tree e9034adc21c6fc3ad6fc775e8f3225e35b015d50
parent eb81cf9d0e18d438e27339e0d1a49d3ac8644674
author Goldwyn Rodrigues <rgoldwyn@suse.com> 1571442250 -0700
committer Darrick J. Wong <darrick.wong@oracle.com> 1571673119 -0700

iomap: use a srcmap for a read-modify-write I/O

The srcmap is used to identify where the read is to be performed from.
It is passed to ->iomap_begin, which can fill it in if we need to read
data for partially written blocks from a different location than the
write target.  The srcmap is only supported for buffered writes so far.

Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
[hch: merged two patches, removed the IOMAP_F_COW flag, use iomap as
      srcmap if not set, adjust length down to srcmap end as well]
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Acked-by: Goldwyn Rodrigues <rgoldwyn@suse.com>