/*
* Read a filesystem table (uncompressed sequence of bytes) from disk
*/
void *squashfs_read_table(struct super_block *sb, u64 block, int length)
{
int pages = (length + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
int i, res;
void *table, *buffer, **data;
table = buffer = kmalloc(length, GFP_KERNEL);
if (table == NULL)
return ERR_PTR(-ENOMEM);
data = kcalloc(pages, sizeof(void *), GFP_KERNEL);
if (data == NULL) {
res = -ENOMEM;
goto failed;
}
for (i = 0; i < pages; i++, buffer += PAGE_CACHE_SIZE)
data[i] = buffer;
res = squashfs_read_data(sb, data, block, length |
SQUASHFS_COMPRESSED_BIT_BLOCK, NULL, length, pages);
kfree(data);
if (res < 0)
goto failed;
return table;
failed:
kfree(table);
return ERR_PTR(res);
}
void *squashfs_decompressor_init(struct super_block *sb, unsigned short flags)
{
struct squashfs_sb_info *msblk = sb->s_fs_info;
void *strm, *buffer = NULL;
int length = 0;
/*
* Read decompressor specific options from file system if present
*/
if (SQUASHFS_COMP_OPTS(flags)) {
buffer = kmalloc(PAGE_CACHE_SIZE, GFP_KERNEL);
if (buffer == NULL)
return ERR_PTR(-ENOMEM);
length = squashfs_read_data(sb, &buffer,
sizeof(struct squashfs_super_block), 0, NULL,
PAGE_CACHE_SIZE, 1);
if (length < 0) {
strm = ERR_PTR(length);
goto finished;
}
}
strm = msblk->decompressor->init(msblk, buffer, length);
finished:
kfree(buffer);
return strm;
}
/*
* Read a filesystem table (uncompressed sequence of bytes) from disk
*/
int squashfs_read_table(struct super_block *sb, void *buffer, u64 block,
int length)
{
int pages = (length + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
int i, res;
void **data = kcalloc(pages, sizeof(void *), GFP_KERNEL);
if (data == NULL)
return -ENOMEM;
for (i = 0; i < pages; i++, buffer += PAGE_CACHE_SIZE)
data[i] = buffer;
res = squashfs_read_data(sb, data, block, length |
SQUASHFS_COMPRESSED_BIT_BLOCK, NULL, length, pages);
kfree(data);
return res;
}
static int read_fragment_index_table_2(struct super_block *s)
{
struct squashfs_sb_info *msblk = s->s_fs_info;
struct squashfs_super_block *sblk = &msblk->sblk;
if (!(msblk->fragment_index_2 = kmalloc(SQUASHFS_FRAGMENT_INDEX_BYTES_2
(sblk->fragments), GFP_KERNEL))) {
ERROR("Failed to allocate uid/gid table\n");
return 0;
}
if (SQUASHFS_FRAGMENT_INDEX_BYTES_2(sblk->fragments) &&
!squashfs_read_data(s, (char *)
msblk->fragment_index_2,
sblk->fragment_table_start,
SQUASHFS_FRAGMENT_INDEX_BYTES_2
(sblk->fragments) |
SQUASHFS_COMPRESSED_BIT_BLOCK, NULL, SQUASHFS_FRAGMENT_INDEX_BYTES_2(sblk->fragments))) {
ERROR("unable to read fragment index table\n");
return 0;
}
if (msblk->swap) {
int i;
unsigned int fragment;
for (i = 0; i < SQUASHFS_FRAGMENT_INDEXES_2(sblk->fragments);
i++) {
SQUASHFS_SWAP_FRAGMENT_INDEXES_2((&fragment),
&msblk->fragment_index_2[i], 1);
msblk->fragment_index_2[i] = fragment;
}
}
return 1;
}
/*
* Look-up block in cache, and increment usage count. If not in cache, read
* and decompress it from disk.
*/
struct squashfs_cache_entry *squashfs_cache_get(struct super_block *sb,
struct squashfs_cache *cache, u64 block, int length)
{
int i, n;
struct squashfs_cache_entry *entry;
spin_lock(&cache->lock);
while (1) {
for (i = cache->curr_blk, n = 0; n < cache->entries; n++) {
if (cache->entry[i].block == block) {
cache->curr_blk = i;
break;
}
i = (i + 1) % cache->entries;
}
if (n == cache->entries) {
/*
* Block not in cache, if all cache entries are used
* go to sleep waiting for one to become available.
*/
if (cache->unused == 0) {
cache->num_waiters++;
spin_unlock(&cache->lock);
wait_event(cache->wait_queue, cache->unused);
spin_lock(&cache->lock);
cache->num_waiters--;
continue;
}
/*
* At least one unused cache entry. A simple
* round-robin strategy is used to choose the entry to
* be evicted from the cache.
