Re: [PATCH RESEND] udf: extent cache implementation for manipulating block map

[Jan Kara <jack@suse.cz>]

On Wed 22-08-12 19:02:26, Namjae Jeon wrote:
> 2012/8/21, Jan Kara <jack@suse.cz>:
> Hi. Jan.
> Okay, We are trying to do it from your comment.
> 1. Change udf_ext_cache structure to following which would also include *bh.
> struct udf_ext_cache {
> 
> /* Position of the cached extent */
> struct extent_position epos;
> 
> /* Logical block where cached extent starts */
> sector_t block;
> };
  OK.

> 2. Remove call to brelse(epos.bh) from all the callers of inode_bmap()
> and move it to udf_evict_inode()
  It might be easier to keep brelse() where it is and add get_bh() to
udf_add_extent_cache() and brelse() to udf_clear_extent_cache(). It is then
easier to audit we don't leak bh references...

> 3. As now we are not caching elen, etype and eloc, we have to change
> the cache_hit logic in inode_bmap.
> The call to function udf_next_aext is now necessary from inode_bmap.
  Yes.

> 4. Remove call to udf_clear_extent_cache() from udf_get_block as with
> new scheme, it is not required.
  You still need this when you write before the cached location (e.g. when
the file has holes, and you write into them, extents will shift).


								Honza
-- 
Jan Kara <jack@suse.cz>
SUSE Labs, CR