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489 lines
12 KiB
489 lines
12 KiB
// 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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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(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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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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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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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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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 = 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_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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