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![Kirill A. Shutemov](/assets/img/avatar_default.png)
PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} macros were introduced *long* time ago with promise that one day it will be possible to implement page cache with bigger chunks than PAGE_SIZE. This promise never materialized. And unlikely will. We have many places where PAGE_CACHE_SIZE assumed to be equal to PAGE_SIZE. And it's constant source of confusion on whether PAGE_CACHE_* or PAGE_* constant should be used in a particular case, especially on the border between fs and mm. Global switching to PAGE_CACHE_SIZE != PAGE_SIZE would cause to much breakage to be doable. Let's stop pretending that pages in page cache are special. They are not. The changes are pretty straight-forward: - <foo> << (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>; - <foo> >> (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>; - PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} -> PAGE_{SIZE,SHIFT,MASK,ALIGN}; - page_cache_get() -> get_page(); - page_cache_release() -> put_page(); This patch contains automated changes generated with coccinelle using script below. For some reason, coccinelle doesn't patch header files. I've called spatch for them manually. The only adjustment after coccinelle is revert of changes to PAGE_CAHCE_ALIGN definition: we are going to drop it later. There are few places in the code where coccinelle didn't reach. I'll fix them manually in a separate patch. Comments and documentation also will be addressed with the separate patch. virtual patch @@ expression E; @@ - E << (PAGE_CACHE_SHIFT - PAGE_SHIFT) + E @@ expression E; @@ - E >> (PAGE_CACHE_SHIFT - PAGE_SHIFT) + E @@ @@ - PAGE_CACHE_SHIFT + PAGE_SHIFT @@ @@ - PAGE_CACHE_SIZE + PAGE_SIZE @@ @@ - PAGE_CACHE_MASK + PAGE_MASK @@ expression E; @@ - PAGE_CACHE_ALIGN(E) + PAGE_ALIGN(E) @@ expression E; @@ - page_cache_get(E) + get_page(E) @@ expression E; @@ - page_cache_release(E) + put_page(E) Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
142 lines
2.9 KiB
C
142 lines
2.9 KiB
C
/*
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* Copyright (c) 2013, 2014
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* Phillip Lougher <phillip@squashfs.org.uk>
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*
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* This work is licensed under the terms of the GNU GPL, version 2. See
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* the COPYING file in the top-level directory.
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*/
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#include <linux/buffer_head.h>
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#include <linux/mutex.h>
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#include <linux/slab.h>
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#include <linux/vmalloc.h>
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#include <linux/lz4.h>
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#include "squashfs_fs.h"
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#include "squashfs_fs_sb.h"
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#include "squashfs.h"
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#include "decompressor.h"
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#include "page_actor.h"
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#define LZ4_LEGACY 1
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struct lz4_comp_opts {
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__le32 version;
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__le32 flags;
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};
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struct squashfs_lz4 {
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void *input;
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void *output;
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};
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static void *lz4_comp_opts(struct squashfs_sb_info *msblk,
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void *buff, int len)
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{
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struct lz4_comp_opts *comp_opts = buff;
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/* LZ4 compressed filesystems always have compression options */
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if (comp_opts == NULL || len < sizeof(*comp_opts))
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return ERR_PTR(-EIO);
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if (le32_to_cpu(comp_opts->version) != LZ4_LEGACY) {
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/* LZ4 format currently used by the kernel is the 'legacy'
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* format */
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ERROR("Unknown LZ4 version\n");
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return ERR_PTR(-EINVAL);
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}
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return NULL;
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}
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static void *lz4_init(struct squashfs_sb_info *msblk, void *buff)
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{
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int block_size = max_t(int, msblk->block_size, SQUASHFS_METADATA_SIZE);
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struct squashfs_lz4 *stream;
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stream = kzalloc(sizeof(*stream), GFP_KERNEL);
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if (stream == NULL)
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goto failed;
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stream->input = vmalloc(block_size);
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if (stream->input == NULL)
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goto failed2;
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stream->output = vmalloc(block_size);
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if (stream->output == NULL)
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goto failed3;
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return stream;
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failed3:
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vfree(stream->input);
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failed2:
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kfree(stream);
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failed:
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ERROR("Failed to initialise LZ4 decompressor\n");
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return ERR_PTR(-ENOMEM);
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}
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static void lz4_free(void *strm)
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{
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struct squashfs_lz4 *stream = strm;
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if (stream) {
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vfree(stream->input);
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vfree(stream->output);
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}
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kfree(stream);
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}
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static int lz4_uncompress(struct squashfs_sb_info *msblk, void *strm,
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struct buffer_head **bh, int b, int offset, int length,
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struct squashfs_page_actor *output)
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{
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struct squashfs_lz4 *stream = strm;
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void *buff = stream->input, *data;
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int avail, i, bytes = length, res;
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size_t dest_len = output->length;
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for (i = 0; i < b; i++) {
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avail = min(bytes, msblk->devblksize - offset);
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memcpy(buff, bh[i]->b_data + offset, avail);
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buff += avail;
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bytes -= avail;
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offset = 0;
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put_bh(bh[i]);
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}
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res = lz4_decompress_unknownoutputsize(stream->input, length,
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stream->output, &dest_len);
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if (res)
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return -EIO;
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bytes = dest_len;
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data = squashfs_first_page(output);
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buff = stream->output;
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while (data) {
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if (bytes <= PAGE_SIZE) {
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memcpy(data, buff, bytes);
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break;
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}
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memcpy(data, buff, PAGE_SIZE);
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buff += PAGE_SIZE;
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bytes -= PAGE_SIZE;
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data = squashfs_next_page(output);
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}
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squashfs_finish_page(output);
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return dest_len;
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}
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const struct squashfs_decompressor squashfs_lz4_comp_ops = {
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.init = lz4_init,
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.comp_opts = lz4_comp_opts,
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.free = lz4_free,
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.decompress = lz4_uncompress,
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.id = LZ4_COMPRESSION,
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.name = "lz4",
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.supported = 1
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};
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