Creates RAM based block devices (/dev/ramzswapX) which can be used (only) as swap disks. Pages swapped to these are compressed and stored in memory itself.
The module is called ramzswap.ko. It depends on: - xvmalloc.ko: memory allocator - lzo_compress.ko - lzo_decompress.ko See Documentation/blockdev/ramzswap.txt for usage details. Signed-off-by: Nitin Gupta <[email protected]> --- drivers/block/Kconfig | 22 + drivers/block/Makefile | 1 + drivers/block/ramzswap/ramzswap.c | 1518 +++++++++++++++++++++++++++++++++++++ drivers/block/ramzswap/ramzswap.h | 182 +++++ include/linux/ramzswap_ioctl.h | 51 ++ 5 files changed, 1774 insertions(+), 0 deletions(-) diff --git a/drivers/block/Kconfig b/drivers/block/Kconfig index 1d886e0..9c769e1 100644 --- a/drivers/block/Kconfig +++ b/drivers/block/Kconfig @@ -371,6 +371,28 @@ config BLK_DEV_RAM_SIZE The default value is 4096 kilobytes. Only change this if you know what you are doing. +config BLK_DEV_RAMZSWAP + tristate "Compressed in-memory swap device" + depends on SWAP + select LZO_COMPRESS + select LZO_DECOMPRESS + default m + help + Creates virtual block device which can be used (only) as a swap + device. Pages swapped to this device are compressed and stored in + memory itself. + + See Documentation/blockdev/ramzswap.txt for more information. + Project home: http://compcache.googlecode.com/ + +config BLK_DEV_RAMZSWAP_STATS + bool "Enable ramzswap stats" + depends on BLK_DEV_RAMZSWAP + default y + help + Enable statistics collection for ramzswap. This adds only a minimal + overhead. In unsure, say Y. + config BLK_DEV_XIP bool "Support XIP filesystems on RAM block device" depends on BLK_DEV_RAM diff --git a/drivers/block/Makefile b/drivers/block/Makefile index cdaa3f8..174efcc 100644 --- a/drivers/block/Makefile +++ b/drivers/block/Makefile @@ -14,6 +14,7 @@ obj-$(CONFIG_PS3_VRAM) += ps3vram.o obj-$(CONFIG_ATARI_FLOPPY) += ataflop.o obj-$(CONFIG_AMIGA_Z2RAM) += z2ram.o obj-$(CONFIG_BLK_DEV_RAM) += brd.o +obj-$(CONFIG_BLK_DEV_RAMZSWAP) += ramzswap/ obj-$(CONFIG_BLK_DEV_LOOP) += loop.o obj-$(CONFIG_BLK_DEV_XD) += xd.o obj-$(CONFIG_BLK_CPQ_DA) += cpqarray.o diff --git a/drivers/block/ramzswap/ramzswap.c b/drivers/block/ramzswap/ramzswap.c new file mode 100644 index 0000000..de1b8b0 --- /dev/null +++ b/drivers/block/ramzswap/ramzswap.c @@ -0,0 +1,1518 @@ +/* + * Compressed RAM based swap device + * + * Copyright (C) 2008, 2009 Nitin Gupta + * + * This code is released using a dual license strategy: BSD/GPL + * You can choose the licence that better fits your requirements. + * + * Released under the terms of 3-clause BSD License + * Released under the terms of GNU General Public License Version 2.0 + * + * Project home: http://compcache.googlecode.com + */ + +#include <linux/module.h> +#include <linux/kernel.h> +#include <linux/bitops.h> +#include <linux/blkdev.h> +#include <linux/buffer_head.h> +#include <linux/device.h> +#include <linux/genhd.h> +#include <linux/highmem.h> +#include <linux/lzo.h> +#include <linux/marker.h> +#include <linux/mutex.h> +#include <linux/string.h> +#include <linux/swap.h> +#include <linux/swapops.h> +#include <linux/vmalloc.h> +#include <linux/version.h> + +#include "ramzswap.h" + +/* Globals */ +static int RAMZSWAP_MAJOR; +static struct ramzswap *DEVICES; + +/* + * Pages that compress to larger than this size are + * forwarded to backing swap, if present or stored + * uncompressed in memory otherwise. + */ +static unsigned int MAX_CPAGE_SIZE; + +/* Module params (documentation at end) */ +static unsigned long NUM_DEVICES; + +/* Function declarations */ +static int __init ramzswap_init(void); +static int ramzswap_ioctl(struct block_device *, fmode_t, + unsigned, unsigned long); +static int setup_swap_header(struct ramzswap *, union swap_header *); +static void ramzswap_set_memlimit(struct ramzswap *, size_t); +static void ramzswap_set_disksize(struct ramzswap *, size_t); +static void reset_device(struct ramzswap *rzs); + +static struct block_device_operations ramzswap_devops = { + .ioctl = ramzswap_ioctl, + .owner = THIS_MODULE, +}; + +static int test_flag(struct ramzswap *rzs, u32 index, enum rzs_pageflags flag) +{ + return rzs->table[index].flags & BIT(flag); +} + +static void set_flag(struct ramzswap *rzs, u32 index, enum rzs_pageflags flag) +{ + rzs->table[index].flags |= BIT(flag); +} + +static void clear_flag(struct ramzswap *rzs, u32 index, + enum rzs_pageflags flag) +{ + rzs->table[index].flags &= ~BIT(flag); +} + +static int page_zero_filled(void *ptr) +{ + u32 pos; + u64 *page; + + page = (u64 *)ptr; + + for (pos = 0; pos != PAGE_SIZE / sizeof(*page); pos++) { + if (page[pos]) + return 0; + } + + return 1; +} + +/* + * Given <pagenum, offset> pair, provide a dereferencable pointer. + */ +static void *get_ptr_atomic(u32 pagenum, u16 offset, enum km_type type) +{ + unsigned char *page; + + page = kmap_atomic(pfn_to_page(pagenum), type); + return page + offset; +} + +static void put_ptr_atomic(void *ptr, enum km_type type) +{ + kunmap_atomic(ptr, type); +} + +static void ramzswap_flush_dcache_page(struct page *page) +{ +#ifdef CONFIG_ARM + int flag = 0; + /* + * Ugly hack to get flush_dcache_page() work on ARM. + * page_mapping(page) == NULL after clearing this swap cache flag. + * Without clearing this flag, flush_dcache_page() will simply set + * "PG_dcache_dirty" bit and return. + */ + if (PageSwapCache(page)) { + flag = 1; + ClearPageSwapCache(page); + } +#endif + flush_dcache_page(page); +#ifdef CONFIG_ARM + if (flag) + SetPageSwapCache(page); +#endif +} + +void ramzswap_ioctl_get_stats(struct ramzswap *rzs, + struct ramzswap_ioctl_stats *s) +{ + strncpy(s->backing_swap_name, rzs->backing_swap_name, + MAX_SWAP_NAME_LEN - 1); + s->backing_swap_name[MAX_SWAP_NAME_LEN - 1] = '\0'; + + s->disksize = rzs->disksize; + s->memlimit = rzs->memlimit; + +#if defined(STATS) + { + struct ramzswap_stats *rs = &rzs->stats; + size_t succ_writes, mem_used; + unsigned int