Date:   Tue, 2 Jul 2019 20:50:13 -0700
From:   "Darrick J. Wong" <darrick.wong@...cle.com>
To:     "Theodore Ts'o" <tytso@....edu>
Cc:     Ext4 Developers List <linux-ext4@...r.kernel.org>
Subject: Re: [PATCH 1/3] ext4: rename "dirent_csum" functions to use
 "dirblock"

On Tue, Jul 02, 2019 at 05:29:23PM -0400, Theodore Ts'o wrote:
> Functions such as ext4_dirent_csum_verify() and ext4_dirent_csum_set()
> don't actually operate on a directory entry, but a directory block.
> And while they take a struct ext4_dir_entry *dirent as an argument, it
> had better be the first directory at the beginning of the direct
> block, or things will go very wrong.
> 
> Rename the following functions so that things make more sense, and
> remove a lot of confusing casts along the way:
> 
>    ext4_dirent_csum_verify	 -> ext4_dirblock_csum_verify
>    ext4_dirent_csum_set		 -> ext4_dirblock_csum_set
>    ext4_dirent_csum		 -> ext4_dirblock_csum
>    ext4_handle_dirty_dirent_node -> ext4_handle_dirty_dirblock
> 
> Signed-off-by: Theodore Ts'o <tytso@....edu>

