From: Jan Kara Subject: Re: [PATCH v3 3/7] mm: add find_get_entries_tag() Date: Fri, 18 Dec 2015 10:33:23 +0100 Message-ID: <20151218093323.GC4297@quack.suse.cz> References: <1449602325-20572-1-git-send-email-ross.zwisler@linux.intel.com> <1449602325-20572-4-git-send-email-ross.zwisler@linux.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-kernel@vger.kernel.org, "H. Peter Anvin" , "J. Bruce Fields" , Theodore Ts'o , Alexander Viro , Andreas Dilger , Dave Chinner , Ingo Molnar , Jan Kara , Jeff Layton , Matthew Wilcox , Thomas Gleixner , linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-nvdimm@lists.01.org, x86@kernel.org, xfs@oss.sgi.com, Andrew Morton , Dan Williams , Matthew Wilcox , Dave Hansen To: Ross Zwisler Return-path: Content-Disposition: inline In-Reply-To: <1449602325-20572-4-git-send-email-ross.zwisler@linux.intel.com> Sender: owner-linux-mm@kvack.org List-Id: linux-ext4.vger.kernel.org On Tue 08-12-15 12:18:41, Ross Zwisler wrote: > Add find_get_entries_tag() to the family of functions that include > find_get_entries(), find_get_pages() and find_get_pages_tag(). This is > needed for DAX dirty page handling because we need a list of both page > offsets and radix tree entries ('indices' and 'entries' in this function) > that are marked with the PAGECACHE_TAG_TOWRITE tag. > > Signed-off-by: Ross Zwisler The patch looks good to me. You can add: Reviewed-by: Jan Kara But I agree with Daniel that some refactoring to remove common code would be good. Honza > --- > include/linux/pagemap.h | 3 +++ > mm/filemap.c | 68 +++++++++++++++++++++++++++++++++++++++++++++++++ > 2 files changed, 71 insertions(+) > > diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h > index 26eabf5..4db0425 100644 > --- a/include/linux/pagemap.h > +++ b/include/linux/pagemap.h > @@ -361,6 +361,9 @@ unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t start, > unsigned int nr_pages, struct page **pages); > unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index, > int tag, unsigned int nr_pages, struct page **pages); > +unsigned find_get_entries_tag(struct address_space *mapping, pgoff_t start, > + int tag, unsigned int nr_entries, > + struct page **entries, pgoff_t *indices); > > struct page *grab_cache_page_write_begin(struct address_space *mapping, > pgoff_t index, unsigned flags); > diff --git a/mm/filemap.c b/mm/filemap.c > index 167a4d9..99dfbc9 100644 > --- a/mm/filemap.c > +++ b/mm/filemap.c > @@ -1498,6 +1498,74 @@ repeat: > } > EXPORT_SYMBOL(find_get_pages_tag); > > +/** > + * find_get_entries_tag - find and return entries that match @tag > + * @mapping: the address_space to search > + * @start: the starting page cache index > + * @tag: the tag index > + * @nr_entries: the maximum number of entries > + * @entries: where the resulting entries are placed > + * @indices: the cache indices corresponding to the entries in @entries > + * > + * Like find_get_entries, except we only return entries which are tagged with > + * @tag. > + */ > +unsigned find_get_entries_tag(struct address_space *mapping, pgoff_t start, > + int tag, unsigned int nr_entries, > + struct page **entries, pgoff_t *indices) > +{ > + void **slot; > + unsigned int ret = 0; > + struct radix_tree_iter iter; > + > + if (!nr_entries) > + return 0; > + > + rcu_read_lock(); > +restart: > + radix_tree_for_each_tagged(slot, &mapping->page_tree, > + &iter, start, tag) { > + struct page *page; > +repeat: > + page = radix_tree_deref_slot(slot); > + if (unlikely(!page)) > + continue; > + if (radix_tree_exception(page)) { > + if (radix_tree_deref_retry(page)) { > + /* > + * Transient condition which can only trigger > + * when entry at index 0 moves out of or back > + * to root: none yet gotten, safe to restart. > + */ > + goto restart; > + } > + > + /* > + * A shadow entry of a recently evicted page, a swap > + * entry from shmem/tmpfs or a DAX entry. Return it > + * without attempting to raise page count. > + */ > + goto export; > + } > + if (!page_cache_get_speculative(page)) > + goto repeat; > + > + /* Has the page moved? */ > + if (unlikely(page != *slot)) { > + page_cache_release(page); > + goto repeat; > + } > +export: > + indices[ret] = iter.index; > + entries[ret] = page; > + if (++ret == nr_entries) > + break; > + } > + rcu_read_unlock(); > + return ret; > +} > +EXPORT_SYMBOL(find_get_entries_tag); > + > /* > * CD/DVDs are error prone. When a medium error occurs, the driver may fail > * a _large_ part of the i/o request. Imagine the worst scenario: > -- > 2.5.0 > > -- Jan Kara SUSE Labs, CR -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org