good_compress_perc = 0, no_compress_perc = 0; + + mem_used = xv_get_total_size_bytes(rzs->mem_pool) + + (rs->pages_expand << PAGE_SHIFT); + succ_writes = rs->num_writes - rs->failed_writes; + + if (succ_writes && rs->pages_stored) { + good_compress_perc = rs->good_compress * 100 + / rs->pages_stored; + no_compress_perc = rs->pages_expand * 100 + / rs->pages_stored; + } + + s->num_reads = rs->num_reads; + s->num_writes = rs->num_writes; + s->failed_reads = rs->failed_reads; + s->failed_writes = rs->failed_writes; + s->invalid_io = rs->invalid_io; + s->notify_free = rs->notify_free; + s->pages_discard = rs->pages_discard; + s->pages_zero = rs->pages_zero; + + s->good_compress_pct = good_compress_perc; + s->pages_expand_pct = no_compress_perc; + + s->pages_stored = rs->pages_stored; + s->pages_used = mem_used >> PAGE_SHIFT; + s->orig_data_size = rs->pages_stored << PAGE_SHIFT; + s->compr_data_size = rs->compr_size; + s->mem_used_total = mem_used; + + s->bdev_num_reads = rs->bdev_num_reads; + s->bdev_num_writes = rs->bdev_num_writes; + } +#endif /* STATS */ +} + +static int add_backing_swap_extent(struct ramzswap *rzs, + unsigned long phy_pagenum, + unsigned long num_pages) +{ + unsigned int idx; + struct list_head *head; + struct page *curr_page, *new_page; + unsigned int extents_per_page = PAGE_SIZE / + sizeof(struct ramzswap_backing_extent); + + idx = rzs->num_extents % extents_per_page; + if (!idx) { + new_page = alloc_page(__GFP_ZERO); + if (!new_page) + return -ENOMEM; + + if (rzs->num_extents) { + curr_page = virt_to_page(rzs->curr_extent); + head = &curr_page->lru; + } else { + head = &rzs->backing_swap_extent_list; + } + + list_add(&new_page->lru, head); + rzs->curr_extent = page_address(new_page); + } + + rzs->curr_extent->phy_pagenum = phy_pagenum; + rzs->curr_extent->num_pages = num_pages; + + pr_debug(C "add_extent: idx=%u, phy_pgnum=%lu, num_pgs=%lu, " + "pg_last=%lu, curr_ext=%p\n", idx, phy_pagenum, num_pages, + phy_pagenum + num_pages - 1, rzs->curr_extent); + + if (idx != extents_per_page - 1) + rzs->curr_extent++; + + return 0; +} + +static int setup_backing_swap_extents(struct ramzswap *rzs, + struct inode *inode, unsigned long *num_pages) +{ + int ret = 0; + unsigned blkbits; + unsigned blocks_per_page; + unsigned long contig_pages = 0, total_pages = 0; + unsigned long pagenum = 0, prev_pagenum = 0; + sector_t probe_block = 0; + sector_t last_block; + + blkbits = inode->i_blkbits; + blocks_per_page = PAGE_SIZE >> blkbits; + + last_block = i_size_read(inode) >> blkbits; + while (probe_block + blocks_per_page <= last_block) { + unsigned block_in_page; + sector_t first_block; + + first_block = bmap(inode, probe_block); + if (first_block == 0) + goto bad_bmap; + + /* It must be PAGE_SIZE aligned on-disk */ + if (first_block & (blocks_per_page - 1)) { + probe_block++; + goto probe_next; + } + + /* All blocks within this page must be contiguous on disk */ + for (block_in_page = 1; block_in_page < blocks_per_page; + block_in_page++) { + sector_t block; + + block = bmap(inode, probe_block + block_in_page); + if (block == 0) + goto bad_bmap; + if (block != first_block + block_in_page) { + /* Discontiguity */ + probe_block++; + goto probe_next; + } + } + + /* + * We found a PAGE_SIZE length, PAGE_SIZE aligned + * run of blocks. + */ + pagenum = first_block >> (PAGE_SHIFT - blkbits); + + if (total_pages && (pagenum != prev_pagenum + 1)) { + ret = add_backing_swap_extent(rzs, prev_pagenum - + (contig_pages - 1), contig_pages); + if (ret < 0) + goto out; + rzs->num_extents++; + contig_pages = 0; + } + total_pages++; + contig_pages++; + prev_pagenum = pagenum; + probe_block += blocks_per_page; + +probe_next: + continue; + } + + if (contig_pages) { + pr_debug(C "adding last extent: pagenum=%lu, " + "contig_pages=%lu\n", pagenum, contig_pages); + ret = add_backing_swap_extent(rzs, + prev_pagenum - (contig_pages - 1), contig_pages); + if (ret < 0) + goto out; + rzs->num_extents++; + } + if (!rzs->num_extents) { + pr_err(C "No swap extents found!\n"); + ret = -EINVAL; + } + + if (!ret) { + *num_pages = total_pages; + pr_info(C "Found %lu extents containing %luk\n", + rzs->num_extents, *num_pages << PAGE_SHIFT); + } + goto out; + +bad_bmap: + pr_err(C "Backing swapfile has holes\n"); + ret = -EINVAL; +out: + while (ret && !list_empty(&rzs->backing_swap_extent_list)) { + struct page *page; + struct list_head *entry = rzs->backing_swap_extent_list.next; + page = list_entry(entry, struct page, lru); + list_del(entry); + __free_page(page); + } + return ret; +} + +static void map_backing_swap_extents(struct ramzswap *rzs) +{ + struct ramzswap_backing_extent *se; + struct page *table_page, *se_page; + unsigned long num_pages, num_table_pages, entry; + unsigned long se_idx, span; + unsigned entries_per_page = PAGE_SIZE / sizeof(*rzs->table); + unsigned extents_per_page = PAGE_SIZE / sizeof(*se); + + /* True for block device */ + if (!rzs->num_extents) + return; + + se_page = list_entry(rzs->backing_swap_extent_list.next, + struct page, lru); + se = page_address(se_page); + span = se->num_pages; + num_pages = rzs->disksize >> PAGE_SHIFT; + num_table_pages = DIV_ROUND_UP(num_pages * sizeof(*rzs->table), + PAGE_SIZE); + + entry = 0; + se_idx = 0; + while (num_table_pages--) { + table_page = vmalloc_to_page(&rzs->table[entry]); + while (span <= entry) { + se_idx++; + if (se_idx == rzs->num_extents) + BUG(); + + if (!