[14/17] writeback: Factor writeback_iter_next() out of write_cache_pages()
Commit Message
From: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Pull the post-processing of the writepage_t callback into a
separate function. That means changing writeback_finish() to
return NULL, and writeback_get_next() to call writeback_finish()
when we naturally run out of folios.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
mm/page-writeback.c | 85 ++++++++++++++++++++++++---------------------
1 file changed, 45 insertions(+), 40 deletions(-)
Comments
On Mon 18-12-23 16:35:50, Christoph Hellwig wrote:
> From: "Matthew Wilcox (Oracle)" <willy@infradead.org>
>
> Pull the post-processing of the writepage_t callback into a
> separate function. That means changing writeback_finish() to
> return NULL, and writeback_get_next() to call writeback_finish()
> when we naturally run out of folios.
The part about writeback_finish() does not seem to be true anymore.
Otherwise feel free to add:
Reviewed-by: Jan Kara <jack@suse.cz>
Honza
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
> mm/page-writeback.c | 85 ++++++++++++++++++++++++---------------------
> 1 file changed, 45 insertions(+), 40 deletions(-)
>
> diff --git a/mm/page-writeback.c b/mm/page-writeback.c
> index 9d37dd5e58ffb6..0771f19950081f 100644
> --- a/mm/page-writeback.c
> +++ b/mm/page-writeback.c
> @@ -2449,8 +2449,10 @@ static struct folio *writeback_get_folio(struct address_space *mapping,
>
> for (;;) {
> folio = writeback_get_next(mapping, wbc);
> - if (!folio)
> + if (!folio) {
> + writeback_finish(mapping, wbc, 0);
> return NULL;
> + }
> folio_lock(folio);
> if (likely(should_writeback_folio(mapping, wbc, folio)))
> break;
> @@ -2477,6 +2479,46 @@ static struct folio *writeback_iter_init(struct address_space *mapping,
> return writeback_get_folio(mapping, wbc);
> }
>
> +static struct folio *writeback_iter_next(struct address_space *mapping,
> + struct writeback_control *wbc, struct folio *folio, int error)
> +{
> + unsigned long nr = folio_nr_pages(folio);
> +
> + wbc->nr_to_write -= nr;
> +
> + /*
> + * Handle the legacy AOP_WRITEPAGE_ACTIVATE magic return value.
> + * Eventually all instances should just unlock the folio themselves and
> + * return 0;
> + */
> + if (error == AOP_WRITEPAGE_ACTIVATE) {
> + folio_unlock(folio);
> + error = 0;
> + }
> +
> + if (error && !wbc->err)
> + wbc->err = error;
> +
> + /*
> + * For integrity sync we have to keep going until we have written all
> + * the folios we tagged for writeback prior to entering the writeback
> + * loop, even if we run past wbc->nr_to_write or encounter errors.
> + * This is because the file system may still have state to clear for
> + * each folio. We'll eventually return the first error encountered.
> + *
> + * For background writeback just push done_index past this folio so that
> + * we can just restart where we left off and media errors won't choke
> + * writeout for the entire file.
> + */
> + if (wbc->sync_mode == WB_SYNC_NONE &&
> + (wbc->err || wbc->nr_to_write <= 0)) {
> + writeback_finish(mapping, wbc, folio->index + nr);
> + return NULL;
> + }
> +
> + return writeback_get_folio(mapping, wbc);
> +}
> +
> /**
> * write_cache_pages - walk the list of dirty pages of the given address space and write all of them.
> * @mapping: address space structure to write
> @@ -2517,47 +2559,10 @@ int write_cache_pages(struct address_space *mapping,
>
> for (folio = writeback_iter_init(mapping, wbc);
> folio;
> - folio = writeback_get_folio(mapping, wbc)) {
> - unsigned long nr;
> -
> + folio = writeback_iter_next(mapping, wbc, folio, error))
> error = writepage(folio, wbc, data);
> - nr = folio_nr_pages(folio);
> - wbc->nr_to_write -= nr;
> -
> - /*
> - * Handle the legacy AOP_WRITEPAGE_ACTIVATE magic return value.
> - * Eventually all instances should just unlock the folio
> - * themselves and return 0;
> - */
> - if (error == AOP_WRITEPAGE_ACTIVATE) {
> - folio_unlock(folio);
> - error = 0;
> - }
> -
> - if (error && !wbc->err)
> - wbc->err = error;
>
> - /*
> - * For integrity sync we have to keep going until we have
> - * written all the folios we tagged for writeback prior to
> - * entering this loop, even if we run past wbc->nr_to_write or
> - * encounter errors. This is because the file system may still
> - * have state to clear for each folio. We'll eventually return
> - * the first error encountered.