Looks ok,
Reviewed-by: Darrick J. Wong <darrick.wong@...cle.com>

--D

> ---
>  fs/ext4/dir.c    |  3 +--
>  fs/ext4/ext4.h   |  9 ++++---
>  fs/ext4/inline.c |  2 +-
>  fs/ext4/namei.c  | 62 ++++++++++++++++++++++--------------------------
>  4 files changed, 35 insertions(+), 41 deletions(-)
> 
> diff --git a/fs/ext4/dir.c b/fs/ext4/dir.c
> index 3a77b7affd09..86054f31fe4d 100644
> --- a/fs/ext4/dir.c
> +++ b/fs/ext4/dir.c
> @@ -194,8 +194,7 @@ static int ext4_readdir(struct file *file, struct dir_context *ctx)
>  
>  		/* Check the checksum */
>  		if (!buffer_verified(bh) &&
> -		    !ext4_dirent_csum_verify(inode,
> -				(struct ext4_dir_entry *)bh->b_data)) {
> +		    !ext4_dirblock_csum_verify(inode, bh)) {
>  			EXT4_ERROR_FILE(file, 0, "directory fails checksum "
>  					"at offset %llu",
>  					(unsigned long long)ctx->pos);
> diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
> index 7215a2a2a0de..5b86df7ec326 100644
> --- a/fs/ext4/ext4.h
> +++ b/fs/ext4/ext4.h
> @@ -2602,8 +2602,8 @@ extern int ext4_ext_migrate(struct inode *);
>  extern int ext4_ind_migrate(struct inode *inode);
>  
>  /* namei.c */
> -extern int ext4_dirent_csum_verify(struct inode *inode,
> -				   struct ext4_dir_entry *dirent);
> +extern int ext4_dirblock_csum_verify(struct inode *inode,
> +				     struct buffer_head *bh);
>  extern int ext4_orphan_add(handle_t *, struct inode *);
>  extern int ext4_orphan_del(handle_t *, struct inode *);
>  extern int ext4_htree_fill_tree(struct file *dir_file, __u32 start_hash,
> @@ -3149,9 +3149,8 @@ extern struct ext4_dir_entry_2 *ext4_init_dot_dotdot(struct inode *inode,
>  				 unsigned int parent_ino, int dotdot_real_len);
>  extern void initialize_dirent_tail(struct ext4_dir_entry_tail *t,
>  				   unsigned int blocksize);
> -extern int ext4_handle_dirty_dirent_node(handle_t *handle,
> -					 struct inode *inode,
> -					 struct buffer_head *bh);
> +extern int ext4_handle_dirty_dirblock(handle_t *handle, struct inode *inode,
> +				      struct buffer_head *bh);
>  extern int ext4_ci_compare(const struct inode *parent,
>  			   const struct qstr *fname,
>  			   const struct qstr *entry, bool quick);
> diff --git a/fs/ext4/inline.c b/fs/ext4/inline.c
> index f73bc3925282..f19dd5a08d0d 100644
> --- a/fs/ext4/inline.c
> +++ b/fs/ext4/inline.c
> @@ -1164,7 +1164,7 @@ static int ext4_finish_convert_inline_dir(handle_t *handle,
>  		initialize_dirent_tail(t, inode->i_sb->s_blocksize);
>  	}
>  	set_buffer_uptodate(dir_block);
> -	err = ext4_handle_dirty_dirent_node(handle, inode, dir_block);
> +	err = ext4_handle_dirty_dirblock(handle, inode, dir_block);
>  	if (err)
>  		return err;
>  	set_buffer_verified(dir_block);
> diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
> index 0cda080f3fd5..4f0bcbbcfe96 100644
> --- a/fs/ext4/namei.c
> +++ b/fs/ext4/namei.c
> @@ -163,7 +163,7 @@ static struct buffer_head *__ext4_read_dirblock(struct inode *inode,
>  		}
>  	}
>  	if (!is_dx_block) {
> -		if (ext4_dirent_csum_verify(inode, dirent))
> +		if (ext4_dirblock_csum_verify(inode, bh))
>  			set_buffer_verified(bh);
>  		else {
>  			ext4_error_inode(inode, func, line, block,
> @@ -304,17 +304,17 @@ void initialize_dirent_tail(struct ext4_dir_entry_tail *t,
>  
>  /* Walk through a dirent block to find a checksum "dirent" at the tail */
>  static struct ext4_dir_entry_tail *get_dirent_tail(struct inode *inode,
> -						   struct ext4_dir_entry *de)
> +						   struct buffer_head *bh)
>  {
>  	struct ext4_dir_entry_tail *t;
>  
>  #ifdef PARANOID
>  	struct ext4_dir_entry *d, *top;
>  
> -	d = de;
> -	top = (struct ext4_dir_entry *)(((void *)de) +
> +	d = (struct ext4_dir_entry *)bh->b_data;
> +	top = (struct ext4_dir_entry *)(bh->b_data +
>  		(EXT4_BLOCK_SIZE(inode->i_sb) -
> -		sizeof(struct ext4_dir_entry_tail)));
> +		 sizeof(struct ext4_dir_entry_tail)));
>  	while (d < top && d->rec_len)
>  		d = (struct ext4_dir_entry *)(((void *)d) +
>  		    le16_to_cpu(d->rec_len));
> @@ -324,7 +324,7 @@ static struct ext4_dir_entry_tail *get_dirent_tail(struct inode *inode,
>  
>  	t = (struct ext4_dir_entry_tail *)d;
>  #else
> -	t = EXT4_DIRENT_TAIL(de, EXT4_BLOCK_SIZE(inode->i_sb));
> +	t = EXT4_DIRENT_TAIL(bh->b_data, EXT4_BLOCK_SIZE(inode->i_sb));
>  #endif
>  
>  	if (t->det_reserved_zero1 ||
> @@ -336,8 +336,7 @@ static struct ext4_dir_entry_tail *get_dirent_tail(struct inode *inode,
>  	return t;
>  }
>  
> -static __le32 ext4_dirent_csum(struct inode *inode,
> -			       struct ext4_dir_entry *dirent, int size)
> +static __le32 ext4_dirblock_csum(struct inode *inode, void *dirent, int size)
>  {
>  	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
>  	struct ext4_inode_info *ei = EXT4_I(inode);
> @@ -357,49 +356,49 @@ static void __warn_no_space_for_csum(struct inode *inode, const char *func,
>  		"No space for directory leaf checksum. Please run e2fsck -D.");
>  }
>  
> -int ext4_dirent_csum_verify(struct inode *inode, struct ext4_dir_entry *dirent)
