[GFS2] The core of GFS2

This patch contains all the core files for GFS2.

Signed-off-by: David Teigland <teigland@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

1 files changed, 876 insertions, 0 deletions

diff --git a/fs/gfs2/meta_io.c b/fs/gfs2/meta_io.c
new file mode 100644
index 00000000000..177b0246d19
--- /dev/null
+++ b/fs/gfs2/meta_io.c
@@ -0,0 +1,876 @@
+/*
+ * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.
+ * Copyright (C) 2004-2005 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 <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/completion.h>
+#include <linux/buffer_head.h>
+#include <linux/mm.h>
+#include <linux/pagemap.h>
+#include <linux/writeback.h>
+#include <linux/swap.h>
+#include <linux/delay.h>
+#include <asm/semaphore.h>
+
+#include "gfs2.h"
+#include "glock.h"
+#include "glops.h"
+#include "inode.h"
+#include "log.h"
+#include "lops.h"
+#include "meta_io.h"
+#include "rgrp.h"
+#include "trans.h"
+
+#define buffer_busy(bh) \
+((bh)->b_state & ((1ul << BH_Dirty) | (1ul << BH_Lock) | (1ul << BH_Pinned)))
+#define buffer_in_io(bh) \
+((bh)->b_state & ((1ul << BH_Dirty) | (1ul << BH_Lock)))
+
+static int aspace_get_block(struct inode *inode, sector_t lblock,
+			    struct buffer_head *bh_result, int create)
+{
+	gfs2_assert_warn(get_v2sdp(inode->i_sb), 0);
+	return -EOPNOTSUPP;
+}
+
+static int gfs2_aspace_writepage(struct page *page,
+				 struct writeback_control *wbc)
+{
+	return block_write_full_page(page, aspace_get_block, wbc);
+}
+
+/**
+ * stuck_releasepage - We're stuck in gfs2_releasepage().  Print stuff out.
+ * @bh: the buffer we're stuck on
+ *
+ */
+
+static void stuck_releasepage(struct buffer_head *bh)
+{
+	struct gfs2_sbd *sdp = get_v2sdp(bh->b_page->mapping->host->i_sb);
+	struct gfs2_bufdata *bd = get_v2bd(bh);
+	struct gfs2_glock *gl;
+
+	fs_warn(sdp, "stuck in gfs2_releasepage()\n");
+	fs_warn(sdp, "blkno = %llu, bh->b_count = %d\n",
+		(uint64_t)bh->b_blocknr, atomic_read(&bh->b_count));
+	fs_warn(sdp, "pinned = %u\n", buffer_pinned(bh));
+	fs_warn(sdp, "get_v2bd(bh) = %s\n", (bd) ? "!NULL" : "NULL");
+
+	if (!bd)
+		return;
+
+	gl = bd->bd_gl;
+
+	fs_warn(sdp, "gl = (%u, %llu)\n", 
+		gl->gl_name.ln_type, gl->gl_name.ln_number);
+
+	fs_warn(sdp, "bd_list_tr = %s, bd_le.le_list = %s\n",
+		(list_empty(&bd->bd_list_tr)) ? "no" : "yes",
+		(list_empty(&bd->bd_le.le_list)) ? "no" : "yes");
+
+	if (gl->gl_ops == &gfs2_inode_glops) {
+		struct gfs2_inode *ip = get_gl2ip(gl);
+		unsigned int x;
+
+		if (!ip)
+			return;
+
+		fs_warn(sdp, "ip = %llu %llu\n",
+			ip->i_num.no_formal_ino, ip->i_num.no_addr);
+		fs_warn(sdp, "ip->i_count = %d, ip->i_vnode = %s\n",
+			atomic_read(&ip->i_count),
+			(ip->i_vnode) ? "!NULL" : "NULL");
+
+		for (x = 0; x < GFS2_MAX_META_HEIGHT; x++)
+			fs_warn(sdp, "ip->i_cache[%u] = %s\n",
+				x, (ip->i_cache[x]) ? "!NULL" : "NULL");
+	}
+}
+
+/**
+ * gfs2_aspace_releasepage - free the metadata associated with a page
+ * @page: the page that's being released
+ * @gfp_mask: passed from Linux VFS, ignored by us
+ *
+ * Call try_to_free_buffers() if the buffers in this page can be
+ * released.
