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19fa1a6756
If a snapshot is created and later deleted the origin dm_thin_device's snapshotted_time will have been updated to reflect the snapshot's creation time. The 'shared' flag in the dm_thin_lookup_result struct returned from dm_thin_find_block() is an approximation based on snapshotted_time -- this is done to avoid 0(n), or worse, time complexity. In this case, the shared flag would be true. But because the 'shared' flag reflects an approximation a block can be incorrectly assumed to be shared (e.g. false positive for 'shared' because the snapshot no longer exists). This could result in discards issued to a thin device not being passed down to the pool's underlying data device. To fix this we double check that a thin block is really still in-use after a mapping is removed using dm_pool_block_is_used(). If the reference count for a block is now zero the discard is allowed to be passed down. Also add a 'definitely_not_shared' member to the dm_thin_new_mapping structure -- reflects that the 'shared' flag in the response from dm_thin_find_block() can only be held as definitive if false is returned. Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1043527 Signed-off-by: Joe Thornber <ejt@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Cc: stable@vger.kernel.org
208 lines
6.0 KiB
C
208 lines
6.0 KiB
C
/*
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* Copyright (C) 2010-2011 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_THIN_METADATA_H
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#define DM_THIN_METADATA_H
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#include "persistent-data/dm-block-manager.h"
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#include "persistent-data/dm-space-map.h"
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#define THIN_METADATA_BLOCK_SIZE 4096
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/*
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* The metadata device is currently limited in size.
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*
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* We have one block of index, which can hold 255 index entries. Each
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* index entry contains allocation info about 16k metadata blocks.
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*/
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#define THIN_METADATA_MAX_SECTORS (255 * (1 << 14) * (THIN_METADATA_BLOCK_SIZE / (1 << SECTOR_SHIFT)))
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/*
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* A metadata device larger than 16GB triggers a warning.
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*/
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#define THIN_METADATA_MAX_SECTORS_WARNING (16 * (1024 * 1024 * 1024 >> SECTOR_SHIFT))
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/*----------------------------------------------------------------*/
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struct dm_pool_metadata;
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struct dm_thin_device;
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/*
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* Device identifier
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*/
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typedef uint64_t dm_thin_id;
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/*
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* Reopens or creates a new, empty metadata volume.
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*/
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struct dm_pool_metadata *dm_pool_metadata_open(struct block_device *bdev,
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sector_t data_block_size,
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bool format_device);
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int dm_pool_metadata_close(struct dm_pool_metadata *pmd);
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/*
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* Compat feature flags. Any incompat flags beyond the ones
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* specified below will prevent use of the thin metadata.
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*/
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#define THIN_FEATURE_COMPAT_SUPP 0UL
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#define THIN_FEATURE_COMPAT_RO_SUPP 0UL
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#define THIN_FEATURE_INCOMPAT_SUPP 0UL
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/*
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* Device creation/deletion.
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*/
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int dm_pool_create_thin(struct dm_pool_metadata *pmd, dm_thin_id dev);
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/*
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* An internal snapshot.
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*
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* You can only snapshot a quiesced origin i.e. one that is either
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* suspended or not instanced at all.
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*/
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int dm_pool_create_snap(struct dm_pool_metadata *pmd, dm_thin_id dev,
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dm_thin_id origin);
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/*
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* Deletes a virtual device from the metadata. It _is_ safe to call this
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* when that device is open. Operations on that device will just start
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* failing. You still need to call close() on the device.
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*/
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int dm_pool_delete_thin_device(struct dm_pool_metadata *pmd,
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dm_thin_id dev);
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/*
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* Commits _all_ metadata changes: device creation, deletion, mapping
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* updates.
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*/
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int dm_pool_commit_metadata(struct dm_pool_metadata *pmd);
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/*
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* Discards all uncommitted changes. Rereads the superblock, rolling back
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* to the last good transaction. Thin devices remain open.
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* dm_thin_aborted_changes() tells you if they had uncommitted changes.
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*
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* If this call fails it's only useful to call dm_pool_metadata_close().
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* All other methods will fail with -EINVAL.
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*/
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int dm_pool_abort_metadata(struct dm_pool_metadata *pmd);
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/*
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* Set/get userspace transaction id.
