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linux/fs/ocfs2/uptodate.c
Paul Mundt 20c2df83d2 mm: Remove slab destructors from kmem_cache_create().
Slab destructors were no longer supported after Christoph's
c59def9f22 change. They've been
BUGs for both slab and slub, and slob never supported them
either.

This rips out support for the dtor pointer from kmem_cache_create()
completely and fixes up every single callsite in the kernel (there were
about 224, not including the slab allocator definitions themselves,
or the documentation references).

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2007-07-20 10:11:58 +09:00

566 lines
16 KiB
C

/* -*- mode: c; c-basic-offset: 8; -*-
* vim: noexpandtab sw=8 ts=8 sts=0:
*
* uptodate.c
*
* Tracking the up-to-date-ness of a local buffer_head with respect to
* the cluster.
*
* Copyright (C) 2002, 2004, 2005 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 as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* 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.
*
* Standard buffer head caching flags (uptodate, etc) are insufficient
* in a clustered environment - a buffer may be marked up to date on
* our local node but could have been modified by another cluster
* member. As a result an additional (and performant) caching scheme
* is required. A further requirement is that we consume as little
* memory as possible - we never pin buffer_head structures in order
* to cache them.
*
* We track the existence of up to date buffers on the inodes which
* are associated with them. Because we don't want to pin
* buffer_heads, this is only a (strong) hint and several other checks
* are made in the I/O path to ensure that we don't use a stale or
* invalid buffer without going to disk:
* - buffer_jbd is used liberally - if a bh is in the journal on
* this node then it *must* be up to date.
* - the standard buffer_uptodate() macro is used to detect buffers
* which may be invalid (even if we have an up to date tracking
* item for them)
*
* For a full understanding of how this code works together, one
* should read the callers in dlmglue.c, the I/O functions in
* buffer_head_io.c and ocfs2_journal_access in journal.c
*/
#include <linux/fs.h>
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/highmem.h>
#include <linux/buffer_head.h>
#include <linux/rbtree.h>
#include <linux/jbd.h>
#define MLOG_MASK_PREFIX ML_UPTODATE
#include <cluster/masklog.h>
#include "ocfs2.h"
#include "inode.h"
#include "uptodate.h"
struct ocfs2_meta_cache_item {
struct rb_node c_node;
sector_t c_block;
};
static struct kmem_cache *ocfs2_uptodate_cachep = NULL;
void ocfs2_metadata_cache_init(struct inode *inode)
{
struct ocfs2_inode_info *oi = OCFS2_I(inode);
struct ocfs2_caching_info *ci = &oi->ip_metadata_cache;
oi->ip_flags |= OCFS2_INODE_CACHE_INLINE;
ci->ci_num_cached = 0;
}
/* No lock taken here as 'root' is not expected to be visible to other
* processes. */
static unsigned int ocfs2_purge_copied_metadata_tree(struct rb_root *root)
{
unsigned int purged = 0;
struct rb_node *node;
struct ocfs2_meta_cache_item *item;
while ((node = rb_last(root)) != NULL) {
item = rb_entry(node, struct ocfs2_meta_cache_item, c_node);
mlog(0, "Purge item %llu\n",
(unsigned long long) item->c_block);
rb_erase(&item->c_node, root);
kmem_cache_free(ocfs2_uptodate_cachep, item);
purged++;
}
return purged;
}
/* Called from locking and called from ocfs2_clear_inode. Dump the
* cache for a given inode.
