[deliverable/linux.git] / fs / gfs2 / meta_io.c

/*
 * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.
 * Copyright (C) 2004-2008 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 version 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 <linux/bio.h>
#include <linux/gfs2_ondisk.h>

#include "gfs2.h"
#include "incore.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"
#include "util.h"
#include "trace_gfs2.h"

static int gfs2_aspace_writepage(struct page *page, struct writeback_control *wbc)
{
	struct buffer_head *bh, *head;
	int nr_underway = 0;
	int write_op = REQ_META | REQ_PRIO |
		(wbc->sync_mode == WB_SYNC_ALL ? WRITE_SYNC : WRITE);

	BUG_ON(!PageLocked(page));
	BUG_ON(!page_has_buffers(page));

	head = page_buffers(page);
	bh = head;

	do {
		if (!buffer_mapped(bh))
			continue;
		/*
		 * If it's a fully non-blocking write attempt and we cannot
		 * lock the buffer then redirty the page.  Note that this can
		 * potentially cause a busy-wait loop from flusher thread and kswapd
		 * activity, but those code paths have their own higher-level
		 * throttling.
		 */
		if (wbc->sync_mode != WB_SYNC_NONE) {
			lock_buffer(bh);
		} else if (!trylock_buffer(bh)) {
			redirty_page_for_writepage(wbc, page);
			continue;
		}
		if (test_clear_buffer_dirty(bh)) {
			mark_buffer_async_write(bh);
		} else {
			unlock_buffer(bh);
		}
	} while ((bh = bh->b_this_page) != head);

	/*
	 * The page and its buffers are protected by PageWriteback(), so we can
	 * drop the bh refcounts early.
	 */
	BUG_ON(PageWriteback(page));
	set_page_writeback(page);

	do {
		struct buffer_head *next = bh->b_this_page;
		if (buffer_async_write(bh)) {
			submit_bh(write_op, bh);
			nr_underway++;
		}
		bh = next;
	} while (bh != head);
	unlock_page(page);

	if (nr_underway == 0)
		end_page_writeback(page);

	return 0;
}

const struct address_space_operations gfs2_meta_aops = {
	.writepage = gfs2_aspace_writepage,
	.releasepage = gfs2_releasepage,
};

/**
 * gfs2_getbuf - Get a buffer with a given address space
 * @gl: the glock
 * @blkno: the block number (filesystem scope)
 * @create: 1 if the buffer should be created
 *
 * Returns: the buffer
 */

struct buffer_head *gfs2_getbuf(struct gfs2_glock *gl, u64 blkno, int create)
{
	struct address_space *mapping = gfs2_glock2aspace(gl);
	struct gfs2_sbd *sdp = gl->gl_sbd;
	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(mapping, index);
			if (page)
				break;
			yield();
		}
	} else {
		page = find_lock_page(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, u64 blkno)
{
	struct buffer_head *bh;
	bh = gfs2_getbuf(gl, 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
 * @bhp: the place where the buffer is returned (NULL on failure)
 *
 * Returns: errno
 */

int gfs2_meta_read(struct gfs2_glock *gl, u64 blkno, int flags,
		   struct buffer_head **bhp)
{
	struct gfs2_sbd *sdp = gl->gl_sbd;
	struct buffer_head *bh;

	if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags))) {
		*bhp = NULL;
		return -EIO;
	}

	*bhp = bh = gfs2_getbuf(gl, blkno, CREATE);

	lock_buffer(bh);
	if (buffer_uptodate(bh)) {
		unlock_buffer(bh);
		return 0;
	}
	bh->b_end_io = end_buffer_read_sync;
	get_bh(bh);
	submit_bh(READ_SYNC | REQ_META | REQ_PRIO, bh);
	if (!(flags & DIO_WAIT))
		return 0;

	wait_on_buffer(bh);
	if (unlikely(!buffer_uptodate(bh))) {
		struct gfs2_trans *tr = current->journal_info;
		if (tr && tr->tr_touched)
			gfs2_io_error_bh(sdp, bh);
		brelse(bh);
		*bhp = NULL;
		return -EIO;
	}

	return 0;
}

/**
 * gfs2_meta_wait - Reread a block from disk
 * @sdp: the filesystem
 * @bh: The block to wait for
 *
 * Returns: errno
 */

