Message-ID: <42186476-5ee1-ff0d-230f-e2efeb530d0b@huawei.com>
Date:   Mon, 24 Jul 2017 20:03:04 +0800
From:   Sun Qiuyang <sunqiuyang@...wei.com>
To:     Jaegeuk Kim <jaegeuk@...nel.org>
CC:     <linux-kernel@...r.kernel.org>, <linux-fsdevel@...r.kernel.org>,
        <linux-f2fs-devel@...ts.sourceforge.net>
Subject: Re: [PATCH v8 1/1] f2fs: dax: implement direct access

Hi Jaegeuk,

Below is the error message I got from this testcase:
---
write (Invalid argument) len 1024 dio [dax to nondax | both nodax]
read (Bad address) len [4096 | 16777216 | 67108864] dio dax to nondax
---
The write error is expected, as F2FS does not support unaligned direct 
IO (1024 B).

The read error is more complex. In the test script, when we mmap the src 
file (dax), the flags (VM_MIXEDMAP | VM_HUGEPAGE) are added into
vma->vm_flags. Later on, when we write to the dest file (nondax) and 
then read from it by direct IO, we will fail to get pages from this 
"special" vma.

Functions involved:
f2fs_direct_IO
blockdev_direct_IO
__blockdev_direct_IO
do_direct_IO
dio_get_page
dio_refill_pages
iov_iter_get_pages
get_user_pages_unlocked
__get_user_pages_fast
__get_user_pages_unlocked
__get_user_pages_locked
__get_user_pages
follow_page_mask
follow_p4d_mask
follow_pud_mask
follow_pmd_mask
follow_page_pte
	vm_normal_page
	follow_pfn_pte

In my test environment HAVE_PTE_SPECIAL is true, and vm_normal_page() 
returns NULL due to VM_MIXEDMAP in vm_flags. Then follow_page_pte() 
continue to call follow_pfn_pte(), which returns -EFAULT. This is how we 
get a "bad address" error finally.

This error also occurs in EXT4-DAX for similar reasons.

Thanks,


> Hi Qiuyang,
>
> This fails xfstests/generic/413.
>
> Thanks,
>
> On 07/20, sunqiuyang wrote:
>> From: Qiuyang Sun <sunqiuyang@...wei.com>
>>
>> This patch implements Direct Access (DAX) in F2FS, including:
>>  - a mount option to choose whether to enable DAX or not
>>  - read/write and mmap of regular files in the DAX way
>>  - zero-out of unaligned partial blocks in the DAX way
>>  - garbage collection of DAX files, by mapping both old and new physical
>>    addresses of a data page into memory and copy data between them directly
>>  - incompatibility of DAX with inline data, atomic or volatile write,
>>    collapse|insert_range, etc.
>>
>> Signed-off-by: Qiuyang Sun <sunqiuyang@...wei.com>
>> ---
>> Changelog v7 -> v8:
>>  - Introduce the macro f2fs_dax_file() to judge if a file is DAX for cases
>>    when CONFIG_FS_DAX is set or not
>>  - Return -ENOTSUPP when an operation does not support DAX
>>  - In f2fs_iomap_begin(), convert the inline data of an inode (if any)
>>    before mapping blocks
>>  - Minor cleanups
>> ---
>>  Documentation/filesystems/f2fs.txt |   2 +
>>  fs/f2fs/data.c                     | 132 +++++++++++++++++++++++++-
>>  fs/f2fs/f2fs.h                     |  15 +++
>>  fs/f2fs/file.c                     | 183 ++++++++++++++++++++++++++++++++++++-
>>  fs/f2fs/gc.c                       | 103 ++++++++++++++++++++-
>>  fs/f2fs/inline.c                   |   3 +
>>  fs/f2fs/inode.c                    |   8 +-
>>  fs/f2fs/namei.c                    |   5 +
>>  fs/f2fs/super.c                    |  15 +++
>>  9 files changed, 454 insertions(+), 12 deletions(-)
>>
>> diff --git a/Documentation/filesystems/f2fs.txt b/Documentation/filesystems/f2fs.txt
>> index 273ccb2..c86c421 100644
>> --- a/Documentation/filesystems/f2fs.txt
>> +++ b/Documentation/filesystems/f2fs.txt
>> @@ -164,6 +164,8 @@ io_bits=%u             Set the bit size of write IO requests. It should be set
>>                         with "mode=lfs".
>>  usrquota               Enable plain user disk quota accounting.
>>  grpquota               Enable plain group disk quota accounting.
>> +dax                    Use direct access (no page cache). See
>> +                       Documentation/filesystems/dax.txt.
>>
>>  ================================================================================
>>  DEBUGFS ENTRIES
>> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
>> index 87c1f41..4eb4b76 100644
>> --- a/fs/f2fs/data.c
>> +++ b/fs/f2fs/data.c
>> @@ -910,6 +910,15 @@ int f2fs_map_blocks(struct inode *inode, struct f2fs_map_blocks *map,
>>  				err = -EIO;
>>  				goto sync_out;
>>  			}
>> +			/*
>> +			 * If newly allocated blocks are to be zeroed out later,
>> +			 * a single f2fs_map_blocks must not contain both old
>> +			 * and new blocks at the same time.