(se_idx % extents_per_page)) { + se_page = list_entry(se_page->lru.next, + struct page, lru); + se = page_address(se_page); + } else + se++; + + span += se->num_pages; + } + table_page->mapping = (struct address_space *)se; + table_page->private = se->num_pages - (span - entry); + pr_debug(C "map_table: entry=%lu, span=%lu, map=%p, priv=%lu\n", + entry, span, table_page->mapping, table_page->private); + entry += entries_per_page; + } +} + +/* + * Check if value of backing_swap module param is sane. + * Claim this device and set ramzswap size equal to + * size of this block device. + */ +static int setup_backing_swap(struct ramzswap *rzs) +{ + int ret = 0; + size_t disksize; + unsigned long num_pages = 0; + struct inode *inode; + struct file *swap_file; + struct address_space *mapping; + struct block_device *bdev = NULL; + + if (!rzs->backing_swap_name[0]) { + pr_debug(C "backing_swap param not given\n"); + goto out; + } + + pr_info(C "Using backing swap device: %s\n", rzs->backing_swap_name); + + swap_file = filp_open(rzs->backing_swap_name, + O_RDWR | O_LARGEFILE, 0); + if (IS_ERR(swap_file)) { + pr_err(C "Error opening backing device: %s\n", + rzs->backing_swap_name); + ret = -EINVAL; + goto out; + } + + mapping = swap_file->f_mapping; + inode = mapping->host; + + if (S_ISBLK(inode->i_mode)) { + bdev = I_BDEV(inode); + ret = bd_claim(bdev, setup_backing_swap); + if (ret < 0) { + bdev = NULL; + goto bad_param; + } + disksize = i_size_read(inode); + } else if (S_ISREG(inode->i_mode)) { + bdev = inode->i_sb->s_bdev; + if (IS_SWAPFILE(inode)) { + ret = -EBUSY; + goto bad_param; + } + ret = setup_backing_swap_extents(rzs, inode, &num_pages); + if (ret < 0) + goto bad_param; + disksize = num_pages << PAGE_SHIFT; + } else { + goto bad_param; + } + + rzs->swap_file = swap_file; + rzs->backing_swap = bdev; + rzs->disksize = disksize; + BUG_ON(!rzs->disksize); + + return 0; + +bad_param: + if (bdev) + bd_release(bdev); + filp_close(swap_file, NULL); + +out: + rzs->backing_swap = NULL; + return ret; +} + +/* + * Map logical page number 'pagenum' to physical page number + * on backing swap device. For block device, this is a nop. + */ +u32 map_backing_swap_page(struct ramzswap *rzs, u32 pagenum) +{ + u32 skip_pages, entries_per_page; + size_t delta, se_offset, skipped; + struct page *table_page, *se_page; + struct ramzswap_backing_extent *se; + + if (!rzs->num_extents) + return pagenum; + + entries_per_page = PAGE_SIZE / sizeof(*rzs->table); + + table_page = vmalloc_to_page(&rzs->table[pagenum]); + se = (struct ramzswap_backing_extent *)table_page->mapping; + se_page = virt_to_page(se); + + skip_pages = pagenum - (pagenum / entries_per_page * entries_per_page); + se_offset = table_page->private + skip_pages; + + if (se_offset < se->num_pages) + return se->phy_pagenum + se_offset; + + skipped = se->num_pages - table_page->private; + do { + struct ramzswap_backing_extent *se_base; + u32 se_entries_per_page = PAGE_SIZE / sizeof(*se); + + /* Get next swap extent */ + se_base = (struct ramzswap_backing_extent *) + page_address(se_page); + if (se - se_base == se_entries_per_page - 1) { + se_page = list_entry(se_page->lru.next, + struct page, lru); + se = page_address(se_page); + } else { + se++; + } + + skipped += se->num_pages; + } while (skipped < skip_pages); + + delta = skipped - skip_pages; + se_offset = se->num_pages - delta; + + return se->phy_pagenum + se_offset; +} + +/* + * Check if request is within bounds and page aligned. + */ +static inline int valid_swap_request(struct ramzswap *rzs, struct bio *bio) +{ + if (unlikely( + (bio->bi_sector >= (rzs->disksize >> SECTOR_SHIFT)) || + (bio->bi_sector & (SECTORS_PER_PAGE - 1)) || + (bio->bi_vcnt != 1) || + (bio->bi_size != PAGE_SIZE) || + (bio->bi_io_vec[0].bv_offset != 0))) { + + return 0; + } + + /* swap request is valid */ + return 1; +} + +static void ramzswap_free_page(struct ramzswap *rzs, size_t index) +{ + u32 clen; + void *obj; + + u32 pagenum = rzs->table[index].pagenum; + u32 offset = rzs->table[index].offset; + + if (unlikely(test_flag(rzs, index, RZS_UNCOMPRESSED))) { + clen = PAGE_SIZE; + __free_page(pfn_to_page(pagenum)); + clear_flag(rzs, index, RZS_UNCOMPRESSED); + stat_dec(rzs->stats.pages_expand); + goto out; + } + + obj = get_ptr_atomic(pagenum, offset, KM_USER0); + clen = xv_get_object_size(obj) - sizeof(struct zobj_header); + put_ptr_atomic(obj, KM_USER0); + + xv_free(rzs->mem_pool, pagenum, offset); + stat_dec_if_less(rzs->stats.good_compress, clen, PAGE_SIZE / 2 + 1); + +out: + rzs->stats.compr_size -= clen; + stat_dec(rzs->stats.pages_stored); + + rzs->table[index].pagenum = 0; + rzs->table[index].offset = 0; +} + +/* + * callback function called when swap_map[offset] == 0 + * i.e page at this swap offset is no longer used + */ +static void ramzswap_free_notify(struct block_device *bdev, + unsigned long index) +{ + struct ramzswap *rzs = bdev->bd_disk->private_data; + + if (rzs->table[index].pagenum) { + ramzswap_free_page(rzs, index); + stat_inc(rzs->stats.notify_free); + } +} + +static int ramzswap_prepare_discard(struct request_queue *q, + struct request *req) +{ + return 0; +} + +/* + * Called by main I/O handler function. This helper + * function handles 'discard' I/O requests which means + * that some swap pages are no longer required, so + * swap device can take needed action -- we free memory + * allocated for these pages. + */ +static int ramzswap_discard(struct ramzswap *rzs, struct bio *bio) +{ + size_t index, start_page, num_pages; + + start_page = bio->bi_sector >> SECTORS_PER_PAGE_SHIFT; + num_pages = bio->bi_size >> (SECTOR_SHIFT + SECTORS_PER_PAGE_SHIFT); + + for (index = start_page; index < start_page + num_pages; index++) { + if (rzs->table[index].pagenum) { + ramzswap_free_page(rzs, index); + stat_inc(rzs->stats.pages_discard); + } + } + + set_bit(BIO_UPTODATE, &bio->bi_flags); + bio_endio(bio, 0); + return 0; +} + +static int handle_zero_page(struct bio *bio) +{ + void *user_mem; + struct page *page = bio->bi_io_vec[0].bv_page; + + user_mem = get_ptr_atomic(page_to_pfn(page), 0, KM_USER0); + memset(user_mem, 0, PAGE_SIZE); + put_ptr_atomic(user_mem, KM_USER0); + + ramzswap_flush_dcache_page(page); + + set_bit(BIO_UPTODATE, &bio->bi_flags); + bio_endio(bio, 0); + return 0; +} + +static int handle_uncompressed_page(struct ramzswap *rzs, struct bio *bio) +{ + u32 index; + struct page *page; + unsigned char *user_mem, *cmem; + + page = bio->bi_io_vec[0].bv_page; + index = bio->bi_sector >> SECTORS_PER_PAGE_SHIFT; + + user_mem = get_ptr_atomic(page_to_pfn(page), 0, KM_USER0); + cmem = get_ptr_atomic(rzs->table[index].pagenum, + rzs->table[index].offset, KM_USER1); + + memcpy(user_mem, cmem, PAGE_SIZE); + put_ptr_atomic(user_mem, KM_USER0); + put_ptr_atomic(cmem, KM_USER1); + + ramzswap_flush_dcache_page(page); + + set_bit(BIO_UPTODATE, &bio->bi_flags); + bio_endio(bio, 0); + return 0; +} + + +/* + * Called when request page is not present in ramzswap. + * Its either in backing swap device (if present) or + * this is an attempt to read before any previous write + * to this location - this happens due to readahead when + * swap device is read from user-space (e.g. during swapon) + */ +static int handle_ramzswap_fault(struct ramzswap *rzs, struct bio *bio) +{ + /* + * Always forward such requests to backing swap + * device (if present) + */ + if (rzs->backing_swap) { + u32 pagenum; + stat_dec(rzs->stats.num_reads); + stat_inc(rzs->stats.bdev_num_reads); + bio->bi_bdev = rzs->backing_swap; + + /* + * In case backing swap is a file, find the right offset within + * the file corresponding to logical position 'index'. For block + * device, this is a nop. + */ + pagenum = bio->bi_sector >> SECTORS_PER_PAGE_SHIFT; + bio->bi_sector = map_backing_swap_page(rzs, pagenum) + << SECTORS_PER_PAGE_SHIFT; + return 1; + } + + /* + * Its unlikely event in case backing dev is + * not present + */ + pr_debug(C "Read before write on swap device: " + "sector=%lu, size=%u, offset=%u\n", + (ulong)(bio->bi_sector), bio->bi_size, + bio->bi_io_vec[0].bv_offset); + + /* Do nothing. Just return success */ + set_bit(BIO_UPTODATE, &bio->bi_flags); + bio_endio(bio, 0); + return 0; +} + +static int ramzswap_read(struct ramzswap *rzs, struct bio *bio) +{ + int ret; + u32 index; + size_t clen; + struct page *page; + struct zobj_header *zheader; + unsigned char *user_mem, *cmem; + + stat_inc(rzs->stats.num_reads); + + page = bio->bi_io_vec[0].bv_page; + index = bio->bi_sector >> SECTORS_PER_PAGE_SHIFT; + + if (unlikely(!rzs->init_notify_callback) && PageSwapCache(page)) { + set_swap_free_notify(bio->bi_bdev, ramzswap_free_notify); + rzs->init_notify_callback = 1; + } + + if (test_flag(rzs, index, RZS_ZERO)) + return handle_zero_page(bio); + + /* Requested page is not present in compressed area */ + if (!rzs->table[index].pagenum) + return handle_ramzswap_fault(rzs, bio); + + /* Page is stored uncompressed since its incompressible */ + if (unlikely(test_flag(rzs, index, RZS_UNCOMPRESSED))) + return handle_uncompressed_page(rzs, bio); + + user_mem = get_ptr_atomic(page_to_pfn(page), 0, KM_USER0); + clen = PAGE_SIZE; + + cmem = get_ptr_atomic(rzs->table[index].pagenum, + rzs->table[index].offset, KM_USER1); + + ret = lzo1x_decompress_safe( + cmem + sizeof(*zheader), + xv_get_object_size(cmem) - sizeof(*zheader), + user_mem, &clen); + + put_ptr_atomic(user_mem, KM_USER0); + put_ptr_atomic(cmem, KM_USER1); + + /* should NEVER happen */ + if (unlikely(ret != LZO_E_OK)) { + pr_err(C "Decompression failed! err=%d, page=%u\n", + ret, index); + stat_inc(rzs->stats.failed_reads); + goto out; + } + + ramzswap_flush_dcache_page(page); + + set_bit(BIO_UPTODATE, &bio->bi_flags); + bio_endio(bio, 0); + return 0; + +out: + bio_io_error(bio); + return 0; +} + +static int ramzswap_write(struct ramzswap *rzs, struct bio *bio) +{ + int ret, fwd_write_request = 0; + u32 offset, index; + size_t clen; + struct zobj_header *zheader; + struct page *page, *page_store; + unsigned char *user_mem, *cmem, *src; + + stat_inc(rzs->stats.num_writes); + + page = bio->bi_io_vec[0].bv_page; + index = bio->bi_sector >> SECTORS_PER_PAGE_SHIFT; + + src = rzs->compress_buffer; + + /* + * System swaps to same sector again when the stored page + * is no longer referenced by any process. So, its now safe + * to free the memory that was allocated for this page. + */ + if (rzs->table[index].pagenum) + ramzswap_free_page(rzs, index); + + /* + * No memory ia allocated for zero filled pages. + * Simply clear zero page flag. + */ + if (test_flag(rzs, index, RZS_ZERO)) { + stat_dec(rzs->stats.pages_zero); + clear_flag(rzs, index, RZS_ZERO); + } + + trace_mark(ramzswap_lock_wait, "ramzswap_lock_wait"); + mutex_lock(&rzs->lock); + trace_mark(ramzswap_lock_acquired, "ramzswap_lock_acquired"); + + user_mem = get_ptr_atomic(page_to_pfn(page), 0, KM_USER0); + if (page_zero_filled(user_mem)) { + put_ptr_atomic(user_mem, KM_USER0); + mutex_unlock(&rzs->lock); + stat_inc(rzs->stats.pages_zero); + set_flag(rzs, index, RZS_ZERO); + + set_bit(BIO_UPTODATE, &bio->bi_flags); + bio_endio(bio, 0); + return 0; + } + + if (rzs->backing_swap && + (rzs->stats.compr_size > rzs->memlimit - PAGE_SIZE)) { + put_ptr_atomic(user_mem, KM_USER0); + mutex_unlock(&rzs->lock); + fwd_write_request = 1; + goto out; + } + + ret = lzo1x_1_compress(user_mem, PAGE_SIZE, src, &clen, + rzs->compress_workmem); + + put_ptr_atomic(user_mem, KM_USER0); + + if (unlikely(ret != LZO_E_OK)) { + mutex_unlock(&rzs->lock); + pr_err(C "Compression failed! err=%d\n", ret); + stat_inc(rzs->stats.failed_writes); + goto out; + } + + /* + * Page is incompressible. Forward it to backing swap + * if present. Otherwise, store it as-is (uncompressed) + * since we do not want to return too many swap write + * errors which has side effect of hanging the system. + */ + if (unlikely(clen > MAX_CPAGE_SIZE)) { + if (rzs->backing_swap) { + mutex_unlock(&rzs->lock); + fwd_write_request = 1; + goto out; + } + + clen = PAGE_SIZE; + page_store = alloc_page(GFP_NOIO | __GFP_HIGHMEM); + if (unlikely(!page_store)) { + mutex_unlock(&rzs->lock); + pr_info(C "Error allocating memory for incompressible " + "page: %u\n", index); + stat_inc(rzs->stats.failed_writes); + goto out; + } + + offset = 0; + set_flag(rzs, index, RZS_UNCOMPRESSED); + stat_inc(rzs->stats.pages_expand); + rzs->table[index].pagenum = page_to_pfn(page_store); + src = get_ptr_atomic(page_to_pfn(page), 0, KM_USER0); + goto memstore; + } + + if (xv_malloc(rzs->mem_pool, clen + sizeof(*zheader), + &rzs->table[index].pagenum, &offset, + GFP_NOIO | __GFP_HIGHMEM)) { + mutex_unlock(&rzs->lock); + pr_info(C "Error allocating memory for compressed " + "page: %u, size=%zu\n", index, clen); + stat_inc(rzs->stats.failed_writes); + if (rzs->backing_swap) + fwd_write_request = 1; + goto out; + } + +memstore: + rzs->table[index].offset = offset; + + cmem = get_ptr_atomic(rzs->table[index].pagenum, + rzs->table[index].offset, KM_USER1); + +#if 0 + /* Back-reference needed for memory defragmentation */ + if (!test_flag(rzs, index, RZS_UNCOMPRESSED)) { + zheader = (struct zobj_header *)cmem; + zheader->table_idx = index; + cmem += sizeof(*zheader); + } +#endif + + memcpy(cmem, src, clen); + + put_ptr_atomic(cmem, KM_USER1); + if (unlikely(test_flag(rzs, index, RZS_UNCOMPRESSED))) + put_ptr_atomic(src, KM_USER0); + + /* Update stats */ + rzs->stats.compr_size += clen; + stat_inc(rzs->stats.pages_stored); + stat_inc_if_less(rzs->stats.good_compress, clen, PAGE_SIZE / 2 + 1); + + mutex_unlock(&rzs->lock); + + set_bit(BIO_UPTODATE, &bio->bi_flags); + bio_endio(bio, 0); + return 0; + +out: + if (fwd_write_request) { + stat_inc(rzs->stats.bdev_num_writes); + bio->bi_bdev = rzs->backing_swap; +#if 0 + /* + * TODO: We currently have linear mapping of ramzswap and + * backing swap sectors. This is not desired since we want + * to optimize writes to backing swap to minimize disk seeks + * or have effective wear leveling (for SSDs). Also, a + * non-linear mapping is required to implement compressed + * on-disk swapping. + */ + bio->bi_sector = get_backing_swap_page() + << SECTORS_PER_PAGE_SHIFT; +#endif + /* + * In case backing swap is a file, find the right offset within + * the file corresponding to logical position 'index'. For block + * device, this is a nop. + */ + bio->bi_sector = map_backing_swap_page(rzs, index) + << SECTORS_PER_PAGE_SHIFT; + return 1; + } + + bio_io_error(bio); + return 0; +} + +/* + * Handler function for all ramzswap I/O requests. + */ +static int ramzswap_make_request(struct request_queue *queue, struct bio *bio) +{ + int ret = 0; + struct ramzswap *rzs = queue->queuedata; + + if (unlikely(!rzs->init_done)) { + bio_io_error(bio); + return 0; + } + + if (bio_discard(bio)) + return ramzswap_discard(rzs, bio); + + if (!valid_swap_request(rzs, bio)) { + stat_inc(rzs->stats.invalid_io); + bio_io_error(bio); + return 0; + } + + switch (bio_data_dir(bio)) { + case READ: + ret = ramzswap_read(rzs, bio); + break; + + case WRITE: + ret = ramzswap_write(rzs, bio); + break; + } + + return ret; +} + +static int ramzswap_ioctl_init_device(struct ramzswap *rzs) +{ + int ret; + size_t num_pages, totalram_bytes; + struct sysinfo i; + struct page *page; + void *swap_header; + + if (rzs->init_done) { + pr_info(C "Device already initialized!\n"); + return -EBUSY; + } + + ret = setup_backing_swap(rzs); + if (ret) + goto fail; + + si_meminfo(&i); + /* Here is a trivia: guess unit used for i.totalram !! */ + totalram_bytes = i.totalram << PAGE_SHIFT; + + if (rzs->backing_swap) + ramzswap_set_memlimit(rzs, totalram_bytes); + else + ramzswap_set_disksize(rzs, totalram_bytes); + + rzs->compress_workmem = kzalloc(LZO1X_MEM_COMPRESS, GFP_KERNEL); + if (rzs->compress_workmem == NULL) { + pr_err(C "Error allocating compressor working memory!\n"); + ret = -ENOMEM; + goto fail; + } + + rzs->compress_buffer = kzalloc(2 * PAGE_SIZE, GFP_KERNEL); + if (rzs->compress_buffer == NULL) { + pr_err(C "Error allocating compressor buffer space\n"); + ret = -ENOMEM; + goto fail; + } + + num_pages = rzs->disksize >> PAGE_SHIFT; + rzs->table = vmalloc(num_pages * sizeof(*rzs->table)); + if (rzs->table == NULL) { + pr_err(C "Error allocating ramzswap address table\n"); + ret = -ENOMEM; + goto fail; + } + memset(rzs->table, 0, num_pages * sizeof(*rzs->table)); + + map_backing_swap_extents(rzs); + + page = alloc_page(__GFP_ZERO); + if (page == NULL) { + pr_err(C "Error allocating swap header page\n"); + ret = -ENOMEM; + goto fail; + } + rzs->table[0].pagenum = page_to_pfn(page); + set_flag(rzs, 0, RZS_UNCOMPRESSED); + + swap_header = kmap(page); + ret = setup_swap_header(rzs, (union swap_header *)(swap_header)); + kunmap(page); + if (ret) { + pr_err(C "Error setting swap header\n"); + goto fail; + } + + set_capacity(rzs->disk, rzs->disksize >> SECTOR_SHIFT); + + /* + * We have ident mapping of sectors for ramzswap and + * and the backing swap device. So, this queue flag + * should be according to backing dev. + */ + if (!rzs->backing_swap || + blk_queue_nonrot(rzs->backing_swap->bd_disk->queue)) + queue_flag_set_unlocked(QUEUE_FLAG_NONROT, rzs->disk->queue); + + blk_queue_set_discard(rzs->disk->queue, ramzswap_prepare_discard); + blk_queue_logical_block_size(rzs->disk->queue, PAGE_SIZE); + + rzs->mem_pool = xv_create_pool(); + if (!rzs->mem_pool) { + pr_err(C "Error creating memory pool\n"); + ret = -ENOMEM; + goto fail; + } + + /* + * Pages that compress to size greater than this are forwarded + * to physical swap disk (if backing dev is provided) + * TODO: make this configurable + */ + if (rzs->backing_swap) + MAX_CPAGE_SIZE = MAX_CPAGE_SIZE_BDEV; + else + MAX_CPAGE_SIZE = MAX_CPAGE_SIZE_NOBDEV; + + pr_debug(C "Max compressed page size: %u bytes\n", MAX_CPAGE_SIZE); + + rzs->init_done = 1; + + pr_debug(C "Initialization done!