*/
i = cache->next_blk;
for (n = 0; n < cache->entries; n++) {
if (cache->entry[i].refcount == 0)
break;
i = (i + 1) % cache->entries;
}
cache->next_blk = (i + 1) % cache->entries;
entry = &cache->entry[i];
/*
* Initialise chosen cache entry, and fill it in from
* disk.
*/
cache->unused--;
entry->block = block;
entry->refcount = 1;
entry->pending = 1;
entry->num_waiters = 0;
entry->error = 0;
spin_unlock(&cache->lock);
entry->length = squashfs_read_data(sb, entry->data,
block, length, &entry->next_index,
cache->block_size, cache->pages);
spin_lock(&cache->lock);
if (entry->length < 0)
entry->error = entry->length;
entry->pending = 0;
/*
* While filling this entry one or more other processes
* have looked it up in the cache, and have slept
* waiting for it to become available.
*/
if (entry->num_waiters) {
spin_unlock(&cache->lock);
wake_up_all(&entry->wait_queue);
} else
spin_unlock(&cache->lock);
goto out;
}
/*
* Block already in cache. Increment refcount so it doesn't
* get reused until we're finished with it, if it was
* previously unused there's one less cache entry available
* for reuse.
*/
entry = &cache->entry[i];
if (entry->refcount == 0)
cache->unused--;
entry->refcount++;
/*
* If the entry is currently being filled in by another process
* go to sleep waiting for it to become available.
*/
if (entry->pending) {
entry->num_waiters++;
spin_unlock(&cache->lock);
wait_event(entry->wait_queue, !entry->pending);
} else
spin_unlock(&cache->lock);
goto out;
}
out:
TRACE("Got %s %d, start block %lld, refcount %d, error %d\n",
cache->name, i, entry->block, entry->refcount, entry->error);
if (entry->error)
ERROR("Unable to read %s cache entry [%llx]\n", cache->name,
block);
return entry;
}
/* Read separately compressed datablock directly into page cache */
int squashfs_readpage_block(struct page *target_page, u64 block, int bsize)
{
struct inode *inode = target_page->mapping->host;
struct squashfs_sb_info *msblk = inode->i_sb->s_fs_info;
int file_end = (i_size_read(inode) - 1) >> PAGE_CACHE_SHIFT;
int mask = (1 << (msblk->block_log - PAGE_CACHE_SHIFT)) - 1;
int start_index = target_page->index & ~mask;
int end_index = start_index | mask;
int i, n, pages, missing_pages, bytes, res = -ENOMEM;
struct page **page;
struct squashfs_page_actor *actor;
void *pageaddr;
if (end_index > file_end)
end_index = file_end;
pages = end_index - start_index + 1;
page = kmalloc(sizeof(void *) * pages, GFP_KERNEL);
if (page == NULL)
return res;
/*
* Create a "page actor" which will kmap and kunmap the
* page cache pages appropriately within the decompressor
*/
actor = squashfs_page_actor_init_special(page, pages, 0);
if (actor == NULL)
goto out;
/* Try to grab all the pages covered by the Squashfs block */
for (missing_pages = 0, i = 0, n = start_index; i < pages; i++, n++) {
page[i] = (n == target_page->index) ? target_page :
grab_cache_page_nowait(target_page->mapping, n);
if (page[i] == NULL) {
missing_pages++;
continue;
}
if (PageUptodate(page[i])) {
unlock_page(page[i]);
page_cache_release(page[i]);
page[i] = NULL;
missing_pages++;
}
}
if (missing_pages) {
/*
* Couldn't get one or more pages, this page has either
* been VM reclaimed, but others are still in the page cache
* and uptodate, or we're racing with another thread in
* squashfs_readpage also trying to grab them. Fall back to
* using an intermediate buffer.
*/
res = squashfs_read_cache(target_page, block, bsize, pages,
page);
if (res < 0)
goto mark_errored;
goto out;
}
/* Decompress directly into the page cache buffers */
res = squashfs_read_data(inode->i_sb, block, bsize, NULL, actor);
if (res < 0)
goto mark_errored;
/* Last page may have trailing bytes not filled */
bytes = res % PAGE_CACHE_SIZE;
if (bytes) {
pageaddr = kmap_atomic(page[pages - 1]);
memset(pageaddr + bytes, 0, PAGE_CACHE_SIZE - bytes);
kunmap_atomic(pageaddr);
}
/* Mark pages as uptodate, unlock and release */
for (i = 0; i < pages; i++) {
flush_dcache_page(page[i]);
SetPageUptodate(page[i]);
unlock_page(page[i]);
if (page[i] != target_page)
page_cache_release(page[i]);
}
kfree(actor);
kfree(page);
return 0;
mark_errored:
/* Decompression failed, mark pages as errored. Target_page is
* dealt with by the caller
*/
for (i = 0; i < pages; i++) {
if (page[i] == NULL || page[i] == target_page)
continue;
flush_dcache_page(page[i]);
SetPageError(page[i]);
unlock_page(page[i]);
page_cache_release(page[i]);
}
out:
kfree(actor);
kfree(page);
return res;
}