int gfs2_meta_wait(struct gfs2_sbd *sdp, struct buffer_head *bh)
{
	if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
		return -EIO;

	wait_on_buffer(bh);

	if (!buffer_uptodate(bh)) {
		struct gfs2_trans *tr = current->journal_info;
		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;
}

void gfs2_remove_from_journal(struct buffer_head *bh, struct gfs2_trans *tr, int meta)
{
	struct address_space *mapping = bh->b_page->mapping;
	struct gfs2_sbd *sdp = gfs2_mapping2sbd(mapping);
	struct gfs2_bufdata *bd = bh->b_private;

	if (test_clear_buffer_pinned(bh)) {
		trace_gfs2_pin(bd, 0);
		atomic_dec(&sdp->sd_log_pinned);
		list_del_init(&bd->bd_list);
		if (meta) {
			gfs2_assert_warn(sdp, sdp->sd_log_num_buf);
			sdp->sd_log_num_buf--;
			tr->tr_num_buf_rm++;
		} else {
			gfs2_assert_warn(sdp, sdp->sd_log_num_databuf);
			sdp->sd_log_num_databuf--;
			tr->tr_num_databuf_rm++;
		}
		tr->tr_touched = 1;
		brelse(bh);
	}
	if (bd) {
		spin_lock(&sdp->sd_ail_lock);
		if (bd->bd_tr) {
			gfs2_trans_add_revoke(sdp, bd);
		}
		spin_unlock(&sdp->sd_ail_lock);
	}
	clear_buffer_dirty(bh);
	clear_buffer_uptodate(bh);
}

/**
 * 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, u64 bstart, u32 blen)
{
	struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
	struct buffer_head *bh;

	while (blen) {
		bh = gfs2_getbuf(ip->i_gl, bstart, NO_CREATE);
		if (bh) {
			lock_buffer(bh);
			gfs2_log_lock(sdp);
			gfs2_remove_from_journal(bh, current->journal_info, 1);
			gfs2_log_unlock(sdp);
			unlock_buffer(bh);
			brelse(bh);
		}

		bstart++;
		blen--;
	}
}

/**
 * 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
 * @bhp: the buffer is returned here
 *
 * Returns: errno
 */

int gfs2_meta_indirect_buffer(struct gfs2_inode *ip, int height, u64 num,
			      struct buffer_head **bhp)
{
	struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
	struct gfs2_glock *gl = ip->i_gl;
	struct buffer_head *bh;
	int ret = 0;
	u32 mtype = height ? GFS2_METATYPE_IN : GFS2_METATYPE_DI;

	ret = gfs2_meta_read(gl, num, DIO_WAIT, &bh);
	if (ret == 0 && gfs2_metatype_check(sdp, bh, mtype)) {
		brelse(bh);
		ret = -EIO;
	}
	*bhp = bh;
	return ret;
}

/**
 * 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
 *
 * returns: the first buffer in the extent
 */

struct buffer_head *gfs2_meta_ra(struct gfs2_glock *gl, u64 dblock, u32 extlen)
{
	struct gfs2_sbd *sdp = gl->gl_sbd;
	struct buffer_head *first_bh, *bh;
	u32 max_ra = gfs2_tune_get(sdp, gt_max_readahead) >>
			  sdp->sd_sb.sb_bsize_shift;

	BUG_ON(!extlen);

	if (max_ra < 1)
		max_ra = 1;
	if (extlen > max_ra)
		extlen = max_ra;

	first_bh = gfs2_getbuf(gl, dblock, CREATE);

	if (buffer_uptodate(first_bh))
		goto out;
	if (!buffer_locked(first_bh))
		ll_rw_block(READ_SYNC | REQ_META, 1, &first_bh);

	dblock++;
	extlen--;

	while (extlen) {
		bh = gfs2_getbuf(gl, dblock, CREATE);

		if (!buffer_uptodate(bh) && !buffer_locked(bh))
			ll_rw_block(READA | REQ_META, 1, &bh);
		brelse(bh);
		dblock++;
		extlen--;
		if (!buffer_locked(first_bh) && buffer_uptodate(first_bh))
			goto out;
	}

