mm,fs: Remove aops->readpage

With all implementations of aops->readpage converted to aops->read_folio,
we can stop checking whether it's set and remove the member from aops.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>

fs/btrfs/file.c

@@ -2402,7 +2402,7 @@ static int btrfs_file_mmap(struct file	*filp, struct vm_area_struct *vma)
 {
 	struct address_space *mapping = filp->f_mapping;
 
-	if (!mapping->a_ops->readpage && !mapping->a_ops->read_folio)
+	if (!mapping->a_ops->read_folio)
 		return -ENOEXEC;
 
 	file_accessed(filp);

fs/buffer.c

@@ -2827,10 +2827,7 @@ int nobh_truncate_page(struct address_space *mapping,
 
 	/* Ok, it's mapped. Make sure it's up-to-date */
 	if (!folio_test_uptodate(folio)) {
-		if (mapping->a_ops->read_folio)
-			err = mapping->a_ops->read_folio(NULL, folio);
-		else
-			err = mapping->a_ops->readpage(NULL, &folio->page);
+		err = mapping->a_ops->read_folio(NULL, folio);
 		if (err) {
 			folio_put(folio);
 			goto out;

fs/ceph/addr.c

@@ -1772,7 +1772,7 @@ int ceph_mmap(struct file *file, struct vm_area_struct *vma)
 {
 	struct address_space *mapping = file->f_mapping;
 
-	if (!mapping->a_ops->readpage && !mapping->a_ops->read_folio)
+	if (!mapping->a_ops->read_folio)
 		return -ENOEXEC;
 	file_accessed(file);
 	vma->vm_ops = &ceph_vmops;

include/linux/fs.h

@@ -262,7 +262,7 @@ struct iattr {
  *  			trying again.  The aop will be taking reasonable
  *  			precautions not to livelock.  If the caller held a page
  *  			reference, it should drop it before retrying.  Returned
- *  			by readpage().
+ *  			by read_folio().
  *
  * address_space_operation functions return these large constants to indicate
  * special semantics to the caller.  These are much larger than the bytes in a
@@ -335,7 +335,6 @@ static inline bool is_sync_kiocb(struct kiocb *kiocb)
 
 struct address_space_operations {
 	int (*writepage)(struct page *page, struct writeback_control *wbc);
-	int (*readpage)(struct file *, struct page *);
 	int (*read_folio)(struct file *, struct folio *);
 
 	/* Write back some dirty pages from this mapping. */

kernel/events/uprobes.c

@@ -787,10 +787,10 @@ static int __copy_insn(struct address_space *mapping, struct file *filp,
 	struct page *page;
 	/*
 	 * Ensure that the page that has the original instruction is populated
-	 * and in page-cache. If ->readpage == NULL it must be shmem_mapping(),
+	 * and in page-cache. If ->read_folio == NULL it must be shmem_mapping(),
 	 * see uprobe_register().
 	 */
-	if (mapping->a_ops->read_folio || mapping->a_ops->readpage)
+	if (mapping->a_ops->read_folio)
 		page = read_mapping_page(mapping, offset >> PAGE_SHIFT, filp);
 	else
 		page = shmem_read_mapping_page(mapping, offset >> PAGE_SHIFT);
@@ -1144,7 +1144,6 @@ static int __uprobe_register(struct inode *inode, loff_t offset,
 
 	/* copy_insn() uses read_mapping_page() or shmem_read_mapping_page() */
 	if (!inode->i_mapping->a_ops->read_folio &&
-	    !inode->i_mapping->a_ops->readpage &&
 	    !shmem_mapping(inode->i_mapping))
 		return -EIO;
 	/* Racy, just to catch the obvious mistakes */

mm/filemap.c

@@ -2414,15 +2414,12 @@ static int filemap_read_folio(struct file *file, struct address_space *mapping,
 
 	/*
 	 * A previous I/O error may have been due to temporary failures,
-	 * eg. multipath errors.  PG_error will be set again if readpage
+	 * eg. multipath errors.  PG_error will be set again if read_folio
 	 * fails.
 	 */
 	folio_clear_error(folio);
 	/* Start the actual read. The read will unlock the page. */
-	if (mapping->a_ops->read_folio)
-		error = mapping->a_ops->read_folio(file, folio);
-	else
-		error = mapping->a_ops->readpage(file, &folio->page);
+	error = mapping->a_ops->read_folio(file, folio);
 	if (error)
 		return error;
 
