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SubjectRe: [PATCH v7 1/1] f2fs: dax: implement direct access
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Hi Jaegeuk,

Thank you for the edits and comments. I will accept them, except that
f2fs_iomap_end() does not need to return any error. See below for details.

> Hi Qiuyang,
>
> On 07/18, sunqiuyang wrote:
>> From: Qiuyang Sun <sunqiuyang@huawei.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, etc.
>>
>> Signed-off-by: Qiuyang Sun <sunqiuyang@huawei.com>
>> ---
>> Changlog v6 -> v7:
>> - Document the mount option "dax" for this feature in f2fs.txt
>> - Minor cleanup in dax_move_data_page()
>>
>> ---
>> Documentation/filesystems/f2fs.txt | 2 +
>> fs/f2fs/data.c | 132 +++++++++++++++++++++++--
>> fs/f2fs/f2fs.h | 9 ++
>> fs/f2fs/file.c | 192 ++++++++++++++++++++++++++++++++++++-
>> fs/f2fs/gc.c | 105 +++++++++++++++++++-
>> fs/f2fs/inline.c | 4 +
>> fs/f2fs/inode.c | 8 +-
>> fs/f2fs/namei.c | 5 +
>> fs/f2fs/super.c | 15 +++
>> 9 files changed, 459 insertions(+), 13 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..26b908a 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++;
>> @@ -938,7 +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)
>
> } else if () {
> }
>
>> + goto sync_out;
>>
>> if (flag == F2FS_GET_BLOCK_PRE_AIO)
>> goto skip;
>> @@ -996,6 +1006,12 @@ 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 +1824,19 @@ 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 +2019,7 @@ 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 +2096,7 @@ 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 +2293,104 @@ 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;
>> +
>> + if (WARN_ON_ONCE(f2fs_has_inline_data(inode)))
>> + return -ERANGE;
>
> Why not f2fs_convert_inline_inode(inode)?
>
>> +
>> + map.m_lblk = first_block;
>> + map.m_len = last_block - first_block + 1;
>> + map.m_next_pgofs = NULL;
>> +
>> + if (!(flags & IOMAP_WRITE))
>
> if () {
> ...
> } else {
> ...
> }
>
>> + 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;
>
> if () {
> ...
> } else if {
> ...
> } else {
> ...
> }
>
>> + 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);
>
> Don't we need to return any error, if (written_blk < end_blk) ?
>

In this patch, f2fs_iomap_end() is called from 3 paths:
1. dax_iomap_rw() => iomap_apply() => iomap_end()
2. iomap_zero_range() => iomap_apply() => iomap_end()
3. dax_iomap_fault() => dax_iomap_[pte|pmd]_fault() => iomap_end()

For 1 & 2: The return value of f2fs_iomap_end() will affect that of
iomap_apply() only if (written == 0), written being the return value of
actor(). In that case, no matter f2fs_iomap_end() returns 0 or some
negative value (error), the return value of iomap_apply() will always be
<=0, thus making no difference in dax_iomap_rw() or iomap_zero_range(),
which only checks "if (ret <= 0)".

For 3: the return value of f2fs_iomap_end() is simply discarded.

Therefore, I think we can just return 0 in all situations.

