Re: [PATCH v2 3/6] iomap: advance the ifs allocation if we have more than one blocks per folio

yangerkun
2024-08-12T12:47:48Z

在 2024/8/12 20:11, Zhang Yi 写道:
> From: Zhang Yi <yi.zhang@huawei.com>
>
> Now we allocate ifs if i_blocks_per_folio is larger than one when
> writing back dirty folios in iomap_writepage_map(), so we don't attach
> an ifs after buffer write to an entire folio until it starts writing
> back, if we partial truncate that folio, iomap_invalidate_folio() can't
> clear counterpart block's dirty bit as expected. Fix this by advance the
> ifs allocation to __iomap_write_begin().
>
> Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
> ---
> fs/iomap/buffered-io.c | 17 ++++++++++++-----
> 1 file changed, 12 insertions(+), 5 deletions(-)
>
> diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
> index 763deabe8331..79031b7517e5 100644
> --- a/fs/iomap/buffered-io.c
> +++ b/fs/iomap/buffered-io.c
> @@ -699,6 +699,12 @@ static int __iomap_write_begin(const struct iomap_iter *iter, loff_t pos,
> size_t from = offset_in_folio(folio, pos), to = from + len;
> size_t poff, plen;
>
> + if (nr_blocks > 1) {
> + ifs = ifs_alloc(iter->inode, folio, iter->flags);
> + if ((iter->flags & IOMAP_NOWAIT) && !ifs)
> + return -EAGAIN;
> + }
> +
> /*
> * If the write or zeroing completely overlaps the current folio, then
> * entire folio will be dirtied so there is no need for

The comments upper need change too.

> @@ -710,10 +716,6 @@ static int __iomap_write_begin(const struct iomap_iter *iter, loff_t pos,
> pos + len >= folio_pos(folio) + folio_size(folio))
> return 0;
>
> - ifs = ifs_alloc(iter->inode, folio, iter->flags);
> - if ((iter->flags & IOMAP_NOWAIT) && !ifs && nr_blocks > 1)
> - return -EAGAIN;
> -
> if (folio_test_uptodate(folio))
> return 0;
>
> @@ -1928,7 +1930,12 @@ static int iomap_writepage_map(struct iomap_writepage_ctx *wpc,
> WARN_ON_ONCE(end_pos <= pos);
>
> if (i_blocks_per_folio(inode, folio) > 1) {
> - if (!ifs) {
> + /*
> + * This should not happen since we always allocate ifs in
> + * iomap_folio_mkwrite_iter() and there is more than one
> + * blocks per folio in __iomap_write_begin().
> + */
> + if (WARN_ON_ONCE(!ifs)) {
> ifs = ifs_alloc(inode, folio, 0);
> iomap_set_range_dirty(folio, 0, end_pos - pos);
> }