tree eda62586bb95967a4001f8fb70e6955b531cf801
parent e688b7252f784c2479d559f9f70ca8354752c5e7
author Chris Mason <chris.mason@oracle.com> 1320156486 -0400
committer Chris Mason <chris.mason@oracle.com> 1320566628 -0500

Btrfs: make sure to flush queued bios if write_cache_pages waits

write_cache_pages tries to build up a large bio to stuff down the pipe.
But if it needs to wait for a page lock, it needs to make sure and send
down any pending writes so we don't deadlock with anyone who has the
page lock and is waiting for writeback of things inside the bio.

Dave Sterba triggered this as a deadlock between the autodefrag code and
the extent write_cache_pages

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