>> +			 */
>> +			if (flag == F2FS_GET_BLOCK_ZERO
>> +					&& (map->m_flags & F2FS_MAP_MAPPED)
>> +					&& !(map->m_flags & F2FS_MAP_NEW))
>> +				goto sync_out;
>>  			if (flag == F2FS_GET_BLOCK_PRE_AIO) {
>>  				if (blkaddr == NULL_ADDR) {
>>  					prealloc++;
>> @@ -938,6 +947,8 @@ int f2fs_map_blocks(struct inode *inode, struct f2fs_map_blocks *map,
>>  						blkaddr != NEW_ADDR)
>>  				goto sync_out;
>>  		}
>> +	} else if (flag == F2FS_GET_BLOCK_ZERO && map->m_flags & F2FS_MAP_NEW) {
>> +		goto sync_out;
>>  	}
>>
>>  	if (flag == F2FS_GET_BLOCK_PRE_AIO)
>> @@ -996,6 +1007,12 @@ int f2fs_map_blocks(struct inode *inode, struct f2fs_map_blocks *map,
>>  	goto next_dnode;
>>
>>  sync_out:
>> +	if (flag == F2FS_GET_BLOCK_ZERO && map->m_flags & F2FS_MAP_NEW) {
>> +		clean_bdev_aliases(inode->i_sb->s_bdev,
>> +				map->m_pblk, map->m_len);
>> +		err = sb_issue_zeroout(inode->i_sb, map->m_pblk,
>> +				map->m_len, GFP_NOFS);
>> +	}
>>  	f2fs_put_dnode(&dn);
>>  unlock_out:
>>  	if (create) {
>> @@ -1808,16 +1825,19 @@ static int f2fs_write_data_pages(struct address_space *mapping,
>>  	return 0;
>>  }
>>
>> -static void f2fs_write_failed(struct address_space *mapping, loff_t to)
>> +static void f2fs_write_failed(struct address_space *mapping, loff_t to,
>> +								bool lock)
>>  {
>>  	struct inode *inode = mapping->host;
>>  	loff_t i_size = i_size_read(inode);
>>
>>  	if (to > i_size) {
>> -		down_write(&F2FS_I(inode)->i_mmap_sem);
>> +		if (lock)
>> +			down_write(&F2FS_I(inode)->i_mmap_sem);
>>  		truncate_pagecache(inode, i_size);
>>  		truncate_blocks(inode, i_size, true);
>> -		up_write(&F2FS_I(inode)->i_mmap_sem);
>> +		if (lock)
>> +			up_write(&F2FS_I(inode)->i_mmap_sem);
>>  	}
>>  }
>>
>> @@ -2000,7 +2020,7 @@ static int f2fs_write_begin(struct file *file, struct address_space *mapping,
>>
>>  fail:
>>  	f2fs_put_page(page, 1);
>> -	f2fs_write_failed(mapping, pos + len);
>> +	f2fs_write_failed(mapping, pos + len, true);
>>  	return err;
>>  }
>>
>> @@ -2077,7 +2097,7 @@ static ssize_t f2fs_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
>>  		if (err > 0)
>>  			set_inode_flag(inode, FI_UPDATE_WRITE);
>>  		else if (err < 0)
>> -			f2fs_write_failed(mapping, offset + count);
>> +			f2fs_write_failed(mapping, offset + count, true);
>>  	}
>>
>>  	trace_f2fs_direct_IO_exit(inode, offset, count, rw, err);
>> @@ -2274,3 +2294,105 @@ int f2fs_migrate_page(struct address_space *mapping,
>>  	.migratepage    = f2fs_migrate_page,
>>  #endif
>>  };
>> +
>> +#ifdef CONFIG_FS_DAX
>> +#include <linux/iomap.h>
>> +#include <linux/dax.h>
>> +
>> +static int f2fs_iomap_begin(struct inode *inode, loff_t offset,
>> +	loff_t length, unsigned int flags, struct iomap *iomap)
>> +{
>> +	struct block_device *bdev;
>> +	unsigned long first_block = F2FS_BYTES_TO_BLK(offset);
>> +	unsigned long last_block = F2FS_BYTES_TO_BLK(offset + length - 1);
>> +	struct f2fs_map_blocks map;
>> +	int ret;
>> +
>> +	ret = f2fs_convert_inline_inode(inode);
>> +	if (ret)
>> +		return ret;
>> +
>> +	map.m_lblk = first_block;
>> +	map.m_len = last_block - first_block + 1;
>> +	map.m_next_pgofs = NULL;
>> +
>> +	if (!(flags & IOMAP_WRITE)) {
>> +		ret = f2fs_map_blocks(inode, &map, 0, F2FS_GET_BLOCK_FIEMAP);
