iomap: mark newly allocated buffer heads as new

In iomap_to_bh, not only mark buffer heads in IOMAP_UNWRITTEN maps as
new, but also buffer heads in IOMAP_MAPPED maps with the IOMAP_F_NEW
flag set.  This will be used by filesystems like gfs2, which allocate
blocks in iomap->begin.

Minor corrections to the comment for IOMAP_UNWRITTEN maps.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
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>

diff --git a/fs/buffer.c b/fs/buffer.c
index aba2a948b235f4ef1fdcc1287821cd3b13a0a198..c8c2b7d8b8d6cec6d77dc980cfd2920b27a1d8c3 100644 (file)
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -1900,15 +1900,16 @@ iomap_to_bh(struct inode *inode, sector_t block, struct buffer_head *bh,
                break;
        case IOMAP_UNWRITTEN:
                /*
-                * For unwritten regions, we always need to ensure that
-                * sub-block writes cause the regions in the block we are not
-                * writing to are zeroed. Set the buffer as new to ensure this.
+                * For unwritten regions, we always need to ensure that regions
+                * in the block we are not writing to are zeroed. Mark the
+                * buffer as new to ensure this.
                 */
                set_buffer_new(bh);
                set_buffer_unwritten(bh);
                /* FALLTHRU */
        case IOMAP_MAPPED:
-               if (offset >= i_size_read(inode))
+               if ((iomap->flags & IOMAP_F_NEW) ||
+                   offset >= i_size_read(inode))
                        set_buffer_new(bh);
                bh->b_blocknr = (iomap->addr + offset - iomap->offset) >>
                                inode->i_blkbits;