+ *
+ * Returns: 0
+ */
+
+static int gfs2_aspace_releasepage(struct page *page, gfp_t gfp_mask)
+{
+	struct inode *aspace = page->mapping->host;
+	struct gfs2_sbd *sdp = get_v2sdp(aspace->i_sb);
+	struct buffer_head *bh, *head;
+	struct gfs2_bufdata *bd;
+	unsigned long t;
+
+	if (!page_has_buffers(page))
+		goto out;
+
+	head = bh = page_buffers(page);
+	do {
+		t = jiffies;
+
+		while (atomic_read(&bh->b_count)) {
+			if (atomic_read(&aspace->i_writecount)) {
+				if (time_after_eq(jiffies, t +
+				    gfs2_tune_get(sdp, gt_stall_secs) * HZ)) {
+					stuck_releasepage(bh);
+					t = jiffies;
+				}
+
+				yield();
+				continue;
+			}
+
+			return 0;
+		}
+
+		gfs2_assert_warn(sdp, !buffer_pinned(bh));
+
+		bd = get_v2bd(bh);
+		if (bd) {
+			gfs2_assert_warn(sdp, bd->bd_bh == bh);
+			gfs2_assert_warn(sdp, list_empty(&bd->bd_list_tr));
+			gfs2_assert_warn(sdp, list_empty(&bd->bd_le.le_list));
+			gfs2_assert_warn(sdp, !bd->bd_ail);
+			kmem_cache_free(gfs2_bufdata_cachep, bd);
+			atomic_dec(&sdp->sd_bufdata_count);
+			set_v2bd(bh, NULL);
+		}
+
+		bh = bh->b_this_page;
+	}
+	while (bh != head);
+
+ out:
+	return try_to_free_buffers(page);
+}
+
+static struct address_space_operations aspace_aops = {
+	.writepage = gfs2_aspace_writepage,
+	.releasepage = gfs2_aspace_releasepage,
+};
+
+/**
+ * gfs2_aspace_get - Create and initialize a struct inode structure
+ * @sdp: the filesystem the aspace is in
+ *
+ * Right now a struct inode is just a struct inode.  Maybe Linux
+ * will supply a more lightweight address space construct (that works)
+ * in the future.
+ *
+ * Make sure pages/buffers in this aspace aren't in high memory.
+ *
+ * Returns: the aspace
+ */
+
+struct inode *gfs2_aspace_get(struct gfs2_sbd *sdp)
+{
+	struct inode *aspace;
+
+	aspace = new_inode(sdp->sd_vfs);
+	if (aspace) {
+		mapping_set_gfp_mask(aspace->i_mapping, GFP_KERNEL);
+		aspace->i_mapping->a_ops = &aspace_aops;
+		aspace->i_size = ~0ULL;
+		set_v2ip(aspace, NULL);
+		insert_inode_hash(aspace);
+	}
+
+	return aspace;
+}
+
+void gfs2_aspace_put(struct inode *aspace)
+{
+	remove_inode_hash(aspace);
+	iput(aspace);
+}
+
+/**
+ * gfs2_ail1_start_one - Start I/O on a part of the AIL
+ * @sdp: the filesystem
+ * @tr: the part of the AIL
+ *
+ */
+
+void gfs2_ail1_start_one(struct gfs2_sbd *sdp, struct gfs2_ail *ai)
+{
+	struct gfs2_bufdata *bd, *s;
+	struct buffer_head *bh;
+	int retry;
+
+	do {
+		retry = 0;
+
+		list_for_each_entry_safe_reverse(bd, s, &ai->ai_ail1_list,
+						 bd_ail_st_list) {
+			bh = bd->bd_bh;
+
+			gfs2_assert(sdp, bd->bd_ail == ai);
+
+			if (!buffer_busy(bh)) {
+				if (!buffer_uptodate(bh))
+					gfs2_io_error_bh(sdp, bh);
+				list_move(&bd->bd_ail_st_list,
+					  &ai->ai_ail2_list);
+				continue;
+			}
+
+			if (!buffer_dirty(bh))
+				continue;
+
+			list_move(&bd->bd_ail_st_list, &ai->ai_ail1_list);