>> +	} else {
>> +	/* i_size should be kept here and changed later in f2fs_iomap_end */
>> +		loff_t original_i_size = i_size_read(inode);
>> +
>> +		ret = f2fs_map_blocks(inode, &map, 1, F2FS_GET_BLOCK_ZERO);
>> +		if (i_size_read(inode) > original_i_size) {
>> +			f2fs_i_size_write(inode, original_i_size);
>> +			if (ret)
>> +				f2fs_write_failed(inode->i_mapping,
>> +						offset + length,
>> +						!(flags & IOMAP_FAULT));
>> +		}
>> +	}
>> +
>> +	if (ret)
>> +		return ret;
>> +
>> +	iomap->flags = 0;
>> +	bdev = inode->i_sb->s_bdev;
>> +	iomap->bdev = bdev;
>> +	if (blk_queue_dax(bdev->bd_queue))
>> +		iomap->dax_dev = dax_get_by_host(bdev->bd_disk->disk_name);
>> +	else
>> +		iomap->dax_dev = NULL;
>> +	iomap->offset = F2FS_BLK_TO_BYTES((u64)first_block);
>> +
>> +	if (map.m_len == 0) {
>> +		iomap->type = IOMAP_HOLE;
>> +		iomap->blkno = IOMAP_NULL_BLOCK;
>> +		iomap->length = F2FS_BLKSIZE;
>> +	} else {
>> +		if (map.m_flags & F2FS_MAP_UNWRITTEN) {
>> +			iomap->type = IOMAP_UNWRITTEN;
>> +		} else if (map.m_flags & F2FS_MAP_MAPPED) {
>> +			iomap->type = IOMAP_MAPPED;
>> +		} else {
>> +			WARN_ON_ONCE(1);
>> +			return -EIO;
>> +		}
>> +		iomap->blkno =
>> +			(sector_t)map.m_pblk << F2FS_LOG_SECTORS_PER_BLOCK;
>> +		iomap->length = F2FS_BLK_TO_BYTES((u64)map.m_len);
>> +	}
>> +
>> +	if (map.m_flags & F2FS_MAP_NEW)
>> +		iomap->flags |= IOMAP_F_NEW;
>> +	return 0;
>> +}
>> +
>> +static int f2fs_iomap_end(struct inode *inode, loff_t offset, loff_t length,
>> +	ssize_t written, unsigned int flags, struct iomap *iomap)
>> +{
>> +	put_dax(iomap->dax_dev);
>> +	if (!(flags & IOMAP_WRITE) || (flags & IOMAP_FAULT))
>> +		return 0;
>> +
>> +	if (offset + written > i_size_read(inode))
>> +		f2fs_i_size_write(inode, offset + written);
>> +
>> +	if (iomap->offset + iomap->length >
>> +			ALIGN(i_size_read(inode), F2FS_BLKSIZE)) {
>> +		block_t written_blk = F2FS_BYTES_TO_BLK(offset + written);
>> +		block_t end_blk = F2FS_BYTES_TO_BLK(offset + length);
>> +
>> +		if (written_blk < end_blk)
>> +			f2fs_write_failed(inode->i_mapping, offset + length,
>> +									true);
>> +	}
>> +
>> +	f2fs_update_time(F2FS_I_SB(inode), REQ_TIME);
>> +	return 0;
>> +}
>> +
>> +struct iomap_ops f2fs_iomap_ops = {
>> +	.iomap_begin	= f2fs_iomap_begin,
>> +	.iomap_end	= f2fs_iomap_end,
>> +};
>> +#endif
>> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
>> index 70777a8..b6d629a 100644
>> --- a/fs/f2fs/f2fs.h
>> +++ b/fs/f2fs/f2fs.h
>> @@ -91,6 +91,11 @@ struct f2fs_fault_info {
>>  #define F2FS_MOUNT_LFS			0x00040000
>>  #define F2FS_MOUNT_USRQUOTA		0x00080000
>>  #define F2FS_MOUNT_GRPQUOTA		0x00100000
>> +#ifdef CONFIG_FS_DAX
>> +#define F2FS_MOUNT_DAX			0x00400000 /* Direct Access */
>> +#else
>> +#define F2FS_MOUNT_DAX			0
>> +#endif
>>
>>  #define clear_opt(sbi, option)	((sbi)->mount_opt.opt &= ~F2FS_MOUNT_##option)
>>  #define set_opt(sbi, option)	((sbi)->mount_opt.opt |= F2FS_MOUNT_##option)
>> @@ -482,6 +487,7 @@ struct f2fs_map_blocks {
>>  #define F2FS_GET_BLOCK_BMAP		3
>>  #define F2FS_GET_BLOCK_PRE_DIO		4
>>  #define F2FS_GET_BLOCK_PRE_AIO		5
>> +#define F2FS_GET_BLOCK_ZERO		6
>>
>>  /*
>>   * i_advise uses FADVISE_XXX_BIT. We can add additional hints later.
