buffer_head *bget_generic(struct gfs2_sbd *sdp, uint64_t num,
int find_existing, int read_disk)
{
struct gfs2_buffer_head *bh;
if (find_existing) {
bh = bfind(sdp, num);
if (bh)
return bh;
}
zalloc(bh, sizeof(struct gfs2_buffer_head) + sdp->bsize);
bh->b_count = 1;
bh->b_blocknr = num;
bh->b_data = (char *)bh + sizeof(struct gfs2_buffer_head);
bh->b_size = sdp->bsize;
if (read_disk) {
do_lseek(sdp->device_fd, num * sdp->bsize);
do_read(sdp->device_fd, bh->b_data, sdp->bsize);
}
add_buffer(sdp, bh);
bh->b_changed = FALSE;
return bh;
}
struct gfs2_buffer_head *bget(struct gfs2_sbd *sdp, uint64_t num)
{
return bget_generic(sdp, num, TRUE, FALSE);
}
struct gfs2_buffer_head *bread(struct gfs2_sbd *sdp, uint64_t num)
{
return bget_generic(sdp, num, TRUE, TRUE);
}
struct gfs2_buffer_head *bget_zero(struct gfs2_sbd *sdp, uint64_t num)
{
return bget_generic(sdp, num, FALSE, FALSE);
}
struct gfs2_buffer_head *bhold(struct gfs2_buffer_head *bh)
{
if (!bh->b_count)
die("buffer hold error for block %" PRIu64 " (0x%" PRIx64")\n",
bh->b_blocknr, bh->b_blocknr);
bh->b_count++;
return bh;
}
void brelse(struct gfs2_buffer_head *bh, enum update_flags updated)
{
/* We can't just say b_changed = updated because we don't want to */
/* set it FALSE if it's TRUE until we write the changed data to disk. */
if (updated)
bh->b_changed = TRUE;
if (!bh->b_count)
die("buffer count underflow for block %" PRIu64 " (0x%" PRIx64")\n",
bh->b_blocknr, bh->b_blocknr);
bh->b_count--;
}
void bsync(struct gfs2_sbd *sdp)
{
struct gfs2_buffer_head *bh;
while (!osi_list_empty(&sdp->buf_list)) {
bh = osi_list_entry(sdp->buf_list.prev, struct gfs2_buffer_head,
b_list);
if (bh->b_count)
die("buffer still held for block: %" PRIu64 " (0x%" PRIx64")\n",
bh->b_blocknr, bh->b_blocknr);
write_buffer(sdp, bh);
}
}
/* commit buffers to disk but do not discard */
void bcommit(struct gfs2_sbd *sdp)
{
osi_list_t *tmp, *x;
struct gfs2_buffer_head *bh;
osi_list_foreach_safe(tmp, &sdp->buf_list, x) {
bh = osi_list_entry(tmp, struct gfs2_buffer_head, b_list);
if (!bh->b_count) /* if not reserved for later */
write_buffer(sdp, bh); /* write the data, free the memory */
else if (bh->b_changed) { /* if buffer has changed */
do_lseek(sdp->device_fd, bh->b_blocknr * sdp->bsize);
do_write(sdp->device_fd, bh->b_data, sdp->bsize); /* write it out */
bh->b_changed = FALSE; /* no longer changed */
}
}
}
/* Check for unreleased buffers */
void bcheck(struct gfs2_sbd *sdp)
{
osi_list_t *tmp;
struct gfs2_buffer_head *bh;
osi_list_foreach(tmp, &sdp->buf_list) {
bh = osi_list_entry(tmp, struct gfs2_buffer_head, b_list);
if (bh->b_count)
die("buffer still held: %"PRIu64"\n", bh->b_blocknr);
}
}

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