tree 6b17f1361099e8b579d10e892a8d919eae037354
parent 5e69e3a4492ea5abfd2e8ddc575448becf28e4d9
author Frederic Weisbecker <fweisbec@gmail.com> 1241133052 +0200
committer Frederic Weisbecker <fweisbec@gmail.com> 1252905490 +0200

kill-the-BKL/reiserfs: release the write lock inside get_neighbors()

get_neighbors() is used to get the left and/or right blocks
against a given one in order to balance a tree.

sb_bread() is used to read the buffer of these neighors blocks and
while it waits for this operation, it might sleep.

The bkl was released at this point, and then we can also release
the write lock before calling sb_bread().

This is safe because if the filesystem is changed after this
lock release, the function returns REPEAT_SEARCH (aka SCHEDULE_OCCURRED
in the function header comments) in order to repeat the neighbhor
research.

[ Impact: release the reiserfs write lock when it is not needed ]

Cc: Jeff Mahoney <jeffm@suse.com>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Alexander Beregalov <a.beregalov@gmail.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>