[PATCH v2] xfs: Fix overallocation in xfs_buf_allocate_memory()

[Dave Chinner]

On Wed, Jun 06, 2012 at 12:32:26AM +0200, Jan Kara wrote:
> Commit de1cbee which removed b_file_offset in favor of b_bn introduced a bug
> causing xfs_buf_allocate_memory() to overestimate the number of necessary
> pages. The problem is that xfs_buf_alloc() sets b_bn to -1 and thus effectively
> every buffer is straddling a page boundary which causes
> xfs_buf_allocate_memory() to allocate two pages and use vmalloc() for access
> which is unnecessary.
> 
> Dave says xfs_buf_alloc() doesn't need to set b_bn to -1 anymore since the
> buffer is inserted into the cache only after being fully initialized now.
> So just make xfs_buf_alloc() fill in proper block number from the beginning.
> 
> CC: David Chinner <dchinner at redhat.com>
> Signed-off-by: Jan Kara <jack at suse.cz>

Hmmm, the

Reviewed-by: Dave Chinner <dchinner at redhat.com>

I sent yesterday doesn't appear to have made it to the list. Oh
well, try again...

Cheers,

Dave.
-- 
Dave Chinner
david at fromorbit.com