+
+			gfs2_log_unlock(sdp);
+			wait_on_buffer(bh);
+			ll_rw_block(WRITE, 1, &bh);
+			gfs2_log_lock(sdp);
+
+			retry = 1;
+			break;
+		}
+	} while (retry);
+}
+
+/**
+ * gfs2_ail1_empty_one - Check whether or not a trans in the AIL has been synced
+ * @sdp: the filesystem
+ * @ai: the AIL entry
+ *
+ */
+
+int gfs2_ail1_empty_one(struct gfs2_sbd *sdp, struct gfs2_ail *ai, int flags)
+{
+	struct gfs2_bufdata *bd, *s;
+	struct buffer_head *bh;
+
+	list_for_each_entry_safe_reverse(bd, s, &ai->ai_ail1_list,
+					 bd_ail_st_list) {
+		bh = bd->bd_bh;
+
+		gfs2_assert(sdp, bd->bd_ail == ai);
+
+		if (buffer_busy(bh)) {
+			if (flags & DIO_ALL)
+				continue;
+			else
+				break;
+		}
+
+		if (!buffer_uptodate(bh))
+			gfs2_io_error_bh(sdp, bh);
+
+		list_move(&bd->bd_ail_st_list, &ai->ai_ail2_list);
+	}
+
+	return list_empty(&ai->ai_ail1_list);
+}
+
+/**
+ * gfs2_ail2_empty_one - Check whether or not a trans in the AIL has been synced
+ * @sdp: the filesystem
+ * @ai: the AIL entry
+ *
+ */
+
+void gfs2_ail2_empty_one(struct gfs2_sbd *sdp, struct gfs2_ail *ai)
+{
+	struct list_head *head = &ai->ai_ail2_list;
+	struct gfs2_bufdata *bd;
+
+	while (!list_empty(head)) {
+		bd = list_entry(head->prev, struct gfs2_bufdata,
+				bd_ail_st_list);
+		gfs2_assert(sdp, bd->bd_ail == ai);
+		bd->bd_ail = NULL;
+		list_del(&bd->bd_ail_st_list);
+		list_del(&bd->bd_ail_gl_list);
+		atomic_dec(&bd->bd_gl->gl_ail_count);
+		brelse(bd->bd_bh);
+	}
+}
+
+/**
+ * ail_empty_gl - remove all buffers for a given lock from the AIL
+ * @gl: the glock
+ *
+ * None of the buffers should be dirty, locked, or pinned.
+ */
+
+void gfs2_ail_empty_gl(struct gfs2_glock *gl)
+{
+	struct gfs2_sbd *sdp = gl->gl_sbd;
+	unsigned int blocks;
+	struct list_head *head = &gl->gl_ail_list;
+	struct gfs2_bufdata *bd;
+	struct buffer_head *bh;
+	uint64_t blkno;
+	int error;
+
+	blocks = atomic_read(&gl->gl_ail_count);
+	if (!blocks)
+		return;
+
+	error = gfs2_trans_begin(sdp, 0, blocks);
+	if (gfs2_assert_withdraw(sdp, !error))
+		return;
+
+	gfs2_log_lock(sdp);
+	while (!list_empty(head)) {
+		bd = list_entry(head->next, struct gfs2_bufdata,
+				bd_ail_gl_list);
+		bh = bd->bd_bh;
+		blkno = bh->b_blocknr;
+		gfs2_assert_withdraw(sdp, !buffer_busy(bh));
+
+		bd->bd_ail = NULL;
+		list_del(&bd->bd_ail_st_list);
+		list_del(&bd->bd_ail_gl_list);
+		atomic_dec(&gl->gl_ail_count);
+		brelse(bh);
+		gfs2_log_unlock(sdp);
+
+		gfs2_trans_add_revoke(sdp, blkno);
+
+		gfs2_log_lock(sdp);
+	}
+	gfs2_assert_withdraw(sdp, !atomic_read(&gl->gl_ail_count));
+	gfs2_log_unlock(sdp);
+
+	gfs2_trans_end(sdp);
+	gfs2_log_flush(sdp);
+}
+
+/**
+ * gfs2_meta_inval - Invalidate all buffers associated with a glock
+ * @gl: the glock
+ *
+ */
+
+void gfs2_meta_inval(struct gfs2_glock *gl)
+{
+	struct gfs2_sbd *sdp = gl->gl_sbd;
+	struct inode *aspace = gl->gl_aspace;
