Re: [PATCH] ext4: restart ext4_ext_remove_space() after transaction restart V2

[tytso@mit.edu]

On Wed, May 26, 2010 at 06:23:55PM +0400, Dmitry Monakhov wrote:
> 
> Later if we face a needs to restart transaction which result in
> i_data_sem indernal drop/acquire.
> And when the sem was dropped new block may be allocated by a
> flusher task (delay allocation writeback in the middle of the file)
> 
> *Flusher* will discover than STATE_EXT_TRUNC is set and clear it
> is allocation is really necessary(EXT4_GET_BLOCKS_CREATE is set)
> By clearing STATE_EXT_TRUNC bit flusher let truncate task to know
> what it have to restart it's job. 

OK, but why not have the truncate *always* restart its job after
restarting the transaction?  #1, it's relatively rare in most
workloads that we need to restart the transaction at all in the first
place, and #2, it's easier to test if we always restart the truncate,
and #3, it's not like we'll be doing that much extra work if we
restart the truncate and the file wasn't extended significantly...

	    	     	     	  - Ted