[GFS2] Use a bio to read the superblock
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>
diff --git a/fs/gfs2/super.c b/fs/gfs2/super.c
index f2d2876..48fd4cb49 100644
--- a/fs/gfs2/super.c
+++ b/fs/gfs2/super.c
@@ -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 @@
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_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 @@
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 */