tree fd4293998868758f4e522165babcd4ecbff417a4
parent 72b4daa241295440f98e80ae21294a67b27ca091
author Christoph Hellwig <hch@lst.de> 1529446258 -0700
committer Darrick J. Wong <darrick.wong@oracle.com> 1529512361 -0700

iomap: add initial support for writes without buffer heads

For now just limited to blocksize == PAGE_SIZE, where we can simply read
in the full page in write begin, and just set the whole page dirty after
copying data into it.  This code is enabled by default and XFS will now
be feed pages without buffer heads in ->writepage and ->writepages.

If a file system sets the IOMAP_F_BUFFER_HEAD flag on the iomap the old
path will still be used, this both helps the transition in XFS and
prepares for the gfs2 migration to the iomap infrastructure.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>