	wait_on_buffer(first_bh);
out:
	return first_bh;
}
Commit	Line	Data
b3b94faa DT	1	/*
b3b94faa DT	2	* Copyright (C) Sistina Software, Inc. 1997-2003 All rights reserved.
091806ed	3	* Copyright (C) 2004-2008 Red Hat, Inc. All rights reserved.
b3b94faa DT	4	*
	5	* This copyrighted material is made available to anyone wishing to use,
	6	* modify, copy, or redistribute it subject to the terms and conditions
e9fc2aa0	7	* of the GNU General Public License version 2.
b3b94faa DT	8	*/
	9
	10	#include <linux/sched.h>
	11	#include <linux/slab.h>
	12	#include <linux/spinlock.h>
	13	#include <linux/completion.h>
	14	#include <linux/buffer_head.h>
	15	#include <linux/mm.h>
	16	#include <linux/pagemap.h>
	17	#include <linux/writeback.h>
	18	#include <linux/swap.h>
	19	#include <linux/delay.h>
2e565bb6	20	#include <linux/bio.h>
5c676f6d	21	#include <linux/gfs2_ondisk.h>
b3b94faa DT	22
b3b94faa DT	23	#include "gfs2.h"
5c676f6d	24	#include "incore.h"
b3b94faa DT	25	#include "glock.h"
	26	#include "glops.h"
	27	#include "inode.h"
	28	#include "log.h"
	29	#include "lops.h"
	30	#include "meta_io.h"
	31	#include "rgrp.h"
	32	#include "trans.h"
5c676f6d	33	#include "util.h"
627c10b7	34	#include "trace_gfs2.h"
b3b94faa	35
4a0f9a32	36	static int gfs2_aspace_writepage(struct page page, struct writeback_control wbc)
b3b94faa	37	{
4a0f9a32 SW	38	struct buffer_head bh, head;
4a0f9a32 SW	39	int nr_underway = 0;
65299a3b	40	int write_op = REQ_META \| REQ_PRIO \|
721a9602	41	(wbc->sync_mode == WB_SYNC_ALL ? WRITE_SYNC : WRITE);
b3b94faa	42
4a0f9a32 SW	43	BUG_ON(!PageLocked(page));
	44	BUG_ON(!page_has_buffers(page));
	45
	46	head = page_buffers(page);
	47	bh = head;
	48
	49	do {
	50	if (!buffer_mapped(bh))
	51	continue;
	52	/*
	53	* If it's a fully non-blocking write attempt and we cannot
	54	* lock the buffer then redirty the page. Note that this can
e76e0ec9	55	* potentially cause a busy-wait loop from flusher thread and kswapd
4a0f9a32 SW	56	* activity, but those code paths have their own higher-level
	57	* throttling.
	58	*/
1b430bee	59	if (wbc->sync_mode != WB_SYNC_NONE) {
4a0f9a32 SW	60	lock_buffer(bh);
	61	} else if (!trylock_buffer(bh)) {
	62	redirty_page_for_writepage(wbc, page);
	63	continue;
	64	}
	65	if (test_clear_buffer_dirty(bh)) {
	66	mark_buffer_async_write(bh);
	67	} else {
	68	unlock_buffer(bh);
	69	}
	70	} while ((bh = bh->b_this_page) != head);
	71
	72	/*
	73	* The page and its buffers are protected by PageWriteback(), so we can
	74	* drop the bh refcounts early.
	75	*/
	76	BUG_ON(PageWriteback(page));
	77	set_page_writeback(page);
	78
	79	do {
	80	struct buffer_head *next = bh->b_this_page;
	81	if (buffer_async_write(bh)) {
	82	submit_bh(write_op, bh);
	83	nr_underway++;
	84	}
	85	bh = next;
	86	} while (bh != head);
	87	unlock_page(page);
	88
4a0f9a32 SW	89	if (nr_underway == 0)
	90	end_page_writeback(page);
	91
eaefbf96	92	return 0;
b3b94faa DT	93	}
b3b94faa DT	94
009d8518	95	const struct address_space_operations gfs2_meta_aops = {
b3b94faa	96	.writepage = gfs2_aspace_writepage,
