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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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4feaef830d
The space-maps track the reference counts for disk blocks allocated by both the thin-provisioning and cache targets. There are variants for tracking metadata blocks and data blocks. Transactionality is implemented by never touching blocks from the previous transaction, so we can rollback in the event of a crash. When allocating a new block we need to ensure the block is free (has reference count of 0) in both the current and previous transaction. Prior to this fix we were doing this by searching for a free block in the previous transaction, and relying on a 'begin' counter to track where the last allocation in the current transaction was. This 'begin' field was not being updated in all code paths (eg, increment of a data block reference count due to breaking sharing of a neighbour block in the same btree leaf). This fix keeps the 'begin' field, but now it's just a hint to speed up the search. Instead the current transaction is searched for a free block, and then the old transaction is double checked to ensure it's free. Much simpler. This fixes reports of sm_disk_new_block()'s BUG_ON() triggering when DM thin-provisioning's snapshots are heavily used. Reported-by: Eric Wheeler <dm-devel@lists.ewheeler.net> Cc: stable@vger.kernel.org Signed-off-by: Joe Thornber <ejt@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
130 lines
3.5 KiB
C
130 lines
3.5 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_SPACE_MAP_COMMON_H
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#define DM_SPACE_MAP_COMMON_H
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#include "dm-btree.h"
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/*----------------------------------------------------------------*/
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/*
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* Low level disk format
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*
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* Bitmap btree
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* ------------
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*
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* Each value stored in the btree is an index_entry. This points to a
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* block that is used as a bitmap. Within the bitmap hold 2 bits per
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* entry, which represent UNUSED = 0, REF_COUNT = 1, REF_COUNT = 2 and
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* REF_COUNT = many.
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*
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* Refcount btree
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* --------------
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*
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* Any entry that has a ref count higher than 2 gets entered in the ref
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* count tree. The leaf values for this tree is the 32-bit ref count.
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*/
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struct disk_index_entry {
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__le64 blocknr;
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__le32 nr_free;
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__le32 none_free_before;
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} __packed;
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#define MAX_METADATA_BITMAPS 255
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struct disk_metadata_index {
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__le32 csum;
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__le32 padding;
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__le64 blocknr;
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struct disk_index_entry index[MAX_METADATA_BITMAPS];
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} __packed;
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struct ll_disk;
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typedef int (*load_ie_fn)(struct ll_disk *ll, dm_block_t index, struct disk_index_entry *result);
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typedef int (*save_ie_fn)(struct ll_disk *ll, dm_block_t index, struct disk_index_entry *ie);
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typedef int (*init_index_fn)(struct ll_disk *ll);
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typedef int (*open_index_fn)(struct ll_disk *ll);
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typedef dm_block_t (*max_index_entries_fn)(struct ll_disk *ll);
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typedef int (*commit_fn)(struct ll_disk *ll);
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struct ll_disk {
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struct dm_transaction_manager *tm;
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struct dm_btree_info bitmap_info;
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struct dm_btree_info ref_count_info;
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uint32_t block_size;
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uint32_t entries_per_block;
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dm_block_t nr_blocks;
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dm_block_t nr_allocated;
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/*
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* bitmap_root may be a btree root or a simple index.
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*/
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dm_block_t bitmap_root;
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dm_block_t ref_count_root;
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struct disk_metadata_index mi_le;
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load_ie_fn load_ie;
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save_ie_fn save_ie;
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init_index_fn init_index;
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open_index_fn open_index;
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max_index_entries_fn max_entries;
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commit_fn commit;
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bool bitmap_index_changed:1;
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};
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struct disk_sm_root {
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__le64 nr_blocks;
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__le64 nr_allocated;
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__le64 bitmap_root;
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__le64 ref_count_root;
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} __packed;
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#define ENTRIES_PER_BYTE 4
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struct disk_bitmap_header {
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__le32 csum;
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__le32 not_used;
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__le64 blocknr;
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} __packed;
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enum allocation_event {
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SM_NONE,
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SM_ALLOC,
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SM_FREE,
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};
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/*----------------------------------------------------------------*/
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int sm_ll_extend(struct ll_disk *ll, dm_block_t extra_blocks);
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int sm_ll_lookup_bitmap(struct ll_disk *ll, dm_block_t b, uint32_t *result);
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int sm_ll_lookup(struct ll_disk *ll, dm_block_t b, uint32_t *result);
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int sm_ll_find_free_block(struct ll_disk *ll, dm_block_t begin,
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dm_block_t end, dm_block_t *result);
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int sm_ll_find_common_free_block(struct ll_disk *old_ll, struct ll_disk *new_ll,
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dm_block_t begin, dm_block_t end, dm_block_t *result);
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int sm_ll_insert(struct ll_disk *ll, dm_block_t b, uint32_t ref_count, enum allocation_event *ev);
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int sm_ll_inc(struct ll_disk *ll, dm_block_t b, enum allocation_event *ev);
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int sm_ll_dec(struct ll_disk *ll, dm_block_t b, enum allocation_event *ev);
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int sm_ll_commit(struct ll_disk *ll);
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int sm_ll_new_metadata(struct ll_disk *ll, struct dm_transaction_manager *tm);
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int sm_ll_open_metadata(struct ll_disk *ll, struct dm_transaction_manager *tm,
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void *root_le, size_t len);
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int sm_ll_new_disk(struct ll_disk *ll, struct dm_transaction_manager *tm);
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int sm_ll_open_disk(struct ll_disk *ll, struct dm_transaction_manager *tm,
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void *root_le, size_t len);
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/*----------------------------------------------------------------*/
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#endif /* DM_SPACE_MAP_COMMON_H */
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