tree 9a749224ef5cf24d556f5f08bcae93714520c3c8
parent 816cd71b0c723a7296d14aadb8ff1ba42f6181d2
author Jan Kara <jack@suse.cz> 1463114295 -0400
committer Theodore Ts'o <tytso@mit.edu> 1463114295 -0400

dax: call get_blocks() with create == 1 for write faults to unwritten extents

Currently, __dax_fault() does not call get_blocks() callback with create
argument set, when we got back unwritten extent from the initial
get_blocks() call during a write fault. This is because originally
filesystems were supposed to convert unwritten extents to written ones
using complete_unwritten() callback. Later this was abandoned in favor of
using pre-zeroed blocks however the condition whether get_blocks() needs
to be called with create == 1 remained.

Fix the condition so that filesystems are not forced to zero-out and
convert unwritten extents when get_blocks() is called with create == 0
(which introduces unnecessary overhead for read faults and can be
problematic as the filesystem may possibly be read-only).

Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>