> - *
> - * For background writeback just push done_index past this folio
> - * so that we can just restart where we left off and media
> - * errors won't choke writeout for the entire file.
> - */
> - if (wbc->sync_mode == WB_SYNC_NONE &&
> - (wbc->err || wbc->nr_to_write <= 0)) {
> - writeback_finish(mapping, wbc, folio->index + nr);
> - return error;
> - }
> - }
> -
> - writeback_finish(mapping, wbc, 0);
> - return 0;
> + return wbc->err;
> }
> EXPORT_SYMBOL(write_cache_pages);
>
> --
> 2.39.2
>
@@ -2449,8 +2449,10 @@ static struct folio *writeback_get_folio(struct address_space *mapping,
for (;;) {
folio = writeback_get_next(mapping, wbc);
- if (!folio)
+ if (!folio) {
+ writeback_finish(mapping, wbc, 0);
return NULL;
+ }
folio_lock(folio);
if (likely(should_writeback_folio(mapping, wbc, folio)))
break;
@@ -2477,6 +2479,46 @@ static struct folio *writeback_iter_init(struct address_space *mapping,
return writeback_get_folio(mapping, wbc);
}
+static struct folio *writeback_iter_next(struct address_space *mapping,
+ struct writeback_control *wbc, struct folio *folio, int error)
+{
+ unsigned long nr = folio_nr_pages(folio);
+
+ wbc->nr_to_write -= nr;
+
+ /*
+ * Handle the legacy AOP_WRITEPAGE_ACTIVATE magic return value.
+ * Eventually all instances should just unlock the folio themselves and
+ * return 0;
+ */
+ if (error == AOP_WRITEPAGE_ACTIVATE) {
+ folio_unlock(folio);
+ error = 0;
+ }
+
+ if (error && !wbc->err)
+ wbc->err = error;
+
+ /*
+ * For integrity sync we have to keep going until we have written all
+ * the folios we tagged for writeback prior to entering the writeback
+ * loop, even if we run past wbc->nr_to_write or encounter errors.
+ * This is because the file system may still have state to clear for
+ * each folio. We'll eventually return the first error encountered.
+ *
+ * For background writeback just push done_index past this folio so that
+ * we can just restart where we left off and media errors won't choke
+ * writeout for the entire file.
+ */
+ if (wbc->sync_mode == WB_SYNC_NONE &&
+ (wbc->err || wbc->nr_to_write <= 0)) {
+ writeback_finish(mapping, wbc, folio->index + nr);
+ return NULL;
+ }
+
+ return writeback_get_folio(mapping, wbc);
+}
+
/**
* write_cache_pages - walk the list of dirty pages of the given address space and write all of them.
* @mapping: address space structure to write
@@ -2517,47 +2559,10 @@ int write_cache_pages(struct address_space *mapping,
for (folio = writeback_iter_init(mapping, wbc);
folio;
- folio = writeback_get_folio(mapping, wbc)) {
- unsigned long nr;
-
+ folio = writeback_iter_next(mapping, wbc, folio, error))
error = writepage(folio, wbc, data);
- nr = folio_nr_pages(folio);
- wbc->nr_to_write -= nr;
-
- /*
- * Handle the legacy AOP_WRITEPAGE_ACTIVATE magic return value.
- * Eventually all instances should just unlock the folio
- * themselves and return 0;
- */
- if (error == AOP_WRITEPAGE_ACTIVATE) {
- folio_unlock(folio);
- error = 0;
- }
-
- if (error && !wbc->err)
- wbc->err = error;
- /*
- * For integrity sync we have to keep going until we have
- * written all the folios we tagged for writeback prior to
- * entering this loop, even if we run past wbc->nr_to_write or
- * encounter errors. This is because the file system may still
- * have state to clear for each folio. We'll eventually return
- * the first error encountered.
- *
- * For background writeback just push done_index past this folio
- * so that we can just restart where we left off and media
- * errors won't choke writeout for the entire file.
- */
- if (wbc->sync_mode == WB_SYNC_NONE &&
- (wbc->err || wbc->nr_to_write <= 0)) {
- writeback_finish(mapping, wbc, folio->index + nr);
- return error;
- }
- }
-
- writeback_finish(mapping, wbc, 0);
- return 0;
+ return wbc->err;
}
EXPORT_SYMBOL(write_cache_pages);