tree f65f2883e5c1f46691eea046e5986a28558cb687
parent ed923b5776a2d2e949bd5b20f3956d68f3c826b7
author Matthew Wilcox <willy@linux.intel.com> 1441749562 -0700
committer Linus Torvalds <torvalds@linux-foundation.org> 1441751728 -0700

ext4: start transaction before calling into DAX

Jan Kara pointed out that in the case where we are writing to a hole, we
can end up with a lock inversion between the page lock and the journal
lock.  We can avoid this by starting the transaction in ext4 before
calling into DAX.  The journal lock nests inside the superblock
pagefault lock, so we have to duplicate that code from dax_fault, like
XFS does.

Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>