Re: [PATCH v8 05/18] ext4, dax: introduce ext4_dax_aops

[Jan Kara]

On Fri 30-03-18 21:02:36, Dan Williams wrote:
> In preparation for the dax implementation to start associating dax pages
> to inodes via page->mapping, we need to provide a 'struct
> address_space_operations' instance for dax. Otherwise, direct-I/O
> triggers incorrect page cache assumptions and warnings.
> 
> Cc: "Theodore Ts'o" 
> Cc: Andreas Dilger 
> Cc: linux-e...@vger.kernel.org
> Cc: Jan Kara 
> Signed-off-by: Dan Williams 

Looks good. You can add:

Reviewed-by: Jan Kara 

Honza

> ---
>  fs/ext4/inode.c |   42 +++---
>  1 file changed, 31 insertions(+), 11 deletions(-)
> 
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index c94780075b04..249a97b19181 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -2725,12 +2725,6 @@ static int ext4_writepages(struct address_space 
> *mapping,
>   percpu_down_read(>s_journal_flag_rwsem);
>   trace_ext4_writepages(inode, wbc);
>  
> - if (dax_mapping(mapping)) {
> - ret = dax_writeback_mapping_range(mapping, inode->i_sb->s_bdev,
> -   wbc);
> - goto out_writepages;
> - }
> -
>   /*
>* No pages to write? This is mainly a kludge to avoid starting
>* a transaction for special inodes like journal inode on last iput()
> @@ -2955,6 +2949,27 @@ static int ext4_writepages(struct address_space 
> *mapping,
>   return ret;
>  }
>  
> +static int ext4_dax_writepages(struct address_space *mapping,
> +struct writeback_control *wbc)
> +{
> + int ret;
> + long nr_to_write = wbc->nr_to_write;
> + struct inode *inode = mapping->host;
> + struct ext4_sb_info *sbi = EXT4_SB(mapping->host->i_sb);
> +
> + if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb
> + return -EIO;
> +
> + percpu_down_read(>s_journal_flag_rwsem);
> + trace_ext4_writepages(inode, wbc);
> +
> + ret = dax_writeback_mapping_range(mapping, inode->i_sb->s_bdev, wbc);
> + trace_ext4_writepages_result(inode, wbc, ret,
> +  nr_to_write - wbc->nr_to_write);
> + percpu_up_read(>s_journal_flag_rwsem);
> + return ret;
> +}
> +
>  static int ext4_nonda_switch(struct super_block *sb)
>  {
>   s64 free_clusters, dirty_clusters;
> @@ -3857,10 +3872,6 @@ static ssize_t ext4_direct_IO(struct kiocb *iocb, 
> struct iov_iter *iter)
>   if (ext4_has_inline_data(inode))
>   return 0;
>  
> - /* DAX uses iomap path now */
> - if (WARN_ON_ONCE(IS_DAX(inode)))
> - return 0;
> -
>   trace_ext4_direct_IO_enter(inode, offset, count, iov_iter_rw(iter));
>   if (iov_iter_rw(iter) == READ)
>   ret = ext4_direct_IO_read(iocb, iter);
> @@ -3946,6 +3957,13 @@ static const struct address_space_operations 
> ext4_da_aops = {
>   .error_remove_page  = generic_error_remove_page,
>  };
>  
> +static const struct address_space_operations ext4_dax_aops = {
> + .writepages = ext4_dax_writepages,
> + .direct_IO  = noop_direct_IO,
> + .set_page_dirty = noop_set_page_dirty,
> + .invalidatepage = noop_invalidatepage,
> +};
> +
>  void ext4_set_aops(struct inode *inode)
>  {
>   switch (ext4_inode_journal_mode(inode)) {
> @@ -3958,7 +3976,9 @@ void ext4_set_aops(struct inode *inode)
>   default:
>   BUG();
>   }
> - if (test_opt(inode->i_sb, DELALLOC))
> + if (IS_DAX(inode))
> + inode->i_mapping->a_ops = _dax_aops;
> + else if (test_opt(inode->i_sb, DELALLOC))
>   inode->i_mapping->a_ops = _da_aops;
>   else
>   inode->i_mapping->a_ops = _aops;
> 
-- 
Jan Kara 
SUSE Labs, CR

