527 lines
12 KiB
C
527 lines
12 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (C) 2008 Oracle. All rights reserved.
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*/
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#include <linux/kernel.h>
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#include <linux/slab.h>
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#include <linux/mm.h>
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#include <linux/init.h>
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#include <linux/err.h>
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#include <linux/sched.h>
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#include <linux/pagemap.h>
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#include <linux/bio.h>
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#include <linux/lzo.h>
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#include <linux/refcount.h>
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#include "compression.h"
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#define LZO_LEN 4
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/*
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* Btrfs LZO compression format
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*
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* Regular and inlined LZO compressed data extents consist of:
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*
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* 1. Header
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* Fixed size. LZO_LEN (4) bytes long, LE32.
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* Records the total size (including the header) of compressed data.
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*
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* 2. Segment(s)
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* Variable size. Each segment includes one segment header, followed by data
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* payload.
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* One regular LZO compressed extent can have one or more segments.
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* For inlined LZO compressed extent, only one segment is allowed.
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* One segment represents at most one page of uncompressed data.
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*
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* 2.1 Segment header
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* Fixed size. LZO_LEN (4) bytes long, LE32.
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* Records the total size of the segment (not including the header).
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* Segment header never crosses page boundary, thus it's possible to
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* have at most 3 padding zeros at the end of the page.
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*
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* 2.2 Data Payload
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* Variable size. Size up limit should be lzo1x_worst_compress(PAGE_SIZE)
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* which is 4419 for a 4KiB page.
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*
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* Example:
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* Page 1:
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* 0 0x2 0x4 0x6 0x8 0xa 0xc 0xe 0x10
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* 0x0000 | Header | SegHdr 01 | Data payload 01 ... |
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* ...
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* 0x0ff0 | SegHdr N | Data payload N ... |00|
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* ^^ padding zeros
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* Page 2:
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* 0x1000 | SegHdr N+1| Data payload N+1 ... |
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*/
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struct workspace {
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void *mem;
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void *buf; /* where decompressed data goes */
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void *cbuf; /* where compressed data goes */
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struct list_head list;
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};
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static struct workspace_manager wsm;
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static void lzo_init_workspace_manager(void)
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{
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btrfs_init_workspace_manager(&wsm, &btrfs_lzo_compress);
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}
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static void lzo_cleanup_workspace_manager(void)
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{
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btrfs_cleanup_workspace_manager(&wsm);
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}
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static struct list_head *lzo_get_workspace(unsigned int level)
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{
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return btrfs_get_workspace(&wsm, level);
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}
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static void lzo_put_workspace(struct list_head *ws)
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{
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btrfs_put_workspace(&wsm, ws);
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}
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static void lzo_free_workspace(struct list_head *ws)
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{
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struct workspace *workspace = list_entry(ws, struct workspace, list);
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kvfree(workspace->buf);
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kvfree(workspace->cbuf);
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kvfree(workspace->mem);
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kfree(workspace);
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}
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static struct list_head *lzo_alloc_workspace(unsigned int level)
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{
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struct workspace *workspace;
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workspace = kzalloc(sizeof(*workspace), GFP_KERNEL);
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if (!workspace)
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return ERR_PTR(-ENOMEM);
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workspace->mem = kvmalloc(LZO1X_MEM_COMPRESS, GFP_KERNEL);
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workspace->buf = kvmalloc(lzo1x_worst_compress(PAGE_SIZE), GFP_KERNEL);
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workspace->cbuf = kvmalloc(lzo1x_worst_compress(PAGE_SIZE), GFP_KERNEL);
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if (!workspace->mem || !workspace->buf || !workspace->cbuf)
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goto fail;
