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![Fabio M. De Francesco](/assets/img/avatar_default.png)
The use of kmap() is being deprecated in favor of kmap_local_page() where it is feasible. With kmap_local_page(), the mapping is per thread, CPU local and not globally visible. Therefore, use kmap_local_page() / kunmap_local() in lzo.c wherever the mappings are per thread and not globally visible. Tested on QEMU + KVM 32 bits VM with 4GB of RAM and HIGHMEM64G enabled. Suggested-by: Ira Weiny <ira.weiny@intel.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
494 lines
13 KiB
C
494 lines
13 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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#include "ctree.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 sector 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 sector boundary, thus it's possible to
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* have at most 3 padding zeros at the end of the sector.
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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(sectorsize)
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* which is 4419 for a 4KiB sectorsize.
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*
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* Example with 4K sectorsize:
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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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#define WORKSPACE_BUF_LENGTH (lzo1x_worst_compress(PAGE_SIZE))
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#define WORKSPACE_CBUF_LENGTH (lzo1x_worst_compress(PAGE_SIZE))
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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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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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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(WORKSPACE_BUF_LENGTH, GFP_KERNEL);
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workspace->cbuf = kvmalloc(WORKSPACE_CBUF_LENGTH, 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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/*
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* Will do:
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*
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* - Write a segment header into the destination
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* - Copy the compressed buffer into the destination
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* - Make sure we have enough space in the last sector to fit a segment header
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* If not, we will pad at most (LZO_LEN (4)) - 1 bytes of zeros.
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*
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* Will allocate new pages when needed.
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*/
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static int copy_compressed_data_to_page(char *compressed_data,
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size_t compressed_size,
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struct page **out_pages,
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unsigned long max_nr_page,
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u32 *cur_out,
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const u32 sectorsize)
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{
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u32 sector_bytes_left;
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u32 orig_out;
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struct page *cur_page;
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char *kaddr;
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if ((*cur_out / PAGE_SIZE) >= max_nr_page)
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return -E2BIG;
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/*
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* We never allow a segment header crossing sector boundary, previous
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* run should ensure we have enough space left inside the sector.
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*/
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ASSERT((*cur_out / sectorsize) == (*cur_out + LZO_LEN - 1) / sectorsize);
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cur_page = out_pages[*cur_out / PAGE_SIZE];
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/* Allocate a new page */
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if (!cur_page) {
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cur_page = alloc_page(GFP_NOFS);
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if (!cur_page)
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return -ENOMEM;
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out_pages[*cur_out / PAGE_SIZE] = cur_page;
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}
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kaddr = kmap_local_page(cur_page);
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write_compress_length(kaddr + offset_in_page(*cur_out),
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compressed_size);
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*cur_out += LZO_LEN;
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orig_out = *cur_out;
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/* Copy compressed data */
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while (*cur_out - orig_out < compressed_size) {
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u32 copy_len = min_t(u32, sectorsize - *cur_out % sectorsize,
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orig_out + compressed_size - *cur_out);
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kunmap_local(kaddr);
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if ((*cur_out / PAGE_SIZE) >= max_nr_page)
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return -E2BIG;
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cur_page = out_pages[*cur_out / PAGE_SIZE];
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/* Allocate a new page */
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if (!cur_page) {
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cur_page = alloc_page(GFP_NOFS);
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if (!cur_page)
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return -ENOMEM;
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out_pages[*cur_out / PAGE_SIZE] = cur_page;
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}
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kaddr = kmap_local_page(cur_page);
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memcpy(kaddr + offset_in_page(*cur_out),
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compressed_data + *cur_out - orig_out, copy_len);
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*cur_out += copy_len;
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}
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/*
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* Check if we can fit the next segment header into the remaining space
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* of the sector.
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*/
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sector_bytes_left = round_up(*cur_out, sectorsize) - *cur_out;
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if (sector_bytes_left >= LZO_LEN || sector_bytes_left == 0)
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goto out;
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/* The remaining size is not enough, pad it with zeros */
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memset(kaddr + offset_in_page(*cur_out), 0,
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sector_bytes_left);
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*cur_out += sector_bytes_left;
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out:
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kunmap_local(kaddr);
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return 0;
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}
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int lzo_compress_pages(struct list_head *ws, struct address_space *mapping,
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u64 start, struct page **pages, unsigned long *out_pages,
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unsigned long *total_in, 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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const u32 sectorsize = btrfs_sb(mapping->host->i_sb)->sectorsize;
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struct page *page_in = NULL;
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char *sizes_ptr;
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const unsigned long max_nr_page = *out_pages;
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int ret = 0;
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/* Points to the file offset of input data */
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u64 cur_in = start;
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/* Points to the current output byte */
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u32 cur_out = 0;
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u32 len = *total_out;
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ASSERT(max_nr_page > 0);
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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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/*
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* Skip the header for now, we will later come back and write the total
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* compressed size
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*/
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cur_out += LZO_LEN;
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while (cur_in < start + len) {
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char *data_in;
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const u32 sectorsize_mask = sectorsize - 1;
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u32 sector_off = (cur_in - start) & sectorsize_mask;
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u32 in_len;
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size_t out_len;
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/* Get the input page first */
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if (!page_in) {
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page_in = find_get_page(mapping, cur_in >> PAGE_SHIFT);
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ASSERT(page_in);
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}
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/* Compress at most one sector of data each time */
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in_len = min_t(u32, start + len - cur_in, sectorsize - sector_off);
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ASSERT(in_len);
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data_in = kmap_local_page(page_in);
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ret = lzo1x_1_compress(data_in +
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offset_in_page(cur_in), in_len,
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workspace->cbuf, &out_len,
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workspace->mem);
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kunmap_local(data_in);
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if (ret < 0) {
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pr_debug("BTRFS: lzo in loop returned %d\n", ret);
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ret = -EIO;
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goto out;
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}
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ret = copy_compressed_data_to_page(workspace->cbuf, out_len,
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pages, max_nr_page,
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&cur_out, sectorsize);
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if (ret < 0)
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goto out;
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cur_in += in_len;
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/*
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* Check if we're making it bigger after two sectors. And if
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* it is so, give up.
