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Diffstat (limited to 'fs/ocfs2/uptodate.c')
| -rw-r--r-- | fs/ocfs2/uptodate.c | 637 |
1 files changed, 637 insertions, 0 deletions
diff --git a/fs/ocfs2/uptodate.c b/fs/ocfs2/uptodate.c new file mode 100644 index 000000000..78f09c76a --- /dev/null +++ b/fs/ocfs2/uptodate.c @@ -0,0 +1,637 @@ +/* -*- 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 <cluster/masklog.h> + +#include "ocfs2.h" + +#include "inode.h" +#include "uptodate.h" +#include "ocfs2_trace.h" + +struct ocfs2_meta_cache_item { + struct rb_node c_node; + sector_t c_block; +}; + +static struct kmem_cache *ocfs2_uptodate_cachep; + +u64 ocfs2_metadata_cache_owner(struct ocfs2_caching_info *ci) +{ + BUG_ON(!ci || !ci->ci_ops); + + return ci->ci_ops->co_owner(ci); +} + +struct super_block *ocfs2_metadata_cache_get_super(struct ocfs2_caching_info *ci) +{ + BUG_ON(!ci || !ci->ci_ops); + + return ci->ci_ops->co_get_super(ci); +} + +static void ocfs2_metadata_cache_lock(struct ocfs2_caching_info *ci) +{ + BUG_ON(!ci || !ci->ci_ops); + + ci->ci_ops->co_cache_lock(ci); +} + +static void ocfs2_metadata_cache_unlock(struct ocfs2_caching_info *ci) +{ + BUG_ON(!ci || !ci->ci_ops); + + ci->ci_ops->co_cache_unlock(ci); +} + +void ocfs2_metadata_cache_io_lock(struct ocfs2_caching_info *ci) +{ + BUG_ON(!ci || !ci->ci_ops); + + ci->ci_ops->co_io_lock(ci); +} + +void ocfs2_metadata_cache_io_unlock(struct ocfs2_caching_info *ci) +{ + BUG_ON(!ci || !ci->ci_ops); + + ci->ci_ops->co_io_unlock(ci); +} + + +static void ocfs2_metadata_cache_reset(struct ocfs2_caching_info *ci, + int clear) +{ + ci->ci_flags |= OCFS2_CACHE_FL_INLINE; + ci->ci_num_cached = 0; + + if (clear) { + ci->ci_created_trans = 0; + ci->ci_last_trans = 0; + } +} + +void ocfs2_metadata_cache_init(struct ocfs2_caching_info *ci, + const struct ocfs2_caching_operations *ops) +{ + BUG_ON(!ops); + + ci->ci_ops = ops; + ocfs2_metadata_cache_reset(ci, 1); +} + +void ocfs2_metadata_cache_exit(struct ocfs2_caching_info *ci) +{ + ocfs2_metadata_cache_purge(ci); + ocfs2_metadata_cache_reset(ci, 1); +} + + +/* 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); + + trace_ocfs2_purge_copied_metadata_tree( + (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 ocfs2_caching_info *ci) +{ + unsigned int tree, to_purge, purged; + struct rb_root root = RB_ROOT; + + BUG_ON(!ci || !ci->ci_ops); + + ocfs2_metadata_cache_lock(ci); + tree = !(ci->ci_flags & OCFS2_CACHE_FL_INLINE); + to_purge = ci->ci_num_cached; + + trace_ocfs2_metadata_cache_purge( + (unsigned long long)ocfs2_metadata_cache_owner(ci), + to_purge, tree); + + /* 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_reset(ci, 0); + ocfs2_metadata_cache_unlock(ci); + + 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, "Owner %llu, count = %u, purged = %u\n", + (unsigned long long)ocfs2_metadata_cache_owner(ci), + 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_caching_info *ci, + struct buffer_head *bh) +{ + int index = -1; + struct ocfs2_meta_cache_item *item = NULL; + + ocfs2_metadata_cache_lock(ci); + + trace_ocfs2_buffer_cached_begin( + (unsigned long long)ocfs2_metadata_cache_owner(ci), + (unsigned long long) bh->b_blocknr, + !!