Message-ID: <20131002120142.GA25126@quack.suse.cz>
Date:	Wed, 2 Oct 2013 14:01:42 +0200
From:	Jan Kara <jack@...e.cz>
To:	Miklos Szeredi <miklos@...redi.hu>
Cc:	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
	viro@...IV.linux.org.uk, torvalds@...ux-foundation.org,
	hch@...radead.org, akpm@...ux-foundation.org, dhowells@...hat.com,
	zab@...hat.com, jack@...e.cz, tytso@....edu, mszeredi@...e.cz
Subject: Re: [PATCH 4/7] ext4: rename: create ext4_renament structure for
 local vars

On Tue 01-10-13 18:00:36, Miklos Szeredi wrote:
> From: Miklos Szeredi <mszeredi@...e.cz>
> 
> Need to split up ext4_rename() into helpers but there are two many local
> variables involved, so create a new structure.  This also, apparently,
> makes the generated code size slightly smaller.
> 
> Signed-off-by: Miklos Szeredi <mszeredi@...e.cz>
> ---
>  fs/ext4/namei.c | 207 ++++++++++++++++++++++++++++++--------------------------
>  1 file changed, 110 insertions(+), 97 deletions(-)
> 
> diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
> index 1bec5a5..01bd80e 100644
> --- a/fs/ext4/namei.c
> +++ b/fs/ext4/namei.c
> @@ -3002,6 +3002,18 @@ static struct buffer_head *ext4_get_first_dir_block(handle_t *handle,
>  	return ext4_get_first_inline_block(inode, parent_de, retval);
>  }
>  
> +struct ext4_renament {
> +	struct inode *dir;
> +	struct dentry *dentry;
> +	struct inode *inode;
> +	struct buffer_head *bh;
> +	struct buffer_head *dir_bh;
> +	struct ext4_dir_entry_2 *de;
> +	struct ext4_dir_entry_2 *parent_de;
> +	int inlined;
> +	int parent_inlined;
> +};
  The patch looks good to me. Only the inline handling looks a bit strange.
The structure have inlined and parent_inlined however you only use
new.inlined and old.parent_inlined. Now new.inlined actually means whether
new.dir is inlined (i.e. the destination directory of rename) and
old.parent_inlined is set when the source for rename is an inlined
directory. So at least the naming looks the other way around to me.

Also as the code currently is including 'inlined' and 'parent_inlined' in
ext4_renament looks like overdoing it a bit. But I haven't checked the
other two patches yet.

								Honza
>  /*
>   * Anybody can rename anything with this: the permission checks are left to the
>   * higher-level routines.
> @@ -3014,193 +3026,194 @@ static int ext4_rename(struct inode *old_dir, struct dentry *old_dentry,
>  		       struct inode *new_dir, struct dentry *new_dentry)
>  {
>  	handle_t *handle = NULL;
> -	struct inode *old_inode, *new_inode;
> -	struct buffer_head *old_bh, *new_bh, *dir_bh;
> -	struct ext4_dir_entry_2 *old_de, *new_de;
> +	struct ext4_renament old = {
> +		.dir = old_dir,
> +		.dentry = old_dentry,
> +	};
> +	struct ext4_renament new = {
> +		.dir = new_dir,
> +		.dentry = new_dentry,
> +	};
>  	int retval;
> -	int inlined = 0, new_inlined = 0;
> -	struct ext4_dir_entry_2 *parent_de;
> -
> -	dquot_initialize(old_dir);
> -	dquot_initialize(new_dir);
>  
> -	old_bh = new_bh = dir_bh = NULL;
> +	dquot_initialize(old.dir);
> +	dquot_initialize(new.dir);
>  
>  	/* Initialize quotas before so that eventual writes go
>  	 * in separate transaction */
> -	if (new_dentry->d_inode)
> -		dquot_initialize(new_dentry->d_inode);
> +	if (new.dentry->d_inode)
> +		dquot_initialize(new.dentry->d_inode);
>  
> -	old_bh = ext4_find_entry(old_dir, &old_dentry->d_name, &old_de, NULL);
> +	old.bh = ext4_find_entry(old.dir, &old.dentry->d_name, &old.de, NULL);
>  	/*
>  	 *  Check for inode number is _not_ due to possible IO errors.
