From: Josef Bacik <josef@redhat.com>
Date: Tue, 25 Jan 2011 21:30:38 +0000 (-0500)
Subject: Btrfs: change reserved_extents to an atomic_t
X-Git-Tag: v2.6.39-rc1~19^2~41
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=57a45ced94fe48a701361d64230fc16eefa189dd;p=pandora-kernel.git

Btrfs: change reserved_extents to an atomic_t

We track delayed allocation per inodes via 2 counters, one is
outstanding_extents and reserved_extents.  Outstanding_extents is already an
atomic_t, but reserved_extents is not and is protected by a spinlock.  So
convert this to an atomic_t and instead of using a spinlock, use atomic_cmpxchg
when releasing delalloc bytes.  This makes our inode 72 bytes smaller, and
reduces locking overhead (albiet it was minimal to begin with).  Thanks,

Signed-off-by: Josef Bacik <josef@redhat.com>
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