*
* This function is a few more lines longer than necessary due to some
* accounting done here, but I think it's worth tracking down those
* bugs sooner -- Mark */
void ocfs2_metadata_cache_purge(struct inode *inode)
{
struct ocfs2_inode_info *oi = OCFS2_I(inode);
unsigned int tree, to_purge, purged;
struct ocfs2_caching_info *ci = &oi->ip_metadata_cache;
struct rb_root root = RB_ROOT;
spin_lock(&oi->ip_lock);
tree = !(oi->ip_flags & OCFS2_INODE_CACHE_INLINE);
to_purge = ci->ci_num_cached;
mlog(0, "Purge %u %s items from Inode %llu\n", to_purge,
tree ? "array" : "tree", (unsigned long long)oi->ip_blkno);
/* If we're a tree, save off the root so that we can safely
* initialize the cache. We do the work to free tree members
* without the spinlock. */
if (tree)
root = ci->ci_cache.ci_tree;
ocfs2_metadata_cache_init(inode);
spin_unlock(&oi->ip_lock);
purged = ocfs2_purge_copied_metadata_tree(&root);
/* If possible, track the number wiped so that we can more
* easily detect counting errors. Unfortunately, this is only
* meaningful for trees. */
if (tree && purged != to_purge)
mlog(ML_ERROR, "Inode %llu, count = %u, purged = %u\n",
(unsigned long long)oi->ip_blkno, to_purge, purged);
}
/* Returns the index in the cache array, -1 if not found.
* Requires ip_lock. */
static int ocfs2_search_cache_array(struct ocfs2_caching_info *ci,
sector_t item)
{
int i;
for (i = 0; i < ci->ci_num_cached; i++) {
if (item == ci->ci_cache.ci_array[i])
return i;
}
return -1;
}
/* Returns the cache item if found, otherwise NULL.
* Requires ip_lock. */
static struct ocfs2_meta_cache_item *
ocfs2_search_cache_tree(struct ocfs2_caching_info *ci,
sector_t block)
{
struct rb_node * n = ci->ci_cache.ci_tree.rb_node;
struct ocfs2_meta_cache_item *item = NULL;
while (n) {
item = rb_entry(n, struct ocfs2_meta_cache_item, c_node);
if (block < item->c_block)
n = n->rb_left;
else if (block > item->c_block)
n = n->rb_right;
else
return item;
}
return NULL;
}
static int ocfs2_buffer_cached(struct ocfs2_inode_info *oi,
struct buffer_head *bh)
{
int index = -1;
struct ocfs2_meta_cache_item *item = NULL;
spin_lock(&oi->ip_lock);
mlog(0, "Inode %llu, query block %llu (inline = %u)\n",
(unsigned long long)oi->ip_blkno,
(unsigned long long) bh->b_blocknr,
!!(oi->ip_flags & OCFS2_INODE_CACHE_INLINE));
if (oi->ip_flags & OCFS2_INODE_CACHE_INLINE)
index = ocfs2_search_cache_array(&oi->ip_metadata_cache,
bh->b_blocknr);
else
item = ocfs2_search_cache_tree(&oi->ip_metadata_cache,
bh->b_blocknr);
spin_unlock(&oi->ip_lock);
mlog(0, "index = %d, item = %p\n", index, item);
return (index != -1) || (item != NULL);
}
/* Warning: even if it returns true, this does *not* guarantee that
* the block is stored in our inode metadata cache.
*
* This can be called under lock_buffer()
*/
int ocfs2_buffer_uptodate(struct inode *inode,
struct buffer_head *bh)
{
/* Doesn't matter if the bh is in our cache or not -- if it's
* not marked uptodate then we know it can't have correct
* data. */
if (!buffer_uptodate(bh))
return 0;
/* OCFS2 does not allow multiple nodes to be changing the same
* block at the same time. */
if (buffer_jbd(bh))
return 1;
/* Ok, locally the buffer is marked as up to date, now search
* our cache to see if we can trust that. */
return ocfs2_buffer_cached(OCFS2_I(inode), bh);
}
/*
* Determine whether a buffer is currently out on a read-ahead request.
* ip_io_sem should be held to serialize submitters with the logic here.
