--- /dev/null
+/* -*- 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 kmem_cache_t *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 %"MLFu64"\n", to_purge,
+ tree ? "array" : "tree", 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 %"MLFu64", count = %u, purged = %u\n",
+ 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 %"MLFu64", query block %llu (inline = %u)\n",
+ 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. */
+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);
+}
+
+/* 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 %"MLFu64", num cached = %u, should be %u\n",
+ oi->ip_blkno, ci->ci_num_cached,
+ OCFS2_INODE_MAX_CACHE_ARRAY);
+ mlog_bug_on_msg(!(oi->ip_flags & OCFS2_INODE_CACHE_INLINE),
+ "Inode %"MLFu64" not marked as inline anymore!\n",
+ 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 %"MLFu64" to a tree cache: flags 0x%x, num = %u\n",
+ 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 %"MLFu64", block %llu, expand = %d\n",
+ oi->ip_blkno, (unsigned long long) block, expand_tree);
+
+ new = kmem_cache_alloc(ocfs2_uptodate_cachep, GFP_KERNEL);
+ 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_KERNEL);
+ 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_sem, 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) */
+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 %"MLFu64", inserting block %llu\n", oi->ip_blkno,
+ (unsigned long long) bh->b_blocknr);
+
+ /* No need to recheck under spinlock - insertion is guarded by
+ * ip_io_sem */
+ 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_sem 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);
+
+ down(&oi->ip_io_sem);
+ ocfs2_set_buffer_uptodate(inode, bh);
+ up(&oi->ip_io_sem);
+}
+
+/* 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 %"MLFu64", remove %llu, items = %u, array = %u\n",
+ 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, 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 exit_ocfs2_uptodate_cache(void)
+{
+ if (ocfs2_uptodate_cachep)
+ kmem_cache_destroy(ocfs2_uptodate_cachep);
+}
git.openpandora.org / pandora-kernel.git / blobdiff