>> @@ -506,6 +512,12 @@ struct f2fs_map_blocks {
>>  #define file_keep_isize(inode)	is_file(inode, FADVISE_KEEP_SIZE_BIT)
>>  #define file_set_keep_isize(inode) set_file(inode, FADVISE_KEEP_SIZE_BIT)
>>
>> +#ifdef CONFIG_FS_DAX
>> +#define f2fs_dax_file(inode)	IS_DAX(inode)
>> +#else
>> +#define f2fs_dax_file(inode)	false
>> +#endif
>> +
>>  #define DEF_DIR_LEVEL		0
>>
>>  struct f2fs_inode_info {
>> @@ -2439,6 +2451,9 @@ void f2fs_invalidate_page(struct page *page, unsigned int offset,
>>  int f2fs_migrate_page(struct address_space *mapping, struct page *newpage,
>>  			struct page *page, enum migrate_mode mode);
>>  #endif
>> +#ifdef CONFIG_FS_DAX
>> +extern struct iomap_ops f2fs_iomap_ops;
>> +#endif
>>
>>  /*
>>   * gc.c
>> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
>> index 2706130..e26114f 100644
>> --- a/fs/f2fs/file.c
>> +++ b/fs/f2fs/file.c
>> @@ -23,6 +23,10 @@
>>  #include <linux/uio.h>
>>  #include <linux/uuid.h>
>>  #include <linux/file.h>
>> +#ifdef CONFIG_FS_DAX
>> +#include <linux/dax.h>
>> +#include <linux/iomap.h>
>> +#endif
>>
>>  #include "f2fs.h"
>>  #include "node.h"
>> @@ -121,6 +125,64 @@ static int f2fs_vm_page_mkwrite(struct vm_fault *vmf)
>>  	.page_mkwrite	= f2fs_vm_page_mkwrite,
>>  };
>>
>> +#ifdef CONFIG_FS_DAX
>> +static int f2fs_dax_huge_fault(struct vm_fault *vmf,
>> +	enum page_entry_size pe_size)
>> +{
>> +	int result;
>> +	struct inode *inode = file_inode(vmf->vma->vm_file);
>> +	struct super_block *sb = inode->i_sb;
>> +	bool write = vmf->flags & FAULT_FLAG_WRITE;
>> +
>> +	if (write) {
>> +		sb_start_pagefault(sb);
>> +		file_update_time(vmf->vma->vm_file);
>> +	}
>> +	down_read(&F2FS_I(inode)->i_mmap_sem);
>> +	result = dax_iomap_fault(vmf, pe_size, &f2fs_iomap_ops);
>> +	up_read(&F2FS_I(inode)->i_mmap_sem);
>> +	if (write)
>> +		sb_end_pagefault(sb);
>> +
>> +	return result;
>> +}
>> +
>> +static int f2fs_dax_fault(struct vm_fault *vmf)
>> +{
>> +	return f2fs_dax_huge_fault(vmf, PE_SIZE_PTE);
>> +}
>> +
>> +static int f2fs_dax_pfn_mkwrite(struct vm_fault *vmf)
>> +{
>> +	struct inode *inode = file_inode(vmf->vma->vm_file);
>> +	struct super_block *sb = inode->i_sb;
>> +	loff_t size;
>> +	int ret;
>> +
>> +	sb_start_pagefault(sb);
>> +	file_update_time(vmf->vma->vm_file);
>> +	down_read(&F2FS_I(inode)->i_mmap_sem);
>> +	size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT;
>> +	if (vmf->pgoff >= size)
>> +		ret = VM_FAULT_SIGBUS;
>> +	else
>> +		ret = dax_pfn_mkwrite(vmf);
>> +	up_read(&F2FS_I(inode)->i_mmap_sem);
>> +	sb_end_pagefault(sb);
>> +
>> +	return ret;
>> +}
>> +
>> +static const struct vm_operations_struct f2fs_dax_vm_ops = {
>> +	.fault		= f2fs_dax_fault,
>> +	.huge_fault	= f2fs_dax_huge_fault,
>> +	.page_mkwrite	= f2fs_dax_fault,
>> +	.pfn_mkwrite	= f2fs_dax_pfn_mkwrite,
>> +};
>> +#else
>> +#define f2fs_dax_vm_ops f2fs_file_vm_ops
>> +#endif
>> +
>>  static int get_parent_ino(struct inode *inode, nid_t *pino)
>>  {
>>  	struct dentry *dentry;
>> @@ -436,7 +498,13 @@ static int f2fs_file_mmap(struct file *file, struct vm_area_struct *vma)
>>  		return err;
>>
>>  	file_accessed(file);
>> -	vma->vm_ops = &f2fs_file_vm_ops;
>> +
>> +	if (f2fs_dax_file(inode)) {
>> +		vma->vm_ops = &f2fs_dax_vm_ops;
>> +		vma->vm_flags |= VM_MIXEDMAP | VM_HUGEPAGE;
>> +	} else {
>> +		vma->vm_ops = &f2fs_file_vm_ops;
>> +	}
>>  	return 0;
>>  }
>>