*/
int ocfs2_buffer_read_ahead(struct inode *inode,
struct buffer_head *bh)
{
return buffer_locked(bh) && ocfs2_buffer_cached(OCFS2_I(inode), bh);
}
/* Requires ip_lock */
static void ocfs2_append_cache_array(struct ocfs2_caching_info *ci,
sector_t block)
{
BUG_ON(ci->ci_num_cached >= OCFS2_INODE_MAX_CACHE_ARRAY);
mlog(0, "block %llu takes position %u\n", (unsigned long long) block,
ci->ci_num_cached);
ci->ci_cache.ci_array[ci->ci_num_cached] = block;
ci->ci_num_cached++;
}
/* By now the caller should have checked that the item does *not*
* exist in the tree.
* Requires ip_lock. */
static void __ocfs2_insert_cache_tree(struct ocfs2_caching_info *ci,
struct ocfs2_meta_cache_item *new)
{
sector_t block = new->c_block;
struct rb_node *parent = NULL;
struct rb_node **p = &ci->ci_cache.ci_tree.rb_node;
struct ocfs2_meta_cache_item *tmp;
mlog(0, "Insert block %llu num = %u\n", (unsigned long long) block,
ci->ci_num_cached);
while(*p) {
parent = *p;
tmp = rb_entry(parent, struct ocfs2_meta_cache_item, c_node);
if (block < tmp->c_block)
p = &(*p)->rb_left;
else if (block > tmp->c_block)
p = &(*p)->rb_right;
else {
/* This should never happen! */
mlog(ML_ERROR, "Duplicate block %llu cached!\n",
(unsigned long long) block);
BUG();
}
}
rb_link_node(&new->c_node, parent, p);
rb_insert_color(&new->c_node, &ci->ci_cache.ci_tree);
ci->ci_num_cached++;
}
static inline int ocfs2_insert_can_use_array(struct ocfs2_inode_info *oi,
struct ocfs2_caching_info *ci)
{
assert_spin_locked(&oi->ip_lock);
return (oi->ip_flags & OCFS2_INODE_CACHE_INLINE) &&
(ci->ci_num_cached < OCFS2_INODE_MAX_CACHE_ARRAY);
}
/* tree should be exactly OCFS2_INODE_MAX_CACHE_ARRAY wide. NULL the
* pointers in tree after we use them - this allows caller to detect
* when to free in case of error. */
static void ocfs2_expand_cache(struct ocfs2_inode_info *oi,
struct ocfs2_meta_cache_item **tree)
{
int i;
struct ocfs2_caching_info *ci = &oi->ip_metadata_cache;
mlog_bug_on_msg(ci->ci_num_cached != OCFS2_INODE_MAX_CACHE_ARRAY,
"Inode %llu, num cached = %u, should be %u\n",
(unsigned long long)oi->ip_blkno, ci->ci_num_cached,
OCFS2_INODE_MAX_CACHE_ARRAY);
mlog_bug_on_msg(!(oi->ip_flags & OCFS2_INODE_CACHE_INLINE),
"Inode %llu not marked as inline anymore!\n",
(unsigned long long)oi->ip_blkno);
assert_spin_locked(&oi->ip_lock);
/* Be careful to initialize the tree members *first* because
* once the ci_tree is used, the array is junk... */
for(i = 0; i < OCFS2_INODE_MAX_CACHE_ARRAY; i++)
tree[i]->c_block = ci->ci_cache.ci_array[i];
oi->ip_flags &= ~OCFS2_INODE_CACHE_INLINE;
ci->ci_cache.ci_tree = RB_ROOT;
/* this will be set again by __ocfs2_insert_cache_tree */
ci->ci_num_cached = 0;
for(i = 0; i < OCFS2_INODE_MAX_CACHE_ARRAY; i++) {
