linux/fs/ocfs2/extent_map.c
Mark Fasheh 8341897882 ocfs2: Cache extent records
The extent map code was ripped out earlier because of an inability to deal
with holes. This patch adds back a simpler caching scheme requiring far less
code.

Our old extent map caching was designed back when meta data block caching in
Ocfs2 didn't work very well, resulting in many disk reads. These days our
metadata caching is much better, resulting in no un-necessary disk reads. As
a result, extent caching doesn't have to be as fancy, nor does it have to
cache as many extents. Keeping the last 3 extents seen should be sufficient
to give us a small performance boost on some streaming workloads.

Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>
2007-04-26 15:10:40 -07:00

552 lines
13 KiB
C

/* -*- mode: c; c-basic-offset: 8; -*-
* vim: noexpandtab sw=8 ts=8 sts=0:
*
* extent_map.c
*
* Block/Cluster mapping functions
*
* Copyright (C) 2004 Oracle. All rights reserved.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public
* License, version 2, as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public
* License along with this program; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 021110-1307, USA.
*/
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/types.h>
#define MLOG_MASK_PREFIX ML_EXTENT_MAP
#include <cluster/masklog.h>
#include "ocfs2.h"
#include "alloc.h"
#include "extent_map.h"
#include "inode.h"
#include "super.h"
#include "buffer_head_io.h"
/*
* The extent caching implementation is intentionally trivial.
*
* We only cache a small number of extents stored directly on the
* inode, so linear order operations are acceptable. If we ever want
* to increase the size of the extent map, then these algorithms must
* get smarter.
*/
void ocfs2_extent_map_init(struct inode *inode)
{
struct ocfs2_inode_info *oi = OCFS2_I(inode);
oi->ip_extent_map.em_num_items = 0;
INIT_LIST_HEAD(&oi->ip_extent_map.em_list);
}
static void __ocfs2_extent_map_lookup(struct ocfs2_extent_map *em,
unsigned int cpos,
struct ocfs2_extent_map_item **ret_emi)
{
unsigned int range;
struct ocfs2_extent_map_item *emi;
*ret_emi = NULL;
list_for_each_entry(emi, &em->em_list, ei_list) {
range = emi->ei_cpos + emi->ei_clusters;
if (cpos >= emi->ei_cpos && cpos < range) {
list_move(&emi->ei_list, &em->em_list);
*ret_emi = emi;
break;
}
}
}
static int ocfs2_extent_map_lookup(struct inode *inode, unsigned int cpos,
unsigned int *phys, unsigned int *len,
unsigned int *flags)
{
unsigned int coff;
struct ocfs2_inode_info *oi = OCFS2_I(inode);
struct ocfs2_extent_map_item *emi;
spin_lock(&oi->ip_lock);
__ocfs2_extent_map_lookup(&oi->ip_extent_map, cpos, &emi);
if (emi) {
coff = cpos - emi->ei_cpos;
*phys = emi->ei_phys + coff;
if (len)
*len = emi->ei_clusters - coff;
if (flags)
*flags = emi->ei_flags;
}
spin_unlock(&oi->ip_lock);
if (emi == NULL)
return -ENOENT;
return 0;
}
/*
* Forget about all clusters equal to or greater than cpos.
