diff options
| -rw-r--r-- | drivers/md/persistent-data/Makefile | 1 | ||||
| -rw-r--r-- | drivers/md/persistent-data/dm-bitset.c | 163 | ||||
| -rw-r--r-- | drivers/md/persistent-data/dm-bitset.h | 165 |
3 files changed, 329 insertions, 0 deletions
diff --git a/drivers/md/persistent-data/Makefile b/drivers/md/persistent-data/Makefile index ebd8d80..ff52879 100644 --- a/drivers/md/persistent-data/Makefile +++ b/drivers/md/persistent-data/Makefile @@ -1,6 +1,7 @@ obj-$(CONFIG_DM_PERSISTENT_DATA) += dm-persistent-data.o dm-persistent-data-objs := \ dm-array.o \ + dm-bitset.o \ dm-block-manager.o \ dm-space-map-common.o \ dm-space-map-disk.o \ diff --git a/drivers/md/persistent-data/dm-bitset.c b/drivers/md/persistent-data/dm-bitset.c new file mode 100644 index 0000000..cd9a86d --- /dev/null +++ b/drivers/md/persistent-data/dm-bitset.c @@ -0,0 +1,163 @@ +/* + * Copyright (C) 2012 Red Hat, Inc. + * + * This file is released under the GPL. + */ + +#include "dm-bitset.h" +#include "dm-transaction-manager.h" + +#include <linux/export.h> +#include <linux/device-mapper.h> + +#define DM_MSG_PREFIX "bitset" +#define BITS_PER_ARRAY_ENTRY 64 + +/*----------------------------------------------------------------*/ + +static struct dm_btree_value_type bitset_bvt = { + .context = NULL, + .size = sizeof(__le64), + .inc = NULL, + .dec = NULL, + .equal = NULL, +}; + +/*----------------------------------------------------------------*/ + +void dm_disk_bitset_init(struct dm_transaction_manager *tm, + struct dm_disk_bitset *info) +{ + dm_array_info_init(&info->array_info, tm, &bitset_bvt); + info->current_index_set = false; +} +EXPORT_SYMBOL_GPL(dm_disk_bitset_init); + +int dm_bitset_empty(struct dm_disk_bitset *info, dm_block_t *root) +{ + return dm_array_empty(&info->array_info, root); +} +EXPORT_SYMBOL_GPL(dm_bitset_empty); + +int dm_bitset_resize(struct dm_disk_bitset *info, dm_block_t root, + uint32_t old_nr_entries, uint32_t new_nr_entries, + bool default_value, dm_block_t *new_root) +{ + uint32_t old_blocks = dm_div_up(old_nr_entries, BITS_PER_ARRAY_ENTRY); + uint32_t new_blocks = dm_div_up(new_nr_entries, BITS_PER_ARRAY_ENTRY); + __le64 value = default_value ? cpu_to_le64(~0) : cpu_to_le64(0); + + __dm_bless_for_disk(&value); + return dm_array_resize(&info->array_info, root, old_blocks, new_blocks, + &value, new_root); +} +EXPORT_SYMBOL_GPL(dm_bitset_resize); + +int dm_bitset_del(struct dm_disk_bitset *info, dm_block_t root) +{ + return dm_array_del(&info->array_info, root); +} +EXPORT_SYMBOL_GPL(dm_bitset_del); + +int dm_bitset_flush(struct dm_disk_bitset *info, dm_block_t root, + dm_block_t *new_root) +{ + int r; + __le64 value; + + if (!info->current_index_set) + return 0; + + value = cpu_to_le64(info->current_bits); + + __dm_bless_for_disk(&value); + r = dm_array_set_value(&info->array_info, root, info->current_index, + &value, new_root); + if (r) + return r; + + info->current_index_set = false; + return 0; +} +EXPORT_SYMBOL_GPL(dm_bitset_flush); + +static int read_bits(struct dm_disk_bitset *info, dm_block_t root, + uint32_t array_index) +{ + int r; + __le64 value; + + r = dm_array_get_value(&info->array_info, root, array_index, &value); + if (r) + return r; + + info->current_bits = le64_to_cpu(value); + info->current_index_set = true; + info->current_index = array_index; + return 0; +} + +static int get_array_entry(struct dm_disk_bitset *info, dm_block_t root, + uint32_t index, dm_block_t *new_root) +{ + int r; + unsigned array_index = index / BITS_PER_ARRAY_ENTRY; + + if (info->current_index_set) { + if (info->current_index == array_index) + return 0; + + r = dm_bitset_flush(info, root, new_root); + if (r) + return r; + } + + return read_bits(info, root, array_index); +} + +int dm_bitset_set_bit(struct dm_disk_bitset *info, dm_block_t root, + uint32_t index, dm_block_t *new_root) +{ + int r; + unsigned b = index % BITS_PER_ARRAY_ENTRY; + + r = get_array_entry(info, root, index, new_root); + if (r) + return r; + + set_bit(b, (unsigned long *) &info->current_bits); + return 0; +} +EXPORT_SYMBOL_GPL(dm_bitset_set_bit); + +int dm_bitset_clear_bit(struct dm_disk_bitset *info, dm_block_t root, + uint32_t index, dm_block_t *new_root) +{ + int r; + unsigned b = index % BITS_PER_ARRAY_ENTRY; + + r = get_array_entry(info, root, index, new_root); + if (r) + return r; + + clear_bit(b, (unsigned long *) &info->current_bits); + return 0; +} +EXPORT_SYMBOL_GPL(dm_bitset_clear_bit); + +int dm_bitset_test_bit(struct dm_disk_bitset *info, dm_block_t root, + uint32_t index, dm_block_t *new_root, bool *result) +{ + int r; + unsigned b = index % BITS_PER_ARRAY_ENTRY; + + r = get_array_entry(info, root, index, new_root); + if (r) + return r; + + *result = test_bit(b, (unsigned long *) &info->current_bits); + return 0; +} +EXPORT_SYMBOL_GPL(dm_bitset_test_bit); + +/*----------------------------------------------------------------*/ diff --git a/drivers/md/persistent-data/dm-bitset.h b/drivers/md/persistent-data/dm-bitset.h new file mode 100644 index 0000000..e1b9bea --- /dev/null +++ b/drivers/md/persistent-data/dm-bitset.h @@ -0,0 +1,165 @@ +/* + * 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 */ |