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Thu, 8 Oct 2026 10:23:13 +0000 (UTC) Received: from warthog.com (unknown [10.44.32.90]) by mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 3BF581956086; Thu, 8 Oct 2026 10:23:06 +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 v17 1/8] mm: Make readahead store folio count in readahead_control Date: Thu, 8 Oct 2026 11:22:45 +0100 Message-ID: <20261008102253.1003776-2-dhowells@redhat.com> In-Reply-To: <20261008102253.1003776-1-dhowells@redhat.com> References: <20261008102253.1003776-1-dhowells@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 X-Mimecast-MFC-PROC-ID: ZyRzPNCNIJJ7aWV6gFyrpBIVE_p1g7SmkriIuWdRSYE_1791454994 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: rspam07 X-Rspamd-Queue-Id: 10A811C0011 X-Stat-Signature: aec81bdtdwutmk3xt39hqf6zhjr9xr35 X-HE-Tag: 1791455002-240478 X-HE-Meta: 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 vXFOQ9Mg 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 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;