*/
void ocfs2_extent_map_trunc(struct inode *inode, unsigned int cpos)
{
struct list_head *p, *n;
struct ocfs2_extent_map_item *emi;
struct ocfs2_inode_info *oi = OCFS2_I(inode);
struct ocfs2_extent_map *em = &oi->ip_extent_map;
LIST_HEAD(tmp_list);
unsigned int range;
spin_lock(&oi->ip_lock);
list_for_each_safe(p, n, &em->em_list) {
emi = list_entry(p, struct ocfs2_extent_map_item, ei_list);
if (emi->ei_cpos >= cpos) {
/* Full truncate of this record. */
list_move(&emi->ei_list, &tmp_list);
BUG_ON(em->em_num_items == 0);
em->em_num_items--;
continue;
}
range = emi->ei_cpos + emi->ei_clusters;
if (range > cpos) {
/* Partial truncate */
emi->ei_clusters = cpos - emi->ei_cpos;
}
}
spin_unlock(&oi->ip_lock);
list_for_each_safe(p, n, &tmp_list) {
emi = list_entry(p, struct ocfs2_extent_map_item, ei_list);
list_del(&emi->ei_list);
kfree(emi);
}
}
/*
* Is any part of emi2 contained within emi1
*/
static int ocfs2_ei_is_contained(struct ocfs2_extent_map_item *emi1,
struct ocfs2_extent_map_item *emi2)
{
unsigned int range1, range2;
/*
* Check if logical start of emi2 is inside emi1
*/
range1 = emi1->ei_cpos + emi1->ei_clusters;
if (emi2->ei_cpos >= emi1->ei_cpos && emi2->ei_cpos < range1)
return 1;
/*
* Check if logical end of emi2 is inside emi1
*/
range2 = emi2->ei_cpos + emi2->ei_clusters;
if (range2 > emi1->ei_cpos && range2 <= range1)
return 1;
return 0;
}
static void ocfs2_copy_emi_fields(struct ocfs2_extent_map_item *dest,
struct ocfs2_extent_map_item *src)
{
dest->ei_cpos = src->ei_cpos;
dest->ei_phys = src->ei_phys;
dest->ei_clusters = src->ei_clusters;
dest->ei_flags = src->ei_flags;
}
/*
* Try to merge emi with ins. Returns 1 if merge succeeds, zero
* otherwise.
*/
static int ocfs2_try_to_merge_extent_map(struct ocfs2_extent_map_item *emi,
struct ocfs2_extent_map_item *ins)
{
/*
* Handle contiguousness
*/
if (ins->ei_phys == (emi->ei_phys + emi->ei_clusters) &&
ins->ei_cpos == (emi->ei_cpos + emi->ei_clusters) &&
ins->ei_flags == emi->ei_flags) {
emi->ei_clusters += ins->ei_clusters;
return 1;
} else if ((ins->ei_phys + ins->ei_clusters) == emi->ei_phys &&
(ins->ei_cpos + ins->ei_clusters) == emi->ei_phys &&
ins->ei_flags == emi->ei_flags) {
emi->ei_phys = ins->ei_phys;
emi->ei_cpos = ins->ei_cpos;
emi->ei_clusters += ins->ei_clusters;
return 1;
}
/*
* Overlapping extents - this shouldn't happen unless we've
* split an extent to change it's flags. That is exceedingly
* rare, so there's no sense in trying to optimize it yet.
*/
if (ocfs2_ei_is_contained(emi, ins) ||
ocfs2_ei_is_contained(ins, emi)) {
ocfs2_copy_emi_fields(emi, ins);
return 1;
}
/* No merge was possible. */
return 0;
}
/*
* In order to reduce complexity on the caller, this insert function
* is intentionally liberal in what it will accept.
*
* The only rule is that the truncate call *must* be used whenever
* records have been deleted. This avoids inserting overlapping
* records with different physical mappings.
*/
void ocfs2_extent_map_insert_rec(struct inode *inode,
struct ocfs2_extent_rec *rec)
{
struct ocfs2_inode_info *oi = OCFS2_I(inode);
struct ocfs2_extent_map *em = &oi->ip_extent_map;
struct ocfs2_extent_map_item *emi, *new_emi = NULL;
struct ocfs2_extent_map_item ins;
ins.ei_cpos = le32_to_cpu(rec->e_cpos);
ins.ei_phys = ocfs2_blocks_to_clusters(inode->i_sb,
le64_to_cpu(rec->e_blkno));
ins.ei_clusters = le16_to_cpu(rec->e_leaf_clusters);
ins.ei_flags = rec->e_flags;
search:
spin_lock(&oi->ip_lock);
list_for_each_entry(emi, &em->em_list, ei_list) {
if (ocfs2_try_to_merge_extent_map(emi, &ins)) {
list_move(&emi->ei_list, &em->em_list);
spin_unlock(&oi->ip_lock);
goto out;
}
}
/*
* No item could be merged.
*
* Either allocate and add a new item, or overwrite the last recently
* inserted.
