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Squashfs: Restructure squashfs_readpage() 

Restructure squashfs_readpage() splitting it into separate
functions for datablocks, fragments and sparse blocks.

Move the memcpying (from squashfs cache entry) implementation of
squashfs_readpage_block into file_cache.c

This allows different implementations to be supported.

Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk>
Reviewed-by: Minchan Kim <minchan@kernel.org>
This commit is contained in:
Phillip Lougher 2013-10-31 19:24:27 +00:00
parent 846b730e99
commit 5f55dbc0c5
4 changed files with 118 additions and 71 deletions
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2
fs/squashfs/Makefile
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@ -4,7 +4,7 @@
obj-$(CONFIG_SQUASHFS) += squashfs.o
squashfs-y += block.o cache.o dir.o export.o file.o fragment.o id.o inode.o
squashfs-y += namei.o super.o symlink.o decompressor.o
squashfs-y += namei.o super.o symlink.o decompressor.o file_cache.o
squashfs-$(CONFIG_SQUASHFS_DECOMP_SINGLE) += decompressor_single.o
squashfs-$(CONFIG_SQUASHFS_DECOMP_MULTI) += decompressor_multi.o
squashfs-$(CONFIG_SQUASHFS_DECOMP_MULTI_PERCPU) += decompressor_multi_percpu.o

142
fs/squashfs/file.c
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@ -370,77 +370,15 @@ static int read_blocklist(struct inode *inode, int index, u64 *block)
return le32_to_cpu(size);
}
static int squashfs_readpage(struct file *file, struct page *page)
/* Copy data into page cache */
void squashfs_copy_cache(struct page *page, struct squashfs_cache_entry *buffer,
int bytes, int offset)
{
struct inode *inode = page->mapping->host;
struct squashfs_sb_info *msblk = inode->i_sb->s_fs_info;
int bytes, i, offset = 0, sparse = 0;
struct squashfs_cache_entry *buffer = NULL;
void *pageaddr;
int mask = (1 << (msblk->block_log - PAGE_CACHE_SHIFT)) - 1;
int index = page->index >> (msblk->block_log - PAGE_CACHE_SHIFT);
int start_index = page->index & ~mask;
int end_index = start_index | mask;
int file_end = i_size_read(inode) >> msblk->block_log;
TRACE("Entered squashfs_readpage, page index %lx, start block %llx\n",
page->index, squashfs_i(inode)->start);
if (page->index >= ((i_size_read(inode) + PAGE_CACHE_SIZE - 1) >>
PAGE_CACHE_SHIFT))
goto out;
if (index < file_end || squashfs_i(inode)->fragment_block ==
SQUASHFS_INVALID_BLK) {
/*
* Reading a datablock from disk. Need to read block list
* to get location and block size.
*/
u64 block = 0;
int bsize = read_blocklist(inode, index, &block);
if (bsize < 0)
goto error_out;
if (bsize == 0) { /* hole */
bytes = index == file_end ?
(i_size_read(inode) & (msblk->block_size - 1)) :
msblk->block_size;
sparse = 1;
} else {
/*
* Read and decompress datablock.
*/
buffer = squashfs_get_datablock(inode->i_sb,
block, bsize);
if (buffer->error) {
ERROR("Unable to read page, block %llx, size %x"
"\n", block, bsize);
squashfs_cache_put(buffer);
goto error_out;
}
bytes = buffer->length;
}
} else {
/*
* Datablock is stored inside a fragment (tail-end packed
* block).
*/
buffer = squashfs_get_fragment(inode->i_sb,
squashfs_i(inode)->fragment_block,
squashfs_i(inode)->fragment_size);
if (buffer->error) {
ERROR("Unable to read page, block %llx, size %x\n",
squashfs_i(inode)->fragment_block,
squashfs_i(inode)->fragment_size);
squashfs_cache_put(buffer);
goto error_out;
}
bytes = i_size_read(inode) & (msblk->block_size - 1);
offset = squashfs_i(inode)->fragment_offset;
}
int i, mask = (1 << (msblk->block_log - PAGE_CACHE_SHIFT)) - 1;
int start_index = page->index & ~mask, end_index = start_index | mask;
/*
* Loop copying datablock into pages. As the datablock likely covers
@ -451,7 +389,7 @@ static int squashfs_readpage(struct file *file, struct page *page)
for (i = start_index; i <= end_index && bytes > 0; i++,
bytes -= PAGE_CACHE_SIZE, offset += PAGE_CACHE_SIZE) {
struct page *push_page;
int avail = sparse ? 0 : min_t(int, bytes, PAGE_CACHE_SIZE);
int avail = buffer ? min_t(int, bytes, PAGE_CACHE_SIZE) : 0;
TRACE("bytes %d, i %d, available_bytes %d\n", bytes, i, avail);
@ -475,11 +413,75 @@ static int squashfs_readpage(struct file *file, struct page *page)
if (i != page->index)
page_cache_release(push_page);
}
}
if (!sparse)
squashfs_cache_put(buffer);
/* Read datablock stored packed inside a fragment (tail-end packed block) */
static int squashfs_readpage_fragment(struct page *page)
{
struct inode *inode = page->mapping->host;
struct squashfs_sb_info *msblk = inode->i_sb->s_fs_info;
struct squashfs_cache_entry *buffer = squashfs_get_fragment(inode->i_sb,
squashfs_i(inode)->fragment_block,
squashfs_i(inode)->fragment_size);
int res = buffer->error;
if (res)
ERROR("Unable to read page, block %llx, size %x\n",
squashfs_i(inode)->fragment_block,
squashfs_i(inode)->fragment_size);
else
squashfs_copy_cache(page, buffer, i_size_read(inode) &
(msblk->block_size - 1),
squashfs_i(inode)->fragment_offset);
squashfs_cache_put(buffer);
return res;
}
static int squashfs_readpage_sparse(struct page *page, int index, int file_end)
{
struct inode *inode = page->mapping->host;
struct squashfs_sb_info *msblk = inode->i_sb->s_fs_info;
int bytes = index == file_end ?
(i_size_read(inode) & (msblk->block_size - 1)) :
msblk->block_size;
squashfs_copy_cache(page, NULL, bytes, 0);
return 0;
}
static int squashfs_readpage(struct file *file, struct page *page)
{
struct inode *inode = page->mapping->host;
struct squashfs_sb_info *msblk = inode->i_sb->s_fs_info;
int index = page->index >> (msblk->block_log - PAGE_CACHE_SHIFT);
int file_end = i_size_read(inode) >> msblk->block_log;
int res;
void *pageaddr;
TRACE("Entered squashfs_readpage, page index %lx, start block %llx\n",
page->index, squashfs_i(inode)->start);
if (page->index >= ((i_size_read(inode) + PAGE_CACHE_SIZE - 1) >>
PAGE_CACHE_SHIFT))
goto out;
if (index < file_end || squashfs_i(inode)->fragment_block ==
SQUASHFS_INVALID_BLK) {
u64 block = 0;
int bsize = read_blocklist(inode, index, &block);
if (bsize < 0)
goto error_out;
if (bsize == 0)
res = squashfs_readpage_sparse(page, index, file_end);
else
res = squashfs_readpage_block(page, block, bsize);
} else
res = squashfs_readpage_fragment(page);
if (!res)
return 0;
error_out:
SetPageError(page);

