ext4: Use a folio in ext4_page_mkwrite()

Convert to the folio API, saving a few calls to compound_head().

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Link: https://lore.kernel.org/r/20230324180129.1220691-26-willy@infradead.org
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index b6e556c..6d628d6 100644 (file)
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -6075,7 +6075,7 @@ static int ext4_bh_unmapped(handle_t *handle, struct inode *inode,
 vm_fault_t ext4_page_mkwrite(struct vm_fault *vmf)
 {
        struct vm_area_struct *vma = vmf->vma;
-       struct page *page = vmf->page;
+       struct folio *folio = page_folio(vmf->page);
        loff_t size;
        unsigned long len;
        int err;
@@ -6119,19 +6119,18 @@ vm_fault_t ext4_page_mkwrite(struct vm_fault *vmf)
                goto out_ret;
        }
 
-       lock_page(page);
+       folio_lock(folio);
        size = i_size_read(inode);
        /* Page got truncated from under us? */
-       if (page->mapping != mapping || page_offset(page) > size) {
-               unlock_page(page);
+       if (folio->mapping != mapping || folio_pos(folio) > size) {
+               folio_unlock(folio);
                ret = VM_FAULT_NOPAGE;
                goto out;
        }
 
-       if (page->index == size >> PAGE_SHIFT)
-               len = size & ~PAGE_MASK;
-       else
-               len = PAGE_SIZE;
+       len = folio_size(folio);
+       if (folio_pos(folio) + len > size)
+               len = size - folio_pos(folio);
        /*
         * Return if we have all the buffers mapped. This avoids the need to do
         * journal_start/journal_stop which can block and take a long time
@@ -6139,17 +6138,17 @@ vm_fault_t ext4_page_mkwrite(struct vm_fault *vmf)
         * This cannot be done for data journalling, as we have to add the
         * inode to the transaction's list to writeprotect pages on commit.
         */
-       if (page_has_buffers(page)) {
-               if (!ext4_walk_page_buffers(NULL, inode, page_buffers(page),
+       if (folio_buffers(folio)) {
+               if (!ext4_walk_page_buffers(NULL, inode, folio_buffers(folio),
                                            0, len, NULL,
                                            ext4_bh_unmapped)) {
                        /* Wait so that we don't change page under IO */
-                       wait_for_stable_page(page);
+                       folio_wait_stable(folio);
                        ret = VM_FAULT_LOCKED;
                        goto out;
                }
        }
-       unlock_page(page);
+       folio_unlock(folio);
        /* OK, we need to fill the hole... */
        if (ext4_should_dioread_nolock(inode))
                get_block = ext4_get_block_unwritten;
@@ -6170,26 +6169,25 @@ retry_alloc:
        if (!ext4_should_journal_data(inode)) {
                err = block_page_mkwrite(vma, vmf, get_block);
        } else {
-               lock_page(page);
+               folio_lock(folio);
                size = i_size_read(inode);
                /* Page got truncated from under us? */
-               if (page->mapping != mapping || page_offset(page) > size) {
+               if (folio->mapping != mapping || folio_pos(folio) > size) {
                        ret = VM_FAULT_NOPAGE;
                        goto out_error;
                }
 
-               if (page->index == size >> PAGE_SHIFT)
-                       len = size & ~PAGE_MASK;
-               else
-                       len = PAGE_SIZE;
+               len = folio_size(folio);
+               if (folio_pos(folio) + len > size)
+                       len = size - folio_pos(folio);
 
-               err = __block_write_begin(page, 0, len, ext4_get_block);
+               err = __block_write_begin(&folio->page, 0, len, ext4_get_block);
                if (!err) {
                        ret = VM_FAULT_SIGBUS;
-                       if (ext4_journal_page_buffers(handle, page, len))
+                       if (ext4_journal_page_buffers(handle, &folio->page, len))
                                goto out_error;
                } else {
-                       unlock_page(page);
+                       folio_unlock(folio);
                }
        }
        ext4_journal_stop(handle);
@@ -6202,7 +6200,7 @@ out:
        sb_end_pagefault(inode->i_sb);
        return ret;
 out_error:
-       unlock_page(page);
+       folio_unlock(folio);
        ext4_journal_stop(handle);
        goto out;
 }