Thanks,

>> + 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 94a88b2..0bbe011 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 0x00200000 /* Direct Access */
>
> Could you assign 0x00400000 for upcoming F2FS_MOUNT_PRJQUOTA?
>
>> +#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)
>> @@ -479,6 +484,7 @@ 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.
>> @@ -2437,6 +2443,9 @@ 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 a0e6d2c..0e62e97 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 (IS_DAX(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 +587,17 @@ static int truncate_partial_data_page(struct inode *inode, u64 from,
>> if (!offset && !cache_only)
>> return 0;
>>
>> +#ifdef CONFIG_FS_DAX
>
> Do we need CONFIG_FS_DAX? If it's not set, it seems IS_DAX() is always false.
>
>> + if (IS_DAX(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;
>> + }
>> +#endif
>> if (cache_only) {
>> page = find_lock_page(mapping, index);
>> if (page && PageUptodate(page))
>> @@ -799,6 +878,18 @@ static int fill_zero(struct inode *inode, pgoff_t index,
>> if (!len)
>> return 0;
>>
>> +#ifdef CONFIG_FS_DAX
>
> Ditto.
>
>> + if (IS_DAX(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;
>> + }
>> +#endif
>> f2fs_balance_fs(sbi, true);
>>
>> f2fs_lock_op(sbi);
>> @@ -1121,6 +1212,11 @@ static int f2fs_collapse_range(struct inode *inode, loff_t offset, loff_t len)
>> loff_t new_size;
>> int ret;
>>
>> +#ifdef CONFIG_FS_DAX
>> + /* The current implementation does not apply to DAX files. */
>> + if (IS_DAX(inode))
>> + return -EINVAL;
>> +#endif
>
> How about adding f2fs_dax_file()?
>
> if (f2fs_dax_file(inode))
> return -ENOTSUPP;
>
> #ifdef CONFIG_FS_DAX
> #define f2fs_dax_file(inode) IS_DAX(inode)
> #else
> #define f2fs_dax_file(inode) false
> #fi
>
>> if (offset + len >= i_size_read(inode))
>> return -EINVAL;
>>
>> @@ -1311,6 +1407,11 @@ static int f2fs_insert_range(struct inode *inode, loff_t offset, loff_t len)
>> loff_t new_size;
>> int ret = 0;
>>
>> +#ifdef CONFIG_FS_DAX
>> + /* The current implementation does not apply to DAX files. */
>> + if (IS_DAX(inode))
>> + return -EINVAL;
>> +#endif
>
> if (f2fs_dax_file(inode))
> return -ENOTSUPP;
>
>> new_size = i_size_read(inode) + len;
>> ret = inode_newsize_ok(inode, new_size);
>> if (ret)
>> @@ -1581,6 +1682,10 @@ static int f2fs_ioc_start_atomic_write(struct file *filp)
>> struct inode *inode = file_inode(filp);
>> int ret;
>>
>> +#ifdef CONFIG_FS_DAX
>> + if (IS_DAX(inode))
>> + return -EINVAL;
>> +#endif
>
> if (f2fs_dax_file(inode))
> return -ENOTSUPP;
>
>> if (!inode_owner_or_capable(inode))
>> return -EACCES;
>>
>> @@ -1630,6 +1735,9 @@ static int f2fs_ioc_commit_atomic_write(struct file *filp)
>> struct inode *inode = file_inode(filp);
>> int ret;
>>
>> +#ifdef CONFIG_FS_DAX
>> + f2fs_bug_on(F2FS_I_SB(inode), IS_DAX(inode));
>> +#endif
>
> if (f2fs_dax_file(inode))
> return -ENOTSUPP;
>
>> if (!inode_owner_or_capable(inode))
>> return -EACCES;
>>
>> @@ -1666,6 +1774,10 @@ static int f2fs_ioc_start_volatile_write(struct file *filp)
>> struct inode *inode = file_inode(filp);
>> int ret;
>>
>> +#ifdef CONFIG_FS_DAX
>> + if (IS_DAX(inode))
>> + return -EINVAL;
>> +#endif
>
> if (f2fs_dax_file(inode))
> return -ENOTSUPP;
>
>> if (!inode_owner_or_capable(inode))
>> return -EACCES;
>>
>> @@ -1701,6 +1813,9 @@ static int f2fs_ioc_release_volatile_write(struct file *filp)
>> struct inode *inode = file_inode(filp);