__ocfs2_insert_cache_tree(ci, tree[i]);
tree[i] = NULL;
}
mlog(0, "Expanded %llu to a tree cache: flags 0x%x, num = %u\n",
(unsigned long long)oi->ip_blkno, oi->ip_flags, ci->ci_num_cached);
}
/* Slow path function - memory allocation is necessary. See the
* comment above ocfs2_set_buffer_uptodate for more information. */
static void __ocfs2_set_buffer_uptodate(struct ocfs2_inode_info *oi,
sector_t block,
int expand_tree)
{
int i;
struct ocfs2_caching_info *ci = &oi->ip_metadata_cache;
struct ocfs2_meta_cache_item *new = NULL;
struct ocfs2_meta_cache_item *tree[OCFS2_INODE_MAX_CACHE_ARRAY] =
{ NULL, };
mlog(0, "Inode %llu, block %llu, expand = %d\n",
(unsigned long long)oi->ip_blkno,
(unsigned long long)block, expand_tree);
new = kmem_cache_alloc(ocfs2_uptodate_cachep, GFP_NOFS);
if (!new) {
mlog_errno(-ENOMEM);
return;
}
new->c_block = block;
if (expand_tree) {
/* Do *not* allocate an array here - the removal code
* has no way of tracking that. */
for(i = 0; i < OCFS2_INODE_MAX_CACHE_ARRAY; i++) {
tree[i] = kmem_cache_alloc(ocfs2_uptodate_cachep,
GFP_NOFS);
if (!tree[i]) {
mlog_errno(-ENOMEM);
goto out_free;
}
/* These are initialized in ocfs2_expand_cache! */
}
}
spin_lock(&oi->ip_lock);
if (ocfs2_insert_can_use_array(oi, ci)) {
mlog(0, "Someone cleared the tree underneath us\n");
/* Ok, items were removed from the cache in between
* locks. Detect this and revert back to the fast path */
ocfs2_append_cache_array(ci, block);
spin_unlock(&oi->ip_lock);
goto out_free;
}
if (expand_tree)
ocfs2_expand_cache(oi, tree);
__ocfs2_insert_cache_tree(ci, new);
spin_unlock(&oi->ip_lock);
new = NULL;
out_free:
if (new)
kmem_cache_free(ocfs2_uptodate_cachep, new);
/* If these were used, then ocfs2_expand_cache re-set them to
* NULL for us. */
if (tree[0]) {
for(i = 0; i < OCFS2_INODE_MAX_CACHE_ARRAY; i++)
if (tree[i])
kmem_cache_free(ocfs2_uptodate_cachep,
tree[i]);
}
}
/* Item insertion is guarded by ip_io_mutex, so the insertion path takes
* advantage of this by not rechecking for a duplicate insert during
* the slow case. Additionally, if the cache needs to be bumped up to
* a tree, the code will not recheck after acquiring the lock --
* multiple paths cannot be expanding to a tree at the same time.
*
* The slow path takes into account that items can be removed
* (including the whole tree wiped and reset) when this process it out
* allocating memory. In those cases, it reverts back to the fast
* path.
*
* Note that this function may actually fail to insert the block if
* memory cannot be allocated. This is not fatal however (but may
* result in a performance penalty)
*
* Readahead buffers can be passed in here before the I/O request is
* completed.
