/* * Copyright (C) 2012 Red Hat, Inc. * * This file is released under the GPL. */#ifndef _LINUX_DM_BITSET_H#define _LINUX_DM_BITSET_H #include "dm-array.h" /*----------------------------------------------------------------*/ /* * This bitset type is a thin wrapper round a dm_array of 64bit words.  It * uses a tiny, one word cache to reduce the number of array lookups and so * increase performance. * * Like the dm-array that it's based on, the caller needs to keep track of * the size of the bitset separately.  The underlying dm-array implicitly * knows how many words it's storing and will return -ENODATA if you try * and access an out of bounds word.  However, an out of bounds bit in the * final word will _not_ be detected, you have been warned. * * Bits are indexed from zero.  * Typical use: * * a) Initialise a dm_disk_bitset structure with dm_disk_bitset_init(). *    This describes the bitset and includes the cache.  It's not called it *    dm_bitset_info in line with other data structures because it does *    include instance data. * * b) Get yourself a root.  The root is the index of a block of data on the *    disk that holds a particular instance of an bitset.  You may have a *    pre existing root in your metadata that you wish to use, or you may *    want to create a brand new, empty bitset with dm_bitset_empty(). * * Like the other data structures in this library, dm_bitset objects are * immutable between transactions.  Update functions will return you the * root for a _new_ array.  If you've incremented the old root, via * dm_tm_inc(), before calling the update function you may continue to use * it in parallel with the new root. * * Even read operations may trigger the cache to be flushed and as such * return a root for a new, updated bitset. * * c) resize a bitset with dm_bitset_resize(). * * d) Set a bit with dm_bitset_set_bit(). * * e) Clear a bit with dm_bitset_clear_bit(). * * f) Test a bit with dm_bitset_test_bit(). * * g) Flush all updates from the cache with dm_bitset_flush(). * * h) Destroy the bitset with dm_bitset_del().  This tells the transaction *    manager that you're no longer using this data structure so it can *    recycle it's blocks.  (dm_bitset_dec() would be a better name for it, *    but del is in keeping with dm_btree_del()). */ /* * Opaque object.  Unlike dm_array_info, you should have one of these per * bitset.  Initialise with dm_disk_bitset_init(). */struct dm_disk_bitset {	struct dm_array_info array_info; 	uint32_t current_index;	uint64_t current_bits; 	bool current_index_set:1;}; /* * Sets up a dm_disk_bitset structure.  You don't need to do anything with * this structure when you finish using it. * * tm - the transaction manager that should supervise this structure * info - the structure being initialised */void dm_disk_bitset_init(struct dm_transaction_manager *tm,			 struct dm_disk_bitset *info); /* * Create an empty, zero length bitset. * * info - describes the bitset * new_root - on success, points to the new root block */int dm_bitset_empty(struct dm_disk_bitset *info, dm_block_t *new_root); /* * Resize the bitset. * * info - describes the bitset * old_root - the root block of the array on disk * old_nr_entries - the number of bits in the old bitset * new_nr_entries - the number of bits you want in the new bitset * default_value - the value for any new bits * new_root - on success, points to the new root block */int dm_bitset_resize(struct dm_disk_bitset *info, dm_block_t old_root,		     uint32_t old_nr_entries, uint32_t new_nr_entries,		     bool default_value, dm_block_t *new_root); /* * Frees the bitset. */int dm_bitset_del(struct dm_disk_bitset *info, dm_block_t root); /* * Set a bit. * * info - describes the bitset * root - the root block of the bitset * index - the bit index * new_root - on success, points to the new root block * * -ENODATA will be returned if the index is out of bounds. */int dm_bitset_set_bit(struct dm_disk_bitset *info, dm_block_t root,		      uint32_t index, dm_block_t *new_root); /* * Clears a bit. * * info - describes the bitset * root - the root block of the bitset * index - the bit index * new_root - on success, points to the new root block * * -ENODATA will be returned if the index is out of bounds. */int dm_bitset_clear_bit(struct dm_disk_bitset *info, dm_block_t root,			uint32_t index, dm_block_t *new_root); /* * Tests a bit. * * info - describes the bitset * root - the root block of the bitset * index - the bit index * new_root - on success, points to the new root block (cached values may have been written) * result - the bit value you're after * * -ENODATA will be returned if the index is out of bounds. */int dm_bitset_test_bit(struct dm_disk_bitset *info, dm_block_t root,		       uint32_t index, dm_block_t *new_root, bool *result); /* * Flush any cached changes to disk. * * info - describes the bitset * root - the root block of the bitset * new_root - on success, points to the new root block */int dm_bitset_flush(struct dm_disk_bitset *info, dm_block_t root,		    dm_block_t *new_root); /*----------------------------------------------------------------*/ #endif /* _LINUX_DM_BITSET_H */