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Commit 1db17542 authored by Jan Kara's avatar Jan Kara Committed by Dan Williams
Browse files

ext4: Simplify DAX fault path 



Now that dax_iomap_fault() calls ->iomap_begin() without entry lock, we
can use transaction starting in ext4_iomap_begin() and thus simplify
ext4_dax_fault(). It also provides us proper retries in case of ENOSPC.

Signed-off-by: default avatarJan Kara <jack@suse.cz>
Signed-off-by: default avatarDan Williams <dan.j.williams@intel.com>
parent 9f141d6e

fs/ext4/file.c

+10 −38
Original line number Diff line number Diff line
@@ -258,7 +258,6 @@ ext4_file_write_iter(struct kiocb *iocb, struct iov_iter *from) 
static int ext4_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf)

{

	int result;

	handle_t *handle = NULL;

	struct inode *inode = file_inode(vma->vm_file);

	struct super_block *sb = inode->i_sb;

	bool write = vmf->flags & FAULT_FLAG_WRITE;
@@ -266,24 +265,12 @@ static int ext4_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf) 
	if (write) {

		sb_start_pagefault(sb);

		file_update_time(vma->vm_file);

	}

	down_read(&EXT4_I(inode)->i_mmap_sem);

		handle = ext4_journal_start_sb(sb, EXT4_HT_WRITE_PAGE,

						EXT4_DATA_TRANS_BLOCKS(sb));

	} else

		down_read(&EXT4_I(inode)->i_mmap_sem);



	if (IS_ERR(handle))

		result = VM_FAULT_SIGBUS;

	else

	result = dax_iomap_fault(vma, vmf, &ext4_iomap_ops);



	if (write) {

		if (!IS_ERR(handle))

			ext4_journal_stop(handle);

	up_read(&EXT4_I(inode)->i_mmap_sem);

	if (write)

		sb_end_pagefault(sb);

	} else

		up_read(&EXT4_I(inode)->i_mmap_sem);



	return result;

}
@@ -292,7 +279,6 @@ static int ext4_dax_pmd_fault(struct vm_area_struct *vma, unsigned long addr, 
						pmd_t *pmd, unsigned int flags)

{

	int result;

	handle_t *handle = NULL;

	struct inode *inode = file_inode(vma->vm_file);

	struct super_block *sb = inode->i_sb;

	bool write = flags & FAULT_FLAG_WRITE;
@@ -300,27 +286,13 @@ static int ext4_dax_pmd_fault(struct vm_area_struct *vma, unsigned long addr, 
	if (write) {

		sb_start_pagefault(sb);

		file_update_time(vma->vm_file);

	}

	down_read(&EXT4_I(inode)->i_mmap_sem);

		handle = ext4_journal_start_sb(sb, EXT4_HT_WRITE_PAGE,

				ext4_chunk_trans_blocks(inode,

							PMD_SIZE / PAGE_SIZE));

	} else

		down_read(&EXT4_I(inode)->i_mmap_sem);



	if (IS_ERR(handle))

		result = VM_FAULT_SIGBUS;

	else {

	result = dax_iomap_pmd_fault(vma, addr, pmd, flags,

				     &ext4_iomap_ops);

	}



	if (write) {

		if (!IS_ERR(handle))

			ext4_journal_stop(handle);

	up_read(&EXT4_I(inode)->i_mmap_sem);

	if (write)

		sb_end_pagefault(sb);

	} else

		up_read(&EXT4_I(inode)->i_mmap_sem);



	return result;

}