ceph: Use a folio in ceph_page_mkwrite()

Convert the passed page to a folio and use it
throughout ceph_page_mkwrite().  Removes the last call to
page_mkwrite_check_truncate(), the last call to offset_in_thp() and one
of the last calls to thp_size().  Saves a few calls to compound_head().

Signed-off-by: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Link: https://lore.kernel.org/r/20250217185119.430193-3-willy@infradead.org
Tested-by: Viacheslav Dubeyko <Slava.Dubeyko@ibm.com>
Reviewed-by: Viacheslav Dubeyko <Slava.Dubeyko@ibm.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>

Author: Matthew Wilcox (Oracle)

fs/ceph/addr.c

@@ -2042,8 +2042,8 @@ static vm_fault_t ceph_page_mkwrite(struct vm_fault *vmf)
 	struct ceph_inode_info *ci = ceph_inode(inode);
 	struct ceph_file_info *fi = vma->vm_file->private_data;
 	struct ceph_cap_flush *prealloc_cf;
-	struct page *page = vmf->page;
-	loff_t off = page_offset(page);
+	struct folio *folio = page_folio(vmf->page);
+	loff_t off = folio_pos(folio);
 	loff_t size = i_size_read(inode);
 	size_t len;
 	int want, got, err;
@@ -2060,10 +2060,10 @@ static vm_fault_t ceph_page_mkwrite(struct vm_fault *vmf)
 	sb_start_pagefault(inode->i_sb);
 	ceph_block_sigs(&oldset);
 
-	if (off + thp_size(page) <= size)
-		len = thp_size(page);
+	if (off + folio_size(folio) <= size)
+		len = folio_size(folio);
 	else
-		len = offset_in_thp(page, size);
+		len = offset_in_folio(folio, size);
 
 	doutc(cl, "%llx.%llx %llu~%zd getting caps i_size %llu\n",
 	      ceph_vinop(inode), off, len, size);
@@ -2080,30 +2080,30 @@ static vm_fault_t ceph_page_mkwrite(struct vm_fault *vmf)
 	doutc(cl, "%llx.%llx %llu~%zd got cap refs on %s\n", ceph_vinop(inode),
 	      off, len, ceph_cap_string(got));
 
-	/* Update time before taking page lock */
+	/* Update time before taking folio lock */
 	file_update_time(vma->vm_file);
 	inode_inc_iversion_raw(inode);
 
 	do {
 		struct ceph_snap_context *snapc;
 
-		lock_page(page);
+		folio_lock(folio);
 
-		if (page_mkwrite_check_truncate(page, inode) < 0) {
-			unlock_page(page);
+		if (folio_mkwrite_check_truncate(folio, inode) < 0) {
+			folio_unlock(folio);
 			ret = VM_FAULT_NOPAGE;
 			break;
 		}
 
-		snapc = ceph_find_incompatible(page);
+		snapc = ceph_find_incompatible(&folio->page);
 		if (!snapc) {
-			/* success.  we'll keep the page locked. */
-			set_page_dirty(page);
+			/* success.  we'll keep the folio locked. */
+			folio_mark_dirty(folio);
 			ret = VM_FAULT_LOCKED;
 			break;
 		}
 
-		unlock_page(page);
+		folio_unlock(folio);
 
 		if (IS_ERR(snapc)) {
 			ret = VM_FAULT_SIGBUS;