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[GFS2] Use a bio to read the superblock

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This means that we don't need to create a special inode just to contain
a struct address_space in order to read a single disk block. Instead
we read the disk block directly. Its slightly faster, and uses slightly
less memory, but the real reason for doing this is that it removes a
special case from the glock code.

Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
This commit is contained in:
Steven Whitehouse
2006-07-27 13:53:53 -04:00
parent ae4a382004
commit f45b7ddd2b
4 changed files with 64 additions and 35 deletions
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69
fs/gfs2/super.c
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@@ -14,6 +14,7 @@
#include <linux/buffer_head.h>
#include <linux/crc32.h>
#include <linux/gfs2_ondisk.h>
#include <linux/bio.h>
#include "gfs2.h"
#include "lm_interface.h"
@@ -157,6 +158,54 @@ int gfs2_check_sb(struct gfs2_sbd *sdp, struct gfs2_sb *sb, int silent)
return 0;
}
static int end_bio_io_page(struct bio *bio, unsigned int bytes_done, int error)
{
struct page *page = bio->bi_private;
if (bio->bi_size)
return 1;
if (!error)
SetPageUptodate(page);
unlock_page(page);
return 0;
}
static struct page *gfs2_read_super(struct super_block *sb, sector_t sector)
{
struct page *page;
struct bio *bio;
page = alloc_page(GFP_KERNEL);
if (unlikely(!page))
return NULL;
ClearPageUptodate(page);
ClearPageDirty(page);
lock_page(page);
bio = bio_alloc(GFP_KERNEL, 1);
if (unlikely(!bio)) {
__free_page(page);
return NULL;
}
bio->bi_sector = sector;
bio->bi_bdev = sb->s_bdev;
bio_add_page(bio, page, PAGE_SIZE, 0);
bio->bi_end_io = end_bio_io_page;
bio->bi_private = page;
submit_bio(READ | BIO_RW_SYNC, bio);
wait_on_page_locked(page);
bio_put(bio);
if (!PageUptodate(page)) {
__free_page(page);
return NULL;
}
return page;
}
/**
* gfs2_read_sb - Read super block
* @sdp: The GFS2 superblock
@@ -167,23 +216,23 @@ int gfs2_check_sb(struct gfs2_sbd *sdp, struct gfs2_sb *sb, int silent)
int gfs2_read_sb(struct gfs2_sbd *sdp, struct gfs2_glock *gl, int silent)
{
struct buffer_head *bh;
uint32_t hash_blocks, ind_blocks, leaf_blocks;
uint32_t tmp_blocks;
unsigned int x;
int error;
struct page *page;
char *sb;
error = gfs2_meta_read(gl, GFS2_SB_ADDR >> sdp->sd_fsb2bb_shift,
DIO_FORCE | DIO_START | DIO_WAIT, &bh);
if (error) {
page = gfs2_read_super(sdp->sd_vfs, GFS2_SB_ADDR >> sdp->sd_fsb2bb_shift);
if (!page) {
if (!silent)
fs_err(sdp, "can't read superblock\n");
return error;
return -EIO;
}
gfs2_assert(sdp, sizeof(struct gfs2_sb) <= bh->b_size);
gfs2_sb_in(&sdp->sd_sb, bh->b_data);
brelse(bh);
sb = kmap(page);
gfs2_sb_in(&sdp->sd_sb, sb);
kunmap(page);
__free_page(page);
error = gfs2_check_sb(sdp, &sdp->sd_sb, silent);
if (error)
@@ -202,7 +251,7 @@ int gfs2_read_sb(struct gfs2_sbd *sdp, struct gfs2_glock *gl, int silent)
sdp->sd_hash_ptrs = sdp->sd_hash_bsize / sizeof(uint64_t);
sdp->sd_qc_per_block = (sdp->sd_sb.sb_bsize -
sizeof(struct gfs2_meta_header)) /
sizeof(struct gfs2_quota_change);
sizeof(struct gfs2_quota_change);
/* Compute maximum reservation required to add a entry to a directory */