The btree_for_each API is implemented with macros that internally call
btree_get_prev(), so if btree_get_prev() isn't exported then modules fail
to link if they try to use one of the btree_for_each macros.  Since the
rest of the btree API is exported, we should keep things orthogonal and
make this work too.
Signed-off-by: NRoland Dreier <roland@purestorage.com>
Signed-off-by: NSteve Hodgson <steve@purestorage.com>
Acked-by: NJoern Engel <joern@logfs.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Fixes generated by 'codespell' and manually reviewed.
Signed-off-by: NLucas De Marchi <lucas.demarchi@profusion.mobi>

mempool_alloc() can return null in atomic case.
Signed-off-by: NDenis Kirjanov <kirjanov@gmail.com>
Cc: Joern Engel <joern@logfs.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This is a new flash file system. See
Documentation/filesystems/logfs.txt
Signed-off-by: NJoern Engel <joern@logfs.org>