[PATCH 3/3] f2fs:dax: Implement direct access

From: sunqiuyang
Date: Wed May 03 2017 - 20:15:35 EST

This patch implements Direct Access (DAX) in F2FS, including:
- a mount option to enable DAX
- read/write and mmap of regular files in the DAX way
- zero-out of non-aligned partial blocks in the DAX way
- garbage collection of DAX files
- incompatibility of DAX with inline data, atomic or volatile write

TODO: We may need new implementation of f2fs_collapse/insert_range() for
DAX files, as filemap_write_and_wait_range() does not work for DAX files,
and thus the data pages cannot be moved correctly.

Signed-off-by: Qiuyang Sun <sunqiuyang@xxxxxxxxxx>
---
fs/f2fs/f2fs.h | 8 +++
fs/f2fs/file.c | 197 ++++++++++++++++++++++++++++++++++++++++++++++++++++++-
fs/f2fs/gc.c | 69 +++++++++++++++++--
fs/f2fs/inline.c | 4 ++
fs/f2fs/inode.c | 88 +++++++++++++++++++++++++
fs/f2fs/namei.c | 7 ++
fs/f2fs/super.c | 16 +++++
7 files changed, 383 insertions(+), 6 deletions(-)

diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index f7957ca..d0e8af5 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -87,6 +87,11 @@ struct f2fs_fault_info {
#define F2FS_MOUNT_FAULT_INJECTION 0x00010000
#define F2FS_MOUNT_ADAPTIVE 0x00020000
#define F2FS_MOUNT_LFS 0x00040000
+#ifdef CONFIG_FS_DAX
+#define F2FS_MOUNT_DAX 0x00080000 /* 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)
@@ -2063,6 +2068,9 @@ int f2fs_getattr(const struct path *path, struct kstat *stat,
int f2fs_write_inode(struct inode *inode, struct writeback_control *wbc);
void f2fs_evict_inode(struct inode *inode);
void handle_failed_inode(struct inode *inode);
+#ifdef CONFIG_FS_DAX
+extern struct iomap_ops f2fs_iomap_ops;
+#endif

/*
* namei.c
diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index 165acbf..4eeb17b 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -23,6 +23,8 @@
#include <linux/uio.h>
#include <linux/uuid.h>
#include <linux/file.h>
+#include <linux/dax.h>
+#include <linux/iomap.h>

#include "f2fs.h"
#include "node.h"
@@ -106,6 +108,64 @@ 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;
@@ -434,7 +494,13 @@ 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(file_inode(file))) {
+ vma->vm_ops = &f2fs_dax_vm_ops;
+ vma->vm_flags |= VM_MIXEDMAP | VM_HUGEPAGE;
+ } else {
+ vma->vm_ops = &f2fs_file_vm_ops;
+ }
+
return 0;
}

@@ -518,6 +584,18 @@ static int truncate_partial_data_page(struct inode *inode, u64 from,
if (!offset && !cache_only)
return 0;

+#ifdef CONFIG_FS_DAX
+ 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))
@@ -750,6 +828,19 @@ static int fill_zero(struct inode *inode, pgoff_t index,
if (!len)
return 0;

+#ifdef CONFIG_FS_DAX
+ 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);
@@ -1073,6 +1164,12 @@ 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 original implementation does not apply to DAX files. */
+ if (IS_DAX(inode))
+ return -EINVAL;
+#endif
+
if (offset + len >= i_size_read(inode))
return -EINVAL;

@@ -1265,6 +1362,12 @@ 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 original implementation does not apply to DAX files. */
+ if (IS_DAX(inode))
+ return -EINVAL;
+#endif
+
new_size = i_size_read(inode) + len;
if (new_size > inode->i_sb->s_maxbytes)
return -EFBIG;
@@ -1527,6 +1630,11 @@ static int f2fs_ioc_start_atomic_write(struct file *filp)
if (!inode_owner_or_capable(inode))
return -EACCES;

+#ifdef CONFIG_FS_DAX
+ if (IS_DAX(inode))
+ return -EINVAL;
+#endif
+
ret = mnt_want_write_file(filp);
if (ret)
return ret;
@@ -1568,6 +1676,11 @@ static int f2fs_ioc_commit_atomic_write(struct file *filp)
if (!inode_owner_or_capable(inode))
return -EACCES;