@@ -2639,7 +2636,7 @@ static int filemap_get_pages(struct kiocb *iocb, struct iov_iter *iter,
  * @already_read: Number of bytes already read by the caller.
  *
  * Copies data from the page cache.  If the data is not currently present,
- * uses the readahead and readpage address_space operations to fetch it.
+ * uses the readahead and read_folio address_space operations to fetch it.
  *
  * Return: Total number of bytes copied, including those already read by
  * the caller.  If an error happens before any bytes are copied, returns
@@ -3450,7 +3447,7 @@ int generic_file_mmap(struct file *file, struct vm_area_struct *vma)
 {
 	struct address_space *mapping = file->f_mapping;
 
-	if (!mapping->a_ops->read_folio && !mapping->a_ops->readpage)
+	if (!mapping->a_ops->read_folio)
 		return -ENOEXEC;
 	file_accessed(file);
 	vma->vm_ops = &generic_file_vm_ops;
@@ -3508,10 +3505,8 @@ static struct folio *do_read_cache_folio(struct address_space *mapping,
 filler:
 		if (filler)
 			err = filler(data, &folio->page);
-		else if (mapping->a_ops->read_folio)
-			err = mapping->a_ops->read_folio(data, folio);
 		else
-			err = mapping->a_ops->readpage(data, &folio->page);
+			err = mapping->a_ops->read_folio(data, folio);
 
 		if (err < 0) {
 			folio_put(folio);

mm/memory.c

@@ -555,11 +555,11 @@ static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr,
 		dump_page(page, "bad pte");
 	pr_alert("addr:%px vm_flags:%08lx anon_vma:%px mapping:%px index:%lx\n",
 		 (void *)addr, vma->vm_flags, vma->anon_vma, mapping, index);
-	pr_alert("file:%pD fault:%ps mmap:%ps readpage:%ps\n",
+	pr_alert("file:%pD fault:%ps mmap:%ps read_folio:%ps\n",
 		 vma->vm_file,
 		 vma->vm_ops ? vma->vm_ops->fault : NULL,
 		 vma->vm_file ? vma->vm_file->f_op->mmap : NULL,
-		 mapping ? mapping->a_ops->readpage : NULL);
+		 mapping ? mapping->a_ops->read_folio : NULL);
 	dump_stack();
 	add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
 }

mm/readahead.c

@@ -170,12 +170,9 @@ static void read_pages(struct readahead_control *rac)
 			}
 			folio_unlock(folio);
 		}
-	} else if (aops->read_folio) {
-		while ((folio = readahead_folio(rac)) != NULL)
-			aops->read_folio(rac->file, folio);
 	} else {
 		while ((folio = readahead_folio(rac)) != NULL)
-			aops->readpage(rac->file, &folio->page);
+			aops->read_folio(rac->file, folio);
 	}
 
 	blk_finish_plug(&plug);
@@ -256,8 +253,8 @@ void page_cache_ra_unbounded(struct readahead_control *ractl,
 	}
 
 	/*
-	 * Now start the IO.  We ignore I/O errors - if the page is not
-	 * uptodate then the caller will launch readpage again, and
+	 * Now start the IO.  We ignore I/O errors - if the folio is not
+	 * uptodate then the caller will launch read_folio again, and
 	 * will then handle the error.
 	 */
 	read_pages(ractl);
@@ -305,8 +302,7 @@ void force_page_cache_ra(struct readahead_control *ractl,
 	struct backing_dev_info *bdi = inode_to_bdi(mapping->host);
 	unsigned long max_pages, index;
 
-	if (unlikely(!mapping->a_ops->read_folio &&
-		     !mapping->a_ops->readpage && !mapping->a_ops->readahead))
+	if (unlikely(!mapping->a_ops->read_folio && !mapping->a_ops->readahead))
 		return;
 
 	/*

mm/shmem.c

@@ -4162,7 +4162,7 @@ int shmem_zero_setup(struct vm_area_struct *vma)
  *
  * This behaves as a tmpfs "read_cache_page_gfp(mapping, index, gfp)",
  * with any new page allocations done using the specified allocation flags.
- * But read_cache_page_gfp() uses the ->readpage() method: which does not
+ * But read_cache_page_gfp() uses the ->read_folio() method: which does not
  * suit tmpfs, since it may have pages in swapcache, and needs to find those
  * for itself; although drivers/gpu/drm i915 and ttm rely upon this support.
  *

mm/swapfile.c

@@ -3041,7 +3041,7 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
 	/*
 	 * Read the swap header.
 	 */
-	if (!mapping->a_ops->read_folio && !mapping->a_ops->readpage) {
+	if (!mapping->a_ops->read_folio) {
 		error = -EINVAL;
 		goto bad_swap_unlock_inode;
 	}