>> @@ -519,6 +587,16 @@ static int truncate_partial_data_page(struct inode *inode, u64 from,
>>  	if (!offset && !cache_only)
>>  		return 0;
>>
>> +	if (f2fs_dax_file(inode)) {
>> +		int ret;
>> +
>> +		down_read(&F2FS_I(inode)->dio_rwsem[WRITE]);
>> +		ret = iomap_zero_range(inode, from, PAGE_SIZE - offset,
>> +			NULL, &f2fs_iomap_ops);
>> +		up_read(&F2FS_I(inode)->dio_rwsem[WRITE]);
>> +		return ret;
>> +	}
>> +
>>  	if (cache_only) {
>>  		page = find_lock_page(mapping, index);
>>  		if (page && PageUptodate(page))
>> @@ -799,6 +877,17 @@ static int fill_zero(struct inode *inode, pgoff_t index,
>>  	if (!len)
>>  		return 0;
>>
>> +	if (f2fs_dax_file(inode)) {
>> +		int ret;
>> +
>> +		down_read(&F2FS_I(inode)->dio_rwsem[WRITE]);
>> +		ret = iomap_zero_range(inode,
>> +			F2FS_BLK_TO_BYTES((loff_t)index) + start,
>> +			len, NULL, &f2fs_iomap_ops);
>> +		up_read(&F2FS_I(inode)->dio_rwsem[WRITE]);
>> +		return ret;
>> +	}
>> +
>>  	f2fs_balance_fs(sbi, true);
>>
>>  	f2fs_lock_op(sbi);
>> @@ -1121,6 +1210,10 @@ static int f2fs_collapse_range(struct inode *inode, loff_t offset, loff_t len)
>>  	loff_t new_size;
>>  	int ret;
>>
>> +	/* The current implementation does not apply to DAX files. */
>> +	if (f2fs_dax_file(inode))
>> +		return -ENOTSUPP;
>> +
>>  	if (offset + len >= i_size_read(inode))
>>  		return -EINVAL;
>>
>> @@ -1311,6 +1404,10 @@ static int f2fs_insert_range(struct inode *inode, loff_t offset, loff_t len)
>>  	loff_t new_size;
>>  	int ret = 0;
>>
>> +	/* The current implementation does not apply to DAX files. */
>> +	if (f2fs_dax_file(inode))
>> +		return -ENOTSUPP;
>> +
>>  	new_size = i_size_read(inode) + len;
>>  	ret = inode_newsize_ok(inode, new_size);
>>  	if (ret)
>> @@ -1578,6 +1675,9 @@ static int f2fs_ioc_start_atomic_write(struct file *filp)
>>  	struct inode *inode = file_inode(filp);
>>  	int ret;
>>
>> +	if (f2fs_dax_file(inode))
>> +		return -ENOTSUPP;
>> +
>>  	if (!inode_owner_or_capable(inode))
>>  		return -EACCES;
>>
>> @@ -1627,6 +1727,9 @@ static int f2fs_ioc_commit_atomic_write(struct file *filp)
>>  	struct inode *inode = file_inode(filp);
>>  	int ret;
>>
>> +	if (f2fs_dax_file(inode))
>> +		return -ENOTSUPP;
>> +
>>  	if (!inode_owner_or_capable(inode))
>>  		return -EACCES;
>>
>> @@ -1663,6 +1766,9 @@ static int f2fs_ioc_start_volatile_write(struct file *filp)
>>  	struct inode *inode = file_inode(filp);
>>  	int ret;
>>
>> +	if (f2fs_dax_file(inode))
>> +		return -ENOTSUPP;
>> +
>>  	if (!inode_owner_or_capable(inode))
>>  		return -EACCES;
>>
>> @@ -1698,6 +1804,9 @@ static int f2fs_ioc_release_volatile_write(struct file *filp)
>>  	struct inode *inode = file_inode(filp);
>>  	int ret;
>>
>> +	if (f2fs_dax_file(inode))
>> +		return -ENOTSUPP;
>> +
>>  	if (!inode_owner_or_capable(inode))
>>  		return -EACCES;
>>
>> @@ -1727,6 +1836,9 @@ static int f2fs_ioc_abort_volatile_write(struct file *filp)
>>  	struct inode *inode = file_inode(filp);
>>  	int ret;
>>
>> +	if (f2fs_dax_file(inode))
>> +		return -ENOTSUPP;
>> +
>>  	if (!inode_owner_or_capable(inode))
>>  		return -EACCES;
>>
>> @@ -2141,6 +2253,9 @@ static int f2fs_ioc_defragment(struct file *filp, unsigned long arg)
>>  	struct f2fs_defragment range;
>>  	int err;
>>
>> +	if (f2fs_dax_file(inode))
>> +		return -ENOTSUPP;
>> +
>>  	if (!capable(CAP_SYS_ADMIN))
>>  		return -EPERM;
>>
>> @@ -2190,6 +2305,9 @@ static int f2fs_move_file_range(struct file *file_in, loff_t pos_in,