4340fe62	97	.releasepage = gfs2_releasepage,
b3b94faa DT	98	};
b3b94faa DT	99
b3b94faa	100	/**
6802e340	101	* gfs2_getbuf - Get a buffer with a given address space
cb4c0313	102	* @gl: the glock
b3b94faa DT	103	* @blkno: the block number (filesystem scope)
	104	* @create: 1 if the buffer should be created
	105	*
	106	* Returns: the buffer
	107	*/
	108
6802e340	109	struct buffer_head gfs2_getbuf(struct gfs2_glock gl, u64 blkno, int create)
b3b94faa	110	{
009d8518	111	struct address_space *mapping = gfs2_glock2aspace(gl);
cb4c0313	112	struct gfs2_sbd *sdp = gl->gl_sbd;
b3b94faa DT	113	struct page *page;
	114	struct buffer_head *bh;
	115	unsigned int shift;
	116	unsigned long index;
	117	unsigned int bufnum;
	118
	119	shift = PAGE_CACHE_SHIFT - sdp->sd_sb.sb_bsize_shift;
	120	index = blkno >> shift; /* convert block to page */
	121	bufnum = blkno - (index << shift); /* block buf index within page */
	122
	123	if (create) {
	124	for (;;) {
cb4c0313	125	page = grab_cache_page(mapping, index);
b3b94faa DT	126	if (page)
	127	break;
	128	yield();
	129	}
	130	} else {
cb4c0313	131	page = find_lock_page(mapping, index);
b3b94faa DT	132	if (!page)
	133	return NULL;
	134	}
	135
	136	if (!page_has_buffers(page))
	137	create_empty_buffers(page, sdp->sd_sb.sb_bsize, 0);
	138
	139	/* Locate header for our buffer within our page */
	140	for (bh = page_buffers(page); bufnum--; bh = bh->b_this_page)
	141	/* Do nothing */;
	142	get_bh(bh);
	143
	144	if (!buffer_mapped(bh))
	145	map_bh(bh, sdp->sd_vfs, blkno);
	146
	147	unlock_page(page);
	148	mark_page_accessed(page);
	149	page_cache_release(page);
	150
	151	return bh;
	152	}
	153
	154	static void meta_prep_new(struct buffer_head *bh)
	155	{
	156	struct gfs2_meta_header mh = (struct gfs2_meta_header )bh->b_data;
	157
	158	lock_buffer(bh);
	159	clear_buffer_dirty(bh);
	160	set_buffer_uptodate(bh);
	161	unlock_buffer(bh);
	162
	163	mh->mh_magic = cpu_to_be32(GFS2_MAGIC);
	164	}
	165
	166	/**
	167	* gfs2_meta_new - Get a block
	168	* @gl: The glock associated with this block
	169	* @blkno: The block number
	170	*
	171	* Returns: The buffer
	172	*/
	173
cd915493	174	struct buffer_head gfs2_meta_new(struct gfs2_glock gl, u64 blkno)
b3b94faa DT	175	{
b3b94faa DT	176	struct buffer_head *bh;
6802e340	177	bh = gfs2_getbuf(gl, blkno, CREATE);
b3b94faa DT	178	meta_prep_new(bh);
	179	return bh;
	180	}
	181
	182	/**
	183	* gfs2_meta_read - Read a block from disk
	184	* @gl: The glock covering the block
	185	* @blkno: The block number
7276b3b0	186	* @flags: flags
b3b94faa DT	187	* @bhp: the place where the buffer is returned (NULL on failure)
	188	*
	189	* Returns: errno
	190	*/
	191
cd915493	192	int gfs2_meta_read(struct gfs2_glock *gl, u64 blkno, int flags,
b3b94faa DT	193	struct buffer_head **bhp)
b3b94faa DT	194	{
c969f58c SW	195	struct gfs2_sbd *sdp = gl->gl_sbd;
	196	struct buffer_head *bh;
	197
44b8db13 MY	198	if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags))) {
44b8db13 MY	199	*bhp = NULL;
c969f58c	200	return -EIO;