*/
void ocfs2_set_buffer_uptodate(struct inode *inode,
struct buffer_head *bh)
{
int expand;
struct ocfs2_inode_info *oi = OCFS2_I(inode);
struct ocfs2_caching_info *ci = &oi->ip_metadata_cache;
/* The block may very well exist in our cache already, so avoid
* doing any more work in that case. */
if (ocfs2_buffer_cached(oi, bh))
return;
mlog(0, "Inode %llu, inserting block %llu\n",
(unsigned long long)oi->ip_blkno,
(unsigned long long)bh->b_blocknr);
/* No need to recheck under spinlock - insertion is guarded by
* ip_io_mutex */
spin_lock(&oi->ip_lock);
if (ocfs2_insert_can_use_array(oi, ci)) {
/* Fast case - it's an array and there's a free
* spot. */
ocfs2_append_cache_array(ci, bh->b_blocknr);
spin_unlock(&oi->ip_lock);
return;
}
expand = 0;
if (oi->ip_flags & OCFS2_INODE_CACHE_INLINE) {
/* We need to bump things up to a tree. */
expand = 1;
}
spin_unlock(&oi->ip_lock);
__ocfs2_set_buffer_uptodate(oi, bh->b_blocknr, expand);
}
/* Called against a newly allocated buffer. Most likely nobody should
* be able to read this sort of metadata while it's still being
* allocated, but this is careful to take ip_io_mutex anyway. */
void ocfs2_set_new_buffer_uptodate(struct inode *inode,
struct buffer_head *bh)
{
struct ocfs2_inode_info *oi = OCFS2_I(inode);
/* This should definitely *not* exist in our cache */
BUG_ON(ocfs2_buffer_cached(oi, bh));
set_buffer_uptodate(bh);
mutex_lock(&oi->ip_io_mutex);
ocfs2_set_buffer_uptodate(inode, bh);
mutex_unlock(&oi->ip_io_mutex);
}
/* Requires ip_lock. */
static void ocfs2_remove_metadata_array(struct ocfs2_caching_info *ci,
int index)
{
sector_t *array = ci->ci_cache.ci_array;
int bytes;
BUG_ON(index < 0 || index >= OCFS2_INODE_MAX_CACHE_ARRAY);
BUG_ON(index >= ci->ci_num_cached);
BUG_ON(!ci->ci_num_cached);
mlog(0, "remove index %d (num_cached = %u\n", index,
ci->ci_num_cached);
ci->ci_num_cached--;
/* don't need to copy if the array is now empty, or if we
* removed at the tail */
if (ci->ci_num_cached && index < ci->ci_num_cached) {
bytes = sizeof(sector_t) * (ci->ci_num_cached - index);
memmove(&array[index], &array[index + 1], bytes);
}
}
/* Requires ip_lock. */
static void ocfs2_remove_metadata_tree(struct ocfs2_caching_info *ci,
struct ocfs2_meta_cache_item *item)
{
mlog(0, "remove block %llu from tree\n",
(unsigned long long) item->c_block);
rb_erase(&item->c_node, &ci->ci_cache.ci_tree);
ci->ci_num_cached--;
}
/* Called when we remove a chunk of metadata from an inode. We don't
* bother reverting things to an inlined array in the case of a remove
* which moves us back under the limit. */
void ocfs2_remove_from_cache(struct inode *inode,
struct buffer_head *bh)
{
int index;
sector_t block = bh->b_blocknr;
struct ocfs2_meta_cache_item *item = NULL;
struct ocfs2_inode_info *oi = OCFS2_I(inode);
struct ocfs2_caching_info *ci = &oi->ip_metadata_cache;
spin_lock(&oi->ip_lock);
mlog(0, "Inode %llu, remove %llu, items = %u, array = %u\n",
(unsigned long long)oi->ip_blkno,
(unsigned long long) block, ci->ci_num_cached,
oi->ip_flags & OCFS2_INODE_CACHE_INLINE);
if (oi->ip_flags & OCFS2_INODE_CACHE_INLINE) {
index = ocfs2_search_cache_array(ci, block);
if (index != -1)
ocfs2_remove_metadata_array(ci, index);
} else {
item = ocfs2_search_cache_tree(ci, block);
if (item)
ocfs2_remove_metadata_tree(ci, item);
}
spin_unlock(&oi->ip_lock);
if (item)
kmem_cache_free(ocfs2_uptodate_cachep, item);
}
int __init init_ocfs2_uptodate_cache(void)
{
ocfs2_uptodate_cachep = kmem_cache_create("ocfs2_uptodate",
sizeof(struct ocfs2_meta_cache_item),
0, SLAB_HWCACHE_ALIGN, NULL);
if (!ocfs2_uptodate_cachep)
return -ENOMEM;
mlog(0, "%u inlined cache items per inode.\n",
OCFS2_INODE_MAX_CACHE_ARRAY);
return 0;
}
void exit_ocfs2_uptodate_cache(void)
{
if (ocfs2_uptodate_cachep)
kmem_cache_destroy(ocfs2_uptodate_cachep);
}