+#ifdef CONFIG_FS_DAX
+ if (IS_DAX(inode))
+ return -EINVAL;
+#endif
+
ret = mnt_want_write_file(filp);
if (ret)
return ret;
@@ -1604,6 +1717,11 @@ static int f2fs_ioc_start_volatile_write(struct file *filp)
if (!inode_owner_or_capable(inode))
return -EACCES;

+#ifdef CONFIG_FS_DAX
+ if (IS_DAX(inode))
+ return -EINVAL;
+#endif
+
ret = mnt_want_write_file(filp);
if (ret)
return ret;
@@ -1633,6 +1751,11 @@ static int f2fs_ioc_release_volatile_write(struct file *filp)
if (!inode_owner_or_capable(inode))
return -EACCES;

+#ifdef CONFIG_FS_DAX
+ if (IS_DAX(inode))
+ return -EINVAL;
+#endif
+
ret = mnt_want_write_file(filp);
if (ret)
return ret;
@@ -1662,6 +1785,11 @@ static int f2fs_ioc_abort_volatile_write(struct file *filp)
if (!inode_owner_or_capable(inode))
return -EACCES;

+#ifdef CONFIG_FS_DAX
+ if (IS_DAX(inode))
+ return -EINVAL;
+#endif
+
ret = mnt_want_write_file(filp);
if (ret)
return ret;
@@ -2252,6 +2380,64 @@ 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_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
+{
+ if (!iov_iter_count(to))
+ return 0; /* skip atime */
+
+ if (IS_DAX(file_inode(iocb->ki_filp)))
+ return f2fs_dax_read_iter(iocb, to);
+
+ return generic_file_read_iter(iocb, to);
+}
+
+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
+static ssize_t f2fs_dax_write_iter(struct kiocb *iocb, struct iov_iter *from)
+{
+ return __generic_file_write_iter(iocb, from);
+}
+#endif
+
static ssize_t f2fs_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
{
struct file *file = iocb->ki_filp;
@@ -2278,7 +2464,10 @@ 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))
+ 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);
}
@@ -2326,7 +2515,11 @@ long f2fs_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)

const struct file_operations f2fs_file_operations = {
.llseek = f2fs_llseek,
+#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 418fd98..70cbd39 100644
--- a/fs/f2fs/gc.c
+++ b/fs/f2fs/gc.c
@@ -16,6 +16,7 @@
#include <linux/kthread.h>
#include <linux/delay.h>
#include <linux/freezer.h>
+#include <linux/dax.h>

#include "f2fs.h"
#include "node.h"
@@ -671,6 +672,64 @@ static void move_encrypted_block(struct inode *inode, block_t bidx,
f2fs_put_page(page, 1);
}

+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 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;
+ struct blk_dax_ctl old_dax, new_dax;
+ int err;
+
+ if (!check_valid_map(sbi, segno, off))
+ return;
+
+ if (f2fs_is_atomic_file(inode))
+ return;
+
+ if (!down_write_trylock(&F2FS_I(inode)->i_mmap_sem))
+ return;
+
+ 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 || dn.data_blkaddr == NULL_ADDR)
+ return;
+ old_blkaddr = dn.data_blkaddr;
+
+ /* allocate a new block address */
+ get_node_info(sbi, dn.nid, &ni);
+ set_summary(&sum, dn.nid, dn.ofs_in_node, ni.version);
+ mutex_lock(&sbi->wio_mutex[DATA]);
+ allocate_data_block(sbi, NULL, old_blkaddr,
+ &new_blkaddr, &sum, CURSEG_COLD_DATA);
+ /* copy data page within directly accessed bdev */
+ old_dax.sector = SECTOR_FROM_BLOCK(old_blkaddr);
+ new_dax.sector = SECTOR_FROM_BLOCK(new_blkaddr);
+ old_dax.size = new_dax.size = PAGE_SIZE;
+ dax_map_atomic(bdev, &old_dax);
+ dax_map_atomic(bdev, &new_dax);
+ copy_page((void __force *)new_dax.addr, (void __force *)old_dax.addr);
+ dax_unmap_atomic(bdev, &new_dax);
+ dax_unmap_atomic(bdev, &old_dax);
+ mutex_unlock(&sbi->wio_mutex[DATA]);
+
+ 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);
+ f2fs_put_dnode(&dn);
+
+ unmap_mapping_range(inode->i_mapping,
+ (loff_t)bidx << PAGE_SHIFT, PAGE_SIZE, 1);
+ up_write(&F2FS_I(inode)->i_mmap_sem);
+}
+
static void move_data_page(struct inode *inode, block_t bidx, int gc_type,
unsigned int segno, int off)
{
@@ -786,9 +845,9 @@ 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;
}
@@ -826,7 +885,9 @@ 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))
+ 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 e32a9e5..4b9d853 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
return true;
}