> +int ext4_dirblock_csum_verify(struct inode *inode, struct buffer_head *bh)
>  {
>  	struct ext4_dir_entry_tail *t;
>  
>  	if (!ext4_has_metadata_csum(inode->i_sb))
>  		return 1;
>  
> -	t = get_dirent_tail(inode, dirent);
> +	t = get_dirent_tail(inode, bh);
>  	if (!t) {
>  		warn_no_space_for_csum(inode);
>  		return 0;
>  	}
>  
> -	if (t->det_checksum != ext4_dirent_csum(inode, dirent,
> -						(void *)t - (void *)dirent))
> +	if (t->det_checksum != ext4_dirblock_csum(inode, bh->b_data,
> +						(char *)t - bh->b_data))
>  		return 0;
>  
>  	return 1;
>  }
>  
> -static void ext4_dirent_csum_set(struct inode *inode,
> -				 struct ext4_dir_entry *dirent)
> +static void ext4_dirblock_csum_set(struct inode *inode,
> +				 struct buffer_head *bh)
>  {
>  	struct ext4_dir_entry_tail *t;
>  
>  	if (!ext4_has_metadata_csum(inode->i_sb))
>  		return;
>  
> -	t = get_dirent_tail(inode, dirent);
> +	t = get_dirent_tail(inode, bh);
>  	if (!t) {
>  		warn_no_space_for_csum(inode);
>  		return;
>  	}
>  
> -	t->det_checksum = ext4_dirent_csum(inode, dirent,
> -					   (void *)t - (void *)dirent);
> +	t->det_checksum = ext4_dirblock_csum(inode, bh->b_data,
> +					   (char *)t - bh->b_data);
>  }
>  
> -int ext4_handle_dirty_dirent_node(handle_t *handle,
> -				  struct inode *inode,
> -				  struct buffer_head *bh)
> +int ext4_handle_dirty_dirblock(handle_t *handle,
> +			       struct inode *inode,
> +			       struct buffer_head *bh)
>  {
> -	ext4_dirent_csum_set(inode, (struct ext4_dir_entry *)bh->b_data);
> +	ext4_dirblock_csum_set(inode, bh);
>  	return ext4_handle_dirty_metadata(handle, inode, bh);
>  }
>  
> @@ -1530,8 +1529,7 @@ static struct buffer_head *__ext4_find_entry(struct inode *dir,
>  		if (!buffer_verified(bh) &&
>  		    !is_dx_internal_node(dir, block,
>  					 (struct ext4_dir_entry *)bh->b_data) &&
> -		    !ext4_dirent_csum_verify(dir,
> -				(struct ext4_dir_entry *)bh->b_data)) {
> +		    !ext4_dirblock_csum_verify(dir, bh)) {
>  			EXT4_ERROR_INODE(dir, "checksumming directory "
>  					 "block %lu", (unsigned long)block);
>  			brelse(bh);
> @@ -1894,7 +1892,7 @@ static struct ext4_dir_entry_2 *do_split(handle_t *handle, struct inode *dir,
>  		de = de2;
>  	}
>  	dx_insert_block(frame, hash2 + continued, newblock);
> -	err = ext4_handle_dirty_dirent_node(handle, dir, bh2);
> +	err = ext4_handle_dirty_dirblock(handle, dir, bh2);
>  	if (err)
>  		goto journal_error;
>  	err = ext4_handle_dirty_dx_node(handle, dir, frame->bh);
> @@ -2022,7 +2020,7 @@ static int add_dirent_to_buf(handle_t *handle, struct ext4_filename *fname,
>  	inode_inc_iversion(dir);
>  	ext4_mark_inode_dirty(handle, dir);
>  	BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata");
> -	err = ext4_handle_dirty_dirent_node(handle, dir, bh);
> +	err = ext4_handle_dirty_dirblock(handle, dir, bh);
>  	if (err)
>  		ext4_std_error(dir->i_sb, err);
>  	return 0;
> @@ -2126,7 +2124,7 @@ static int make_indexed_dir(handle_t *handle, struct ext4_filename *fname,
>  	retval = ext4_handle_dirty_dx_node(handle, dir, frame->bh);
>  	if (retval)
>  		goto out_frames;	
> -	retval = ext4_handle_dirty_dirent_node(handle, dir, bh2);
> +	retval = ext4_handle_dirty_dirblock(handle, dir, bh2);
>  	if (retval)
>  		goto out_frames;	
>  
> @@ -2512,7 +2510,7 @@ static int ext4_delete_entry(handle_t *handle,
>  		goto out;
>  
>  	BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata");
> -	err = ext4_handle_dirty_dirent_node(handle, dir, bh);
> +	err = ext4_handle_dirty_dirblock(handle, dir, bh);
>  	if (unlikely(err))
>  		goto out;
>  
> @@ -2744,7 +2742,7 @@ static int ext4_init_new_dir(handle_t *handle, struct inode *dir,
>  	}
>  
>  	BUFFER_TRACE(dir_block, "call ext4_handle_dirty_metadata");
> -	err = ext4_handle_dirty_dirent_node(handle, inode, dir_block);
> +	err = ext4_handle_dirty_dirblock(handle, inode, dir_block);
>  	if (err)
>  		goto out;
>  	set_buffer_verified(dir_block);
> @@ -3492,9 +3490,8 @@ static int ext4_rename_dir_finish(handle_t *handle, struct ext4_renament *ent,
>  							   ent->inode,
>  							   ent->dir_bh);
>  		} else {
> -			retval = ext4_handle_dirty_dirent_node(handle,
> -							       ent->inode,
> -							       ent->dir_bh);
> +			retval = ext4_handle_dirty_dirblock(handle, ent->inode,
> +							    ent->dir_bh);
>  		}
>  	} else {
>  		retval = ext4_mark_inode_dirty(handle, ent->inode);
> @@ -3524,8 +3521,7 @@ static int ext4_setent(handle_t *handle, struct ext4_renament *ent,
>  	ext4_mark_inode_dirty(handle, ent->dir);
>  	BUFFER_TRACE(ent->bh, "call ext4_handle_dirty_metadata");
>  	if (!ent->inlined) {
> -		retval = ext4_handle_dirty_dirent_node(handle,
> -						       ent->dir, ent->bh);
> +		retval = ext4_handle_dirty_dirblock(handle, ent->dir, ent->bh);
>  		if (unlikely(retval)) {
>  			ext4_std_error(ent->dir->i_sb, retval);
>  			return retval;
> -- 
> 2.22.0
> 

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