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Mon, 5 Oct 2026 07:12:52 +0000 (UTC) Received: from warthog.com (unknown [10.44.32.90]) by mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 322B119373D8; Mon, 5 Oct 2026 07:12:45 +0000 (UTC) From: David Howells To: Christian Brauner Cc: David Howells , Paulo Alcantara , Matthew Wilcox , Namjae Jeon , Marc Dionne , Stefan Metzmacher , Eric Van Hensbergen , Dominique Martinet , Ilya Dryomov , netfs@lists.linux.dev, linux-afs@lists.infradead.org, linux-cifs@vger.kernel.org, linux-nfs@vger.kernel.org, ceph-devel@vger.kernel.org, v9fs@lists.linux.dev, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH v12 1/8] mm: Make readahead store folio count in readahead_control Date: Mon, 5 Oct 2026 08:12:18 +0100 Message-ID: <20261005071227.147182-2-dhowells@redhat.com> In-Reply-To: <20261005071227.147182-1-dhowells@redhat.com> References: <20261005071227.147182-1-dhowells@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 X-Mimecast-MFC-PROC-ID: zRsrhugkNMl4HwyJF0BXQ6R00rAYP071Ce9OVSq787o_1791184373 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: 8bit content-type: text/plain; charset="US-ASCII"; x-default=true X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 1C42E180002 X-Stat-Signature: mrffbty5xs5s17tip9hayqeun939xzkg X-HE-Tag: 1791184381-715474 X-HE-Meta: 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 sKV72kQ3 6NWwYYVjqkETkwSzctu9gTG3B50/zZ1V7AhOstvygLrY6JG0D2tw4S5bDIn/9eU/vNp8kG0P171hgvPvHMhu1iOB7yOI+R7voBxlxwrS0kyDoTSqf1207bqy9afTLxdqDaEqCZ7rxTQg2cs5HsQbjicMT5gPvyh/Juuu2FgRhIXK7QoXOLqyBDbL/KKexqC0fjbEdDJm2lB+UiQ0pBTFlOOvFIXNx0JVntHdiMU4ROn++Ntw8omwpbgOcZyefOxLf5M7+JFXTuA2/OGQxS6P+fBTx/1S+56UULwOe9UCKushl5YTHY2H1S0LxEs1B185fXug7CiFOgkgD/eBPBNlbtYpYpjQ+cf2CdNRGRvz8GzQfFI2yxwAMkPg/3/82sOq9mCuOn9Bgj8EAPl4nEPh6hvXP8PJ17ZRSpcqRqspOnbuFZX++xeLREDiMgz1cQdtmsJIVptMjiiQJ0lnOgTadb/KHjxJKsXFZCl5KLgU+etKJg0ITlCw3h15+9V3aY+zSuUg3JgErQvb6OChKinOwg/Lwm0QJ55F7WSWjnL479aSn5AjNDaqhO97ixJYwDAqFJqaje3DCAlKEV5kdwB8YKnm2DQ== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Make readahead store folio count in readahead_control so that the filesystem can know in advance how many folios it needs to keep track of. This is cleared by read_pages() in case it is called from a loop. The count is accessed by the filesystem with readahead_folio_count(). Signed-off-by: David Howells Reviewed-by: Paulo Alcantara (Red Hat) cc: Matthew Wilcox cc: netfs@lists.linux.dev cc: linux-mm@kvack.org cc: linux-fsdevel@vger.kernel.org --- include/linux/pagemap.h | 10 ++++++++++ mm/readahead.c | 5 +++++ 2 files changed, 15 insertions(+) diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h index 0adfa6605653..b7154b81d0d7 100644 --- a/include/linux/pagemap.h +++ b/include/linux/pagemap.h @@ -1411,6 +1411,7 @@ struct readahead_control { struct file_ra_state *ra; /* private: use the readahead_* accessors instead */ pgoff_t _index; + unsigned int _nr_folios; unsigned int _nr_pages; unsigned int _batch_count; bool dropbehind; @@ -1590,6 +1591,15 @@ static inline size_t readahead_batch_length(const struct readahead_control *rac) return rac->_batch_count * PAGE_SIZE; } +/** + * readahead_folio_count - Get the number of folios in this readahead request. + * @rac: The readahead request. + */ +static inline unsigned int readahead_folio_count(const struct readahead_control *rac) +{ + return rac->_nr_folios; +} + static inline unsigned long dir_pages(const struct inode *inode) { return (unsigned long)(inode->i_size + PAGE_SIZE - 1) >> diff --git a/mm/readahead.c b/mm/readahead.c index 6e5563290287..196542fb1c93 100644 --- a/mm/readahead.c +++ b/mm/readahead.c @@ -188,6 +188,7 @@ static void read_pages(struct readahead_control *rac) if (unlikely(rac->_workingset)) psi_memstall_leave(&rac->_pflags); rac->_workingset = false; + rac->_nr_folios = 0; BUG_ON(readahead_count(rac)); } @@ -303,6 +304,7 @@ void page_cache_ra_unbounded(struct readahead_control *ractl, if (i == mark) folio_set_readahead(folio); ractl->_workingset |= folio_test_workingset(folio); + ractl->_nr_folios++; ractl->_nr_pages += min_nrpages; i += min_nrpages; } @@ -473,6 +475,7 @@ static inline int ra_alloc_folio(struct readahead_control *ractl, pgoff_t index, return err; } + ractl->_nr_folios++; ractl->_nr_pages += 1UL << order; ractl->_workingset |= folio_test_workingset(folio); return 0; @@ -822,6 +825,7 @@ void readahead_expand(struct readahead_control *ractl, ractl->_workingset = true; psi_memstall_enter(&ractl->_pflags); } + ractl->_nr_folios++; ractl->_nr_pages += min_nrpages; ractl->_index = folio->index; } @@ -851,6 +855,7 @@ void readahead_expand(struct readahead_control *ractl, ractl->_workingset = true; psi_memstall_enter(&ractl->_pflags); } + ractl->_nr_folios++; ractl->_nr_pages += min_nrpages; if (ra) { ra->size += min_nrpages;