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Subject: Re: [RFC PATCH 17/18] ext4: partial enable iomap for regular file's
 buffered IO path
To: linux-ext4@vger.kernel.org
Cc: linux-fsdevel@vger.kernel.org, tytso@mit.edu, adilger.kernel@dilger.ca,
 jack@suse.cz, ritesh.list@gmail.com, hch@infradead.org, djwong@kernel.org,
 yi.zhang@huawei.com, chengzhihao1@huawei.com, yukuai3@huawei.com
References: <20231123125121.4064694-1-yi.zhang@huaweicloud.com>
 <20231123125121.4064694-18-yi.zhang@huaweicloud.com>
From: Zhang Yi <yi.zhang@huaweicloud.com>
Message-ID: <3792c75a-d2ea-6818-862c-fe8f828bf457@huaweicloud.com>
Date: Fri, 24 Nov 2023 21:57:36 +0800
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This one is redundant and not correct, please look the next one
in this series. I'm sorry about it.

https://lore.kernel.org/linux-ext4/20231123125121.4064694-19-yi.zhang@huaweicloud.com/T/#u

On 2023/11/23 20:51, Zhang Yi wrote:
> From: Zhang Yi <yi.zhang@huawei.com>
> 
> Partial enable iomap for regular file's buffered IO path on default
> mount option and default filesystem features. Does not support inline
> data, fs_verity, fs_crypt, bigalloc, dax and data=journal mode yet,
> those will be supported in the future.
> 
> Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
> ---
>  fs/ext4/ext4.h        |  2 ++
>  fs/ext4/ext4_jbd2.c   |  3 ++-
>  fs/ext4/file.c        |  8 +++++++-
>  fs/ext4/ialloc.c      |  3 +++
>  fs/ext4/inode.c       | 31 +++++++++++++++++++++++++++++++
>  fs/ext4/move_extent.c |  8 ++++++++
>  6 files changed, 53 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
> index 6b3e34ea58ad..7ce688cb1b07 100644
> --- a/fs/ext4/ext4.h
> +++ b/fs/ext4/ext4.h
> @@ -2959,6 +2959,7 @@ int ext4_walk_page_buffers(handle_t *handle,
>  				     struct buffer_head *bh));
>  int do_journal_get_write_access(handle_t *handle, struct inode *inode,
>  				struct buffer_head *bh);
> +extern bool ext4_should_use_buffered_iomap(struct inode *inode);
>  #define FALL_BACK_TO_NONDELALLOC 1
>  #define CONVERT_INLINE_DATA	 2
>  
> @@ -3822,6 +3823,7 @@ static inline void ext4_clear_io_unwritten_flag(ext4_io_end_t *io_end)
>  extern const struct iomap_ops ext4_iomap_ops;
>  extern const struct iomap_ops ext4_iomap_overwrite_ops;
>  extern const struct iomap_ops ext4_iomap_report_ops;
> +extern const struct iomap_ops ext4_iomap_buffered_write_ops;
>  
>  static inline int ext4_buffer_uptodate(struct buffer_head *bh)
>  {
> diff --git a/fs/ext4/ext4_jbd2.c b/fs/ext4/ext4_jbd2.c
> index d1a2e6624401..cf25cdda7234 100644
> --- a/fs/ext4/ext4_jbd2.c
> +++ b/fs/ext4/ext4_jbd2.c
> @@ -16,7 +16,8 @@ int ext4_inode_journal_mode(struct inode *inode)
>  	    ext4_test_inode_flag(inode, EXT4_INODE_EA_INODE) ||
>  	    test_opt(inode->i_sb, DATA_FLAGS) == EXT4_MOUNT_JOURNAL_DATA ||
>  	    (ext4_test_inode_flag(inode, EXT4_INODE_JOURNAL_DATA) &&
> -	    !test_opt(inode->i_sb, DELALLOC))) {
> +	     !ext4_test_inode_state(inode, EXT4_STATE_BUFFERED_IOMAP) &&
> +	     !test_opt(inode->i_sb, DELALLOC))) {
>  		/* We do not support data journalling for encrypted data */
>  		if (S_ISREG(inode->i_mode) && IS_ENCRYPTED(inode))
>  			return EXT4_INODE_ORDERED_DATA_MODE;  /* ordered */
> diff --git a/fs/ext4/file.c b/fs/ext4/file.c
> index 15fe65744cba..7e3352b3b752 100644
> --- a/fs/ext4/file.c
> +++ b/fs/ext4/file.c
> @@ -296,7 +296,11 @@ static ssize_t ext4_buffered_write_iter(struct kiocb *iocb,
>  	if (ret <= 0)
>  		goto out;
>  
> -	ret = generic_perform_write(iocb, from);
> +	if (ext4_test_inode_state(inode, EXT4_STATE_BUFFERED_IOMAP))
> +		ret = iomap_file_buffered_write(iocb, from,
> +						&ext4_iomap_buffered_write_ops);
> +	else
> +		ret = generic_perform_write(iocb, from);
>  
>  out:
>  	inode_unlock(inode);