+	struct address_space *mapping = gl->gl_aspace->i_mapping;
+
+	gfs2_assert_withdraw(sdp, !atomic_read(&gl->gl_ail_count));
+
+	atomic_inc(&aspace->i_writecount);
+	truncate_inode_pages(mapping, 0);
+	atomic_dec(&aspace->i_writecount);
+
+	gfs2_assert_withdraw(sdp, !mapping->nrpages);
+}
+
+/**
+ * gfs2_meta_sync - Sync all buffers associated with a glock
+ * @gl: The glock
+ * @flags: DIO_START | DIO_WAIT
+ *
+ */
+
+void gfs2_meta_sync(struct gfs2_glock *gl, int flags)
+{
+	struct address_space *mapping = gl->gl_aspace->i_mapping;
+	int error = 0;
+
+	if (flags & DIO_START)
+		filemap_fdatawrite(mapping);
+	if (!error && (flags & DIO_WAIT))
+		error = filemap_fdatawait(mapping);
+
+	if (error)
+		gfs2_io_error(gl->gl_sbd);
+}
+
+/**
+ * getbuf - Get a buffer with a given address space
+ * @sdp: the filesystem
+ * @aspace: the address space
+ * @blkno: the block number (filesystem scope)
+ * @create: 1 if the buffer should be created
+ *
+ * Returns: the buffer
+ */
+
+static struct buffer_head *getbuf(struct gfs2_sbd *sdp, struct inode *aspace,
+				  uint64_t blkno, int create)
+{
+	struct page *page;
+	struct buffer_head *bh;
+	unsigned int shift;
+	unsigned long index;
+	unsigned int bufnum;
+
+	shift = PAGE_CACHE_SHIFT - sdp->sd_sb.sb_bsize_shift;
+	index = blkno >> shift;             /* convert block to page */
+	bufnum = blkno - (index << shift);  /* block buf index within page */
+
+	if (create) {
+		for (;;) {
+			page = grab_cache_page(aspace->i_mapping, index);
+			if (page)
+				break;
+			yield();
+		}
+	} else {
+		page = find_lock_page(aspace->i_mapping, index);
+		if (!page)
+			return NULL;
+	}
+
+	if (!page_has_buffers(page))
+		create_empty_buffers(page, sdp->sd_sb.sb_bsize, 0);
+
+	/* Locate header for our buffer within our page */
+	for (bh = page_buffers(page); bufnum--; bh = bh->b_this_page)
+		/* Do nothing */;
+	get_bh(bh);
+
+	if (!buffer_mapped(bh))
+		map_bh(bh, sdp->sd_vfs, blkno);
+
+	unlock_page(page);
+	mark_page_accessed(page);
+	page_cache_release(page);
+
+	return bh;
+}
+
+static void meta_prep_new(struct buffer_head *bh)
+{
+	struct gfs2_meta_header *mh = (struct gfs2_meta_header *)bh->b_data;
+
+	lock_buffer(bh);
+	clear_buffer_dirty(bh);
+	set_buffer_uptodate(bh);
+	unlock_buffer(bh);
+
+	mh->mh_magic = cpu_to_be32(GFS2_MAGIC);
+}
+
+/**
+ * gfs2_meta_new - Get a block
+ * @gl: The glock associated with this block
+ * @blkno: The block number
+ *
+ * Returns: The buffer
+ */
+
+struct buffer_head *gfs2_meta_new(struct gfs2_glock *gl, uint64_t blkno)
+{
+	struct buffer_head *bh;
+	bh = getbuf(gl->gl_sbd, gl->gl_aspace, blkno, CREATE);
+	meta_prep_new(bh);
+	return bh;
+}
+
+/**
+ * gfs2_meta_read - Read a block from disk
+ * @gl: The glock covering the block
+ * @blkno: The block number
+ * @flags: flags to gfs2_dreread()
+ * @bhp: the place where the buffer is returned (NULL on failure)
