fs/ocfs2/mmap.c

Source file repositories/reference/linux-study-clean/fs/ocfs2/mmap.c

File Facts

System
Linux kernel
Corpus path
fs/ocfs2/mmap.c
Extension
.c
Size
4392 bytes
Lines
178
Domain
Core OS
Bucket
VFS And Filesystem Core
Inferred role
Core OS: implementation source
Status
source implementation candidate

Why This File Exists

Core operating-system implementation surface: boot, tasks, memory, VFS, syscall-facing interfaces, synchronization, credentials, and isolation.

Dependency Surface

Detected Declarations

Annotated Snippet

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * mmap.c
 *
 * Code to deal with the mess that is clustered mmap.
 *
 * Copyright (C) 2002, 2004 Oracle.  All rights reserved.
 */

#include <linux/fs.h>
#include <linux/types.h>
#include <linux/highmem.h>
#include <linux/pagemap.h>
#include <linux/uio.h>
#include <linux/signal.h>
#include <linux/rbtree.h>

#include <cluster/masklog.h>

#include "ocfs2.h"

#include "aops.h"
#include "dlmglue.h"
#include "file.h"
#include "inode.h"
#include "mmap.h"
#include "super.h"
#include "ocfs2_trace.h"


static vm_fault_t ocfs2_fault(struct vm_fault *vmf)
{
	unsigned long long ip_blkno =
		OCFS2_I(file_inode(vmf->vma->vm_file))->ip_blkno;
	sigset_t oldset;
	vm_fault_t ret;

	ocfs2_block_signals(&oldset);
	ret = filemap_fault(vmf);
	ocfs2_unblock_signals(&oldset);

	trace_ocfs2_fault(ip_blkno, vmf->page, vmf->pgoff);
	return ret;
}
static vm_fault_t __ocfs2_page_mkwrite(struct file *file,
			struct buffer_head *di_bh, struct folio *folio)
{
	int err;
	vm_fault_t ret = VM_FAULT_NOPAGE;
	struct inode *inode = file_inode(file);
	struct address_space *mapping = inode->i_mapping;
	loff_t pos = folio_pos(folio);
	unsigned int len = PAGE_SIZE;
	pgoff_t last_index;
	struct folio *locked_folio = NULL;
	void *fsdata;
	loff_t size = i_size_read(inode);

	last_index = (size - 1) >> PAGE_SHIFT;

	/*
	 * There are cases that lead to the page no longer belonging to the
	 * mapping.
	 * 1) pagecache truncates locally due to memory pressure.
	 * 2) pagecache truncates when another is taking EX lock against 
	 * inode lock. see ocfs2_data_convert_worker.
	 * 
	 * The i_size check doesn't catch the case where nodes truncated and
	 * then re-extended the file. We'll re-check the page mapping after
	 * taking the page lock inside of ocfs2_write_begin_nolock().
	 *
	 * Let VM retry with these cases.
	 */
	if ((folio->mapping != inode->i_mapping) ||
	    !folio_test_uptodate(folio) ||
	    (pos >= size))
		goto out;

	/*
	 * Call ocfs2_write_begin() and ocfs2_write_end() to take
	 * advantage of the allocation code there. We pass a write
	 * length of the whole page (chopped to i_size) to make sure
	 * the whole thing is allocated.
	 *
	 * Since we know the page is up to date, we don't have to
	 * worry about ocfs2_write_begin() skipping some buffer reads
	 * because the "write" would invalidate their data.
	 */
	if (folio->index == last_index)
		len = ((size - 1) & ~PAGE_MASK) + 1;

Annotation

Implementation Notes