Re: [PATCH v8 05/18] ext4, dax: introduce ext4_dax_aops

[Jan Kara]

On Fri 30-03-18 21:02:36, Dan Williams wrote:
> In preparation for the dax implementation to start associating dax pages
> to inodes via page->mapping, we need to provide a 'struct
> address_space_operations' instance for dax. Otherwise, direct-I/O
> triggers incorrect page cache assumptions and warnings.
> 
> Cc: "Theodore Ts'o" 
> Cc: Andreas Dilger 
> Cc: linux-e...@vger.kernel.org
> Cc: Jan Kara 
> Signed-off-by: Dan Williams 

Looks good. You can add:

Reviewed-by: Jan Kara 

Honza

> ---
>  fs/ext4/inode.c |   42 +++---
>  1 file changed, 31 insertions(+), 11 deletions(-)
> 
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index c94780075b04..249a97b19181 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -2725,12 +2725,6 @@ static int ext4_writepages(struct address_space 
> *mapping,
>   percpu_down_read(>s_journal_flag_rwsem);
>   trace_ext4_writepages(inode, wbc);
>  
> - if (dax_mapping(mapping)) {
> - ret = dax_writeback_mapping_range(mapping, inode->i_sb->s_bdev,
> -   wbc);
> - goto out_writepages;
> - }
> -
>   /*
>* No pages to write? This is mainly a kludge to avoid starting
>* a transaction for special inodes like journal inode on last iput()
> @@ -2955,6 +2949,27 @@ static int ext4_writepages(struct address_space 
> *mapping,
>   return ret;
>  }
>  
> +static int ext4_dax_writepages(struct address_space *mapping,
> +struct writeback_control *wbc)
> +{
> + int ret;
> + long nr_to_write = wbc->nr_to_write;
> + struct inode *inode = mapping->host;
> + struct ext4_sb_info *sbi = EXT4_SB(mapping->host->i_sb);
> +
> + if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb
> + return -EIO;
> +
> + percpu_down_read(>s_journal_flag_rwsem);
> + trace_ext4_writepages(inode, wbc);
> +
> + ret = dax_writeback_mapping_range(mapping, inode->i_sb->s_bdev, wbc);
> + trace_ext4_writepages_result(inode, wbc, ret,
> +  nr_to_write - wbc->nr_to_write);
> + percpu_up_read(>s_journal_flag_rwsem);
> + return ret;
> +}
> +
>  static int ext4_nonda_switch(struct super_block *sb)
>  {
>   s64 free_clusters, dirty_clusters;
> @@ -3857,10 +3872,6 @@ static ssize_t ext4_direct_IO(struct kiocb *iocb, 
> struct iov_iter *iter)
>   if (ext4_has_inline_data(inode))
>   return 0;
>  
> - /* DAX uses iomap path now */
> - if (WARN_ON_ONCE(IS_DAX(inode)))
> - return 0;
> -
>   trace_ext4_direct_IO_enter(inode, offset, count, iov_iter_rw(iter));
>   if (iov_iter_rw(iter) == READ)
>   ret = ext4_direct_IO_read(iocb, iter);
> @@ -3946,6 +3957,13 @@ static const struct address_space_operations 
> ext4_da_aops = {
>   .error_remove_page  = generic_error_remove_page,
>  };
>  
> +static const struct address_space_operations ext4_dax_aops = {
> + .writepages = ext4_dax_writepages,
> + .direct_IO  = noop_direct_IO,
> + .set_page_dirty = noop_set_page_dirty,
> + .invalidatepage = noop_invalidatepage,
> +};
> +
>  void ext4_set_aops(struct inode *inode)
>  {
>   switch (ext4_inode_journal_mode(inode)) {
> @@ -3958,7 +3976,9 @@ void ext4_set_aops(struct inode *inode)
>   default:
>   BUG();
>   }
> - if (test_opt(inode->i_sb, DELALLOC))
> + if (IS_DAX(inode))
> + inode->i_mapping->a_ops = _dax_aops;
> + else if (test_opt(inode->i_sb, DELALLOC))
>   inode->i_mapping->a_ops = _da_aops;
>   else
>   inode->i_mapping->a_ops = _aops;
> 
-- 
Jan Kara 
SUSE Labs, CR