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INIT_LIST_HEAD(&workspace->list);
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return &workspace->list;
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fail:
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lzo_free_workspace(&workspace->list);
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return ERR_PTR(-ENOMEM);
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}
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static inline void write_compress_length(char *buf, size_t len)
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{
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__le32 dlen;
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dlen = cpu_to_le32(len);
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memcpy(buf, &dlen, LZO_LEN);
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}
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static inline size_t read_compress_length(const char *buf)
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{
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__le32 dlen;
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memcpy(&dlen, buf, LZO_LEN);
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return le32_to_cpu(dlen);
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}
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static int lzo_compress_pages(struct list_head *ws,
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struct address_space *mapping,
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u64 start,
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struct page **pages,
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unsigned long *out_pages,
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unsigned long *total_in,
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unsigned long *total_out)
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{
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struct workspace *workspace = list_entry(ws, struct workspace, list);
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int ret = 0;
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char *data_in;
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char *cpage_out;
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int nr_pages = 0;
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struct page *in_page = NULL;
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struct page *out_page = NULL;
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unsigned long bytes_left;
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unsigned long len = *total_out;
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unsigned long nr_dest_pages = *out_pages;
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const unsigned long max_out = nr_dest_pages * PAGE_SIZE;
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size_t in_len;
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size_t out_len;
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char *buf;
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unsigned long tot_in = 0;
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unsigned long tot_out = 0;
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unsigned long pg_bytes_left;
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unsigned long out_offset;
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unsigned long bytes;
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*out_pages = 0;
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*total_out = 0;
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*total_in = 0;
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in_page = find_get_page(mapping, start >> PAGE_SHIFT);
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data_in = kmap(in_page);
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/*
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* store the size of all chunks of compressed data in
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* the first 4 bytes
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*/
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out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
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if (out_page == NULL) {
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ret = -ENOMEM;
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goto out;
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}
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cpage_out = kmap(out_page);
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out_offset = LZO_LEN;
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tot_out = LZO_LEN;
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pages[0] = out_page;
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nr_pages = 1;
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pg_bytes_left = PAGE_SIZE - LZO_LEN;
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/* compress at most one page of data each time */
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in_len = min(len, PAGE_SIZE);
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while (tot_in < len) {
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ret = lzo1x_1_compress(data_in, in_len, workspace->cbuf,
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&out_len, workspace->mem);
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if (ret != LZO_E_OK) {
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pr_debug("BTRFS: lzo in loop returned %d\n",
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ret);
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ret = -EIO;
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goto out;
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}
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/* store the size of this chunk of compressed data */
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write_compress_length(cpage_out + out_offset, out_len);
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tot_out += LZO_LEN;
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out_offset += LZO_LEN;
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pg_bytes_left -= LZO_LEN;
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tot_in += in_len;
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tot_out += out_len;
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/* copy bytes from the working buffer into the pages */
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buf = workspace->cbuf;
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while (out_len) {
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bytes = min_t(unsigned long, pg_bytes_left, out_len);
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memcpy(cpage_out + out_offset, buf, bytes);
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out_len -= bytes;
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pg_bytes_left -= bytes;
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buf += bytes;
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out_offset += bytes;
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/*
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* we need another page for writing out.
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*
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* Note if there's less than 4 bytes left, we just
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* skip to a new page.