>>  	size_t dst_osize;
>>  	int ret;
>>
>> +	if (f2fs_dax_file(src) || f2fs_dax_file(dst))
>> +		return -ENOTSUPP;
>> +
>>  	if (file_in->f_path.mnt != file_out->f_path.mnt ||
>>  				src->i_sb != dst->i_sb)
>>  		return -EXDEV;
>> @@ -2431,6 +2549,62 @@ long f2fs_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
>>  	}
>>  }
>>
>> +#ifdef CONFIG_FS_DAX
>> +static ssize_t f2fs_dax_read_iter(struct kiocb *iocb, struct iov_iter *to)
>> +{
>> +	struct inode *inode = file_inode(iocb->ki_filp);
>> +	ssize_t ret;
>> +
>> +	inode_lock_shared(inode);
>> +
>> +	if (!IS_DAX(inode)) {
>> +		inode_unlock_shared(inode);
>> +		return generic_file_read_iter(iocb, to);
>> +	}
>> +
>> +	down_read(&F2FS_I(inode)->dio_rwsem[READ]);
>> +	ret = dax_iomap_rw(iocb, to, &f2fs_iomap_ops);
>> +	up_read(&F2FS_I(inode)->dio_rwsem[READ]);
>> +	inode_unlock_shared(inode);
>> +
>> +	file_accessed(iocb->ki_filp);
>> +	return ret;
>> +}
>> +
>> +static ssize_t f2fs_dax_write_iter(struct kiocb *iocb, struct iov_iter *from)
>> +{
>> +	struct inode *inode = file_inode(iocb->ki_filp);
>> +	ssize_t ret;
>> +
>> +	ret = file_remove_privs(iocb->ki_filp);
>> +	if (ret)
>> +		return ret;
>> +	ret = file_update_time(iocb->ki_filp);
>> +	if (ret)
>> +		return ret;
>> +
>> +	down_read(&F2FS_I(inode)->dio_rwsem[WRITE]);
>> +	ret = dax_iomap_rw(iocb, from, &f2fs_iomap_ops);
>> +	up_read(&F2FS_I(inode)->dio_rwsem[WRITE]);
>> +
>> +	return ret;
>> +}
>> +#else
>> +#define f2fs_dax_read_iter	generic_file_read_iter
>> +#define f2fs_dax_write_iter	__generic_file_write_iter
>> +#endif
>> +
>> +static ssize_t f2fs_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
>> +{
>> +	if (!iov_iter_count(to))
>> +		return 0; /* skip atime */
>> +
>> +	if (f2fs_dax_file(file_inode(iocb->ki_filp)))
>> +		return f2fs_dax_read_iter(iocb, to);
>> +
>> +	return generic_file_read_iter(iocb, to);
>> +}
>> +
>>  static ssize_t f2fs_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
>>  {
>>  	struct file *file = iocb->ki_filp;
>> @@ -2452,7 +2626,10 @@ static ssize_t f2fs_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
>>  			return err;
>>  		}
>>  		blk_start_plug(&plug);
>> -		ret = __generic_file_write_iter(iocb, from);
>> +		if (f2fs_dax_file(inode))
>> +			ret = f2fs_dax_write_iter(iocb, from);
>> +		else
>> +			ret = __generic_file_write_iter(iocb, from);
>>  		blk_finish_plug(&plug);
>>  		clear_inode_flag(inode, FI_NO_PREALLOC);
>>  	}
>> @@ -2501,7 +2678,7 @@ long f2fs_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
>>
>>  const struct file_operations f2fs_file_operations = {
>>  	.llseek		= f2fs_llseek,
>> -	.read_iter	= generic_file_read_iter,
>> +	.read_iter	= f2fs_file_read_iter,
>>  	.write_iter	= f2fs_file_write_iter,
>>  	.open		= f2fs_file_open,
>>  	.release	= f2fs_release_file,
>> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
>> index fa3d2e2..06b6859 100644
>> --- a/fs/f2fs/gc.c
>> +++ b/fs/f2fs/gc.c
>> @@ -700,6 +700,100 @@ static void move_encrypted_block(struct inode *inode, block_t bidx,
>>  	f2fs_put_page(page, 1);
>>  }
>>
>> +#ifdef CONFIG_FS_DAX
>> +#include <linux/dax.h>
>> +
>> +static void dax_move_data_page(struct inode *inode, block_t bidx,
>> +				unsigned int segno, int off)
>> +{
>> +	struct block_device *bdev = inode->i_sb->s_bdev;
>> +	struct dax_device *dax_dev;
>> +	struct dnode_of_data dn;
>> +	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
