6.1-stable review patch. If anyone has any objections, please let me know.
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From: Vishal Moola (Oracle) vishal.moola@gmail.com
[ Upstream commit 247f9e1feef4e57911510c8f82348efb4491ea0e ]
This is the equivalent of find_get_pages_range_tag(), except for folios instead of pages.
One noteable difference is filemap_get_folios_tag() does not take in a maximum pages argument. It instead tries to fill a folio batch and stops either once full (15 folios) or reaching the end of the search range.
The new function supports large folios, the initial function did not since all callers don't use large folios.
Link: https://lkml.kernel.org/r/20230104211448.4804-3-vishal.moola@gmail.com Signed-off-by: Vishal Moola (Oracle) vishal.moola@gmail.com Reviewed-by: Matthew Wilcow (Oracle) willy@infradead.org Signed-off-by: Andrew Morton akpm@linux-foundation.org Stable-dep-of: c5d3f9b7649a ("f2fs: compress: fix deadloop in f2fs_write_cache_pages()") Signed-off-by: Sasha Levin sashal@kernel.org --- include/linux/pagemap.h | 2 ++ mm/filemap.c | 54 +++++++++++++++++++++++++++++++++++++++++ 2 files changed, 56 insertions(+)
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h index bbccb40442224..03307b72de6c6 100644 --- a/include/linux/pagemap.h +++ b/include/linux/pagemap.h @@ -720,6 +720,8 @@ unsigned filemap_get_folios(struct address_space *mapping, pgoff_t *start, pgoff_t end, struct folio_batch *fbatch); unsigned filemap_get_folios_contig(struct address_space *mapping, pgoff_t *start, pgoff_t end, struct folio_batch *fbatch); +unsigned filemap_get_folios_tag(struct address_space *mapping, pgoff_t *start, + pgoff_t end, xa_mark_t tag, struct folio_batch *fbatch); unsigned find_get_pages_range_tag(struct address_space *mapping, pgoff_t *index, pgoff_t end, xa_mark_t tag, unsigned int nr_pages, struct page **pages); diff --git a/mm/filemap.c b/mm/filemap.c index 322aea78058a0..2d930470aacaa 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -2262,6 +2262,60 @@ unsigned filemap_get_folios_contig(struct address_space *mapping, } EXPORT_SYMBOL(filemap_get_folios_contig);
+/** + * filemap_get_folios_tag - Get a batch of folios matching @tag + * @mapping: The address_space to search + * @start: The starting page index + * @end: The final page index (inclusive) + * @tag: The tag index + * @fbatch: The batch to fill + * + * Same as filemap_get_folios(), but only returning folios tagged with @tag. + * + * Return: The number of folios found. + * Also update @start to index the next folio for traversal. + */ +unsigned filemap_get_folios_tag(struct address_space *mapping, pgoff_t *start, + pgoff_t end, xa_mark_t tag, struct folio_batch *fbatch) +{ + XA_STATE(xas, &mapping->i_pages, *start); + struct folio *folio; + + rcu_read_lock(); + while ((folio = find_get_entry(&xas, end, tag)) != NULL) { + /* + * Shadow entries should never be tagged, but this iteration + * is lockless so there is a window for page reclaim to evict + * a page we saw tagged. Skip over it. + */ + if (xa_is_value(folio)) + continue; + if (!folio_batch_add(fbatch, folio)) { + unsigned long nr = folio_nr_pages(folio); + + if (folio_test_hugetlb(folio)) + nr = 1; + *start = folio->index + nr; + goto out; + } + } + /* + * We come here when there is no page beyond @end. We take care to not + * overflow the index @start as it confuses some of the callers. This + * breaks the iteration when there is a page at index -1 but that is + * already broke anyway. + */ + if (end == (pgoff_t)-1) + *start = (pgoff_t)-1; + else + *start = end + 1; +out: + rcu_read_unlock(); + + return folio_batch_count(fbatch); +} +EXPORT_SYMBOL(filemap_get_folios_tag); + /** * find_get_pages_range_tag - Find and return head pages matching @tag. * @mapping: the address_space to search