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>
diff --git a/fs/squashfs/file.c b/fs/squashfs/file.c
index 8ca62c28..e5c9689 100644
--- a/fs/squashfs/file.c
+++ b/fs/squashfs/file.c
@@ -370,77 +370,15 @@
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 @@
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 @@
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);
