| Message ID | 20231214132544.376574-5-hch@lst.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [01/11] writeback: Factor out writeback_finish() | expand |
On Thu 14-12-23 14:25:37, Christoph Hellwig wrote: > From: "Matthew Wilcox (Oracle)" <willy@infradead.org> > > Collapse the two nested loops into one. This is needed as a step > towards turning this into an iterator. > > Signed-off-by: Christoph Hellwig <hch@lst.de> It would be good to mention in the changelog that we drop the condition index <= end and just rely on filemap_get_folios_tag() to return 0 entries when index > end. This actually has a subtle implication when end == -1 because then the returned index will be -1 as well and thus if there is page present on index -1, we could be looping indefinitely. But I think that's mostly a theoretical concern so I'd be fine with just mentioning this subtlety in the changelog and possibly in a comment in the code. Honza > --- > mm/page-writeback.c | 98 ++++++++++++++++++++++----------------------- > 1 file changed, 49 insertions(+), 49 deletions(-) > > diff --git a/mm/page-writeback.c b/mm/page-writeback.c > index 5a3df8665ff4f9..2087d16115710e 100644 > --- a/mm/page-writeback.c > +++ b/mm/page-writeback.c > @@ -2460,6 +2460,7 @@ int write_cache_pages(struct address_space *mapping, > void *data) > { > int error; > + int i = 0; > > if (wbc->range_cyclic) { > wbc->index = mapping->writeback_index; /* prev offset */ > @@ -2477,67 +2478,66 @@ int write_cache_pages(struct address_space *mapping, > folio_batch_init(&wbc->fbatch); > wbc->err = 0; > > - while (wbc->index <= wbc->end) { > - int i; > - > - writeback_get_batch(mapping, wbc); > + for (;;) { > + struct folio *folio; > + unsigned long nr; > > + if (i == wbc->fbatch.nr) { > + writeback_get_batch(mapping, wbc); > + i = 0; > + } > if (wbc->fbatch.nr == 0) > break; > > - for (i = 0; i < wbc->fbatch.nr; i++) { > - struct folio *folio = wbc->fbatch.folios[i]; > - unsigned long nr; > + folio = wbc->fbatch.folios[i++]; > > - wbc->done_index = folio->index; > + wbc->done_index = folio->index; > > - folio_lock(folio); > - if (!should_writeback_folio(mapping, wbc, folio)) { > - folio_unlock(folio); > - continue; > - } > + folio_lock(folio); > + if (!should_writeback_folio(mapping, wbc, folio)) { > + folio_unlock(folio); > + continue; > + } > > - trace_wbc_writepage(wbc, inode_to_bdi(mapping->host)); > - > - error = writepage(folio, wbc, data); > - nr = folio_nr_pages(folio); > - if (unlikely(error)) { > - /* > - * Handle errors according to the type of > - * writeback. There's no need to continue for > - * background writeback. Just push done_index > - * past this page so media errors won't choke > - * writeout for the entire file. For integrity > - * writeback, we must process the entire dirty > - * set regardless of errors because the fs may > - * still have state to clear for each page. In > - * that case we continue processing and return > - * the first error. > - */ > - if (error == AOP_WRITEPAGE_ACTIVATE) { > - folio_unlock(folio); > - error = 0; > - } else if (wbc->sync_mode != WB_SYNC_ALL) { > - wbc->err = error; > - wbc->done_index = folio->index + nr; > - return writeback_finish(mapping, > - wbc, true); > - } > - if (!wbc->err) > - wbc->err = error; > - } > + trace_wbc_writepage(wbc, inode_to_bdi(mapping->host)); > > + error = writepage(folio, wbc, data); > + nr = folio_nr_pages(folio); > + if (unlikely(error)) { > /* > - * We stop writing back only if we are not doing > - * integrity sync. In case of integrity sync we have to > - * keep going until we have written all the pages > - * we tagged for writeback prior to entering this loop. > + * Handle errors according to the type of > + * writeback. There's no need to continue for > + * background writeback. Just push done_index > + * past this page so media errors won't choke > + * writeout for the entire file. For integrity > + * writeback, we must process the entire dirty > + * set regardless of errors because the fs may > + * still have state to clear for each page. In > + * that case we continue processing and return > + * the first error. > */ > - wbc->nr_to_write -= nr; > - if (wbc->nr_to_write <= 0 && > - wbc->sync_mode == WB_SYNC_NONE) > + if (error == AOP_WRITEPAGE_ACTIVATE) { > + folio_unlock(folio); > + error = 0; > + } else if (wbc->sync_mode != WB_SYNC_ALL) { > + wbc->err = error; > + wbc->done_index = folio->index + nr; > return writeback_finish(mapping, wbc, true); > + } > + if (!wbc->err) > + wbc->err = error; > } > + > + /* > + * We stop writing back only if we are not doing > + * integrity sync. In case of integrity sync we have to > + * keep going until we have written all the pages > + * we tagged for writeback prior to entering this loop. > + */ > + wbc->nr_to_write -= nr; > + if (wbc->nr_to_write <= 0 && > + wbc->sync_mode == WB_SYNC_NONE) > + return writeback_finish(mapping, wbc, true); > } > > return writeback_finish(mapping, wbc, false); > -- > 2.39.2 >
On Thu, Dec 14, 2023 at 02:25:37PM +0100, Christoph Hellwig wrote: > From: "Matthew Wilcox (Oracle)" <willy@infradead.org> > > Collapse the two nested loops into one. This is needed as a step > towards turning this into an iterator. Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> > Signed-off-by: Christoph Hellwig <hch@lst.de> > --- > mm/page-writeback.c | 98 ++++++++++++++++++++++----------------------- > 1 file changed, 49 insertions(+), 49 deletions(-) > > diff --git a/mm/page-writeback.c b/mm/page-writeback.c > index 5a3df8665ff4f9..2087d16115710e 100644 > --- a/mm/page-writeback.c > +++ b/mm/page-writeback.c > @@ -2460,6 +2460,7 @@ int write_cache_pages(struct address_space *mapping, > void *data) > { > int error; > + int i = 0; > > if (wbc->range_cyclic) { > wbc->index = mapping->writeback_index; /* prev offset */ > @@ -2477,67 +2478,66 @@ int write_cache_pages(struct address_space *mapping, > folio_batch_init(&wbc->fbatch); > wbc->err = 0; > > - while (wbc->index <= wbc->end) { > - int i; > - > - writeback_get_batch(mapping, wbc); > + for (;;) { > + struct folio *folio; > + unsigned long nr; > > + if (i == wbc->fbatch.nr) { > + writeback_get_batch(mapping, wbc); > + i = 0; > + } > if (wbc->fbatch.nr == 0) > break; > > - for (i = 0; i < wbc->fbatch.nr; i++) { > - struct folio *folio = wbc->fbatch.folios[i]; > - unsigned long nr; > + folio = wbc->fbatch.folios[i++]; > > - wbc->done_index = folio->index; > + wbc->done_index = folio->index; > > - folio_lock(folio); > - if (!should_writeback_folio(mapping, wbc, folio)) { > - folio_unlock(folio); > - continue; > - } > + folio_lock(folio); > + if (!should_writeback_folio(mapping, wbc, folio)) { > + folio_unlock(folio); > + continue; > + } > > - trace_wbc_writepage(wbc, inode_to_bdi(mapping->host)); > - > - error = writepage(folio, wbc, data); > - nr = folio_nr_pages(folio); > - if (unlikely(error)) { > - /* > - * Handle errors according to the type of > - * writeback. There's no need to continue for > - * background writeback. Just push done_index > - * past this page so media errors won't choke > - * writeout for the entire file. For integrity > - * writeback, we must process the entire dirty > - * set regardless of errors because the fs may > - * still have state to clear for each page. In > - * that case we continue processing and return > - * the first error. > - */ > - if (error == AOP_WRITEPAGE_ACTIVATE) { > - folio_unlock(folio); > - error = 0; > - } else if (wbc->sync_mode != WB_SYNC_ALL) { > - wbc->err = error; > - wbc->done_index = folio->index + nr; > - return writeback_finish(mapping, > - wbc, true); > - } > - if (!wbc->err) > - wbc->err = error; > - } > + trace_wbc_writepage(wbc, inode_to_bdi(mapping->host)); > > + error = writepage(folio, wbc, data); > + nr = folio_nr_pages(folio); > + if (unlikely(error)) { > /* > - * We stop writing back only if we are not doing > - * integrity sync. In case of integrity sync we have to > - * keep going until we have written all the pages > - * we tagged for writeback prior to entering this loop. > + * Handle errors according to the type of > + * writeback. There's no need to continue for > + * background writeback. Just push done_index > + * past this page so media errors won't choke > + * writeout for the entire file. For integrity > + * writeback, we must process the entire dirty > + * set regardless of errors because the fs may > + * still have state to clear for each page. In > + * that case we continue processing and return > + * the first error. > */ > - wbc->nr_to_write -= nr; > - if (wbc->nr_to_write <= 0 && > - wbc->sync_mode == WB_SYNC_NONE) > + if (error == AOP_WRITEPAGE_ACTIVATE) { > + folio_unlock(folio); > + error = 0; > + } else if (wbc->sync_mode != WB_SYNC_ALL) { > + wbc->err = error; > + wbc->done_index = folio->index + nr; > return writeback_finish(mapping, wbc, true); > + } > + if (!wbc->err) > + wbc->err = error; > } > + > + /* > + * We stop writing back only if we are not doing > + * integrity sync. In case of integrity sync we have to > + * keep going until we have written all the pages > + * we tagged for writeback prior to entering this loop. > + */ > + wbc->nr_to_write -= nr; > + if (wbc->nr_to_write <= 0 && > + wbc->sync_mode == WB_SYNC_NONE) > + return writeback_finish(mapping, wbc, true); > } > > return writeback_finish(mapping, wbc, false); > -- > 2.39.2 >
diff --git a/mm/page-writeback.c b/mm/page-writeback.c index 5a3df8665ff4f9..2087d16115710e 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -2460,6 +2460,7 @@ int write_cache_pages(struct address_space *mapping, void *data) { int error; + int i = 0; if (wbc->range_cyclic) { wbc->index = mapping->writeback_index; /* prev offset */ @@ -2477,67 +2478,66 @@ int write_cache_pages(struct address_space *mapping, folio_batch_init(&wbc->fbatch); wbc->err = 0; - while (wbc->index <= wbc->end) { - int i; - - writeback_get_batch(mapping, wbc); + for (;;) { + struct folio *folio; + unsigned long nr; + if (i == wbc->fbatch.nr) { + writeback_get_batch(mapping, wbc); + i = 0; + } if (wbc->fbatch.nr == 0) break; - for (i = 0; i < wbc->fbatch.nr; i++) { - struct folio *folio = wbc->fbatch.folios[i]; - unsigned long nr; + folio = wbc->fbatch.folios[i++]; - wbc->done_index = folio->index; + wbc->done_index = folio->index; - folio_lock(folio); - if (!should_writeback_folio(mapping, wbc, folio)) { - folio_unlock(folio); - continue; - } + folio_lock(folio); + if (!should_writeback_folio(mapping, wbc, folio)) { + folio_unlock(folio); + continue; + } - trace_wbc_writepage(wbc, inode_to_bdi(mapping->host)); - - error = writepage(folio, wbc, data); - nr = folio_nr_pages(folio); - if (unlikely(error)) { - /* - * Handle errors according to the type of - * writeback. There's no need to continue for - * background writeback. Just push done_index - * past this page so media errors won't choke - * writeout for the entire file. For integrity - * writeback, we must process the entire dirty - * set regardless of errors because the fs may - * still have state to clear for each page. In - * that case we continue processing and return - * the first error. - */ - if (error == AOP_WRITEPAGE_ACTIVATE) { - folio_unlock(folio); - error = 0; - } else if (wbc->sync_mode != WB_SYNC_ALL) { - wbc->err = error; - wbc->done_index = folio->index + nr; - return writeback_finish(mapping, - wbc, true); - } - if (!wbc->err) - wbc->err = error; - } + trace_wbc_writepage(wbc, inode_to_bdi(mapping->host)); + error = writepage(folio, wbc, data); + nr = folio_nr_pages(folio); + if (unlikely(error)) { /* - * We stop writing back only if we are not doing - * integrity sync. In case of integrity sync we have to - * keep going until we have written all the pages - * we tagged for writeback prior to entering this loop. + * Handle errors according to the type of + * writeback. There's no need to continue for + * background writeback. Just push done_index + * past this page so media errors won't choke + * writeout for the entire file. For integrity + * writeback, we must process the entire dirty + * set regardless of errors because the fs may + * still have state to clear for each page. In + * that case we continue processing and return + * the first error. */ - wbc->nr_to_write -= nr; - if (wbc->nr_to_write <= 0 && - wbc->sync_mode == WB_SYNC_NONE) + if (error == AOP_WRITEPAGE_ACTIVATE) { + folio_unlock(folio); + error = 0; + } else if (wbc->sync_mode != WB_SYNC_ALL) { + wbc->err = error; + wbc->done_index = folio->index + nr; return writeback_finish(mapping, wbc, true); + } + if (!wbc->err) + wbc->err = error; } + + /* + * We stop writing back only if we are not doing + * integrity sync. In case of integrity sync we have to + * keep going until we have written all the pages + * we tagged for writeback prior to entering this loop. + */ + wbc->nr_to_write -= nr; + if (wbc->nr_to_write <= 0 && + wbc->sync_mode == WB_SYNC_NONE) + return writeback_finish(mapping, wbc, true); } return writeback_finish(mapping, wbc, false);