\n"); + return 0; + +fail: + if (rzs->table && rzs->table[0].pagenum) + __free_page(pfn_to_page(rzs->table[0].pagenum)); + kfree(rzs->compress_workmem); + kfree(rzs->compress_buffer); + vfree(rzs->table); + xv_destroy_pool(rzs->mem_pool); + + pr_err(C "Initialization failed: err=%d\n", ret); + return ret; +} + +static int ramzswap_ioctl_reset_device(struct ramzswap *rzs) +{ + reset_device(rzs); + return 0; +} + +static int ramzswap_ioctl(struct block_device *bdev, fmode_t mode, + unsigned int cmd, unsigned long arg) +{ + int ret = 0; + size_t disksize_kb, memlimit_kb; + + struct ramzswap *rzs = bdev->bd_disk->private_data; + + switch (cmd) { + case RZSIO_SET_DISKSIZE_KB: + if (rzs->init_done) { + ret = -EBUSY; + goto out; + } + if (copy_from_user(&disksize_kb, (void *)arg, + _IOC_SIZE(cmd))) { + ret = -EFAULT; + goto out; + } + rzs->disksize = disksize_kb << 10; + pr_info(C "Disk size set to %zu KB\n", disksize_kb); + break; + + case RZSIO_SET_MEMLIMIT_KB: + if (rzs->init_done) { + /* TODO: allow changing memlimit */ + ret = -EBUSY; + goto out; + } + if (copy_from_user(&memlimit_kb, (void *)arg, + _IOC_SIZE(cmd))) { + ret = -EFAULT; + goto out; + } + rzs->memlimit = memlimit_kb << 10; + pr_info(C "Memory limit set to %zu KB\n", memlimit_kb); + break; + + case RZSIO_SET_BACKING_SWAP: + if (rzs->init_done) { + ret = -EBUSY; + goto out; + } + + if (copy_from_user(&rzs->backing_swap_name, (void *)arg, + _IOC_SIZE(cmd))) { + ret = -EFAULT; + goto out; + } + rzs->backing_swap_name[MAX_SWAP_NAME_LEN - 1] = '\0'; + pr_info(C "Backing swap set to %s\n", rzs->backing_swap_name); + break; + + case RZSIO_GET_STATS: + { + struct ramzswap_ioctl_stats *stats; + if (!rzs->init_done) { + ret = -ENOTTY; + goto out; + } + stats = kzalloc(sizeof(*stats), GFP_KERNEL); + if (!stats) { + ret = -ENOMEM; + goto out; + } + ramzswap_ioctl_get_stats(rzs, stats); + if (copy_to_user((void *)arg, stats, sizeof(*stats))) { + kfree(stats); + ret = -EFAULT; + goto out; + } + kfree(stats); + break; + } + case RZSIO_INIT: + ret = ramzswap_ioctl_init_device(rzs); + break; + + case RZSIO_RESET: + /* Do not reset an active device! */ + if (bdev->bd_holders) { + ret = -EBUSY; + goto out; + } + ret = ramzswap_ioctl_reset_device(rzs); + /* + * Racy! Device has already been swapoff'ed. Bad things + * can happen if another swapon is done before this reset. + * TODO: A callback from swapoff() will solve this problem. + */ + set_swap_free_notify(bdev, NULL); + rzs->init_notify_callback = 0; + break; + + default: + pr_info(C "Invalid ioctl %u\n", cmd); + ret = -ENOTTY; + } + +out: + return ret; +} + +/* + * Swap header (1st page of swap device) contains information + * to indentify it as a swap partition. Prepare such a header + * for ramzswap device (ramzswap0) so that swapon can identify + * it as swap partition. In case backing swap device is provided, + * copy its swap header. + */ +static int setup_swap_header(struct ramzswap *rzs, union swap_header *s) +{ + int ret = 0; + struct page *page; + struct address_space *mapping; + union swap_header *backing_swap_header; + + /* + * There is no backing swap device. Create a swap header + * that is acceptable by swapon. + */ + if (rzs->backing_swap == NULL) { + s->info.version = 1; + s->info.last_page = rzs->disksize >> PAGE_SHIFT; + s->info.nr_badpages = 0; + memcpy(s->magic.magic, "SWAPSPACE2", 10); + return 0; + } + + /* + * We have a backing swap device. Copy its swap header + * to ramzswap device header. If this header contains + * invalid information (backing device not a swap + * partition, etc.), swapon will fail for ramzswap + * which is correct behavior - we don't want to swap + * over filesystem partition! + */ + + /* Read the backing swap header (code from sys_swapon) */ + mapping = rzs->swap_file->f_mapping; + if (!mapping->a_ops->readpage) { + ret = -EINVAL; + goto out; + } + + page = read_mapping_page(mapping, 0, rzs->swap_file); + if (IS_ERR(page)) { + ret = PTR_ERR(page); + goto out; + } + + backing_swap_header = kmap(page); + *s = *backing_swap_header; + + pr_debug("setup_swap_header: last_page = %u\n", s->info.last_page); + + kunmap(page); + +out: + return ret; +} + +static void ramzswap_set_disksize(struct ramzswap *rzs, size_t totalram_bytes) +{ + if (!rzs->disksize) { + pr_info(C + "disk size not provided. You can use disksize_kb module " + "param to specify size.\nUsing default: (%u%% of RAM).\n", + DEFAULT_DISKSIZE_PERC_RAM + ); + rzs->disksize = DEFAULT_DISKSIZE_PERC_RAM * + (totalram_bytes / 100); + } + + if (rzs->disksize > 2 * (totalram_bytes)) { + pr_info(C + "There is little point creating a ramzswap of greater than " + "twice the size of memory since we expect a 2:1 compression " + "ratio. Note that ramzswap uses about 0.1%% of the size of " + "the swap device when not in use so a huge ramzswap is " + "wasteful.\n" + "\tMemory Size: %zu kB\n" + "\tSize you selected: %zu kB\n" + "Continuing anyway ...\n", + totalram_bytes >> 10, rzs->disksize + ); + } + + rzs->disksize &= PAGE_MASK; + pr_info(C "disk size set to %zu kB\n", rzs->disksize >> 10); +} + +/* + * memlimit cannot be greater than backing disk size. + */ +static void ramzswap_set_memlimit(struct ramzswap *rzs, size_t totalram_bytes) +{ + int memlimit_valid = 1; + + if (!rzs->memlimit) { + pr_info(C "Memory limit not set.\n"); + memlimit_valid = 0; + } + + if (rzs->memlimit > rzs->disksize) { + pr_info(C "Memory limit cannot be greater than " + "disksize: limit=%zu, disksize=%zu\n", + rzs->memlimit, rzs->disksize); + memlimit_valid = 0; + } + + if (!memlimit_valid) { + size_t mempart, disksize; + pr_info(C "Using default: smaller of (%u%% of RAM) and " + "(backing disk size).\n", + DEFAULT_MEMLIMIT_PERC_RAM); + mempart = DEFAULT_MEMLIMIT_PERC_RAM * (totalram_bytes / 100); + disksize = rzs->disksize; + rzs->memlimit = mempart > disksize ? disksize : mempart; + } + + if (rzs->memlimit > totalram_bytes / 2) { + pr_info(C + "Its not advisable setting limit more than half of " + "size of memory since we expect a 2:1 compression ratio. " + "Limit represents amount of *compressed* data we can keep " + "in memory!\n" + "\tMemory Size: %zu kB\n" + "\tLimit you selected: %zu kB\n" + "Continuing anyway ...