kill-the-bkl/reiserfs: reduce number of contentions in search_by_key()

search_by_key() is a central function in reiserfs which searches
the patch in the fs tree from the root to a node given its key.

It is the function that is most requesting the write lock
because it's a path very often used.

Also we forget to release the lock while reading the next tree node,
making us holding the lock in a wasteful way.

Then we release the lock while reading the current node and its childs,
all-in-one. It should be safe because we have a reference to these
blocks and even if we read a block that will be concurrently changed,
we have an fs_changed check later that will make us retry the path from
the root.

[ Impact: release the write lock while unused in a hot path ]

Cc: Jeff Mahoney <[email protected]>
Cc: Chris Mason <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Alexander Beregalov <[email protected]>
Signed-off-by: Frederic Weisbecker <[email protected]>

0 files changed, 0 insertions, 0 deletions