>> int ret;
>>
>> +#ifdef CONFIG_FS_DAX
>> + f2fs_bug_on(F2FS_I_SB(inode), IS_DAX(inode));
>> +#endif
>
> if (f2fs_dax_file(inode))
> return -ENOTSUPP;
>
>> if (!inode_owner_or_capable(inode))
>> return -EACCES;
>>
>> @@ -1730,6 +1845,9 @@ static int f2fs_ioc_abort_volatile_write(struct file *filp)
>> struct inode *inode = file_inode(filp);
>> int ret;
>>
>> +#ifdef CONFIG_FS_DAX
>> + f2fs_bug_on(F2FS_I_SB(inode), IS_DAX(inode));
>> +#endif
>
> if (f2fs_dax_file(inode))
> return -ENOTSUPP;
>
>> if (!inode_owner_or_capable(inode))
>> return -EACCES;
>>
>> @@ -2144,6 +2262,10 @@ static int f2fs_ioc_defragment(struct file *filp, unsigned long arg)
>> struct f2fs_defragment range;
>> int err;
>>
>> +#ifdef CONFIG_FS_DAX
>> + if (IS_DAX(inode))
>> + return -EINVAL;
>> +#endif
>
> if (f2fs_dax_file(inode))
> return -ENOTSUPP;
>
>> if (!capable(CAP_SYS_ADMIN))
>> return -EPERM;
>>
>> @@ -2193,6 +2315,10 @@ static int f2fs_move_file_range(struct file *file_in, loff_t pos_in,
>> size_t dst_osize;
>> int ret;
>>
>> +#ifdef CONFIG_FS_DAX
>> + if (IS_DAX(src) || IS_DAX(dst))
>> + return -EINVAL;
>> +#endif
>
> 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;
>> @@ -2434,6 +2560,61 @@ 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;
>> +}
>
> How about this?
>
> #ifdef CONFIG_FS_DAX
> static ssize_t f2fs_dax_read_iter()
> {
> ...
> }
>
> static ssize_t f2fs_dax_write_iter()
> {
> ...
> }
> #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()
> {
> if (!iov_iter_count(to))
> return 0; /* skip atime */
>
> if (f2fs_dax_file(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;
>> @@ -2455,7 +2636,10 @@ 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 (IS_DAX(inode))
>
> 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);
>> }
>> @@ -2504,7 +2688,11 @@ long f2fs_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
>>
>> const struct file_operations f2fs_file_operations = {
>> .llseek = f2fs_llseek,
>
> Let's just add f2fs_file_read_iter() without CONFIG_FS_DAX.
>
>> +#ifdef CONFIG_FS_DAX
>> + .read_iter = f2fs_file_read_iter,
>> +#else
>> .read_iter = generic_file_read_iter,
>> +#endif
>> .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..289d748 100644
>> --- a/fs/f2fs/gc.c
>> +++ b/fs/f2fs/gc.c
>> @@ -700,6 +700,101 @@ 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;
>> +
>> + if (!blk_queue_dax(bdev->bd_queue))
>
> BUG_ON()?
>
>> + return;
>> +
>> + 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);
>
>> + return;
>> +}
>> +#endif
>> +
>> static void move_data_page(struct inode *inode, block_t bidx, int gc_type,
>> unsigned int segno, int off)
>> {
>> @@ -818,9 +913,9 @@ 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 (f2fs_encrypted_inode(inode) &&
>> - S_ISREG(inode->i_mode)) {
>> + /* if DAX or encrypted inode, let's go phase 3 */
>> + if (IS_DAX(inode) || (f2fs_encrypted_inode(inode) &&
>> + S_ISREG(inode->i_mode))) {
>> 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 (IS_DAX(inode))
>
> 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 e0fd437..fd8b290 100644
>> --- a/fs/f2fs/inline.c
>> +++ b/fs/f2fs/inline.c
>> @@ -28,6 +28,10 @@ bool f2fs_may_inline_data(struct inode *inode)
>> if (f2fs_encrypted_inode(inode) && S_ISREG(inode->i_mode))
>> return false;
>>
>> +#ifdef CONFIG_FS_DAX
>> + if (IS_DAX(inode))
>> + return false;
>> +#endif
>
> 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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