+ *
+ * Returns: errno
+ */
+
+int gfs2_meta_read(struct gfs2_glock *gl, uint64_t blkno, int flags,
+		   struct buffer_head **bhp)
+{
+	int error;
+
+	*bhp = getbuf(gl->gl_sbd, gl->gl_aspace, blkno, CREATE);
+	error = gfs2_meta_reread(gl->gl_sbd, *bhp, flags);
+	if (error)
+		brelse(*bhp);
+
+	return error;
+}
+
+/**
+ * gfs2_meta_reread - Reread a block from disk
+ * @sdp: the filesystem
+ * @bh: The block to read
+ * @flags: Flags that control the read
+ *
+ * Returns: errno
+ */
+
+int gfs2_meta_reread(struct gfs2_sbd *sdp, struct buffer_head *bh, int flags)
+{
+	if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
+		return -EIO;
+
+	if (flags & DIO_FORCE)
+		clear_buffer_uptodate(bh);
+
+	if ((flags & DIO_START) && !buffer_uptodate(bh))
+		ll_rw_block(READ, 1, &bh);
+
+	if (flags & DIO_WAIT) {
+		wait_on_buffer(bh);
+
+		if (!buffer_uptodate(bh)) {
+			struct gfs2_trans *tr = get_transaction;
+			if (tr && tr->tr_touched)
+				gfs2_io_error_bh(sdp, bh);
+			return -EIO;
+		}
+		if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
+			return -EIO;
+	}
+
+	return 0;
+}
+
+/**
+ * gfs2_meta_attach_bufdata - attach a struct gfs2_bufdata structure to a buffer
+ * @gl: the glock the buffer belongs to
+ * @bh: The buffer to be attached to
+ *
+ */
+
+void gfs2_meta_attach_bufdata(struct gfs2_glock *gl, struct buffer_head *bh)
+{
+	struct gfs2_bufdata *bd;
+
+	lock_page(bh->b_page);
+
+	if (get_v2bd(bh)) {
+		unlock_page(bh->b_page);
+		return;
+	}
+
+	bd = kmem_cache_alloc(gfs2_bufdata_cachep, GFP_KERNEL | __GFP_NOFAIL),
+	atomic_inc(&gl->gl_sbd->sd_bufdata_count);
+
+	memset(bd, 0, sizeof(struct gfs2_bufdata));
+
+	bd->bd_bh = bh;
+	bd->bd_gl = gl;
+
+	INIT_LIST_HEAD(&bd->bd_list_tr);
+	lops_init_le(&bd->bd_le, &gfs2_buf_lops);
+
+	set_v2bd(bh, bd);
+
+	unlock_page(bh->b_page);
+}
+
+/**
+ * gfs2_meta_pin - Pin a metadata buffer in memory
+ * @sdp: the filesystem the buffer belongs to
+ * @bh: The buffer to be pinned
+ *
+ */
+
+void gfs2_meta_pin(struct gfs2_sbd *sdp, struct buffer_head *bh)
+{
+	struct gfs2_bufdata *bd = get_v2bd(bh);
+
+	gfs2_assert_withdraw(sdp, test_bit(SDF_JOURNAL_LIVE, &sdp->sd_flags));
+
+	if (test_set_buffer_pinned(bh))
+		gfs2_assert_withdraw(sdp, 0);
+
+	wait_on_buffer(bh);
+
+	/* If this buffer is in the AIL and it has already been written
+	   to in-place disk block, remove it from the AIL. */
+
+	gfs2_log_lock(sdp);
+	if (bd->bd_ail && !buffer_in_io(bh))
+		list_move(&bd->bd_ail_st_list, &bd->bd_ail->ai_ail2_list);
+	gfs2_log_unlock(sdp);
+
+	clear_buffer_dirty(bh);
+	wait_on_buffer(bh);
+
+	if (!buffer_uptodate(bh))
+		gfs2_io_error_bh(sdp, bh);
+
+	get_bh(bh);
+}
+
+/**
+ * gfs2_meta_unpin - Unpin a buffer
+ * @sdp: the filesystem the buffer belongs to
+ * @bh: The buffer to unpin
+ * @ai:
+ *
+ */
+
+void gfs2_meta_unpin(struct gfs2_sbd *sdp, struct buffer_head *bh,