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*/
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if (cur_in - start > sectorsize * 2 && cur_in - start < cur_out) {
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ret = -E2BIG;
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goto out;
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}
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/* Check if we have reached page boundary */
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if (IS_ALIGNED(cur_in, PAGE_SIZE)) {
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put_page(page_in);
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page_in = NULL;
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}
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}
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/* Store the size of all chunks of compressed data */
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sizes_ptr = kmap_local_page(pages[0]);
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write_compress_length(sizes_ptr, cur_out);
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kunmap_local(sizes_ptr);
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ret = 0;
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*total_out = cur_out;
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*total_in = cur_in - start;
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out:
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if (page_in)
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put_page(page_in);
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*out_pages = DIV_ROUND_UP(cur_out, PAGE_SIZE);
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return ret;
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}
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/*
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* Copy the compressed segment payload into @dest.
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*
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* For the payload there will be no padding, just need to do page switching.
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*/
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static void copy_compressed_segment(struct compressed_bio *cb,
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char *dest, u32 len, u32 *cur_in)
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{
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u32 orig_in = *cur_in;
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while (*cur_in < orig_in + len) {
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struct page *cur_page;
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u32 copy_len = min_t(u32, PAGE_SIZE - offset_in_page(*cur_in),
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orig_in + len - *cur_in);
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ASSERT(copy_len);
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cur_page = cb->compressed_pages[*cur_in / PAGE_SIZE];
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memcpy_from_page(dest + *cur_in - orig_in, cur_page,
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offset_in_page(*cur_in), copy_len);
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*cur_in += copy_len;
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}
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}
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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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const struct btrfs_fs_info *fs_info = btrfs_sb(cb->inode->i_sb);
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const u32 sectorsize = fs_info->sectorsize;
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char *kaddr;
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int ret;
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/* Compressed data length, can be unaligned */
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u32 len_in;
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/* Offset inside the compressed data */
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u32 cur_in = 0;
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/* Bytes decompressed so far */
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u32 cur_out = 0;
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kaddr = kmap_local_page(cb->compressed_pages[0]);
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len_in = read_compress_length(kaddr);
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kunmap_local(kaddr);
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cur_in += LZO_LEN;
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/*
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* LZO header length check
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*
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* The total length should not exceed the maximum extent length,
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* and all sectors should be used.
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* If this happens, it means the compressed extent is corrupted.
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*/
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if (len_in > min_t(size_t, BTRFS_MAX_COMPRESSED, cb->compressed_len) ||
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round_up(len_in, sectorsize) < cb->compressed_len) {
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btrfs_err(fs_info,
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"invalid lzo header, lzo len %u compressed len %u",
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len_in, cb->compressed_len);
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return -EUCLEAN;
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}
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/* Go through each lzo segment */
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while (cur_in < len_in) {
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struct page *cur_page;
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/* Length of the compressed segment */
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u32 seg_len;
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u32 sector_bytes_left;
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size_t out_len = lzo1x_worst_compress(sectorsize);
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/*
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* We should always have enough space for one segment header
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* inside current sector.
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*/
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ASSERT(cur_in / sectorsize ==
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(cur_in + LZO_LEN - 1) / sectorsize);
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cur_page = cb->compressed_pages[cur_in / PAGE_SIZE];
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ASSERT(cur_page);
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kaddr = kmap_local_page(cur_page);
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seg_len = read_compress_length(kaddr + offset_in_page(cur_in));
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kunmap_local(kaddr);
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cur_in += LZO_LEN;
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if (seg_len > WORKSPACE_CBUF_LENGTH) {
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/*
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* seg_len shouldn't be larger than we have allocated
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* for workspace->cbuf
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*/
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btrfs_err(fs_info, "unexpectedly large lzo segment len %u",
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seg_len);
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ret = -EIO;
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goto out;
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}
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/* Copy the compressed segment payload into workspace */
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copy_compressed_segment(cb, workspace->cbuf, seg_len, &cur_in);
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/* Decompress the data */
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ret = lzo1x_decompress_safe(workspace->cbuf, seg_len,
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workspace->buf, &out_len);
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if (ret != LZO_E_OK) {
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btrfs_err(fs_info, "failed to decompress");
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ret = -EIO;
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goto out;
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}
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/* Copy the data into inode pages */
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ret = btrfs_decompress_buf2page(workspace->buf, out_len, cb, cur_out);
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cur_out += out_len;
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/* All data read, exit */
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if (ret == 0)
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goto out;
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ret = 0;
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/* Check if the sector has enough space for a segment header */
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sector_bytes_left = sectorsize - (cur_in % sectorsize);
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if (sector_bytes_left >= LZO_LEN)
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continue;
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/* Skip the padding zeros */
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cur_in += sector_bytes_left;
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}
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out:
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if (!ret)
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zero_fill_bio(cb->orig_bio);
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return ret;
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}
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int lzo_decompress(struct list_head *ws, unsigned char *data_in,
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struct page *dest_page, unsigned long start_byte, size_t srclen,
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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 = WORKSPACE_BUF_LENGTH;
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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_local_page(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_local(kaddr);
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out:
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return ret;
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}
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const struct btrfs_compress_op btrfs_lzo_compress = {
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.workspace_manager = &wsm,
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.max_level = 1,
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.default_level = 1,
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};
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