>  	 *  We might rmdir the source, keep it as pwd of some process
>  	 *  and merrily kill the link to whatever was created under the
>  	 *  same name. Goodbye sticky bit ;-<
>  	 */
> -	old_inode = old_dentry->d_inode;
> +	old.inode = old.dentry->d_inode;
>  	retval = -ENOENT;
> -	if (!old_bh || le32_to_cpu(old_de->inode) != old_inode->i_ino)
> +	if (!old.bh || le32_to_cpu(old.de->inode) != old.inode->i_ino)
>  		goto end_rename;
>  
> -	new_inode = new_dentry->d_inode;
> -	new_bh = ext4_find_entry(new_dir, &new_dentry->d_name,
> -				 &new_de, &new_inlined);
> -	if (new_bh) {
> -		if (!new_inode) {
> -			brelse(new_bh);
> -			new_bh = NULL;
> +	new.inode = new.dentry->d_inode;
> +	new.bh = ext4_find_entry(new.dir, &new.dentry->d_name,
> +				 &new.de, &new.inlined);
> +	if (new.bh) {
> +		if (!new.inode) {
> +			brelse(new.bh);
> +			new.bh = NULL;
>  		}
>  	}
> -	if (new_inode && !test_opt(new_dir->i_sb, NO_AUTO_DA_ALLOC))
> -		ext4_alloc_da_blocks(old_inode);
> +	if (new.inode && !test_opt(new.dir->i_sb, NO_AUTO_DA_ALLOC))
> +		ext4_alloc_da_blocks(old.inode);
>  
> -	handle = ext4_journal_start(old_dir, EXT4_HT_DIR,
> -		(2 * EXT4_DATA_TRANS_BLOCKS(old_dir->i_sb) +
> +	handle = ext4_journal_start(old.dir, EXT4_HT_DIR,
> +		(2 * EXT4_DATA_TRANS_BLOCKS(old.dir->i_sb) +
>  		 EXT4_INDEX_EXTRA_TRANS_BLOCKS + 2));
>  	if (IS_ERR(handle))
>  		return PTR_ERR(handle);
>  
> -	if (IS_DIRSYNC(old_dir) || IS_DIRSYNC(new_dir))
> +	if (IS_DIRSYNC(old.dir) || IS_DIRSYNC(new.dir))
>  		ext4_handle_sync(handle);
>  
> -	if (S_ISDIR(old_inode->i_mode)) {
> -		if (new_inode) {
> +	if (S_ISDIR(old.inode->i_mode)) {
> +		if (new.inode) {
>  			retval = -ENOTEMPTY;
> -			if (!empty_dir(new_inode))
> +			if (!empty_dir(new.inode))
>  				goto end_rename;
>  		}
>  		retval = -EIO;
> -		dir_bh = ext4_get_first_dir_block(handle, old_inode,
> -						  &retval, &parent_de,
> -						  &inlined);
> -		if (!dir_bh)
> +		old.dir_bh = ext4_get_first_dir_block(handle, old.inode,
> +						  &retval, &old.parent_de,
> +						  &old.parent_inlined);
> +		if (!old.dir_bh)
>  			goto end_rename;
> -		if (le32_to_cpu(parent_de->inode) != old_dir->i_ino)
> +		if (le32_to_cpu(old.parent_de->inode) != old.dir->i_ino)
>  			goto end_rename;
>  		retval = -EMLINK;
> -		if (!new_inode && new_dir != old_dir &&
> -		    EXT4_DIR_LINK_MAX(new_dir))
> +		if (!new.inode && new.dir != old.dir &&
> +		    EXT4_DIR_LINK_MAX(new.dir))
>  			goto end_rename;
> -		BUFFER_TRACE(dir_bh, "get_write_access");
> -		retval = ext4_journal_get_write_access(handle, dir_bh);
> +		BUFFER_TRACE(old.dir_bh, "get_write_access");
> +		retval = ext4_journal_get_write_access(handle, old.dir_bh);
>  		if (retval)
>  			goto end_rename;
>  	}
> -	if (!new_bh) {
> -		retval = ext4_add_entry(handle, new_dentry, old_inode);
> +	if (!new.bh) {
> +		retval = ext4_add_entry(handle, new.dentry, old.inode);
>  		if (retval)
>  			goto end_rename;
>  	} else {
> -		BUFFER_TRACE(new_bh, "get write access");