+		     struct gfs2_ail *ai)
+{
+	struct gfs2_bufdata *bd = get_v2bd(bh);
+
+	gfs2_assert_withdraw(sdp, buffer_uptodate(bh));
+
+	if (!buffer_pinned(bh))
+		gfs2_assert_withdraw(sdp, 0);
+
+	mark_buffer_dirty(bh);
+	clear_buffer_pinned(bh);
+
+	gfs2_log_lock(sdp);
+	if (bd->bd_ail) {
+		list_del(&bd->bd_ail_st_list);
+		brelse(bh);
+	} else {
+		struct gfs2_glock *gl = bd->bd_gl;
+		list_add(&bd->bd_ail_gl_list, &gl->gl_ail_list);
+		atomic_inc(&gl->gl_ail_count);
+	}
+	bd->bd_ail = ai;
+	list_add(&bd->bd_ail_st_list, &ai->ai_ail1_list);
+	gfs2_log_unlock(sdp);
+}
+
+/**
+ * gfs2_meta_wipe - make inode's buffers so they aren't dirty/pinned anymore
+ * @ip: the inode who owns the buffers
+ * @bstart: the first buffer in the run
+ * @blen: the number of buffers in the run
+ *
+ */
+
+void gfs2_meta_wipe(struct gfs2_inode *ip, uint64_t bstart, uint32_t blen)
+{
+	struct gfs2_sbd *sdp = ip->i_sbd;
+	struct inode *aspace = ip->i_gl->gl_aspace;
+	struct buffer_head *bh;
+
+	while (blen) {
+		bh = getbuf(sdp, aspace, bstart, NO_CREATE);
+		if (bh) {
+			struct gfs2_bufdata *bd = get_v2bd(bh);
+
+			if (test_clear_buffer_pinned(bh)) {
+				gfs2_log_lock(sdp);
+				list_del_init(&bd->bd_le.le_list);
+				gfs2_assert_warn(sdp, sdp->sd_log_num_buf);
+				sdp->sd_log_num_buf--;
+				gfs2_log_unlock(sdp);
+				get_transaction->tr_num_buf_rm++;
+				brelse(bh);
+			}
+			if (bd) {
+				gfs2_log_lock(sdp);
+				if (bd->bd_ail) {
+					uint64_t blkno = bh->b_blocknr;
+					bd->bd_ail = NULL;
+					list_del(&bd->bd_ail_st_list);
+					list_del(&bd->bd_ail_gl_list);
+					atomic_dec(&bd->bd_gl->gl_ail_count);
+					brelse(bh);
+					gfs2_log_unlock(sdp);
+					gfs2_trans_add_revoke(sdp, blkno);
+				} else
+					gfs2_log_unlock(sdp);
+			}
+
+			lock_buffer(bh);
+			clear_buffer_dirty(bh);
+			clear_buffer_uptodate(bh);
+			unlock_buffer(bh);
+
+			brelse(bh);
+		}
+
+		bstart++;
+		blen--;
+	}
+}
+
+/**
+ * gfs2_meta_cache_flush - get rid of any references on buffers for this inode
+ * @ip: The GFS2 inode
+ *
+ * This releases buffers that are in the most-recently-used array of
+ * blocks used for indirect block addressing for this inode.
+ */
+
+void gfs2_meta_cache_flush(struct gfs2_inode *ip)
+{
+	struct buffer_head **bh_slot;
+	unsigned int x;
+
+	spin_lock(&ip->i_spin);
+
+	for (x = 0; x < GFS2_MAX_META_HEIGHT; x++) {
+		bh_slot = &ip->i_cache[x];
+		if (!*bh_slot)
+			break;
+		brelse(*bh_slot);
+		*bh_slot = NULL;
+	}
+
+	spin_unlock(&ip->i_spin);
+}
+
+/**
+ * gfs2_meta_indirect_buffer - Get a metadata buffer
+ * @ip: The GFS2 inode
+ * @height: The level of this buf in the metadata (indir addr) tree (if any)
+ * @num: The block number (device relative) of the buffer
+ * @new: Non-zero if we may create a new buffer
+ * @bhp: the buffer is returned here
+ *
+ * Try to use the gfs2_inode's MRU metadata tree cache.
