Re: [PATCH 3/7] btrfs-progs: extent-cache: actually cache extent buffers

On Tue, Jul 25, 2017 at 04:51:34PM -0400, jeffm@suse.com wrote:

From: Jeff Mahoney <redacted>

We have the infrastructure to cache extent buffers but we don't actually
do the caching.  As soon as the last reference is dropped, the buffer
is dropped.  This patch keeps the extent buffers around until the max
cache size is reached (defaults to 25% of memory) and then it drops
the last 10% of the LRU to free up cache space for reallocation.  The
cache size is configurable (for use by e.g. lowmem) when the cache is
initialized.

Signed-off-by: Jeff Mahoney <redacted>

I've started to merge the series, changed code according to the review.
In this patch, test-mkfs and test-check fail (segfaults and assertions).
A debugging build or asan (make D=all,asan) does not reproduce the
errors so this will need to be found by other means.

I also fixed some trivial coding style issues, so the changes are now in
the branch
https://github.com/kdave/btrfs-progs/tree/ext/jeffm/extent-cache

Please use this as a starting point, I'm fine with resending just this
patch or an incremental.