linux-ext4 - Re: [PATCH] libext2fs: write only core inode in update

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Message-ID: <4A397593.8030103@redhat.com>
Date:	Wed, 17 Jun 2009 18:00:35 -0500
From:	Eric Sandeen <sandeen@...hat.com>
To:	Theodore Tso <tytso@....edu>
CC:	ext4 development <linux-ext4@...r.kernel.org>
Subject: Re: [PATCH] libext2fs: write only core inode in update_path()

Theodore Tso wrote:
> This is what I ultimately checked in.  It converts all calls of
> ext2fs_write_inode_full() to ext2fs_write_inode().

Hey thanks for finding those, it fixed the next resize bug I was looking
at!  ;)

Now, put down the laptop and pay attention to that talk, Ted ;)

-Eric

> 							- Ted
> 
> commit 125a36780626cdb0fc4d62fd529486baa8bce54c
> Author: Eric Sandeen <sandeen@...hat.com>
> Date:   Wed Jun 17 18:49:01 2009 -0400
> 
>     libext2fs: write only core inode in update_path()
>     
>     The ext2_extent_handle only has a struct ext2_inode allocated on
>     it, and the same amount copied into it in that same function,
>     but in update_path() we're possibly writing out more than that -
>     for example 256 bytes, from that address.  This causes uninitialized
>     memory to get  written to disk, overwriting the parts of the
>     inode past the osd2 member (the end of the smaller structure).
>     
>     Signed-off-by: Eric Sandeen <sandeen@...hat.com>
>     Signed-off-by: "Theodore Ts'o" <tytso@....edu>
> 
> diff --git a/lib/ext2fs/extent.c b/lib/ext2fs/extent.c
> index 2b88739..35b080e 100644
> --- a/lib/ext2fs/extent.c
> +++ b/lib/ext2fs/extent.c
> @@ -546,8 +546,8 @@ static errcode_t update_path(ext2_extent_handle_t handle)
>  	struct ext3_extent_idx		*ix;
>  
>  	if (handle->level == 0) {
> -		retval = ext2fs_write_inode_full(handle->fs, handle->ino,
> -			   handle->inode, EXT2_INODE_SIZE(handle->fs->super));
> +		retval = ext2fs_write_inode(handle->fs, handle->ino,
> +					    handle->inode);
>  	} else {
>  		ix = handle->path[handle->level - 1].curr;
>  		blk = ext2fs_le32_to_cpu(ix->ei_leaf) +
> @@ -1011,8 +1011,8 @@ static errcode_t extent_node_split(ext2_extent_handle_t handle)
>  
>  	/* new node hooked in, so update inode block count (do this here?) */
>  	handle->inode->i_blocks += handle->fs->blocksize / 512;
> -	retval = ext2fs_write_inode_full(handle->fs, handle->ino,
> -		handle->inode, EXT2_INODE_SIZE(handle->fs->super));
> +	retval = ext2fs_write_inode(handle->fs, handle->ino,
> +				    handle->inode);
>  	if (retval)
>  		goto done;
>  
> @@ -1370,9 +1370,8 @@ errcode_t ext2fs_extent_delete(ext2_extent_handle_t handle, int flags)
>  
>  			retval = ext2fs_extent_delete(handle, flags);
>  			handle->inode->i_blocks -= handle->fs->blocksize / 512;
> -			retval = ext2fs_write_inode_full(handle->fs,
> -					handle->ino, handle->inode,
> -					EXT2_INODE_SIZE(handle->fs->super));
> +			retval = ext2fs_write_inode(handle->fs, handle->ino,
> +						    handle->inode);
>  			ext2fs_block_alloc_stats(handle->fs, extent.e_pblk, -1);
>  		}
>  	} else {

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