Merge patch series "Squashfs: Update code to not use page->index"

Phillip Lougher <phillip@squashfs.org.uk> says:

In the near future page->index will be removed [1].  Any code which
still uses page->index needs to be updated.

This patch-set contains 4 patches which updates most of the code in
Squashfs.  The exceptions are functions which have been fixed in
recent patches [2] & [3].

[1]: https://lore.kernel.org/all/Zp8fgUSIBGQ1TN0D@casper.infradead.org/
[2]: https://lore.kernel.org/all/20240817101146.2347378-1-lizetao1@huawei.com/
[3]: https://lore.kernel.org/all/20240817101146.2347378-2-lizetao1@huawei.com/

* patchesf from https://lore.kernel.org/r/20240818235847.170468-1-phillip@squashfs.org.uk:
  Squashfs: Rewrite and update squashfs_readahead_fragment() to not use page->index
  Squashfs: Update squashfs_readpage_block() to not use page->index
  Squashfs: Update squashfs_readahead() to not use page->index
  Squashfs: Update page_actor to not use page->index

Link: https://lore.kernel.org/r/20240818235847.170468-1-phillip@squashfs.org.uk
Signed-off-by: Christian Brauner <brauner@kernel.org>

fs/squashfs/file.c

@@ -494,39 +494,73 @@ static int squashfs_read_folio(struct file *file, struct folio *folio)
 }
 
 static int squashfs_readahead_fragment(struct page **page,
-	unsigned int pages, unsigned int expected)
+	unsigned int pages, unsigned int expected, loff_t start)
 {
 	struct inode *inode = page[0]->mapping->host;
 	struct squashfs_cache_entry *buffer = squashfs_get_fragment(inode->i_sb,
 		squashfs_i(inode)->fragment_block,
 		squashfs_i(inode)->fragment_size);
 	struct squashfs_sb_info *msblk = inode->i_sb->s_fs_info;
-	unsigned int n, mask = (1 << (msblk->block_log - PAGE_SHIFT)) - 1;
-	int error = buffer->error;
+	int i, bytes, copied;
+	struct squashfs_page_actor *actor;
+	unsigned int offset;
+	void *addr;
+	struct page *last_page;
+
+	if (buffer->error)
+		goto out;
 
-	if (error)
+	actor = squashfs_page_actor_init_special(msblk, page, pages,
+							expected, start);
+	if (!actor)
 		goto out;
 
-	expected += squashfs_i(inode)->fragment_offset;
+	squashfs_actor_nobuff(actor);
+	addr = squashfs_first_page(actor);
+
+	for (copied = offset = 0; offset < expected; offset += PAGE_SIZE) {
+		int avail = min_t(int, expected - offset, PAGE_SIZE);
+
+		if (!IS_ERR(addr)) {
+			bytes = squashfs_copy_data(addr, buffer, offset +
+					squashfs_i(inode)->fragment_offset, avail);
+
+			if (bytes != avail)
+				goto failed;
+		}
+
+		copied += avail;
+		addr = squashfs_next_page(actor);
+	}
 
-	for (n = 0; n < pages; n++) {
-		unsigned int base = (page[n]->index & mask) << PAGE_SHIFT;
-		unsigned int offset = base + squashfs_i(inode)->fragment_offset;
+	last_page = squashfs_page_actor_free(actor);
 
-		if (expected > offset) {
-			unsigned int avail = min_t(unsigned int, expected -
-				offset, PAGE_SIZE);
+	if (copied == expected) {
+		/* Last page (if present) may have trailing bytes not filled */
+		bytes = copied % PAGE_SIZE;
+		if (bytes && last_page)
+			memzero_page(last_page, bytes, PAGE_SIZE - bytes);
 
-			squashfs_fill_page(page[n], buffer, offset, avail);
+		for (i = 0; i < pages; i++) {
+			flush_dcache_page(page[i]);
+			SetPageUptodate(page[i]);
 		}
+	}
 
