/*
* Read length bytes from metadata position <block, offset> (block is the
* start of the compressed block on disk, and offset is the offset into
* the block once decompressed). Data is packed into consecutive blocks,
* and length bytes may require reading more than one block.
*/
int squashfs_read_metadata(struct super_block *sb, void *buffer,
u64 *block, int *offset, int length)
{
struct squashfs_sb_info *msblk = sb->s_fs_info;
int bytes, copied = length;
struct squashfs_cache_entry *entry;
TRACE("Entered squashfs_read_metadata [%llx:%x]\n", *block, *offset);
while (length) {
entry = squashfs_cache_get(sb, msblk->block_cache, *block, 0);
if (entry->error)
return entry->error;
else if (*offset >= entry->length)
return -EIO;
bytes = squashfs_copy_data(buffer, entry, *offset, length);
if (buffer)
buffer += bytes;
length -= bytes;
*offset += bytes;
if (*offset == entry->length) {
*block = entry->next_index;
*offset = 0;
}
squashfs_cache_put(entry);
}
return copied;
}
static int squashfs_symlink_readpage(struct file *file, struct page *page)
{
struct inode *inode = page->mapping->host;
struct super_block *sb = inode->i_sb;
struct squashfs_sb_info *msblk = sb->s_fs_info;
int index = page->index << PAGE_CACHE_SHIFT;
u64 block = squashfs_i(inode)->start;
int offset = squashfs_i(inode)->offset;
int length = min_t(int, i_size_read(inode) - index, PAGE_CACHE_SIZE);
int bytes, copied;
void *pageaddr;
struct squashfs_cache_entry *entry;
TRACE("Entered squashfs_symlink_readpage, page index %ld, start block "
"%llx, offset %x\n", page->index, block, offset);
if (index) {
bytes = squashfs_read_metadata(sb, NULL, &block, &offset,
index);
if (bytes < 0) {
ERROR("Unable to read symlink [%llx:%x]\n",
squashfs_i(inode)->start,
squashfs_i(inode)->offset);
goto error_out;
}
}
for (bytes = 0; bytes < length; offset = 0, bytes += copied) {
entry = squashfs_cache_get(sb, msblk->block_cache, block, 0);
if (entry->error) {
ERROR("Unable to read symlink [%llx:%x]\n",
squashfs_i(inode)->start,
squashfs_i(inode)->offset);
squashfs_cache_put(entry);
goto error_out;
}
pageaddr = kmap_atomic(page);
copied = squashfs_copy_data(pageaddr + bytes, entry, offset,
length - bytes);
if (copied == length - bytes)
memset(pageaddr + length, 0, PAGE_CACHE_SIZE - length);
else
block = entry->next_index;
kunmap_atomic(pageaddr);
squashfs_cache_put(entry);
}
flush_dcache_page(page);
SetPageUptodate(page);
unlock_page(page);
return 0;
error_out:
SetPageError(page);
unlock_page(page);
return 0;
}
static int squashfs_read_cache(struct page *target_page, u64 block, int bsize,
int pages, struct page **page)
{
struct inode *i = target_page->mapping->host;
struct squashfs_cache_entry *buffer = squashfs_get_datablock(i->i_sb,
block, bsize);
int bytes = buffer->length, res = buffer->error, n, offset = 0;
void *pageaddr;
if (res) {
ERROR("Unable to read page, block %llx, size %x\n", block,
bsize);
goto out;
}
for (n = 0; n < pages && bytes > 0; n++,
bytes -= PAGE_CACHE_SIZE, offset += PAGE_CACHE_SIZE) {
int avail = min_t(int, bytes, PAGE_CACHE_SIZE);
if (page[n] == NULL)
continue;
pageaddr = kmap_atomic(page[n]);
squashfs_copy_data(pageaddr, buffer, offset, avail);
memset(pageaddr + avail, 0, PAGE_CACHE_SIZE - avail);
kunmap_atomic(pageaddr);
flush_dcache_page(page[n]);
SetPageUptodate(page[n]);
unlock_page(page[n]);
if (page[n] != target_page)
page_cache_release(page[n]);
}
out:
squashfs_cache_put(buffer);
return res;
}
static int squashfs_symlink_readpage(struct file *file, struct page *page)
{
struct inode *inode = page->mapping->host;
struct super_block *sb = inode->i_sb;
struct squashfs_sb_info *msblk = sb->s_fs_info;
int index = page->index << PAGE_CACHE_SHIFT;
u64 block = squashfs_i(inode)->start;
int offset = squashfs_i(inode)->offset;
int length = min_t(int, i_size_read(inode) - index, PAGE_CACHE_SIZE);
int bytes, copied;
void *pageaddr;
struct squashfs_cache_entry *entry;
TRACE("Entered squashfs_symlink_readpage, page index %ld, start block "
"%llx, offset %x\n", page->index, block, offset);
/*
* Skip index bytes into symlink metadata.
*/
if (index) {
bytes = squashfs_read_metadata(sb, NULL, &block, &offset,
index);
if (bytes < 0) {
ERROR("Unable to read symlink [%llx:%x]\n",
squashfs_i(inode)->start,
squashfs_i(inode)->offset);
goto error_out;
}
}
/*
* Read length bytes from symlink metadata. Squashfs_read_metadata
* is not used here because it can sleep and we want to use
* kmap_atomic to map the page. Instead call the underlying
* squashfs_cache_get routine. As length bytes may overlap metadata
* blocks, we may need to call squashfs_cache_get multiple times.
*/
for (bytes = 0; bytes < length; offset = 0, bytes += copied) {
entry = squashfs_cache_get(sb, msblk->block_cache, block, 0);
if (entry->error) {
ERROR("Unable to read symlink [%llx:%x]\n",
squashfs_i(inode)->start,
squashfs_i(inode)->offset);
squashfs_cache_put(entry);
goto error_out;
}
pageaddr = kmap_atomic(page, KM_USER0);
copied = squashfs_copy_data(pageaddr + bytes, entry, offset,
length - bytes);
if (copied == length - bytes)
memset(pageaddr + length, 0, PAGE_CACHE_SIZE - length);
else
block = entry->next_index;
kunmap_atomic(pageaddr, KM_USER0);
squashfs_cache_put(entry);
}
flush_dcache_page(page);
SetPageUptodate(page);
unlock_page(page);
return 0;
error_out:
SetPageError(page);
unlock_page(page);
return 0;
}