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*/
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int dm_pool_set_metadata_transaction_id(struct dm_pool_metadata *pmd,
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uint64_t current_id,
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uint64_t new_id);
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int dm_pool_get_metadata_transaction_id(struct dm_pool_metadata *pmd,
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uint64_t *result);
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/*
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* Hold/get root for userspace transaction.
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*
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* The metadata snapshot is a copy of the current superblock (minus the
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* space maps). Userland can access the data structures for READ
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* operations only. A small performance hit is incurred by providing this
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* copy of the metadata to userland due to extra copy-on-write operations
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* on the metadata nodes. Release this as soon as you finish with it.
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*/
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int dm_pool_reserve_metadata_snap(struct dm_pool_metadata *pmd);
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int dm_pool_release_metadata_snap(struct dm_pool_metadata *pmd);
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int dm_pool_get_metadata_snap(struct dm_pool_metadata *pmd,
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dm_block_t *result);
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/*
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* Actions on a single virtual device.
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*/
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/*
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* Opening the same device more than once will fail with -EBUSY.
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*/
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int dm_pool_open_thin_device(struct dm_pool_metadata *pmd, dm_thin_id dev,
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struct dm_thin_device **td);
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int dm_pool_close_thin_device(struct dm_thin_device *td);
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dm_thin_id dm_thin_dev_id(struct dm_thin_device *td);
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struct dm_thin_lookup_result {
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dm_block_t block;
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unsigned shared:1;
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};
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/*
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* Returns:
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* -EWOULDBLOCK iff @can_block is set and would block.
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* -ENODATA iff that mapping is not present.
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* 0 success
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*/
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int dm_thin_find_block(struct dm_thin_device *td, dm_block_t block,
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int can_block, struct dm_thin_lookup_result *result);
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/*
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* Obtain an unused block.
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*/
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int dm_pool_alloc_data_block(struct dm_pool_metadata *pmd, dm_block_t *result);
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/*
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* Insert or remove block.
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*/
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int dm_thin_insert_block(struct dm_thin_device *td, dm_block_t block,
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dm_block_t data_block);
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int dm_thin_remove_block(struct dm_thin_device *td, dm_block_t block);
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/*
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* Queries.
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*/
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bool dm_thin_changed_this_transaction(struct dm_thin_device *td);
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bool dm_thin_aborted_changes(struct dm_thin_device *td);
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int dm_thin_get_highest_mapped_block(struct dm_thin_device *td,
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dm_block_t *highest_mapped);
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int dm_thin_get_mapped_count(struct dm_thin_device *td, dm_block_t *result);
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int dm_pool_get_free_block_count(struct dm_pool_metadata *pmd,
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dm_block_t *result);
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int dm_pool_get_free_metadata_block_count(struct dm_pool_metadata *pmd,
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dm_block_t *result);
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int dm_pool_get_metadata_dev_size(struct dm_pool_metadata *pmd,
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dm_block_t *result);
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int dm_pool_get_data_block_size(struct dm_pool_metadata *pmd, sector_t *result);
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int dm_pool_get_data_dev_size(struct dm_pool_metadata *pmd, dm_block_t *result);
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int dm_pool_block_is_used(struct dm_pool_metadata *pmd, dm_block_t b, bool *result);
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/*
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* Returns -ENOSPC if the new size is too small and already allocated
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* blocks would be lost.
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*/
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int dm_pool_resize_data_dev(struct dm_pool_metadata *pmd, dm_block_t new_size);
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int dm_pool_resize_metadata_dev(struct dm_pool_metadata *pmd, dm_block_t new_size);
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/*
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* Flicks the underlying block manager into read only mode, so you know
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* that nothing is changing.
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*/
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void dm_pool_metadata_read_only(struct dm_pool_metadata *pmd);
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void dm_pool_metadata_read_write(struct dm_pool_metadata *pmd);
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int dm_pool_register_metadata_threshold(struct dm_pool_metadata *pmd,
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dm_block_t threshold,
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dm_sm_threshold_fn fn,
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void *context);
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/*----------------------------------------------------------------*/
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#endif
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