38
fs/squashfs/file_cache.c Normal file
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@ -0,0 +1,38 @@
/*
* Copyright (c) 2013
* Phillip Lougher <phillip@squashfs.org.uk>
*
* This work is licensed under the terms of the GNU GPL, version 2. See
* the COPYING file in the top-level directory.
*/
#include <linux/fs.h>
#include <linux/vfs.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/pagemap.h>
#include <linux/mutex.h>
#include "squashfs_fs.h"
#include "squashfs_fs_sb.h"
#include "squashfs_fs_i.h"
#include "squashfs.h"
/* Read separately compressed datablock and memcopy into page cache */
int squashfs_readpage_block(struct page *page, u64 block, int bsize)
{
struct inode *i = page->mapping->host;
struct squashfs_cache_entry *buffer = squashfs_get_datablock(i->i_sb,
block, bsize);
int res = buffer->error;
if (res)
ERROR("Unable to read page, block %llx, size %x\n", block,
bsize);
else
squashfs_copy_cache(page, buffer, buffer->length, 0);
squashfs_cache_put(buffer);
return res;
}

7
fs/squashfs/squashfs.h
View File

@ -66,6 +66,13 @@ extern int squashfs_frag_lookup(struct super_block *, unsigned int, u64 *);
extern __le64 *squashfs_read_fragment_index_table(struct super_block *,
u64, u64, unsigned int);
/* file.c */
void squashfs_copy_cache(struct page *, struct squashfs_cache_entry *, int,
int);
/* file_xxx.c */
extern int squashfs_readpage_block(struct page *, u64, int);
/* id.c */
extern int squashfs_get_id(struct super_block *, unsigned int, unsigned int *);
extern __le64 *squashfs_read_id_index_table(struct super_block *, u64, u64,