1 files changed, 331 insertions, 0 deletions
diff --git a/fs/ext2/file.c b/fs/ext2/file.c
new file mode 100644
index 000000000..4ddc36f4d
--- /dev/null
+++ b/fs/ext2/file.c
@@ -0,0 +1,331 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *  linux/fs/ext2/file.c
+ *
+ * Copyright (C) 1992, 1993, 1994, 1995
+ * Remy Card (card@masi.ibp.fr)
+ * Laboratoire MASI - Institut Blaise Pascal
+ * Universite Pierre et Marie Curie (Paris VI)
+ *
+ *  from
+ *
+ *  linux/fs/minix/file.c
+ *
+ *  Copyright (C) 1991, 1992  Linus Torvalds
+ *
+ *  ext2 fs regular file handling primitives
+ *
+ *  64-bit file support on 64-bit platforms by Jakub Jelinek
+ * 	(jj@sunsite.ms.mff.cuni.cz)
+ */
+
+#include <linux/time.h>
+#include <linux/pagemap.h>
+#include <linux/dax.h>
+#include <linux/quotaops.h>
+#include <linux/iomap.h>
+#include <linux/uio.h>
+#include <linux/buffer_head.h>
+#include "ext2.h"
+#include "xattr.h"
+#include "acl.h"
+#include "trace.h"
+
+#ifdef CONFIG_FS_DAX
+static ssize_t ext2_dax_read_iter(struct kiocb *iocb, struct iov_iter *to)
+{
+	struct inode *inode = iocb->ki_filp->f_mapping->host;
+	ssize_t ret;
+
+	if (!iov_iter_count(to))
+		return 0; /* skip atime */
+
+	inode_lock_shared(inode);
+	ret = dax_iomap_rw(iocb, to, &ext2_iomap_ops);
+	inode_unlock_shared(inode);
+
+	file_accessed(iocb->ki_filp);
+	return ret;
+}
+
+static ssize_t ext2_dax_write_iter(struct kiocb *iocb, struct iov_iter *from)
+{
+	struct file *file = iocb->ki_filp;
+	struct inode *inode = file->f_mapping->host;
+	ssize_t ret;
+
+	inode_lock(inode);
+	ret = generic_write_checks(iocb, from);
+	if (ret <= 0)
+		goto out_unlock;
+	ret = file_remove_privs(file);
+	if (ret)
+		goto out_unlock;
+	ret = file_update_time(file);
+	if (ret)
+		goto out_unlock;
+
+	ret = dax_iomap_rw(iocb, from, &ext2_iomap_ops);
+	if (ret > 0 && iocb->ki_pos > i_size_read(inode)) {
+		i_size_write(inode, iocb->ki_pos);
+		mark_inode_dirty(inode);
+	}
+
+out_unlock:
+	inode_unlock(inode);
+	if (ret > 0)
+		ret = generic_write_sync(iocb, ret);
+	return ret;
+}
+
+/*
+ * The lock ordering for ext2 DAX fault paths is:
+ *
+ * mmap_lock (MM)
+ *   sb_start_pagefault (vfs, freeze)
+ *     address_space->invalidate_lock
+ *       address_space->i_mmap_rwsem or page_lock (mutually exclusive in DAX)
+ *         ext2_inode_info->truncate_mutex
+ *
+ * The default page_lock and i_size verification done by non-DAX fault paths
+ * is sufficient because ext2 doesn't support hole punching.
+ */
+static vm_fault_t ext2_dax_fault(struct vm_fault *vmf)
+{
+	struct inode *inode = file_inode(vmf->vma->vm_file);
+	vm_fault_t ret;
+	bool write = (vmf->flags & FAULT_FLAG_WRITE) &&
+		(vmf->vma->vm_flags & VM_SHARED);
+
+	if (write) {
+		sb_start_pagefault(inode->i_sb);
+		file_update_time(vmf->vma->vm_file);
+	}
+	filemap_invalidate_lock_shared(inode->i_mapping);
+
+	ret = dax_iomap_fault(vmf, 0, NULL, NULL, &ext2_iomap_ops);
+
+	filemap_invalidate_unlock_shared(inode->i_mapping);
+	if (write)
+		sb_end_pagefault(inode->i_sb);
+	return ret;
+}
+
+static const struct vm_operations_struct ext2_dax_vm_ops = {
+	.fault		= ext2_dax_fault,
+	/*
+	 * .huge_fault is not supported for DAX because allocation in ext2
+	 * cannot be reliably aligned to huge page sizes and so pmd faults
+	 * will always fail and fail back to regular faults.