*/
if (em->em_num_items < OCFS2_MAX_EXTENT_MAP_ITEMS) {
if (new_emi == NULL) {
spin_unlock(&oi->ip_lock);
new_emi = kmalloc(sizeof(*new_emi), GFP_NOFS);
if (new_emi == NULL)
goto out;
goto search;
}
ocfs2_copy_emi_fields(new_emi, &ins);
list_add(&new_emi->ei_list, &em->em_list);
em->em_num_items++;
new_emi = NULL;
} else {
BUG_ON(list_empty(&em->em_list) || em->em_num_items == 0);
emi = list_entry(em->em_list.prev,
struct ocfs2_extent_map_item, ei_list);
list_move(&emi->ei_list, &em->em_list);
ocfs2_copy_emi_fields(emi, &ins);
}
spin_unlock(&oi->ip_lock);
out:
if (new_emi)
kfree(new_emi);
}
/*
* Return the 1st index within el which contains an extent start
* larger than v_cluster.
*/
static int ocfs2_search_for_hole_index(struct ocfs2_extent_list *el,
u32 v_cluster)
{
int i;
struct ocfs2_extent_rec *rec;
for(i = 0; i < le16_to_cpu(el->l_next_free_rec); i++) {
rec = &el->l_recs[i];
if (v_cluster < le32_to_cpu(rec->e_cpos))
break;
}
return i;
}
/*
* Figure out the size of a hole which starts at v_cluster within the given
* extent list.
*
* If there is no more allocation past v_cluster, we return the maximum
* cluster size minus v_cluster.
*
* If we have in-inode extents, then el points to the dinode list and
* eb_bh is NULL. Otherwise, eb_bh should point to the extent block
* containing el.
*/
static int ocfs2_figure_hole_clusters(struct inode *inode,
struct ocfs2_extent_list *el,
struct buffer_head *eb_bh,
u32 v_cluster,
u32 *num_clusters)
{
int ret, i;
struct buffer_head *next_eb_bh = NULL;
struct ocfs2_extent_block *eb, *next_eb;
i = ocfs2_search_for_hole_index(el, v_cluster);
if (i == le16_to_cpu(el->l_next_free_rec) && eb_bh) {
eb = (struct ocfs2_extent_block *)eb_bh->b_data;
/*
* Check the next leaf for any extents.
*/
if (le64_to_cpu(eb->h_next_leaf_blk) == 0ULL)
goto no_more_extents;
ret = ocfs2_read_block(OCFS2_SB(inode->i_sb),
le64_to_cpu(eb->h_next_leaf_blk),
&next_eb_bh, OCFS2_BH_CACHED, inode);
if (ret) {
mlog_errno(ret);
goto out;
}
next_eb = (struct ocfs2_extent_block *)next_eb_bh->b_data;
if (!OCFS2_IS_VALID_EXTENT_BLOCK(next_eb)) {
ret = -EROFS;
OCFS2_RO_ON_INVALID_EXTENT_BLOCK(inode->i_sb, next_eb);
goto out;
}
el = &next_eb->h_list;
i = ocfs2_search_for_hole_index(el, v_cluster);
}
no_more_extents:
if (i == le16_to_cpu(el->l_next_free_rec)) {
/*
* We're at the end of our existing allocation. Just
* return the maximum number of clusters we could
* possibly allocate.
*/
*num_clusters = UINT_MAX - v_cluster;
} else {
*num_clusters = le32_to_cpu(el->l_recs[i].e_cpos) - v_cluster;
}
ret = 0;
out:
brelse(next_eb_bh);
return ret;
}
/*
* Return the index of the extent record which contains cluster #v_cluster.
* -1 is returned if it was not found.
*
* Should work fine on interior and exterior nodes.