>> +	struct f2fs_summary sum;
>> +	struct node_info ni;
>> +	block_t old_blkaddr, new_blkaddr;
>> +	int err, id;
>> +	long map_len;
>> +	pgoff_t pgoff;
>> +	void *kaddr_old, *kaddr_new;
>> +	pfn_t pfn;
>> +
>> +	f2fs_bug_on(sbi, f2fs_is_atomic_file(inode));
>> +
>> +	if (!check_valid_map(sbi, segno, off))
>> +		return;
>> +
>> +	f2fs_bug_on(sbi, !blk_queue_dax(bdev->bd_queue));
>> +
>> +	dax_dev = dax_get_by_host(bdev->bd_disk->disk_name);
>> +
>> +	if (!down_write_trylock(&F2FS_I(inode)->i_mmap_sem))
>> +		goto release;
>> +
>> +	unmap_mapping_range(inode->i_mapping, (loff_t)bidx << PAGE_SHIFT,
>> +			PAGE_SIZE, 1);
>> +	/* find the old block address */
>> +	set_new_dnode(&dn, inode, NULL, NULL, 0);
>> +	err = get_dnode_of_data(&dn, bidx, LOOKUP_NODE);
>> +	if (err)
>> +		goto out;
>> +	old_blkaddr = dn.data_blkaddr;
>> +	/* This page is already truncated */
>> +	if (old_blkaddr == NULL_ADDR)
>> +		goto put_dn;
>> +
>> +	/* allocate a new block address */
>> +	get_node_info(sbi, dn.nid, &ni);
>> +	set_summary(&sum, dn.nid, dn.ofs_in_node, ni.version);
>> +	allocate_data_block(sbi, NULL, old_blkaddr, &new_blkaddr,
>> +			&sum, CURSEG_COLD_DATA, NULL, false);
>> +
>> +	/* copy data page from old to new address in dax_bdev */
>> +	id = dax_read_lock();
>> +	err = bdev_dax_pgoff(bdev, SECTOR_FROM_BLOCK(old_blkaddr),
>> +			PAGE_SIZE, &pgoff);
>> +	if (err)
>> +		goto recover;
>> +	map_len = dax_direct_access(dax_dev, pgoff, 1, &kaddr_old, &pfn);
>> +	if (map_len < 0)
>> +		goto recover;
>> +	err = bdev_dax_pgoff(bdev, SECTOR_FROM_BLOCK(new_blkaddr),
>> +			PAGE_SIZE, &pgoff);
>> +	if (err)
>> +		goto recover;
>> +	map_len = dax_direct_access(dax_dev, pgoff, 1, &kaddr_new, &pfn);
>> +	if (map_len < 0)
>> +		goto recover;
>> +	copy_page((void __force *)kaddr_new, (void __force *)kaddr_old);
>> +
>> +	f2fs_update_data_blkaddr(&dn, new_blkaddr);
>> +	set_inode_flag(inode, FI_APPEND_WRITE);
>> +	if (bidx == 0)
>> +		set_inode_flag(inode, FI_FIRST_BLOCK_WRITTEN);
>> +
>> +recover:
>> +	if (err || map_len < 0)
>> +		__f2fs_replace_block(sbi, &sum, new_blkaddr, old_blkaddr,
>> +							true, true);
>> +	dax_read_unlock(id);
>> +put_dn:
>> +	f2fs_put_dnode(&dn);
>> +out:
>> +	unmap_mapping_range(inode->i_mapping, (loff_t)bidx << PAGE_SHIFT,
>> +			PAGE_SIZE, 1);
>> +	up_write(&F2FS_I(inode)->i_mmap_sem);
>> +release:
>> +	put_dax(dax_dev);
>> +}
>> +#else
>> +static void dax_move_data_page(struct inode *inode, block_t bidx,
>> +				unsigned int segno, int off)
>> +{
>> +	BUG_ON(1);
>> +}
>> +#endif
>> +
>>  static void move_data_page(struct inode *inode, block_t bidx, int gc_type,
>>  							unsigned int segno, int off)
>>  {
>> @@ -818,9 +912,10 @@ static void gc_data_segment(struct f2fs_sb_info *sbi, struct f2fs_summary *sum,
>>  			if (IS_ERR(inode) || is_bad_inode(inode))
>>  				continue;
>>
>> -			/* if encrypted inode, let's go phase 3 */
>> +			/* if DAX or encrypted inode, let's go phase 3 */
>>  			if (f2fs_encrypted_inode(inode) &&
>> -						S_ISREG(inode->i_mode)) {
>> +						S_ISREG(inode->i_mode) ||
>> +						f2fs_dax_file(inode)) {
>>  				add_gc_inode(gc_list, inode);
>>  				continue;
>>  			}
>> @@ -858,7 +953,9 @@ static void gc_data_segment(struct f2fs_sb_info *sbi, struct f2fs_summary *sum,
>>
>>  			start_bidx = start_bidx_of_node(nofs, inode)
>>  								+ ofs_in_node;
>> -			if (f2fs_encrypted_inode(inode) && S_ISREG(inode->i_mode))
