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Wong" , linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Jan Kara , Dave Chinner Subject: [PATCH 08/13] writeback: Simplify the loops in write_cache_pages() Date: Sat, 3 Feb 2024 08:11:42 +0100 Message-Id: <20240203071147.862076-9-hch@lst.de> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20240203071147.862076-1-hch@lst.de> References: <20240203071147.862076-1-hch@lst.de> MIME-Version: 1.0 X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html X-Rspamd-Queue-Id: D3D2F8000A X-Rspam-User: X-Rspamd-Server: rspam04 X-Stat-Signature: rd9gxstn8tx3xapfoqe57t3qi5qx7b4r X-HE-Tag: 1706944356-767737 X-HE-Meta: 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 IsGozzP1 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: From: "Matthew Wilcox (Oracle)" Collapse the two nested loops into one. This is needed as a step towards turning this into an iterator. Note that this drops the "index <= end" check in the previous outer loop and just relies 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 as the comment in filemap_get_folios_tag documents this as already broken anyway we should not worry about it here either. The fix for that would probably a change to the filemap_get_folios_tag() calling convention. Signed-off-by: Matthew Wilcox (Oracle) [hch: updated the commit log based on feedback from Jan Kara] Signed-off-by: Christoph Hellwig Reviewed-by: Brian Foster Reviewed-by: Jan Kara Acked-by: Dave Chinner --- mm/page-writeback.c | 75 ++++++++++++++++++++++----------------------- 1 file changed, 36 insertions(+), 39 deletions(-) diff --git a/mm/page-writeback.c b/mm/page-writeback.c index 23363ed712f646..d7ab42def43035 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -2454,6 +2454,7 @@ int write_cache_pages(struct address_space *mapping, int error; struct folio *folio; pgoff_t end; /* Inclusive */ + int i = 0; if (wbc->range_cyclic) { wbc->index = mapping->writeback_index; /* prev offset */ @@ -2467,53 +2468,49 @@ int write_cache_pages(struct address_space *mapping, folio_batch_init(&wbc->fbatch); - while (wbc->index <= end) { - int i; - - writeback_get_batch(mapping, wbc); - + for (;;) { + 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++) { - folio = wbc->fbatch.folios[i]; + folio = wbc->fbatch.folios[i++]; - folio_lock(folio); - if (!folio_prepare_writeback(mapping, wbc, folio)) { - folio_unlock(folio); - continue; - } + folio_lock(folio); + if (!folio_prepare_writeback(mapping, wbc, folio)) { + folio_unlock(folio); + continue; + } - trace_wbc_writepage(wbc, inode_to_bdi(mapping->host)); + trace_wbc_writepage(wbc, inode_to_bdi(mapping->host)); - error = writepage(folio, wbc, data); - wbc->nr_to_write -= folio_nr_pages(folio); + error = writepage(folio, wbc, data); + wbc->nr_to_write -= folio_nr_pages(folio); - if (error == AOP_WRITEPAGE_ACTIVATE) { - folio_unlock(folio); - error = 0; - } + if (error == AOP_WRITEPAGE_ACTIVATE) { + folio_unlock(folio); + error = 0; + } - /* - * For integrity writeback we have to keep going until - * we have written all the folios we tagged for - * writeback above, even if we run past wbc->nr_to_write - * or encounter errors. - * We stash away the first error we encounter in - * wbc->saved_err so that it can be retrieved when we're - * done. This is because the file system may still have - * state to clear for each folio. - * - * For background writeback we exit as soon as we run - * past wbc->nr_to_write or encounter the first error. - */ - if (wbc->sync_mode == WB_SYNC_ALL) { - if (error && !ret) - ret = error; - } else { - if (error || wbc->nr_to_write <= 0) - goto done; - } + /* + * For integrity writeback we have to keep going until we have + * written all the folios we tagged for writeback above, even if + * we run past wbc->nr_to_write or encounter errors. + * We stash away the first error we encounter in wbc->saved_err + * so that it can be retrieved when we're done. This is because + * the file system may still have state to clear for each folio. + * + * For background writeback we exit as soon as we run past + * wbc->nr_to_write or encounter the first error. + */ + if (wbc->sync_mode == WB_SYNC_ALL) { + if (error && !ret) + ret = error; + } else { + if (error || wbc->nr_to_write <= 0) + goto done; } }