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The walk code was using a 'ro_spine' to hold it's locked btree nodes. But this data structure is designed for the rolling lock scheme, and as such automatically unlocks blocks that are two steps up the call chain. This is not suitable for the simple recursive walk algorithm, which retraces its steps. This code is only used by the persistent array code, which in turn is only used by dm-cache. In order to trigger it you need to have a mapping tree that is more than 2 levels deep; which equates to 8-16 million cache blocks. For instance a 4T ssd with a very small block size of 32k only just triggers this bug. The fix just places the locked blocks on the stack, and stops using the ro_spine altogether. Signed-off-by: Joe Thornber <ejt@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Cc: stable@vger.kernel.org
142 lines
3.3 KiB
C
142 lines
3.3 KiB
C
/*
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* Copyright (C) 2011 Red Hat, Inc.
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*
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* This file is released under the GPL.
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*/
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#ifndef DM_BTREE_INTERNAL_H
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#define DM_BTREE_INTERNAL_H
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#include "dm-btree.h"
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/*----------------------------------------------------------------*/
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/*
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* We'll need 2 accessor functions for n->csum and n->blocknr
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* to support dm-btree-spine.c in that case.
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*/
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enum node_flags {
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INTERNAL_NODE = 1,
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LEAF_NODE = 1 << 1
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};
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/*
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* Every btree node begins with this structure. Make sure it's a multiple
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* of 8-bytes in size, otherwise the 64bit keys will be mis-aligned.
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*/
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struct node_header {
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__le32 csum;
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__le32 flags;
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__le64 blocknr; /* Block this node is supposed to live in. */
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__le32 nr_entries;
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__le32 max_entries;
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__le32 value_size;
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__le32 padding;
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} __packed;
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struct btree_node {
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struct node_header header;
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__le64 keys[0];
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} __packed;
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/*
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* Locks a block using the btree node validator.
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*/
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int bn_read_lock(struct dm_btree_info *info, dm_block_t b,
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struct dm_block **result);
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void inc_children(struct dm_transaction_manager *tm, struct btree_node *n,
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struct dm_btree_value_type *vt);
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int new_block(struct dm_btree_info *info, struct dm_block **result);
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int unlock_block(struct dm_btree_info *info, struct dm_block *b);
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/*
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* Spines keep track of the rolling locks. There are 2 variants, read-only
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* and one that uses shadowing. These are separate structs to allow the
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* type checker to spot misuse, for example accidentally calling read_lock
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* on a shadow spine.
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*/
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struct ro_spine {
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struct dm_btree_info *info;
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int count;
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struct dm_block *nodes[2];
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};
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void init_ro_spine(struct ro_spine *s, struct dm_btree_info *info);
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int exit_ro_spine(struct ro_spine *s);
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int ro_step(struct ro_spine *s, dm_block_t new_child);
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void ro_pop(struct ro_spine *s);
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struct btree_node *ro_node(struct ro_spine *s);
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struct shadow_spine {
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struct dm_btree_info *info;
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int count;
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struct dm_block *nodes[2];
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dm_block_t root;
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};
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void init_shadow_spine(struct shadow_spine *s, struct dm_btree_info *info);
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int exit_shadow_spine(struct shadow_spine *s);
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int shadow_step(struct shadow_spine *s, dm_block_t b,
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struct dm_btree_value_type *vt);
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/*
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* The spine must have at least one entry before calling this.
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*/
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struct dm_block *shadow_current(struct shadow_spine *s);
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/*
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* The spine must have at least two entries before calling this.
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*/
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struct dm_block *shadow_parent(struct shadow_spine *s);
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int shadow_has_parent(struct shadow_spine *s);
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int shadow_root(struct shadow_spine *s);
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/*
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* Some inlines.
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*/
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static inline __le64 *key_ptr(struct btree_node *n, uint32_t index)
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{
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return n->keys + index;
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}
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static inline void *value_base(struct btree_node *n)
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{
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return &n->keys[le32_to_cpu(n->header.max_entries)];
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}
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static inline void *value_ptr(struct btree_node *n, uint32_t index)
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{
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uint32_t value_size = le32_to_cpu(n->header.value_size);
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return value_base(n) + (value_size * index);
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}
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/*
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* Assumes the values are suitably-aligned and converts to core format.
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*/
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static inline uint64_t value64(struct btree_node *n, uint32_t index)
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{
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__le64 *values_le = value_base(n);
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return le64_to_cpu(values_le[index]);
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}
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/*
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* Searching for a key within a single node.
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*/
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int lower_bound(struct btree_node *n, uint64_t key);
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extern struct dm_block_validator btree_node_validator;
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#endif /* DM_BTREE_INTERNAL_H */
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