44b8db13	201	}
c969f58c SW	202
	203	*bhp = bh = gfs2_getbuf(gl, blkno, CREATE);
	204
	205	lock_buffer(bh);
	206	if (buffer_uptodate(bh)) {
	207	unlock_buffer(bh);
	208	return 0;
	209	}
	210	bh->b_end_io = end_buffer_read_sync;
	211	get_bh(bh);
65299a3b	212	submit_bh(READ_SYNC \| REQ_META \| REQ_PRIO, bh);
c969f58c SW	213	if (!(flags & DIO_WAIT))
	214	return 0;
	215
	216	wait_on_buffer(bh);
	217	if (unlikely(!buffer_uptodate(bh))) {
	218	struct gfs2_trans *tr = current->journal_info;
	219	if (tr && tr->tr_touched)
	220	gfs2_io_error_bh(sdp, bh);
	221	brelse(bh);
44b8db13	222	*bhp = NULL;
c969f58c	223	return -EIO;
7276b3b0	224	}
b3b94faa	225
7276b3b0	226	return 0;
b3b94faa DT	227	}
	228
	229	/**
7276b3b0	230	* gfs2_meta_wait - Reread a block from disk
b3b94faa	231	* @sdp: the filesystem
7276b3b0	232	* @bh: The block to wait for
b3b94faa DT	233	*
	234	* Returns: errno
	235	*/
	236
7276b3b0	237	int gfs2_meta_wait(struct gfs2_sbd sdp, struct buffer_head bh)
b3b94faa DT	238	{
	239	if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
	240	return -EIO;
	241
7276b3b0	242	wait_on_buffer(bh);
b3b94faa	243
7276b3b0 SW	244	if (!buffer_uptodate(bh)) {
	245	struct gfs2_trans *tr = current->journal_info;
	246	if (tr && tr->tr_touched)
	247	gfs2_io_error_bh(sdp, bh);
	248	return -EIO;
b3b94faa	249	}
7276b3b0 SW	250	if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
7276b3b0 SW	251	return -EIO;
b3b94faa DT	252
	253	return 0;
	254	}
	255
16615be1 SW	256	void gfs2_remove_from_journal(struct buffer_head bh, struct gfs2_trans tr, int meta)
16615be1 SW	257	{
009d8518 SW	258	struct address_space *mapping = bh->b_page->mapping;
009d8518 SW	259	struct gfs2_sbd *sdp = gfs2_mapping2sbd(mapping);
16615be1	260	struct gfs2_bufdata *bd = bh->b_private;
009d8518	261
16615be1	262	if (test_clear_buffer_pinned(bh)) {
627c10b7	263	trace_gfs2_pin(bd, 0);
5e687eac	264	atomic_dec(&sdp->sd_log_pinned);
c0752aa7	265	list_del_init(&bd->bd_list);
16615be1 SW	266	if (meta) {
	267	gfs2_assert_warn(sdp, sdp->sd_log_num_buf);
	268	sdp->sd_log_num_buf--;
	269	tr->tr_num_buf_rm++;
	270	} else {
	271	gfs2_assert_warn(sdp, sdp->sd_log_num_databuf);
	272	sdp->sd_log_num_databuf--;
	273	tr->tr_num_databuf_rm++;
	274	}
	275	tr->tr_touched = 1;
	276	brelse(bh);
	277	}
	278	if (bd) {
c618e87a	279	spin_lock(&sdp->sd_ail_lock);
16ca9412	280	if (bd->bd_tr) {
16615be1 SW	281	gfs2_trans_add_revoke(sdp, bd);
16615be1 SW	282	}
c618e87a	283	spin_unlock(&sdp->sd_ail_lock);
16615be1 SW	284	}
	285	clear_buffer_dirty(bh);
	286	clear_buffer_uptodate(bh);
	287	}
	288
b3b94faa DT	289	/**
	290	* gfs2_meta_wipe - make inode's buffers so they aren't dirty/pinned anymore
	291	* @ip: the inode who owns the buffers
	292	* @bstart: the first buffer in the run
	293	* @blen: the number of buffers in the run
	294	*
	295	*/
	296
cd915493	297	void gfs2_meta_wipe(struct gfs2_inode *ip, u64 bstart, u32 blen)
b3b94faa	298	{
feaa7bba	299	struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
b3b94faa DT	300	struct buffer_head *bh;
