On Tue, Nov 15, 2011 at 04:07:51PM +0800, Yongqiang Yang wrote:
> This patch lets ext4 journal deletion of data blocks. Besides this,
> a unnecessary variable is removed.
>
> Signed-off-by: Yongqiang Yang <xiaoqiangnk@xxxxxxxxx>
I don't see the point of this patch; it seems to be a code
simplification, but in fact it introduces a bug which has to get fixed
in patch 3/5 of this series.
The code here is a little arcane, because if bh is non-null, then
count must be 1. This is expressed in the BUG_ON found in the
function:
> BUG_ON(bh && (count > 1));
The reason for this bit of complexity is to avoid needing to call
sb_find_get_block() in those places where we have the buffer_head
already. This happens in exactly two locations: in an error cleanup
path in fs/ext4/indirect.c, and when releasing an xattr block in
ext4_xattr_release_block().
The better way of dealing with this is to drop the bh argument from
ext4_free_blocks() completely, and explicitly call ext4_forget() on
the bh in those two functions.
This will require changing all of the call sites of
ext4_free_blocks(), but it simplifies the function signature as well
as simplifying the code.
- Ted
> fs/ext4/mballoc.c | 7 ++-----
> 1 files changed, 2 insertions(+), 5 deletions(-)
>
> diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
> index e2d8be8..2529efc 100644
> --- a/fs/ext4/mballoc.c
> +++ b/fs/ext4/mballoc.c
> @@ -4562,19 +4562,16 @@ void ext4_free_blocks(handle_t *handle, struct inode *inode,
> trace_ext4_free_blocks(inode, block, count, flags);
>
> if (flags & EXT4_FREE_BLOCKS_FORGET) {
> - struct buffer_head *tbh = bh;
> int i;
>
> BUG_ON(bh && (count > 1));
>
> for (i = 0; i < count; i++) {
> if (!bh)
> - tbh = sb_find_get_block(inode->i_sb,
> + bh = sb_find_get_block(inode->i_sb,
> block + i);
> - if (unlikely(!tbh))
> - continue;
> ext4_forget(handle, flags & EXT4_FREE_BLOCKS_METADATA,
> - inode, tbh, block + i);
> + inode, bh, block + i);
> }
> }
>
> --
> 1.7.5.1
>
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