+	 */
+	.page_mkwrite	= ext2_dax_fault,
+	.pfn_mkwrite	= ext2_dax_fault,
+};
+
+static int ext2_file_mmap(struct file *file, struct vm_area_struct *vma)
+{
+	if (!IS_DAX(file_inode(file)))
+		return generic_file_mmap(file, vma);
+
+	file_accessed(file);
+	vma->vm_ops = &ext2_dax_vm_ops;
+	return 0;
+}
+#else
+#define ext2_file_mmap	generic_file_mmap
+#endif
+
+/*
+ * Called when filp is released. This happens when all file descriptors
+ * for a single struct file are closed. Note that different open() calls
+ * for the same file yield different struct file structures.
+ */
+static int ext2_release_file (struct inode * inode, struct file * filp)
+{
+	if (filp->f_mode & FMODE_WRITE) {
+		mutex_lock(&EXT2_I(inode)->truncate_mutex);
+		ext2_discard_reservation(inode);
+		mutex_unlock(&EXT2_I(inode)->truncate_mutex);
+	}
+	return 0;
+}
+
+int ext2_fsync(struct file *file, loff_t start, loff_t end, int datasync)
+{
+	int ret;
+	struct super_block *sb = file->f_mapping->host->i_sb;
+
+	ret = generic_buffers_fsync(file, start, end, datasync);
+	if (ret == -EIO)
+		/* We don't really know where the IO error happened... */
+		ext2_error(sb, __func__,
+			   "detected IO error when writing metadata buffers");
+	return ret;
+}
+
+static ssize_t ext2_dio_read_iter(struct kiocb *iocb, struct iov_iter *to)
+{
+	struct file *file = iocb->ki_filp;
+	struct inode *inode = file->f_mapping->host;
+	ssize_t ret;
+
+	trace_ext2_dio_read_begin(iocb, to, 0);
+	inode_lock_shared(inode);
+	ret = iomap_dio_rw(iocb, to, &ext2_iomap_ops, NULL, 0, NULL, 0);
+	inode_unlock_shared(inode);
+	trace_ext2_dio_read_end(iocb, to, ret);
+
+	return ret;
+}
+
+static int ext2_dio_write_end_io(struct kiocb *iocb, ssize_t size,
+				 int error, unsigned int flags)
+{
+	loff_t pos = iocb->ki_pos;
+	struct inode *inode = file_inode(iocb->ki_filp);
+
+	if (error)
+		goto out;
+
+	/*
+	 * If we are extending the file, we have to update i_size here before
+	 * page cache gets invalidated in iomap_dio_rw(). This prevents racing
+	 * buffered reads from zeroing out too much from page cache pages.
+	 * Note that all extending writes always happens synchronously with
+	 * inode lock held by ext2_dio_write_iter(). So it is safe to update
+	 * inode size here for extending file writes.