\n", + totalram_bytes >> 10, rzs->memlimit >> 10 + ); + } + + rzs->memlimit &= PAGE_MASK; + BUG_ON(!rzs->memlimit); + + pr_info(C "Memory limit set to %zu kB\n", rzs->memlimit >> 10); +} + +static void create_device(struct ramzswap *rzs, int device_id) +{ + mutex_init(&rzs->lock); + INIT_LIST_HEAD(&rzs->backing_swap_extent_list); + + rzs->queue = blk_alloc_queue(GFP_KERNEL); + if (!rzs->queue) { + pr_err(C "Error allocating disk queue for device %d\n", + device_id); + return; + } + + blk_queue_make_request(rzs->queue, ramzswap_make_request); + blk_queue_logical_block_size(rzs->queue, PAGE_SIZE); + + rzs->queue->queuedata = rzs; + + /* gendisk structure */ + rzs->disk = alloc_disk(1); + if (!rzs->disk) { + blk_cleanup_queue(rzs->queue); + pr_warning(C "Error allocating disk structure for device %d\n", + device_id); + return; + } + + rzs->disk->major = RAMZSWAP_MAJOR; + rzs->disk->first_minor = device_id; + rzs->disk->fops = &ramzswap_devops; + rzs->disk->queue = rzs->queue; + rzs->disk->private_data = rzs; + snprintf(rzs->disk->disk_name, 16, "ramzswap%d", device_id); + + /* + * Actual capacity set using RZSIO_SET_DISKSIZE_KB ioctl + * or set equal to backing swap device (if provided) + */ + set_capacity(rzs->disk, 0); + add_disk(rzs->disk); + + rzs->init_done = 0; + + return; +} + +static void destroy_device(struct ramzswap *rzs) +{ + if (rzs->disk) { + del_gendisk(rzs->disk); + put_disk(rzs->disk); + } + + if (rzs->queue) + blk_cleanup_queue(rzs->queue); +} + +static void reset_device(struct ramzswap *rzs) +{ + int is_backing_blkdev = 0; + size_t index, num_pages; + unsigned entries_per_page; + unsigned long entry, num_table_pages; + + if (!rzs->init_done) + return; + + if (rzs->backing_swap && !rzs->num_extents) + is_backing_blkdev = 1; + + num_pages = rzs->disksize >> PAGE_SHIFT; + + /* Free various per-device buffers */ + kfree(rzs->compress_workmem); + kfree(rzs->compress_buffer); + + rzs->compress_workmem = NULL; + rzs->compress_buffer = NULL; + + /* Free all pages that are still in this ramzswap device */ + for (index = 0; index < num_pages; index++) { + u32 pagenum, offset; + + pagenum = rzs->table[index].pagenum; + offset = rzs->table[index].offset; + + if (!pagenum) + continue; + + if (unlikely(test_flag(rzs, index, RZS_UNCOMPRESSED))) + __free_page(pfn_to_page(pagenum)); + else + xv_free(rzs->mem_pool, pagenum, offset); + } + + entry = 0; + entries_per_page = PAGE_SIZE / sizeof(*rzs->table); + num_table_pages = DIV_ROUND_UP(num_pages * sizeof(*rzs->table), + PAGE_SIZE); + /* + * Set page->mapping to NULL for every table page. + * Otherwise, we will hit bad_page() during free. + */ + while (rzs->num_extents && num_table_pages--) { + struct page *page; + page = vmalloc_to_page(&rzs->table[entry]); + page->mapping = NULL; + entry += entries_per_page; + } + vfree(rzs->table); + rzs->table = NULL; + + xv_destroy_pool(rzs->mem_pool); + rzs->mem_pool = NULL; + + /* Free all swap extent pages */ + while (!list_empty(&rzs->backing_swap_extent_list)) { + struct page *page; + struct list_head *entry; + entry = rzs->backing_swap_extent_list.next; + page = list_entry(entry, struct page, lru); + list_del(entry); + __free_page(page); + } + INIT_LIST_HEAD(&rzs->backing_swap_extent_list); + rzs->num_extents = 0; + + /* Close backing swap device, if present */ + if (rzs->backing_swap) { + if (is_backing_blkdev) + bd_release(rzs->backing_swap); + filp_close(rzs->swap_file, NULL); + rzs->backing_swap = NULL; + } + + /* Reset stats */ + memset(&rzs->stats, 0, sizeof(rzs->stats)); + + rzs->disksize = 0; + rzs->memlimit = 0; + + /* Back to uninitialized state */ + rzs->init_done = 0; +} + +static int __init ramzswap_init(void) +{ + int i; + + if (NUM_DEVICES > MAX_NUM_DEVICES) { + pr_warning(C "Invalid value for NUM_DEVICES: %lu\n", + NUM_DEVICES); + return -EINVAL; + } + + RAMZSWAP_MAJOR = register_blkdev(0, "ramzswap"); + if (RAMZSWAP_MAJOR <= 0) { + pr_warning(C "Unable to get major number\n"); + return -EBUSY; + } + + if (!NUM_DEVICES) { + pr_info(C "NUM_DEVICES not specified. Using default: 1\n"); + NUM_DEVICES = 1; + } + + /* Allocate the device array and initialize each one */ + pr_info(C "Creating %lu devices ...\n", NUM_DEVICES); + DEVICES = kzalloc(NUM_DEVICES * sizeof(struct ramzswap), GFP_KERNEL); + if (!DEVICES) + goto out; + + for (i = 0; i < NUM_DEVICES; i++) + create_device(&DEVICES[i], i); + + return 0; + +out: + unregister_blkdev(RAMZSWAP_MAJOR, "ramzswap"); + return -ENOMEM; +} + +static void __exit ramzswap_exit(void) +{ + int i; + + for (i = 0; i < NUM_DEVICES; i++) { + destroy_device(&DEVICES[i]); + reset_device(&DEVICES[i]); + } + + unregister_blkdev(RAMZSWAP_MAJOR, "ramzswap"); + + kfree(DEVICES); + pr_debug(C "Cleanup done!\n"); +} + +module_param(NUM_DEVICES, ulong, 0); +MODULE_PARM_DESC(NUM_DEVICES, "Number of ramzswap devices"); + +module_init(ramzswap_init); +module_exit(ramzswap_exit); + +MODULE_LICENSE("Dual BSD/GPL"); +MODULE_AUTHOR("Nitin Gupta <[email protected]>"); +MODULE_DESCRIPTION("Compressed RAM Based Swap Device"); diff --git a/drivers/block/ramzswap/ramzswap.h b/drivers/block/ramzswap/ramzswap.h new file mode 100644 index 0000000..1d2b564 --- /dev/null +++ b/drivers/block/ramzswap/ramzswap.h @@ -0,0 +1,182 @@ +/* + * Compressed RAM based swap device + * + * Copyright (C) 2008, 2009 Nitin Gupta + * + * This code is released using a dual license strategy: BSD/GPL + * You can choose the licence that better fits your requirements. + * + * Released under the terms of 3-clause BSD License + * Released under the terms of GNU General Public License Version 2.0 + * + * Project home: http://compcache.googlecode.com + */ + +#ifndef _RAMZSWAP_H_ +#define _RAMZSWAP_H_ + +#include <linux/ramzswap_ioctl.h> +#include "xvmalloc.h" + +/* + * Some arbitrary value. This is just to catch + * invalid value for NUM_DEVICES module parameter. + */ +#define MAX_NUM_DEVICES 32 + +/* + * Stored at beginning of each compressed object. + * + * It stores back-reference to table entry which points to this + * object. This is required to support memory defragmentation or + * migrating compressed pages to backing swap disk. + */ +struct zobj_header { +#if 0 + u32 table_idx; +#endif +}; + +/*-- Configurable parameters */ + +/* Default ramzswap disk size: 25% of total RAM */ +#define