[PATCH v8 05/18] ext4, dax: introduce ext4_dax_aops

[Dan Williams]

In preparation for the dax implementation to start associating dax pages
to inodes via page->mapping, we need to provide a 'struct
address_space_operations' instance for dax. Otherwise, direct-I/O
triggers incorrect page cache assumptions and warnings.

Cc: "Theodore Ts'o" 
Cc: Andreas Dilger 
Cc: linux-e...@vger.kernel.org
Cc: Jan Kara 
Signed-off-by: Dan Williams 
---
 fs/ext4/inode.c |   42 +++---
 1 file changed, 31 insertions(+), 11 deletions(-)

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index c94780075b04..249a97b19181 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -2725,12 +2725,6 @@ static int ext4_writepages(struct address_space *mapping,
percpu_down_read(>s_journal_flag_rwsem);
trace_ext4_writepages(inode, wbc);
 
-   if (dax_mapping(mapping)) {
-   ret = dax_writeback_mapping_range(mapping, inode->i_sb->s_bdev,
- wbc);
-   goto out_writepages;
-   }
-
/*
 * No pages to write? This is mainly a kludge to avoid starting
 * a transaction for special inodes like journal inode on last iput()
@@ -2955,6 +2949,27 @@ static int ext4_writepages(struct address_space *mapping,
return ret;
 }
 
+static int ext4_dax_writepages(struct address_space *mapping,
+  struct writeback_control *wbc)
+{
+   int ret;
+   long nr_to_write = wbc->nr_to_write;
+   struct inode *inode = mapping->host;
+   struct ext4_sb_info *sbi = EXT4_SB(mapping->host->i_sb);
+
+   if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb
+   return -EIO;
+
+   percpu_down_read(>s_journal_flag_rwsem);
+   trace_ext4_writepages(inode, wbc);
+
+   ret = dax_writeback_mapping_range(mapping, inode->i_sb->s_bdev, wbc);
+   trace_ext4_writepages_result(inode, wbc, ret,
+nr_to_write - wbc->nr_to_write);
+   percpu_up_read(>s_journal_flag_rwsem);
+   return ret;
+}
+
 static int ext4_nonda_switch(struct super_block *sb)
 {
s64 free_clusters, dirty_clusters;
@@ -3857,10 +3872,6 @@ static ssize_t ext4_direct_IO(struct kiocb *iocb, struct 
iov_iter *iter)
if (ext4_has_inline_data(inode))
return 0;
 
-   /* DAX uses iomap path now */
-   if (WARN_ON_ONCE(IS_DAX(inode)))
-   return 0;
-
trace_ext4_direct_IO_enter(inode, offset, count, iov_iter_rw(iter));
if (iov_iter_rw(iter) == READ)
ret = ext4_direct_IO_read(iocb, iter);
@@ -3946,6 +3957,13 @@ static const struct address_space_operations 
ext4_da_aops = {
.error_remove_page  = generic_error_remove_page,
 };
 
+static const struct address_space_operations ext4_dax_aops = {
+   .writepages = ext4_dax_writepages,
+   .direct_IO  = noop_direct_IO,
+   .set_page_dirty = noop_set_page_dirty,
+   .invalidatepage = noop_invalidatepage,
+};
+
 void ext4_set_aops(struct inode *inode)
 {
switch (ext4_inode_journal_mode(inode)) {
@@ -3958,7 +3976,9 @@ void ext4_set_aops(struct inode *inode)
default:
BUG();
}
-   if (test_opt(inode->i_sb, DELALLOC))
+   if (IS_DAX(inode))
+   inode->i_mapping->a_ops = _dax_aops;
+   else if (test_opt(inode->i_sb, DELALLOC))
inode->i_mapping->a_ops = _da_aops;
else
inode->i_mapping->a_ops = _aops;

[PATCH v8 05/18] ext4, dax: introduce ext4_dax_aops

[Dan Williams]

In preparation for the dax implementation to start associating dax pages
to inodes via page->mapping, we need to provide a 'struct
address_space_operations' instance for dax. Otherwise, direct-I/O
triggers incorrect page cache assumptions and warnings.