diff --git a/fs/f2fs/inode.c b/fs/f2fs/inode.c
index 24bb821..96e1f57 100644
--- a/fs/f2fs/inode.c
+++ b/fs/f2fs/inode.c
@@ -13,6 +13,7 @@
#include <linux/buffer_head.h>
#include <linux/backing-dev.h>
#include <linux/writeback.h>
+#include <linux/iomap.h>

#include "f2fs.h"
#include "node.h"
@@ -478,3 +479,90 @@ void handle_failed_inode(struct inode *inode)
/* iput will drop the inode object */
iput(inode);
}
+
+#ifdef CONFIG_FS_DAX
+static int f2fs_iomap_begin(struct inode *inode, loff_t offset,
+ loff_t length, unsigned int flags, struct iomap *iomap)
+{
+ 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;
+ loff_t original_i_size = i_size_read(inode);
+
+ if (WARN_ON_ONCE(f2fs_has_inline_data(inode)))
+ return -ERANGE;
+
+ 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_READ);
+ else {
+ ret = f2fs_map_blocks(inode, &map, 1, F2FS_GET_BLOCK_PRE_DIO);
+ /* i_size should be kept here and changed later in f2fs_iomap_end */
+ if (i_size_read(inode) != original_i_size)
+ f2fs_i_size_write(inode, original_i_size);
+ }
+
+ if (ret)
+ return ret;
+
+ iomap->flags = 0;
+ iomap->bdev = inode->i_sb->s_bdev;
+ 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_MAPPED) {
+ iomap->type = IOMAP_MAPPED;
+ } else if (map.m_flags & F2FS_MAP_UNWRITTEN) {
+ iomap->type = IOMAP_UNWRITTEN;
+ } 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)
+{
+ 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(inode->i_size, 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) {
+ down_write(&F2FS_I(inode)->i_mmap_sem);
+ truncate_inode_pages(inode->i_mapping, inode->i_size);
+ f2fs_truncate(inode);
+ up_write(&F2FS_I(inode)->i_mmap_sem);
+ }
+ }
+
+ return 0;
+}
+
+struct iomap_ops f2fs_iomap_ops = {
+ .iomap_begin = f2fs_iomap_begin,
+ .iomap_end = f2fs_iomap_end,
+};
+#endif
diff --git a/fs/f2fs/namei.c b/fs/f2fs/namei.c
index 98f00a3..922d42f 100644
--- a/fs/f2fs/namei.c
+++ b/fs/f2fs/namei.c
@@ -60,6 +60,13 @@ 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 30855cf..3463bf9 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -106,6 +106,7 @@ enum {
Opt_fault_injection,
Opt_lazytime,
Opt_nolazytime,
+ Opt_dax,
Opt_err,
};

@@ -140,6 +141,7 @@ enum {
{Opt_fault_injection, "fault_injection=%u"},
{Opt_lazytime, "lazytime"},
{Opt_nolazytime, "nolazytime"},
+ {Opt_dax, "dax"},
{Opt_err, NULL},
};

@@ -482,6 +484,16 @@ static int parse_options(struct super_block *sb, char *options)
f2fs_msg(sb, KERN_INFO, "noacl options 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 options not supported");
+ break;
+#endif
+
case Opt_active_logs:
if (args->from && match_int(args, &arg))
return -EINVAL;
@@ -966,6 +978,10 @@ static int f2fs_show_options(struct seq_file *seq, struct dentry *root)
if (test_opt(sbi, FAULT_INJECTION))
seq_puts(seq, ",fault_injection");
#endif
+#ifdef CONFIG_FS_DAX
+ if (test_opt(sbi, DAX))
+ seq_puts(seq, ",dax");
+#endif

return 0;
}
--
1.8.3.1