tree efdc2f768da474a4904dc6c065cc6e4b9a2379d3
parent f85d7d6c8f2ad4a86a1f4f4e3791f36dede2fa76
author Chris Mason <chris.mason@oracle.com> 1253304423 -0400
committer Chris Mason <chris.mason@oracle.com> 1253304532 -0400

Btrfs: search for an allocation hint while filling file COW

The allocator has some nice knobs for sending hints about where
to try and allocate new blocks, but when we're doing file allocations
we're not sending any hint at all.

This commit adds a simple extent map search to see if we can
quickly and easily find a hint for the allocator.

Signed-off-by: Chris Mason <chris.mason@oracle.com>