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*/
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if ((out_len == 0 && pg_bytes_left < LZO_LEN) ||
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pg_bytes_left == 0) {
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if (pg_bytes_left) {
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memset(cpage_out + out_offset, 0,
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pg_bytes_left);
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tot_out += pg_bytes_left;
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}
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/* we're done, don't allocate new page */
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if (out_len == 0 && tot_in >= len)
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break;
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kunmap(out_page);
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if (nr_pages == nr_dest_pages) {
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out_page = NULL;
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ret = -E2BIG;
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goto out;
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}
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out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
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if (out_page == NULL) {
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ret = -ENOMEM;
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goto out;
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}
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cpage_out = kmap(out_page);
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pages[nr_pages++] = out_page;
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pg_bytes_left = PAGE_SIZE;
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out_offset = 0;
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}
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}
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/* we're making it bigger, give up */
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if (tot_in > 8192 && tot_in < tot_out) {
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ret = -E2BIG;
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goto out;
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}
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/* we're all done */
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if (tot_in >= len)
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break;
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if (tot_out > max_out)
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break;
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bytes_left = len - tot_in;
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kunmap(in_page);
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put_page(in_page);
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start += PAGE_SIZE;
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in_page = find_get_page(mapping, start >> PAGE_SHIFT);
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data_in = kmap(in_page);
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in_len = min(bytes_left, PAGE_SIZE);
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}
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if (tot_out >= tot_in) {
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ret = -E2BIG;
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goto out;
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}
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/* store the size of all chunks of compressed data */
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cpage_out = kmap(pages[0]);
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write_compress_length(cpage_out, tot_out);
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kunmap(pages[0]);
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ret = 0;
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*total_out = tot_out;
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*total_in = tot_in;
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out:
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*out_pages = nr_pages;
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if (out_page)
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kunmap(out_page);
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if (in_page) {
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kunmap(in_page);
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put_page(in_page);
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}
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return ret;
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}
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static int lzo_decompress_bio(struct list_head *ws, struct compressed_bio *cb)
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{
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struct workspace *workspace = list_entry(ws, struct workspace, list);
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int ret = 0, ret2;
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char *data_in;
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unsigned long page_in_index = 0;
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size_t srclen = cb->compressed_len;
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unsigned long total_pages_in = DIV_ROUND_UP(srclen, PAGE_SIZE);
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unsigned long buf_start;
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unsigned long buf_offset = 0;
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unsigned long bytes;
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unsigned long working_bytes;
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size_t in_len;
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size_t out_len;
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const size_t max_segment_len = lzo1x_worst_compress(PAGE_SIZE);
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unsigned long in_offset;
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unsigned long in_page_bytes_left;
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unsigned long tot_in;
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unsigned long tot_out;
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unsigned long tot_len;
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char *buf;
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bool may_late_unmap, need_unmap;
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struct page **pages_in = cb->compressed_pages;
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u64 disk_start = cb->start;
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struct bio *orig_bio = cb->orig_bio;
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data_in = kmap(pages_in[0]);
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tot_len = read_compress_length(data_in);
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/*
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* Compressed data header check.
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*
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* The real compressed size can't exceed the maximum extent length, and
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* all pages should be used (whole unused page with just the segment
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* header is not possible). If this happens it means the compressed
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* extent is corrupted.
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*/
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if (tot_len > min_t(size_t, BTRFS_MAX_COMPRESSED, srclen) ||
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tot_len < srclen - PAGE_SIZE) {
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ret = -EUCLEAN;
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goto done;
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}
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tot_in = LZO_LEN;
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in_offset = LZO_LEN;
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in_page_bytes_left = PAGE_SIZE - LZO_LEN;
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tot_out = 0;
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while (tot_in < tot_len) {
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in_len = read_compress_length(data_in + in_offset);
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in_page_bytes_left -= LZO_LEN;
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in_offset += LZO_LEN;
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tot_in += LZO_LEN;
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/*
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* Segment header check.
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*
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* The segment length must not exceed the maximum LZO
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* compression size, nor the total compressed size.
