iomap: Permit pages without an iop to enter writeback

Create an iop in the writeback path if one doesn't exist.  This allows us
to avoid creating the iop in some cases.  We'll initially do that for pages
with inline data, but it can be extended to pages which are entirely within
an extent.  It also allows for an iop to be removed from pages in the
future (eg page split).

Co-developed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>

diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index 41da4f14c00bb515b67acc28fbb0acef3662a9a6..ad976634d56b365482dadcfc93aac0e19847a701 100644 (file)
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -1304,14 +1304,13 @@ iomap_writepage_map(struct iomap_writepage_ctx *wpc,
                struct writeback_control *wbc, struct inode *inode,
                struct page *page, u64 end_offset)
 {
-       struct iomap_page *iop = to_iomap_page(page);
+       struct iomap_page *iop = iomap_page_create(inode, page);
        struct iomap_ioend *ioend, *next;
        unsigned len = i_blocksize(inode);
        u64 file_offset; /* file offset of page */
        int error = 0, count = 0, i;
        LIST_HEAD(submit_list);
 
-       WARN_ON_ONCE(i_blocks_per_page(inode, page) > 1 && !iop);
        WARN_ON_ONCE(iop && atomic_read(&iop->write_bytes_pending) != 0);
 
        /*