(ci->ci_flags & OCFS2_CACHE_FL_INLINE)); + + if (ci->ci_flags & OCFS2_CACHE_FL_INLINE) + index = ocfs2_search_cache_array(ci, bh->b_blocknr); + else + item = ocfs2_search_cache_tree(ci, bh->b_blocknr); + + ocfs2_metadata_cache_unlock(ci); + + trace_ocfs2_buffer_cached_end(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 ocfs2_caching_info *ci, + 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(ci, bh); +} + +/* + * Determine whether a buffer is currently out on a read-ahead request. + * ci_io_sem should be held to serialize submitters with the logic here. + */ +int ocfs2_buffer_read_ahead(struct ocfs2_caching_info *ci, + struct buffer_head *bh) +{ + return buffer_locked(bh) && ocfs2_buffer_cached(ci, 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_CACHE_INFO_MAX_ARRAY); + + trace_ocfs2_append_cache_array( + (unsigned long long)ocfs2_metadata_cache_owner(ci), + (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; + + trace_ocfs2_insert_cache_tree( + (unsigned long long)ocfs2_metadata_cache_owner(ci), + (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++; +} + +/* co_cache_lock() must be held */ +static inline int ocfs2_insert_can_use_array(struct ocfs2_caching_info *ci) +{ + return (ci->ci_flags & OCFS2_CACHE_FL_INLINE) && + (ci->ci_num_cached < OCFS2_CACHE_INFO_MAX_ARRAY); +} + +/* tree should be exactly OCFS2_CACHE_INFO_MAX_ARRAY wide. NULL the + * pointers in tree after we use them - this allows caller to detect + * when to free in case of error. + * + * The co_cache_lock() must be held. */ +static void ocfs2_expand_cache(struct ocfs2_caching_info *ci, + struct ocfs2_meta_cache_item **tree) +{ + int i; + + mlog_bug_on_msg(ci->ci_num_cached != OCFS2_CACHE_INFO_MAX_ARRAY, + "Owner %llu, num cached = %u, should be %u\n", + (unsigned long long)ocfs2_metadata_cache_owner(ci), + ci->ci_num_cached, OCFS2_CACHE_INFO_MAX_ARRAY); + mlog_bug_on_msg(!(ci->ci_flags & OCFS2_CACHE_FL_INLINE), + "Owner %llu not marked as inline anymore!\n", + (unsigned long long)ocfs2_metadata_cache_owner(ci)); + + /* Be careful to initialize the tree members *first* because + * once the ci_tree is used, the array is junk... */ + for (i = 0; i < OCFS2_CACHE_INFO_MAX_ARRAY; i++) + tree[i]->c_block = ci->ci_cache.ci_array[i]; + + ci->ci_flags &= ~OCFS2_CACHE_FL_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_CACHE_INFO_MAX_ARRAY; i++) { + __ocfs2_insert_cache_tree(ci, tree[i]); + tree[i] = NULL; + } + + trace_ocfs2_expand_cache( + (unsigned long long)ocfs2_metadata_cache_owner(ci), + ci->ci_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_caching_info *ci, + sector_t block, + int expand_tree) +{ + int i; + struct ocfs2_meta_cache_item *new = NULL; + struct ocfs2_meta_cache_item *tree[OCFS2_CACHE_INFO_MAX_ARRAY] = + { NULL, }; + + trace_ocfs2_set_buffer_uptodate( + (unsigned long long)ocfs2_metadata_cache_owner(ci), + (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_CACHE_INFO_MAX_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! */ + } + } + + ocfs2_metadata_cache_lock(ci); + if (ocfs2_insert_can_use_array(ci)) { + /* 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); + ocfs2_metadata_cache_unlock(ci); + goto out_free; + } + + if (expand_tree) + ocfs2_expand_cache(ci, tree); + + __ocfs2_insert_cache_tree(ci, new); + ocfs2_metadata_cache_unlock(ci); + + 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_CACHE_INFO_MAX_ARRAY; i++) + if (tree[i]) + kmem_cache_free(ocfs2_uptodate_cachep, + tree[i]); + } +} + +/* Item insertion is guarded by co_io_lock(), 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 ocfs2_caching_info *ci, + struct buffer_head *bh) +{ + int expand; + + /* The block may very well exist in our cache already, so avoid + * doing any more work in that case. */ + if (ocfs2_buffer_cached(ci, bh)) + return; + + trace_ocfs2_set_buffer_uptodate_begin( + (unsigned long long)ocfs2_metadata_cache_owner(ci), + (unsigned long long)bh->b_blocknr); + + /* No need to recheck under spinlock - insertion is guarded by + * co_io_lock() */ + ocfs2_metadata_cache_lock(ci); + if (ocfs2_insert_can_use_array(ci)) { + /* Fast case - it's an array and there's a free + * spot. */ + ocfs2_append_cache_array(ci, bh->b_blocknr); + ocfs2_metadata_cache_unlock(ci); + return; + } + + expand = 0; + if (ci->ci_flags & OCFS2_CACHE_FL_INLINE) { + /* We need to bump things up to a tree. */ + expand = 1; + } + ocfs2_metadata_cache_unlock(ci); + + __ocfs2_set_buffer_uptodate(ci, 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 co_io_lock() anyway. */ +void ocfs2_set_new_buffer_uptodate(struct ocfs2_caching_info *ci, + struct buffer_head *bh) +{ + /* This should definitely *not* exist in our cache */ + BUG_ON(ocfs2_buffer_cached(ci, bh)); + + set_buffer_uptodate(bh); + + ocfs2_metadata_cache_io_lock(ci); + ocfs2_set_buffer_uptodate(ci, bh); + ocfs2_metadata_cache_io_unlock(ci); +} + +/* 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_CACHE_INFO_MAX_ARRAY); + BUG_ON(index >= ci->ci_num_cached); + BUG_ON(!ci->ci_num_cached); + + trace_ocfs2_remove_metadata_array( + (unsigned long long)ocfs2_metadata_cache_owner(ci), + 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) +{ + trace_ocfs2_remove_metadata_tree( + (unsigned long long)ocfs2_metadata_cache_owner(ci), + (unsigned long long)item->c_block); + + rb_erase(&item->c_node, &ci->ci_cache.ci_tree); + ci->ci_num_cached--; +} + +static void ocfs2_remove_block_from_cache(struct ocfs2_caching_info *ci, + sector_t block) +{ + int index; + struct ocfs2_meta_cache_item *item = NULL; + + ocfs2_metadata_cache_lock(ci); + trace_ocfs2_remove_block_from_cache( + (unsigned long long)ocfs2_metadata_cache_owner(ci), + (unsigned long long) block, ci->ci_num_cached, + ci->ci_flags); + + if (ci->ci_flags & OCFS2_CACHE_FL_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); + } + ocfs2_metadata_cache_unlock(ci); + + if (item) + kmem_cache_free(ocfs2_uptodate_cachep, item); +} + +/* + * 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 ocfs2_caching_info *ci, + struct buffer_head *bh) +{ + sector_t block = bh->b_blocknr; + + ocfs2_remove_block_from_cache(ci, block); +} + +/* Called when we remove xattr clusters from an inode. */ +void ocfs2_remove_xattr_clusters_from_cache(struct ocfs2_caching_info *ci, + sector_t block, + u32 c_len) +{ + struct super_block *sb = ocfs2_metadata_cache_get_super(ci); + unsigned int i, b_len = ocfs2_clusters_to_blocks(sb, 1) * c_len; + + for (i = 0; i < b_len; i++, block++) + ocfs2_remove_block_from_cache(ci, block); +} + +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; + + return 0; +} + +void exit_ocfs2_uptodate_cache(void) +{ + kmem_cache_destroy(ocfs2_uptodate_cachep); +} |