DEFAULT_DISKSIZE_PERC_RAM 25 +#define DEFAULT_MEMLIMIT_PERC_RAM 15 + +/* + * Max compressed page size when backing device is provided. + * Pages that compress to size greater than this are sent to + * physical swap disk. + */ +#define MAX_CPAGE_SIZE_BDEV (PAGE_SIZE / 2) + +/* + * Max compressed page size when there is no backing dev. + * Pages that compress to size greater than this are stored + * uncompressed in memory. + */ +#define MAX_CPAGE_SIZE_NOBDEV (PAGE_SIZE / 4 * 3) + +/* + * NOTE: MAX_CPAGE_SIZE_{BDEV,NOBDEV} sizes must be + * less than or equal to: + * XV_MAX_ALLOC_SIZE - sizeof(struct zobj_header) + * since otherwise xvMalloc would always return failure. + */ + +/*-- End of configurable params */ + +#define SECTOR_SHIFT 9 +#define SECTOR_SIZE (1 << SECTOR_SHIFT) +#define SECTORS_PER_PAGE_SHIFT (PAGE_SHIFT - SECTOR_SHIFT) +#define SECTORS_PER_PAGE (1 << SECTORS_PER_PAGE_SHIFT) + +/* Message prefix */ +#define C "ramzswap: " + +/* Debugging and Stats */ +#define NOP do { } while (0) + +#if defined(CONFIG_BLK_DEV_RAMZSWAP_STATS) +#define STATS +#endif + +#if defined(STATS) +#define stat_inc(stat) ((stat)++) +#define stat_dec(stat) ((stat)--) +#define stat_inc_if_less(stat, val1, val2) \ + ((stat) += ((val1) < (val2) ? 1 : 0)) +#define stat_dec_if_less(stat, val1, val2) \ + ((stat) -= ((val1) < (val2) ? 1 : 0)) +#else /* STATS */ +#define stat_inc(x) NOP +#define stat_dec(x) NOP +#define stat_inc_if_less(x, v1, v2) NOP +#define stat_dec_if_less(x, v1, v2) NOP +#endif /* STATS */ + +/* Flags for ramzswap pages (table[page_no].flags) */ +enum rzs_pageflags { + /* Page is stored uncompressed */ + RZS_UNCOMPRESSED, + + /* Page consists entirely of zeros */ + RZS_ZERO, + + __NR_RZS_PAGEFLAGS, +}; + +/*-- Data structures */ + +/* Indexed by page no. */ +struct table { + u32 pagenum; + u16 offset; + u8 count; /* object ref count (not yet used) */ + u8 flags; +}; + +struct ramzswap_backing_extent { + u32 phy_pagenum; + u32 num_pages; +}; + +struct ramzswap_stats { + /* basic stats */ + size_t compr_size; /* compressed size of pages stored - + * needed to enforce memlimit */ + /* more stats */ +#if defined(STATS) + u64 num_reads; /* failed + successful */ + u64 num_writes; /* --do-- */ + u64 failed_reads; /* can happen when memory is too low */ + u64 failed_writes; /* should NEVER! happen */ + u64 invalid_io; /* non-swap I/O requests */ + u64 notify_free; /* no. of pages freed by swap free callback */ + u64 pages_discard; /* no. of pages freed by discard callback */ + u32 pages_zero; /* no. of zero filled pages */ + u32 pages_stored; /* no. of pages currently stored */ + u32 good_compress; /* % of pages with compression ratio<=50% */ + u32 pages_expand; /* % of incompressible pages */ + u64 bdev_num_reads; /* no. of reads on backing dev */ + u64 bdev_num_writes; /* no. of writes on backing dev */ +#endif +}; + +struct ramzswap { + struct xv_pool *mem_pool; + void *compress_workmem; + void *compress_buffer; + struct table *table; + struct mutex lock; + struct request_queue *queue; + struct gendisk *disk; + int init_done; + int init_notify_callback; + /* + * This is limit on compressed data size (stats.compr_size) + * Its applicable only when backing swap device is present. + */ + size_t memlimit; /* bytes */ + /* + * This is limit on amount of *uncompressed* worth of data + * we can hold. When backing swap device is provided, it is + * set equal to device size. + */ + size_t disksize; /* bytes */ + + struct ramzswap_stats stats; + + /* backing swap device info */ + struct ramzswap_backing_extent *curr_extent; + struct list_head backing_swap_extent_list; + unsigned long num_extents; + char backing_swap_name[MAX_SWAP_NAME_LEN]; + struct block_device *backing_swap; + struct file *swap_file; +}; + +/*-- */ + +#endif + diff --git a/include/linux/ramzswap_ioctl.h b/include/linux/ramzswap_ioctl.h new file mode 100644 index 0000000..c9a10a5 --- /dev/null +++ b/include/linux/ramzswap_ioctl.h @@ -0,0 +1,51 @@ +/* + * Compressed RAM based swap device + * + * Copyright (C) 2008, 2009 Nitin Gupta + * + * This code is released using a dual license strategy: BSD/GPL + * You can choose the licence that better fits your requirements. + * + * Released under the terms of 3-clause BSD License + * Released under the terms of GNU General Public License Version 2.0 + * + * Project home: http://compcache.googlecode.com + */ + +#ifndef _RAMZSWAP_IOCTL_H_ +#define _RAMZSWAP_IOCTL_H_ + +#define MAX_SWAP_NAME_LEN 128 + +struct ramzswap_ioctl_stats { + char backing_swap_name[MAX_SWAP_NAME_LEN]; + u64 memlimit; /* only applicable if backing swap present */ + u64 disksize; /* user specified or equal to backing swap + * size (if present) */ + u64 num_reads; /* failed + successful */ + u64 num_writes; /* --do-- */ + u64 failed_reads; /* can happen when memory is too low */ + u64 failed_writes; /* should NEVER! happen */ + u64 invalid_io; /* non-swap I/O requests */ + u64 notify_free; /* no. of pages freed by swap free callback */ + u64 pages_discard; /* no. of pages freed by discard callback */ + u32 pages_zero; /* no. of zero filled pages */ + u32 good_compress_pct; /* no. of pages with compression ratio<=50% */ + u32 pages_expand_pct; /* no. of incompressible pages */ + u32 pages_stored; + u32 pages_used; + u64 orig_data_size; + u64 compr_data_size; + u64 mem_used_total; + u64 bdev_num_reads; /* no. of reads on backing dev */ + u64 bdev_num_writes; /* no. of writes on backing dev */ +} __attribute__ ((packed, aligned(4))); + +#define RZSIO_SET_DISKSIZE_KB _IOW('z', 0, size_t) +#define RZSIO_SET_MEMLIMIT_KB _IOW('z', 1, size_t) +#define RZSIO_SET_BACKING_SWAP _IOW('z', 2, unsigned char[MAX_SWAP_NAME_LEN]) +#define RZSIO_GET_STATS _IOR('z', 3, struct ramzswap_ioctl_stats) +#define RZSIO_INIT _IO('z', 4) +#define RZSIO_RESET _IO('z', 5) + +#endif _______________________________________________ linux-mm-cc mailing list [email protected] http://lists.laptop.org/listinfo/linux-mm-cc