> -		retval = ext4_journal_get_write_access(handle, new_bh);
> +		BUFFER_TRACE(new.bh, "get write access");
> +		retval = ext4_journal_get_write_access(handle, new.bh);
>  		if (retval)
>  			goto end_rename;
> -		new_de->inode = cpu_to_le32(old_inode->i_ino);
> -		if (EXT4_HAS_INCOMPAT_FEATURE(new_dir->i_sb,
> +		new.de->inode = cpu_to_le32(old.inode->i_ino);
> +		if (EXT4_HAS_INCOMPAT_FEATURE(new.dir->i_sb,
>  					      EXT4_FEATURE_INCOMPAT_FILETYPE))
> -			new_de->file_type = old_de->file_type;
> -		new_dir->i_version++;
> -		new_dir->i_ctime = new_dir->i_mtime =
> -					ext4_current_time(new_dir);
> -		ext4_mark_inode_dirty(handle, new_dir);
> -		BUFFER_TRACE(new_bh, "call ext4_handle_dirty_metadata");
> -		if (!new_inlined) {
> +			new.de->file_type = old.de->file_type;
> +		new.dir->i_version++;
> +		new.dir->i_ctime = new.dir->i_mtime =
> +					ext4_current_time(new.dir);
> +		ext4_mark_inode_dirty(handle, new.dir);
> +		BUFFER_TRACE(new.bh, "call ext4_handle_dirty_metadata");
> +		if (!new.inlined) {
>  			retval = ext4_handle_dirty_dirent_node(handle,
> -							       new_dir, new_bh);
> +							       new.dir, new.bh);
>  			if (unlikely(retval)) {
> -				ext4_std_error(new_dir->i_sb, retval);
> +				ext4_std_error(new.dir->i_sb, retval);
>  				goto end_rename;
>  			}
>  		}
> -		brelse(new_bh);
> -		new_bh = NULL;
> +		brelse(new.bh);
> +		new.bh = NULL;
>  	}
>  
>  	/*
>  	 * Like most other Unix systems, set the ctime for inodes on a
>  	 * rename.
>  	 */
> -	old_inode->i_ctime = ext4_current_time(old_inode);
> -	ext4_mark_inode_dirty(handle, old_inode);
> +	old.inode->i_ctime = ext4_current_time(old.inode);
> +	ext4_mark_inode_dirty(handle, old.inode);
>  
>  	/*
>  	 * ok, that's it
>  	 */
> -	if (le32_to_cpu(old_de->inode) != old_inode->i_ino ||
> -	    old_de->name_len != old_dentry->d_name.len ||
> -	    strncmp(old_de->name, old_dentry->d_name.name, old_de->name_len) ||
> -	    (retval = ext4_delete_entry(handle, old_dir,
> -					old_de, old_bh)) == -ENOENT) {
> -		/* old_de could have moved from under us during htree split, so
> +	if (le32_to_cpu(old.de->inode) != old.inode->i_ino ||
> +	    old.de->name_len != old.dentry->d_name.len ||
> +	    strncmp(old.de->name, old.dentry->d_name.name, old.de->name_len) ||
> +	    (retval = ext4_delete_entry(handle, old.dir,
> +					old.de, old.bh)) == -ENOENT) {
> +		/* old.de could have moved from under us during htree split, so
>  		 * make sure that we are deleting the right entry.  We might
>  		 * also be pointing to a stale entry in the unused part of
> -		 * old_bh so just checking inum and the name isn't enough. */
> +		 * old.bh so just checking inum and the name isn't enough. */
>  		struct buffer_head *old_bh2;
>  		struct ext4_dir_entry_2 *old_de2;
>  
> -		old_bh2 = ext4_find_entry(old_dir, &old_dentry->d_name,
> +		old_bh2 = ext4_find_entry(old.dir, &old.dentry->d_name,
>  					  &old_de2, NULL);
>  		if (old_bh2) {
> -			retval = ext4_delete_entry(handle, old_dir,
> +			retval = ext4_delete_entry(handle, old.dir,