	301
	302	while (blen) {
6802e340	303	bh = gfs2_getbuf(ip->i_gl, bstart, NO_CREATE);
b3b94faa	304	if (bh) {
1ad38c43 SW	305	lock_buffer(bh);
1ad38c43 SW	306	gfs2_log_lock(sdp);
16615be1	307	gfs2_remove_from_journal(bh, current->journal_info, 1);
1ad38c43	308	gfs2_log_unlock(sdp);
b3b94faa	309	unlock_buffer(bh);
b3b94faa DT	310	brelse(bh);
	311	}
	312
	313	bstart++;
	314	blen--;
	315	}
	316	}
	317
b3b94faa DT	318	/**
	319	* gfs2_meta_indirect_buffer - Get a metadata buffer
	320	* @ip: The GFS2 inode
	321	* @height: The level of this buf in the metadata (indir addr) tree (if any)
	322	* @num: The block number (device relative) of the buffer
b3b94faa DT	323	* @bhp: the buffer is returned here
b3b94faa DT	324	*
b3b94faa DT	325	* Returns: errno
	326	*/
	327
cd915493	328	int gfs2_meta_indirect_buffer(struct gfs2_inode *ip, int height, u64 num,
f2f9c812	329	struct buffer_head **bhp)
b3b94faa	330	{
7276b3b0 SW	331	struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
7276b3b0 SW	332	struct gfs2_glock *gl = ip->i_gl;
f91a0d3e SW	333	struct buffer_head *bh;
f91a0d3e SW	334	int ret = 0;
f2f9c812	335	u32 mtype = height ? GFS2_METATYPE_IN : GFS2_METATYPE_DI;
b3b94faa	336
f2f9c812 BP	337	ret = gfs2_meta_read(gl, num, DIO_WAIT, &bh);
	338	if (ret == 0 && gfs2_metatype_check(sdp, bh, mtype)) {
	339	brelse(bh);
	340	ret = -EIO;
b3b94faa	341	}
b3b94faa	342	*bhp = bh;
f91a0d3e	343	return ret;
b3b94faa DT	344	}
	345
	346	/**
	347	* gfs2_meta_ra - start readahead on an extent of a file
	348	* @gl: the glock the blocks belong to
	349	* @dblock: the starting disk block
	350	* @extlen: the number of blocks in the extent
	351	*
7276b3b0	352	* returns: the first buffer in the extent
b3b94faa DT	353	*/
b3b94faa DT	354
7276b3b0	355	struct buffer_head gfs2_meta_ra(struct gfs2_glock gl, u64 dblock, u32 extlen)
b3b94faa DT	356	{
b3b94faa DT	357	struct gfs2_sbd *sdp = gl->gl_sbd;
b3b94faa	358	struct buffer_head first_bh, bh;
cd915493	359	u32 max_ra = gfs2_tune_get(sdp, gt_max_readahead) >>
568f4c96	360	sdp->sd_sb.sb_bsize_shift;
b3b94faa	361
7276b3b0 SW	362	BUG_ON(!extlen);
	363
	364	if (max_ra < 1)
	365	max_ra = 1;
b3b94faa DT	366	if (extlen > max_ra)
	367	extlen = max_ra;
	368
6802e340	369	first_bh = gfs2_getbuf(gl, dblock, CREATE);
b3b94faa DT	370
	371	if (buffer_uptodate(first_bh))
	372	goto out;
7276b3b0	373	if (!buffer_locked(first_bh))
20ed0535	374	ll_rw_block(READ_SYNC \| REQ_META, 1, &first_bh);
b3b94faa DT	375
	376	dblock++;
	377	extlen--;
	378
	379	while (extlen) {
6802e340	380	bh = gfs2_getbuf(gl, dblock, CREATE);
b3b94faa	381
7276b3b0	382	if (!buffer_uptodate(bh) && !buffer_locked(bh))
20ed0535	383	ll_rw_block(READA \| REQ_META, 1, &bh);
7276b3b0	384	brelse(bh);
b3b94faa DT	385	dblock++;
b3b94faa DT	386	extlen--;
7276b3b0 SW	387	if (!buffer_locked(first_bh) && buffer_uptodate(first_bh))
7276b3b0 SW	388	goto out;
b3b94faa DT	389	}
b3b94faa DT	390
7276b3b0	391	wait_on_buffer(first_bh);
a91ea69f	392	out:
7276b3b0	393	return first_bh;
b3b94faa DT	394	}
b3b94faa DT	395