+	 */
+	pos += size;
+	if (pos > i_size_read(inode)) {
+		i_size_write(inode, pos);
+		mark_inode_dirty(inode);
+	}
+out:
+	trace_ext2_dio_write_endio(iocb, size, error);
+	return error;
+}
+
+static const struct iomap_dio_ops ext2_dio_write_ops = {
+	.end_io = ext2_dio_write_end_io,
+};
+
+static ssize_t ext2_dio_write_iter(struct kiocb *iocb, struct iov_iter *from)
+{
+	struct file *file = iocb->ki_filp;
+	struct inode *inode = file->f_mapping->host;
+	ssize_t ret;
+	unsigned int flags = 0;
+	unsigned long blocksize = inode->i_sb->s_blocksize;
+	loff_t offset = iocb->ki_pos;
+	loff_t count = iov_iter_count(from);
+	ssize_t status = 0;
+
+	trace_ext2_dio_write_begin(iocb, from, 0);
+	inode_lock(inode);
+	ret = generic_write_checks(iocb, from);
+	if (ret <= 0)
+		goto out_unlock;
+
+	ret = kiocb_modified(iocb);
+	if (ret)
+		goto out_unlock;
+
+	/* use IOMAP_DIO_FORCE_WAIT for unaligned or extending writes */
+	if (iocb->ki_pos + iov_iter_count(from) > i_size_read(inode) ||
+	   (!IS_ALIGNED(iocb->ki_pos | iov_iter_alignment(from), blocksize)))
+		flags |= IOMAP_DIO_FORCE_WAIT;
+
+	ret = iomap_dio_rw(iocb, from, &ext2_iomap_ops, &ext2_dio_write_ops,
+			   flags, NULL, 0);
+
+	/* ENOTBLK is magic return value for fallback to buffered-io */
+	if (ret == -ENOTBLK)
+		ret = 0;
+
+	if (ret < 0 && ret != -EIOCBQUEUED)
+		ext2_write_failed(inode->i_mapping, offset + count);
+
+	/* handle case for partial write and for fallback to buffered write */
+	if (ret >= 0 && iov_iter_count(from)) {
+		loff_t pos, endbyte;
+		int ret2;
+
+		iocb->ki_flags &= ~IOCB_DIRECT;
+		pos = iocb->ki_pos;
+		status = generic_perform_write(iocb, from);
+		if (unlikely(status < 0)) {
+			ret = status;
+			goto out_unlock;
+		}
+
+		ret += status;
+		endbyte = pos + status - 1;
+		ret2 = filemap_write_and_wait_range(inode->i_mapping, pos,
+						    endbyte);
+		if (!ret2)
+			invalidate_mapping_pages(inode->i_mapping,
+						 pos >> PAGE_SHIFT,
+						 endbyte >> PAGE_SHIFT);
+		if (ret > 0)
+			generic_write_sync(iocb, ret);
+	}
+
+out_unlock:
+	inode_unlock(inode);
+	if (status)
+		trace_ext2_dio_write_buff_end(iocb, from, status);
+	trace_ext2_dio_write_end(iocb, from, ret);
+	return ret;
+}
+
+static ssize_t ext2_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
+{
+#ifdef CONFIG_FS_DAX
+	if (IS_DAX(iocb->ki_filp->f_mapping->host))
+		return ext2_dax_read_iter(iocb, to);
+#endif
+	if (iocb->ki_flags & IOCB_DIRECT)
+		return ext2_dio_read_iter(iocb, to);
+
+	return generic_file_read_iter(iocb, to);
+}
+
+static ssize_t ext2_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
+{
+#ifdef CONFIG_FS_DAX
+	if (IS_DAX(iocb->ki_filp->f_mapping->host))
+		return ext2_dax_write_iter(iocb, from);
+#endif
+	if (iocb->ki_flags & IOCB_DIRECT)
+		return ext2_dio_write_iter(iocb, from);
+
+	return generic_file_write_iter(iocb, from);
+}
+
+const struct file_operations ext2_file_operations = {
+	.llseek		= generic_file_llseek,
+	.read_iter	= ext2_file_read_iter,
+	.write_iter	= ext2_file_write_iter,
+	.unlocked_ioctl = ext2_ioctl,
+#ifdef CONFIG_COMPAT
+	.compat_ioctl	= ext2_compat_ioctl,
+#endif
+	.mmap		= ext2_file_mmap,
+	.open		= dquot_file_open,
+	.release	= ext2_release_file,
+	.fsync		= ext2_fsync,
+	.get_unmapped_area = thp_get_unmapped_area,
+	.splice_read	= filemap_splice_read,
+	.splice_write	= iter_file_splice_write,
+};
+
+const struct inode_operations ext2_file_inode_operations = {
+	.listxattr	= ext2_listxattr,
+	.getattr	= ext2_getattr,
+	.setattr	= ext2_setattr,
+	.get_inode_acl	= ext2_get_acl,
+	.set_acl	= ext2_set_acl,
+	.fiemap		= ext2_fiemap,
+	.fileattr_get	= ext2_fileattr_get,
+	.fileattr_set	= ext2_fileattr_set,
+};