> @@ -823,6 +827,8 @@ static int ext4_file_mmap(struct file *file, struct vm_area_struct *vma)
>  	if (IS_DAX(file_inode(file))) {
>  		vma->vm_ops = &ext4_dax_vm_ops;
>  		vm_flags_set(vma, VM_HUGEPAGE);
> +	} else if (ext4_test_inode_state(inode, EXT4_STATE_BUFFERED_IOMAP)) {
> +		vma->vm_ops = &ext4_iomap_file_vm_ops;
>  	} else {
>  		vma->vm_ops = &ext4_file_vm_ops;
>  	}
> diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c
> index b65058d972f9..0aae2810dbf6 100644
> --- a/fs/ext4/ialloc.c
> +++ b/fs/ext4/ialloc.c
> @@ -1336,6 +1336,9 @@ struct inode *__ext4_new_inode(struct mnt_idmap *idmap,
>  		}
>  	}
>  
> +	if (ext4_should_use_buffered_iomap(inode))
> +		ext4_set_inode_state(inode, EXT4_STATE_BUFFERED_IOMAP);
> +
>  	if (ext4_handle_valid(handle)) {
>  		ei->i_sync_tid = handle->h_transaction->t_tid;
>  		ei->i_datasync_tid = handle->h_transaction->t_tid;
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index b2ab202af57b..f95d4c321cbb 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -779,6 +779,8 @@ static int _ext4_get_block(struct inode *inode, sector_t iblock,
>  
>  	if (ext4_has_inline_data(inode))
>  		return -ERANGE;
> +	if (WARN_ON(ext4_test_inode_state(inode, EXT4_STATE_BUFFERED_IOMAP)))
> +		return -EINVAL;
>  
>  	map.m_lblk = iblock;
>  	map.m_len = bh->b_size >> inode->i_blkbits;
> @@ -4121,6 +4123,8 @@ void ext4_set_aops(struct inode *inode)
>  	}
>  	if (IS_DAX(inode))
>  		inode->i_mapping->a_ops = &ext4_dax_aops;
> +	else if (ext4_test_inode_state(inode, EXT4_STATE_BUFFERED_IOMAP))
> +		inode->i_mapping->a_ops = &ext4_iomap_aops;
>  	else if (test_opt(inode->i_sb, DELALLOC))
>  		inode->i_mapping->a_ops = &ext4_da_aops;
>  	else
> @@ -5185,6 +5189,30 @@ static const char *check_igot_inode(struct inode *inode, ext4_iget_flags flags)
>  	return NULL;
>  }
>  
> +bool ext4_should_use_buffered_iomap(struct inode *inode)
> +{
> +	struct super_block *sb = inode->i_sb;
> +
> +	if (ext4_has_feature_inline_data(sb))
> +		return false;
> +	if (ext4_has_feature_verity(sb))
> +		return false;
> +	if (ext4_has_feature_bigalloc(sb))
> +		return false;
> +	if (!IS_DAX(inode))
> +		return false;
> +	if (!S_ISREG(inode->i_mode))
> +		return false;
> +	if (ext4_should_journal_data(inode))
> +		return false;
> +	if (ext4_test_inode_flag(inode, EXT4_INODE_EA_INODE))
> +		return false;
> +	if (ext4_test_inode_flag(inode, EXT4_INODE_ENCRYPT))
> +		return false;
> +
> +	return true;
> +}
> +
>  struct inode *__ext4_iget(struct super_block *sb, unsigned long ino,
>  			  ext4_iget_flags flags, const char *function,
>  			  unsigned int line)
> @@ -5449,6 +5477,9 @@ struct inode *__ext4_iget(struct super_block *sb, unsigned long ino,
>  	if (ret)
>  		goto bad_inode;
>  
> +	if (ext4_should_use_buffered_iomap(inode))
> +		ext4_set_inode_state(inode, EXT4_STATE_BUFFERED_IOMAP);
> +
>  	if (S_ISREG(inode->i_mode)) {
>  		inode->i_op = &ext4_file_inode_operations;
>  		inode->i_fop = &ext4_file_operations;
> diff --git a/fs/ext4/move_extent.c b/fs/ext4/move_extent.c
> index 18a9e7c47975..23b4b77c5af8 100644
> --- a/fs/ext4/move_extent.c
> +++ b/fs/ext4/move_extent.c
> @@ -597,6 +597,14 @@ ext4_move_extents(struct file *o_filp, struct file *d_filp, __u64 orig_blk,
>  		return -EOPNOTSUPP;
>  	}
>  
> +	/* TODO: not supported since block getting function is not switched */
> +	if (ext4_test_inode_state(orig_inode, EXT4_STATE_BUFFERED_IOMAP) ||
> +	    ext4_test_inode_state(donor_inode, EXT4_STATE_BUFFERED_IOMAP)) {
> +		ext4_msg(orig_inode->i_sb, KERN_ERR,
> +			 "Online defrag not supported with buffered iomap");
> +		return -EOPNOTSUPP;
> +	}
> +
>  	if (IS_ENCRYPTED(orig_inode) || IS_ENCRYPTED(donor_inode)) {
>  		ext4_msg(orig_inode->i_sb, KERN_ERR,
>  			 "Online defrag not supported for encrypted files");
>