-		unlock_page(page[n]);
-		put_page(page[n]);
+	for (i = 0; i < pages; i++) {
+		unlock_page(page[i]);
+		put_page(page[i]);
 	}
 
+	squashfs_cache_put(buffer);
+	return 0;
+
+failed:
+	squashfs_page_actor_free(actor);
+
 out:
 	squashfs_cache_put(buffer);
-	return error;
+	return 1;
 }
 
 static void squashfs_readahead(struct readahead_control *ractl)
@@ -551,7 +585,6 @@ static void squashfs_readahead(struct readahead_control *ractl)
 		return;
 
 	for (;;) {
-		pgoff_t index;
 		int res, bsize;
 		u64 block = 0;
 		unsigned int expected;
@@ -570,26 +603,21 @@ static void squashfs_readahead(struct readahead_control *ractl)
 		if (readahead_pos(ractl) >= i_size_read(inode))
 			goto skip_pages;
 
-		index = pages[0]->index >> shift;
-
-		if ((pages[nr_pages - 1]->index >> shift) != index)
-			goto skip_pages;
-
-		if (index == file_end && squashfs_i(inode)->fragment_block !=
-						SQUASHFS_INVALID_BLK) {
+		if (start >> msblk->block_log == file_end &&
+				squashfs_i(inode)->fragment_block != SQUASHFS_INVALID_BLK) {
 			res = squashfs_readahead_fragment(pages, nr_pages,
-							  expected);
+							  expected, start);
 			if (res)
 				goto skip_pages;
 			continue;
 		}
 
-		bsize = read_blocklist(inode, index, &block);
+		bsize = read_blocklist(inode, start >> msblk->block_log, &block);
 		if (bsize == 0)
 			goto skip_pages;
 
 		actor = squashfs_page_actor_init_special(msblk, pages, nr_pages,
-							 expected);
+							expected, start);
 		if (!actor)
 			goto skip_pages;
 
@@ -602,7 +630,7 @@ static void squashfs_readahead(struct readahead_control *ractl)
 
 			/* Last page (if present) may have trailing bytes not filled */
 			bytes = res % PAGE_SIZE;
-			if (index == file_end && bytes && last_page)
+			if (start >> msblk->block_log == file_end && bytes && last_page)
 				memzero_page(last_page, bytes,
 					     PAGE_SIZE - bytes);
 
@@ -616,6 +644,8 @@ static void squashfs_readahead(struct readahead_control *ractl)
 			unlock_page(pages[i]);
 			put_page(pages[i]);
 		}
+
+		start += readahead_batch_length(ractl);
 	}
 
 	kfree(pages);

fs/squashfs/file_direct.c

@@ -23,15 +23,15 @@ int squashfs_readpage_block(struct page *target_page, u64 block, int bsize,
 	int expected)
 
 {
+	struct folio *folio = page_folio(target_page);
 	struct inode *inode = target_page->mapping->host;
 	struct squashfs_sb_info *msblk = inode->i_sb->s_fs_info;
-
 	loff_t file_end = (i_size_read(inode) - 1) >> PAGE_SHIFT;
 	int mask = (1 << (msblk->block_log - PAGE_SHIFT)) - 1;
-	loff_t start_index = target_page->index & ~mask;
+	loff_t start_index = folio->index & ~mask;
 	loff_t end_index = start_index | mask;
 	int i, n, pages, bytes, res = -ENOMEM;
-	struct page **page;
+	struct page **page, *last_page;
 	struct squashfs_page_actor *actor;
 	void *pageaddr;
 
@@ -46,7 +46,7 @@ int squashfs_readpage_block(struct page *target_page, u64 block, int bsize,
 