+ *
+ * Returns: errno
+ */
+
+int gfs2_meta_indirect_buffer(struct gfs2_inode *ip, int height, uint64_t num,
+			      int new, struct buffer_head **bhp)
+{
+	struct buffer_head *bh, **bh_slot = ip->i_cache + height;
+	int error;
+
+	spin_lock(&ip->i_spin);
+	bh = *bh_slot;
+	if (bh) {
+		if (bh->b_blocknr == num)
+			get_bh(bh);
+		else
+			bh = NULL;
+	}
+	spin_unlock(&ip->i_spin);
+
+	if (bh) {
+		if (new)
+			meta_prep_new(bh);
+		else {
+			error = gfs2_meta_reread(ip->i_sbd, bh,
+						 DIO_START | DIO_WAIT);
+			if (error) {
+				brelse(bh);
+				return error;
+			}
+		}
+	} else {
+		if (new)
+			bh = gfs2_meta_new(ip->i_gl, num);
+		else {
+			error = gfs2_meta_read(ip->i_gl, num,
+					       DIO_START | DIO_WAIT, &bh);
+			if (error)
+				return error;
+		}
+
+		spin_lock(&ip->i_spin);
+		if (*bh_slot != bh) {
+			brelse(*bh_slot);
+			*bh_slot = bh;
+			get_bh(bh);
+		}
+		spin_unlock(&ip->i_spin);
+	}
+
+	if (new) {
+		if (gfs2_assert_warn(ip->i_sbd, height)) {
+			brelse(bh);
+			return -EIO;
+		}
+		gfs2_trans_add_bh(ip->i_gl, bh);
+		gfs2_metatype_set(bh, GFS2_METATYPE_IN, GFS2_FORMAT_IN);
+		gfs2_buffer_clear_tail(bh, sizeof(struct gfs2_meta_header));
+
+	} else if (gfs2_metatype_check(ip->i_sbd, bh,
+			     (height) ? GFS2_METATYPE_IN : GFS2_METATYPE_DI)) {
+		brelse(bh);
+		return -EIO;
+	}
+
+	*bhp = bh;
+
+	return 0;
+}
+
+/**
+ * gfs2_meta_ra - start readahead on an extent of a file
+ * @gl: the glock the blocks belong to
+ * @dblock: the starting disk block
+ * @extlen: the number of blocks in the extent
+ *
+ */
+
+void gfs2_meta_ra(struct gfs2_glock *gl, uint64_t dblock, uint32_t extlen)
+{
+	struct gfs2_sbd *sdp = gl->gl_sbd;
+	struct inode *aspace = gl->gl_aspace;
+	struct buffer_head *first_bh, *bh;
+	uint32_t max_ra = gfs2_tune_get(sdp, gt_max_readahead) >> sdp->sd_sb.sb_bsize_shift;
+	int error;
+
+	if (!extlen || !max_ra)
+		return;
+	if (extlen > max_ra)
+		extlen = max_ra;
+
+	first_bh = getbuf(sdp, aspace, dblock, CREATE);
+
+	if (buffer_uptodate(first_bh))
+		goto out;
+	if (!buffer_locked(first_bh)) {
+		error = gfs2_meta_reread(sdp, first_bh, DIO_START);
+		if (error)
+			goto out;
+	}
+
+	dblock++;
+	extlen--;
+
+	while (extlen) {
+		bh = getbuf(sdp, aspace, dblock, CREATE);
+
+		if (!buffer_uptodate(bh) && !buffer_locked(bh)) {
+			error = gfs2_meta_reread(sdp, bh, DIO_START);
+			brelse(bh);
+			if (error)
+				goto out;
+		} else
+			brelse(bh);
+
+		dblock++;
+		extlen--;
+
+		if (buffer_uptodate(first_bh))
+			break;
+	}
+
+ out:
+	brelse(first_bh);
+}
+
+/**
+ * gfs2_meta_syncfs - sync all the buffers in a filesystem
+ * @sdp: the filesystem
+ *
+ */
+
+void gfs2_meta_syncfs(struct gfs2_sbd *sdp)
+{
+	gfs2_log_flush(sdp);
+	for (;;) {
+		gfs2_ail1_start(sdp, DIO_ALL);
+		if (gfs2_ail1_empty(sdp, DIO_ALL))
+			break;
+		msleep(100);
+	}
+}
+