*/
static int ocfs2_search_extent_list(struct ocfs2_extent_list *el,
u32 v_cluster)
{
int ret = -1;
int i;
struct ocfs2_extent_rec *rec;
u32 rec_end, rec_start, clusters;
for(i = 0; i < le16_to_cpu(el->l_next_free_rec); i++) {
rec = &el->l_recs[i];
rec_start = le32_to_cpu(rec->e_cpos);
clusters = ocfs2_rec_clusters(el, rec);
rec_end = rec_start + clusters;
if (v_cluster >= rec_start && v_cluster < rec_end) {
ret = i;
break;
}
}
return ret;
}
int ocfs2_get_clusters(struct inode *inode, u32 v_cluster,
u32 *p_cluster, u32 *num_clusters,
unsigned int *extent_flags)
{
int ret, i;
unsigned int flags = 0;
struct buffer_head *di_bh = NULL;
struct buffer_head *eb_bh = NULL;
struct ocfs2_dinode *di;
struct ocfs2_extent_block *eb;
struct ocfs2_extent_list *el;
struct ocfs2_extent_rec *rec;
u32 coff;
ret = ocfs2_extent_map_lookup(inode, v_cluster, p_cluster,
num_clusters, extent_flags);
if (ret == 0)
goto out;
ret = ocfs2_read_block(OCFS2_SB(inode->i_sb), OCFS2_I(inode)->ip_blkno,
&di_bh, OCFS2_BH_CACHED, inode);
if (ret) {
mlog_errno(ret);
goto out;
}
di = (struct ocfs2_dinode *) di_bh->b_data;
el = &di->id2.i_list;
if (el->l_tree_depth) {
ret = ocfs2_find_leaf(inode, el, v_cluster, &eb_bh);
if (ret) {
mlog_errno(ret);
goto out;
}
eb = (struct ocfs2_extent_block *) eb_bh->b_data;
el = &eb->h_list;
if (el->l_tree_depth) {
ocfs2_error(inode->i_sb,
"Inode %lu has non zero tree depth in "
"leaf block %llu\n", inode->i_ino,
(unsigned long long)eb_bh->b_blocknr);
ret = -EROFS;
goto out;
}
}
i = ocfs2_search_extent_list(el, v_cluster);
if (i == -1) {
/*
* A hole was found. Return some canned values that
* callers can key on. If asked for, num_clusters will
* be populated with the size of the hole.
*/
*p_cluster = 0;
if (num_clusters) {
ret = ocfs2_figure_hole_clusters(inode, el, eb_bh,
v_cluster,
num_clusters);
if (ret) {
mlog_errno(ret);
goto out;
}
}
} else {
rec = &el->l_recs[i];
BUG_ON(v_cluster < le32_to_cpu(rec->e_cpos));
if (!rec->e_blkno) {
ocfs2_error(inode->i_sb, "Inode %lu has bad extent "
"record (%u, %u, 0)", inode->i_ino,
le32_to_cpu(rec->e_cpos),
ocfs2_rec_clusters(el, rec));
ret = -EROFS;
goto out;
}
coff = v_cluster - le32_to_cpu(rec->e_cpos);
*p_cluster = ocfs2_blocks_to_clusters(inode->i_sb,
le64_to_cpu(rec->e_blkno));
*p_cluster = *p_cluster + coff;
if (num_clusters)
*num_clusters = ocfs2_rec_clusters(el, rec) - coff;
flags = rec->e_flags;
ocfs2_extent_map_insert_rec(inode, rec);
}
if (extent_flags)
*extent_flags = flags;
out:
brelse(di_bh);
brelse(eb_bh);
return ret;
}
/*
* This expects alloc_sem to be held. The allocation cannot change at
* all while the map is in the process of being updated.
*/
int ocfs2_extent_map_get_blocks(struct inode *inode, u64 v_blkno, u64 *p_blkno,
u64 *ret_count, unsigned int *extent_flags)
{
int ret;
int bpc = ocfs2_clusters_to_blocks(inode->i_sb, 1);
u32 cpos, num_clusters, p_cluster;
u64 boff = 0;
cpos = ocfs2_blocks_to_clusters(inode->i_sb, v_blkno);
ret = ocfs2_get_clusters(inode, cpos, &p_cluster, &num_clusters,
extent_flags);
if (ret) {
mlog_errno(ret);
goto out;
}
/*
* p_cluster == 0 indicates a hole.
*/
if (p_cluster) {
boff = ocfs2_clusters_to_blocks(inode->i_sb, p_cluster);
boff += (v_blkno & (u64)(bpc - 1));
}
*p_blkno = boff;
if (ret_count) {
*ret_count = ocfs2_clusters_to_blocks(inode->i_sb, num_clusters);
*ret_count -= v_blkno & (u64)(bpc - 1);
}
out:
return ret;
}