Cc: "Theodore Ts'o" 
Cc: Andreas Dilger 
Cc: linux-e...@vger.kernel.org
Cc: Jan Kara 
Signed-off-by: Dan Williams 
---
 fs/ext4/inode.c |   42 +++---
 1 file changed, 31 insertions(+), 11 deletions(-)

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index c94780075b04..249a97b19181 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -2725,12 +2725,6 @@ static int ext4_writepages(struct address_space *mapping,
percpu_down_read(>s_journal_flag_rwsem);
trace_ext4_writepages(inode, wbc);
 
-   if (dax_mapping(mapping)) {
-   ret = dax_writeback_mapping_range(mapping, inode->i_sb->s_bdev,
- wbc);
-   goto out_writepages;
-   }
-
/*
 * No pages to write? This is mainly a kludge to avoid starting
 * a transaction for special inodes like journal inode on last iput()
@@ -2955,6 +2949,27 @@ static int ext4_writepages(struct address_space *mapping,
return ret;
 }
 
+static int ext4_dax_writepages(struct address_space *mapping,
+  struct writeback_control *wbc)
+{
+   int ret;
+   long nr_to_write = wbc->nr_to_write;
+   struct inode *inode = mapping->host;
+   struct ext4_sb_info *sbi = EXT4_SB(mapping->host->i_sb);
+
+   if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb
+   return -EIO;
+
+   percpu_down_read(>s_journal_flag_rwsem);
+   trace_ext4_writepages(inode, wbc);
+
+   ret = dax_writeback_mapping_range(mapping, inode->i_sb->s_bdev, wbc);
+   trace_ext4_writepages_result(inode, wbc, ret,
+nr_to_write - wbc->nr_to_write);
+   percpu_up_read(>s_journal_flag_rwsem);
+   return ret;
+}
+
 static int ext4_nonda_switch(struct super_block *sb)
 {
s64 free_clusters, dirty_clusters;
@@ -3857,10 +3872,6 @@ static ssize_t ext4_direct_IO(struct kiocb *iocb, struct 
iov_iter *iter)
if (ext4_has_inline_data(inode))
return 0;
 
-   /* DAX uses iomap path now */
-   if (WARN_ON_ONCE(IS_DAX(inode)))
-   return 0;
-
trace_ext4_direct_IO_enter(inode, offset, count, iov_iter_rw(iter));
if (iov_iter_rw(iter) == READ)
ret = ext4_direct_IO_read(iocb, iter);
@@ -3946,6 +3957,13 @@ static const struct address_space_operations 
ext4_da_aops = {
.error_remove_page  = generic_error_remove_page,
 };
 
+static const struct address_space_operations ext4_dax_aops = {
+   .writepages = ext4_dax_writepages,
+   .direct_IO  = noop_direct_IO,
+   .set_page_dirty = noop_set_page_dirty,
+   .invalidatepage = noop_invalidatepage,
+};
+
 void ext4_set_aops(struct inode *inode)
 {
switch (ext4_inode_journal_mode(inode)) {
@@ -3958,7 +3976,9 @@ void ext4_set_aops(struct inode *inode)
default:
BUG();
}
-   if (test_opt(inode->i_sb, DELALLOC))
+   if (IS_DAX(inode))
+   inode->i_mapping->a_ops = _dax_aops;
+   else if (test_opt(inode->i_sb, DELALLOC))
inode->i_mapping->a_ops = _da_aops;
else
inode->i_mapping->a_ops = _aops;