 	/* Try to grab all the pages covered by the Squashfs block */
 	for (i = 0, n = start_index; n <= end_index; n++) {
-		page[i] = (n == target_page->index) ? target_page :
+		page[i] = (n == folio->index) ? target_page :
 			grab_cache_page_nowait(target_page->mapping, n);
 
 		if (page[i] == NULL)
@@ -67,14 +67,15 @@ int squashfs_readpage_block(struct page *target_page, u64 block, int bsize,
 	 * Create a "page actor" which will kmap and kunmap the
 	 * page cache pages appropriately within the decompressor
 	 */
-	actor = squashfs_page_actor_init_special(msblk, page, pages, expected);
+	actor = squashfs_page_actor_init_special(msblk, page, pages, expected,
+						start_index << PAGE_SHIFT);
 	if (actor == NULL)
 		goto out;
 
 	/* Decompress directly into the page cache buffers */
 	res = squashfs_read_data(inode->i_sb, block, bsize, NULL, actor);
 
-	squashfs_page_actor_free(actor);
+	last_page = squashfs_page_actor_free(actor);
 
 	if (res < 0)
 		goto mark_errored;
@@ -86,8 +87,8 @@ int squashfs_readpage_block(struct page *target_page, u64 block, int bsize,
 
 	/* Last page (if present) may have trailing bytes not filled */
 	bytes = res % PAGE_SIZE;
-	if (page[pages - 1]->index == end_index && bytes) {
-		pageaddr = kmap_local_page(page[pages - 1]);
+	if (end_index == file_end && last_page && bytes) {
+		pageaddr = kmap_local_page(last_page);
 		memset(pageaddr + bytes, 0, PAGE_SIZE - bytes);
 		kunmap_local(pageaddr);
 	}

fs/squashfs/page_actor.c

@@ -60,6 +60,11 @@ struct squashfs_page_actor *squashfs_page_actor_init(void **buffer,
 }
 
 /* Implementation of page_actor for decompressing directly into page cache. */
+static loff_t page_next_index(struct squashfs_page_actor *actor)
+{
+	return page_folio(actor->page[actor->next_page])->index;
+}
+
 static void *handle_next_page(struct squashfs_page_actor *actor)
 {
 	int max_pages = (actor->length + PAGE_SIZE - 1) >> PAGE_SHIFT;
@@ -68,7 +73,7 @@ static void *handle_next_page(struct squashfs_page_actor *actor)
 		return NULL;
 
 	if ((actor->next_page == actor->pages) ||
-			(actor->next_index != actor->page[actor->next_page]->index)) {
+			(actor->next_index != page_next_index(actor))) {
 		actor->next_index++;
 		actor->returned_pages++;
 		actor->last_page = NULL;
@@ -103,7 +108,7 @@ static void direct_finish_page(struct squashfs_page_actor *actor)
 }
 
 struct squashfs_page_actor *squashfs_page_actor_init_special(struct squashfs_sb_info *msblk,
-	struct page **page, int pages, int length)
+	struct page **page, int pages, int length, loff_t start_index)
 {
 	struct squashfs_page_actor *actor = kmalloc(sizeof(*actor), GFP_KERNEL);
 
@@ -125,7 +130,7 @@ struct squashfs_page_actor *squashfs_page_actor_init_special(struct squashfs_sb_
 	actor->pages = pages;
 	actor->next_page = 0;
 	actor->returned_pages = 0;
-	actor->next_index = page[0]->index & ~((1 << (msblk->block_log - PAGE_SHIFT)) - 1);
+	actor->next_index = start_index >> PAGE_SHIFT;
 	actor->pageaddr = NULL;
 	actor->last_page = NULL;
 	actor->alloc_buffer = msblk->decompressor->alloc_buffer;

fs/squashfs/page_actor.h

@@ -29,7 +29,8 @@ extern struct squashfs_page_actor *squashfs_page_actor_init(void **buffer,
 				int pages, int length);
 extern struct squashfs_page_actor *squashfs_page_actor_init_special(
 				struct squashfs_sb_info *msblk,
-				struct page **page, int pages, int length);
+				struct page **page, int pages, int length,
+				loff_t start_index);
 static inline struct page *squashfs_page_actor_free(struct squashfs_page_actor *actor)
 {
 	struct page *last_page = actor->last_page;