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*/
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if (in_len > max_segment_len || tot_in + in_len > tot_len) {
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ret = -EUCLEAN;
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goto done;
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}
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tot_in += in_len;
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working_bytes = in_len;
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may_late_unmap = need_unmap = false;
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/* fast path: avoid using the working buffer */
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if (in_page_bytes_left >= in_len) {
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buf = data_in + in_offset;
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bytes = in_len;
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may_late_unmap = true;
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goto cont;
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}
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/* copy bytes from the pages into the working buffer */
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buf = workspace->cbuf;
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buf_offset = 0;
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while (working_bytes) {
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bytes = min(working_bytes, in_page_bytes_left);
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memcpy(buf + buf_offset, data_in + in_offset, bytes);
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buf_offset += bytes;
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cont:
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working_bytes -= bytes;
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in_page_bytes_left -= bytes;
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in_offset += bytes;
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/* check if we need to pick another page */
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if ((working_bytes == 0 && in_page_bytes_left < LZO_LEN)
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|| in_page_bytes_left == 0) {
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tot_in += in_page_bytes_left;
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if (working_bytes == 0 && tot_in >= tot_len)
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break;
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if (page_in_index + 1 >= total_pages_in) {
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ret = -EIO;
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goto done;
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}
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if (may_late_unmap)
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need_unmap = true;
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else
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kunmap(pages_in[page_in_index]);
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data_in = kmap(pages_in[++page_in_index]);
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in_page_bytes_left = PAGE_SIZE;
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in_offset = 0;
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}
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}
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out_len = max_segment_len;
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ret = lzo1x_decompress_safe(buf, in_len, workspace->buf,
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&out_len);
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if (need_unmap)
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kunmap(pages_in[page_in_index - 1]);
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if (ret != LZO_E_OK) {
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pr_warn("BTRFS: decompress failed\n");
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ret = -EIO;
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break;
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}
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buf_start = tot_out;
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tot_out += out_len;
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ret2 = btrfs_decompress_buf2page(workspace->buf, buf_start,
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tot_out, disk_start, orig_bio);
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if (ret2 == 0)
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break;
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}
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done:
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kunmap(pages_in[page_in_index]);
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if (!ret)
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zero_fill_bio(orig_bio);
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return ret;
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}
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static int lzo_decompress(struct list_head *ws, unsigned char *data_in,
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struct page *dest_page,
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unsigned long start_byte,
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size_t srclen, size_t destlen)
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{
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struct workspace *workspace = list_entry(ws, struct workspace, list);
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size_t in_len;
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size_t out_len;
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size_t max_segment_len = lzo1x_worst_compress(PAGE_SIZE);
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int ret = 0;
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char *kaddr;
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unsigned long bytes;
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if (srclen < LZO_LEN || srclen > max_segment_len + LZO_LEN * 2)
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return -EUCLEAN;
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in_len = read_compress_length(data_in);
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if (in_len != srclen)
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return -EUCLEAN;
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data_in += LZO_LEN;
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in_len = read_compress_length(data_in);
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if (in_len != srclen - LZO_LEN * 2) {
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ret = -EUCLEAN;
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goto out;
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}
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data_in += LZO_LEN;
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out_len = PAGE_SIZE;
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ret = lzo1x_decompress_safe(data_in, in_len, workspace->buf, &out_len);
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if (ret != LZO_E_OK) {
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pr_warn("BTRFS: decompress failed!\n");
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ret = -EIO;
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goto out;
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}
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if (out_len < start_byte) {
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ret = -EIO;
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goto out;
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}
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/*
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* the caller is already checking against PAGE_SIZE, but lets
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* move this check closer to the memcpy/memset
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*/
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destlen = min_t(unsigned long, destlen, PAGE_SIZE);
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bytes = min_t(unsigned long, destlen, out_len - start_byte);
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kaddr = kmap_atomic(dest_page);
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memcpy(kaddr, workspace->buf + start_byte, bytes);
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/*
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* btrfs_getblock is doing a zero on the tail of the page too,
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* but this will cover anything missing from the decompressed
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* data.
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*/
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if (bytes < destlen)
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memset(kaddr+bytes, 0, destlen-bytes);
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kunmap_atomic(kaddr);
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out:
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return ret;
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}
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static unsigned int lzo_set_level(unsigned int level)
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{
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return 0;
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}
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const struct btrfs_compress_op btrfs_lzo_compress = {
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.init_workspace_manager = lzo_init_workspace_manager,
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.cleanup_workspace_manager = lzo_cleanup_workspace_manager,
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.get_workspace = lzo_get_workspace,
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.put_workspace = lzo_put_workspace,
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.alloc_workspace = lzo_alloc_workspace,
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.free_workspace = lzo_free_workspace,
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.compress_pages = lzo_compress_pages,
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.decompress_bio = lzo_decompress_bio,
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.decompress = lzo_decompress,
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.set_level = lzo_set_level,
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};
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