>> +			if (f2fs_dax_file(inode))
>> +				dax_move_data_page(inode, start_bidx, segno, off);
>> +			else if (f2fs_encrypted_inode(inode) && S_ISREG(inode->i_mode))
>>  				move_encrypted_block(inode, start_bidx, segno, off);
>>  			else
>>  				move_data_page(inode, start_bidx, gc_type, segno, off);
>> diff --git a/fs/f2fs/inline.c b/fs/f2fs/inline.c
>> index 2082816..b8c9116 100644
>> --- a/fs/f2fs/inline.c
>> +++ b/fs/f2fs/inline.c
>> @@ -28,6 +28,9 @@ bool f2fs_may_inline_data(struct inode *inode)
>>  	if (f2fs_encrypted_inode(inode) && S_ISREG(inode->i_mode))
>>  		return false;
>>
>> +	if (f2fs_dax_file(inode))
>> +		return false;
>> +
>>  	return true;
>>  }
>>
>> diff --git a/fs/f2fs/inode.c b/fs/f2fs/inode.c
>> index 6cd312a..7741461 100644
>> --- a/fs/f2fs/inode.c
>> +++ b/fs/f2fs/inode.c
>> @@ -43,8 +43,14 @@ void f2fs_set_inode_flags(struct inode *inode)
>>  		new_fl |= S_NOATIME;
>>  	if (flags & FS_DIRSYNC_FL)
>>  		new_fl |= S_DIRSYNC;
>> +#ifdef CONFIG_FS_DAX
>> +	if (test_opt(F2FS_I_SB(inode), DAX) && S_ISREG(inode->i_mode) &&
>> +		!f2fs_has_inline_data(inode) && !f2fs_encrypted_inode(inode) &&
>> +		!f2fs_is_atomic_file(inode) && !f2fs_is_volatile_file(inode))
>> +		new_fl |= S_DAX;
>> +#endif
>>  	inode_set_flags(inode, new_fl,
>> -			S_SYNC|S_APPEND|S_IMMUTABLE|S_NOATIME|S_DIRSYNC);
>> +			S_SYNC|S_APPEND|S_IMMUTABLE|S_NOATIME|S_DIRSYNC|S_DAX);
>>  }
>>
>>  static void __get_inode_rdev(struct inode *inode, struct f2fs_inode *ri)
>> diff --git a/fs/f2fs/namei.c b/fs/f2fs/namei.c
>> index 760d852..afc52e0 100644
>> --- a/fs/f2fs/namei.c
>> +++ b/fs/f2fs/namei.c
>> @@ -70,6 +70,11 @@ static struct inode *f2fs_new_inode(struct inode *dir, umode_t mode)
>>  	if (f2fs_encrypted_inode(dir) && f2fs_may_encrypt(inode))
>>  		f2fs_set_encrypted_inode(inode);
>>
>> +#ifdef CONFIG_FS_DAX
>> +	if (test_opt(sbi, DAX) && S_ISREG(inode->i_mode) &&
>> +		!f2fs_has_inline_data(inode) && !f2fs_encrypted_inode(inode))
>> +		inode->i_flags |= S_DAX;
>> +#endif
>>  	set_inode_flag(inode, FI_NEW_INODE);
>>
>>  	if (test_opt(sbi, INLINE_XATTR))
>> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
>> index 32e4c02..aefe931 100644
>> --- a/fs/f2fs/super.c
>> +++ b/fs/f2fs/super.c
>> @@ -109,6 +109,7 @@ enum {
>>  	Opt_nolazytime,
>>  	Opt_usrquota,
>>  	Opt_grpquota,
>> +	Opt_dax,
>>  	Opt_err,
>>  };
>>
>> @@ -146,6 +147,7 @@ enum {
>>  	{Opt_nolazytime, "nolazytime"},
>>  	{Opt_usrquota, "usrquota"},
>>  	{Opt_grpquota, "grpquota"},
>> +	{Opt_dax, "dax"},
>>  	{Opt_err, NULL},
>>  };
>>
>> @@ -399,6 +401,15 @@ static int parse_options(struct super_block *sb, char *options)
>>  					"quota operations not supported");
>>  			break;
>>  #endif
>> +#ifdef CONFIG_FS_DAX
>> +		case Opt_dax:
>> +			set_opt(sbi, DAX);
>> +			break;
>> +#else
>> +		case Opt_dax:
>> +			f2fs_msg(sb, KERN_INFO, "dax option not supported");
>> +			break;
>> +#endif
>>  		default:
>>  			f2fs_msg(sb, KERN_ERR,
>>  				"Unrecognized mount option \"%s\" or missing value",
>> @@ -814,6 +825,10 @@ static int f2fs_show_options(struct seq_file *seq, struct dentry *root)
>>  	if (test_opt(sbi, GRPQUOTA))
>>  		seq_puts(seq, ",grpquota");
>>  #endif
>> +#ifdef CONFIG_FS_DAX
>> +	if (test_opt(sbi, DAX))
>> +		seq_puts(seq, ",dax");
>> +#endif
>>
>>  	return 0;
>>  }
>> --
>> 1.8.3.1
>
> .
>

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