>  						   old_de2, old_bh2);
>  			brelse(old_bh2);
>  		}
>  	}
>  	if (retval) {
> -		ext4_warning(old_dir->i_sb,
> +		ext4_warning(old.dir->i_sb,
>  				"Deleting old file (%lu), %d, error=%d",
> -				old_dir->i_ino, old_dir->i_nlink, retval);
> +				old.dir->i_ino, old.dir->i_nlink, retval);
>  	}
>  
> -	if (new_inode) {
> -		ext4_dec_count(handle, new_inode);
> -		new_inode->i_ctime = ext4_current_time(new_inode);
> +	if (new.inode) {
> +		ext4_dec_count(handle, new.inode);
> +		new.inode->i_ctime = ext4_current_time(new.inode);
>  	}
> -	old_dir->i_ctime = old_dir->i_mtime = ext4_current_time(old_dir);
> -	ext4_update_dx_flag(old_dir);
> -	if (dir_bh) {
> -		parent_de->inode = cpu_to_le32(new_dir->i_ino);
> -		BUFFER_TRACE(dir_bh, "call ext4_handle_dirty_metadata");
> -		if (!inlined) {
> -			if (is_dx(old_inode)) {
> +	old.dir->i_ctime = old.dir->i_mtime = ext4_current_time(old.dir);
> +	ext4_update_dx_flag(old.dir);
> +	if (old.dir_bh) {
> +		old.parent_de->inode = cpu_to_le32(new.dir->i_ino);
> +		BUFFER_TRACE(old.dir_bh, "call ext4_handle_dirty_metadata");
> +		if (!old.parent_inlined) {
> +			if (is_dx(old.inode)) {
>  				retval = ext4_handle_dirty_dx_node(handle,
> -								   old_inode,
> -								   dir_bh);
> +								   old.inode,
> +								   old.dir_bh);
>  			} else {
>  				retval = ext4_handle_dirty_dirent_node(handle,
> -							old_inode, dir_bh);
> +							old.inode, old.dir_bh);
>  			}
>  		} else {
> -			retval = ext4_mark_inode_dirty(handle, old_inode);
> +			retval = ext4_mark_inode_dirty(handle, old.inode);
>  		}
>  		if (retval) {
> -			ext4_std_error(old_dir->i_sb, retval);
> +			ext4_std_error(old.dir->i_sb, retval);
>  			goto end_rename;
>  		}
> -		ext4_dec_count(handle, old_dir);
> -		if (new_inode) {
> +		ext4_dec_count(handle, old.dir);
> +		if (new.inode) {
>  			/* checked empty_dir above, can't have another parent,
>  			 * ext4_dec_count() won't work for many-linked dirs */
> -			clear_nlink(new_inode);
> +			clear_nlink(new.inode);
>  		} else {
> -			ext4_inc_count(handle, new_dir);
> -			ext4_update_dx_flag(new_dir);
> -			ext4_mark_inode_dirty(handle, new_dir);
> +			ext4_inc_count(handle, new.dir);
> +			ext4_update_dx_flag(new.dir);
> +			ext4_mark_inode_dirty(handle, new.dir);
>  		}
>  	}
> -	ext4_mark_inode_dirty(handle, old_dir);
> -	if (new_inode) {
> -		ext4_mark_inode_dirty(handle, new_inode);
> -		if (!new_inode->i_nlink)
> -			ext4_orphan_add(handle, new_inode);
> +	ext4_mark_inode_dirty(handle, old.dir);
> +	if (new.inode) {
> +		ext4_mark_inode_dirty(handle, new.inode);
> +		if (!new.inode->i_nlink)
> +			ext4_orphan_add(handle, new.inode);
>  	}
>  	retval = 0;
>  
>  end_rename:
> -	brelse(dir_bh);
> -	brelse(old_bh);
> -	brelse(new_bh);
> +	brelse(old.dir_bh);
> +	brelse(old.bh);
> +	brelse(new.bh);
>  	if (handle)
>  		ext4_journal_stop(handle);
>  	return retval;
> -- 
> 1.8.1.4
> 
-- 
Jan Kara <jack@...e.cz>
SUSE Labs, CR
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