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Date:	Tue, 22 Sep 2009 19:48:38 +0200
From:	Jan Kara <jack@...e.cz>
To:	LKML <linux-kernel@...r.kernel.org>
Cc:	npiggin@...e.de, viro@...IV.linux.org.uk,
	linux-ext4@...r.kernel.org, hch@...radead.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Jan Kara <jack@...e.cz>, tytso@....edu
Subject: Re: [PATCH 5/7] ext4: Convert filesystem to the new truncate
	calling convention

  Oops, sorry for the subject. It should have been just [PATCH] instead
of [PATCH 5/7]...

On Tue 22-09-09 19:42:05, Jan Kara wrote:
> CC: linux-ext4@...r.kernel.org
> CC: tytso@....edu
> Signed-off-by: Jan Kara <jack@...e.cz>
> ---
>  fs/ext4/file.c  |    2 +-
>  fs/ext4/inode.c |  166 ++++++++++++++++++++++++++++++++----------------------
>  2 files changed, 99 insertions(+), 69 deletions(-)
> 
> diff --git a/fs/ext4/file.c b/fs/ext4/file.c
> index 3f1873f..22f49d7 100644
> --- a/fs/ext4/file.c
> +++ b/fs/ext4/file.c
> @@ -198,7 +198,7 @@ const struct file_operations ext4_file_operations = {
>  };
>  
>  const struct inode_operations ext4_file_inode_operations = {
> -	.truncate	= ext4_truncate,
> +	.new_truncate	= 1,
>  	.setattr	= ext4_setattr,
>  	.getattr	= ext4_getattr,
>  #ifdef CONFIG_EXT4_FS_XATTR
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index 58492ab..be25874 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -4682,28 +4686,97 @@ int ext4_write_inode(struct inode *inode, int wait)
>  }
>  
>  /*
> - * ext4_setattr()
> + * ext4_setsize()
> + *
> + * This is a helper for ext4_setattr(). It sets i_size, truncates page cache
> + * and truncates inode blocks if they are over i_size.
>   *
> - * Called from notify_change.
> + * We take care of updating i_disksize and adding inode to the orphan list.
> + * That makes sure that we can guarantee that any commit will leave the blocks
> + * being truncated in an unused state on disk.  (On recovery, the inode will
> + * get truncated and the blocks will be freed, so we have a strong guarantee
> + * that no future commit will leave these blocks visible to the user.)
>   *
> - * We want to trap VFS attempts to truncate the file as soon as
> - * possible.  In particular, we want to make sure that when the VFS
> - * shrinks i_size, we put the inode on the orphan list and modify
> - * i_disksize immediately, so that during the subsequent flushing of
> - * dirty pages and freeing of disk blocks, we can guarantee that any
> - * commit will leave the blocks being flushed in an unused state on
> - * disk.  (On recovery, the inode will get truncated and the blocks will
> - * be freed, so we have a strong guarantee that no future commit will
> - * leave these blocks visible to the user.)
> + * Another thing we have to assure is that if we are in ordered mode and inode
> + * is still attached to the committing transaction, we must we start writeout
> + * of all the dirty pages which are being truncated.  This way we are sure that
> + * all the data written in the previous transaction are already on disk
> + * (truncate waits for pages under writeback).
> + */
> +static int ext4_setsize(struct inode *inode, loff_t newsize)
> +{
> +	int error = 0, rc;
> +	loff_t oldsize = inode->i_size;
> +	handle_t *handle;
> +
> +	error = inode_newsize_ok(inode, newsize);
> +	if (error)
> +		goto out;
> +	/* VFS should have checked these and return error... */
> +	WARN_ON(!S_ISREG(inode->i_mode) || IS_APPEND(inode) ||
> +		IS_IMMUTABLE(inode));
> +
> +	if (newsize < oldsize) {
> +		handle = ext4_journal_start(inode, 3);
> +		if (IS_ERR(handle)) {
> +			error = PTR_ERR(handle);
> +			goto err_out;
> +		}
> +
> +		error = ext4_orphan_add(handle, inode);
> +		EXT4_I(inode)->i_disksize = newsize;
> +		rc = ext4_mark_inode_dirty(handle, inode);
> +		if (!error)
> +			error = rc;
> +		ext4_journal_stop(handle);
> +
> +		if (ext4_should_order_data(inode)) {
> +			error = ext4_begin_ordered_truncate(inode, newsize);
> +			if (error) {
> +				/* Do as much error cleanup as possible */
> +				handle = ext4_journal_start(inode, 3);
> +				if (IS_ERR(handle)) {
> +					ext4_orphan_del(NULL, inode);
> +					goto err_out;
> +				}
> +				ext4_orphan_del(handle, inode);
> +				ext4_journal_stop(handle);
> +				goto err_out;
> +			}
> +		}
> +	} else if (!(EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL)) {
> +		struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
> +
> +		if (newsize > sbi->s_bitmap_maxbytes) {
> +			error = -EFBIG;
> +			goto out;
> +		}
> +	}
> +
> +	i_size_write(inode, newsize);
> +	truncate_pagecache(inode, oldsize, newsize);
> +	ext4_truncate(inode);
> +
> +	/*
> +	 * If we failed to get a transaction handle at all, we need to clean up
> +         * the in-core orphan list manually.
