"Ritesh Harjani (IBM)" <ritesh.list@xxxxxxxxx> writes:
> @@ -1637,7 +1758,7 @@ iomap_writepage_map(struct iomap_writepage_ctx *wpc,
> struct writeback_control *wbc, struct inode *inode,
> struct folio *folio, u64 end_pos)
> {
> - struct iomap_folio_state *ifs = ifs_alloc(inode, folio, 0);
> + struct iomap_folio_state *ifs = folio->private;
> struct iomap_ioend *ioend, *next;
> unsigned len = i_blocksize(inode);
> unsigned nblocks = i_blocks_per_folio(inode, folio);
> @@ -1645,6 +1766,11 @@ iomap_writepage_map(struct iomap_writepage_ctx *wpc,
> int error = 0, count = 0, i;
> LIST_HEAD(submit_list);
>
> + if (!ifs && nblocks > 1) {
> + ifs = ifs_alloc(inode, folio, 0);
> + iomap_set_range_dirty(folio, 0, folio_size(folio));
> + }
> +
> WARN_ON_ONCE(ifs && atomic_read(&ifs->write_bytes_pending) != 0);
>
> /*
> @@ -1653,7 +1779,7 @@ iomap_writepage_map(struct iomap_writepage_ctx *wpc,
> * invalid, grab a new one.
> */
> for (i = 0; i < nblocks && pos < end_pos; i++, pos += len) {
> - if (ifs && !ifs_block_is_uptodate(ifs, i))
> + if (ifs && !ifs_block_is_dirty(folio, ifs, i))
> continue;
>
> error = wpc->ops->map_blocks(wpc, inode, pos);
> @@ -1697,6 +1823,7 @@ iomap_writepage_map(struct iomap_writepage_ctx *wpc,
> }
> }
>
> + iomap_clear_range_dirty(folio, 0, end_pos - folio_pos(folio));
> folio_start_writeback(folio);
> folio_unlock(folio);
>
I think we should fold below change with this patch.
end_pos is calculated in iomap_do_writepage() such that it is either
folio_pos(folio) + folio_size(folio), or if this value becomes more then
isize, than end_pos is made isize.
The current patch does not have a functional problem I guess. But in
some cases where truncate races with writeback, it will end up marking
more bits & later doesn't clear those. Hence I think we should correct
it using below diff.
I have added a WARN_ON_ONCE, but if you think it is obvious and not
required, feel free to drop it.
diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index 2fd9413838de..6c03e5842d44 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -1766,9 +1766,11 @@ iomap_writepage_map(struct iomap_writepage_ctx *wpc,
int error = 0, count = 0, i;
LIST_HEAD(submit_list);
+ WARN_ON_ONCE(end_pos <= pos);
+
if (!ifs && nblocks > 1) {
ifs = ifs_alloc(inode, folio, 0);
- iomap_set_range_dirty(folio, 0, folio_size(folio));
+ iomap_set_range_dirty(folio, 0, end_pos - pos);
}
WARN_ON_ONCE(ifs && atomic_read(&ifs->write_bytes_pending) != 0);
-ritesh