> +	 */
> +	if (inode->i_nlink)
> +		ext4_orphan_del(NULL, inode);
> +err_out:
> +	ext4_std_error(inode->i_sb, error);
> +out:
> +	return error;
> +}
> +
> +
> +/*
> + * ext4_setattr()
>   *
> - * Another thing we have to assure is that if we are in ordered mode
> - * and inode is still attached to the committing transaction, we must
> - * we start writeout of all the dirty pages which are being truncated.
> - * This way we are sure that all the data written in the previous
> - * transaction are already on disk (truncate waits for pages under
> - * writeback).
> + * Handle special things ext4 needs for changing owner of the file, changing
> + * ACLs, or truncating file.
>   *
> - * Called with inode->i_mutex down.
> + * Called from notify_change with inode->i_mutex down.
>   */
>  int ext4_setattr(struct dentry *dentry, struct iattr *attr)
>  {
> @@ -4743,61 +4816,18 @@ int ext4_setattr(struct dentry *dentry, struct iattr *attr)
>  	}
>  
>  	if (attr->ia_valid & ATTR_SIZE) {
> -		if (!(EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL)) {
> -			struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
> -
> -			if (attr->ia_size > sbi->s_bitmap_maxbytes) {
> -				error = -EFBIG;
> -				goto err_out;
> -			}
> -		}
> -	}
> -
> -	if (S_ISREG(inode->i_mode) &&
> -	    attr->ia_valid & ATTR_SIZE && attr->ia_size < inode->i_size) {
> -		handle_t *handle;
> -
> -		handle = ext4_journal_start(inode, 3);
> -		if (IS_ERR(handle)) {
> -			error = PTR_ERR(handle);
> -			goto err_out;
> -		}
> -
> -		error = ext4_orphan_add(handle, inode);
> -		EXT4_I(inode)->i_disksize = attr->ia_size;
> -		rc = ext4_mark_inode_dirty(handle, inode);
> -		if (!error)
> -			error = rc;
> -		ext4_journal_stop(handle);
> -
> -		if (ext4_should_order_data(inode)) {
> -			error = ext4_begin_ordered_truncate(inode,
> -							    attr->ia_size);
> -			if (error) {
> -				/* Do as much error cleanup as possible */
> -				handle = ext4_journal_start(inode, 3);
> -				if (IS_ERR(handle)) {
> -					ext4_orphan_del(NULL, inode);
> -					goto err_out;
> -				}
> -				ext4_orphan_del(handle, inode);
> -				ext4_journal_stop(handle);
> -				goto err_out;
> -			}
> -		}
> +		error = ext4_setsize(inode, attr->ia_size);
> +		if (error)
> +			return error;
>  	}
>  
> -	rc = inode_setattr(inode, attr);
> -
> -	/* If inode_setattr's call to ext4_truncate failed to get a
> -	 * transaction handle at all, we need to clean up the in-core
> -	 * orphan list manually. */
> -	if (inode->i_nlink)
> -		ext4_orphan_del(NULL, inode);
> +	generic_setattr(inode, attr);
>  
> -	if (!rc && (ia_valid & ATTR_MODE))
> +	if (ia_valid & ATTR_MODE)
>  		rc = ext4_acl_chmod(inode);
>  
> +	/* Mark inode dirty due to changes done by generic_setattr() */
> +	mark_inode_dirty(inode);
>  err_out:
>  	ext4_std_error(inode->i_sb, error);
>  	if (!error)
> -- 
> 1.6.0.2
> 
-- 
Jan Kara <jack@...e.cz>
SUSE Labs, CR
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