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Wed, 22 Jul 2026 13:03:32 +0000 (UTC) Received: from warthog.procyon.org.com (unknown [10.44.33.159]) by mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id A8EEC1800623; Wed, 22 Jul 2026 13:03:25 +0000 (UTC) From: David Howells To: Christian Brauner , Matthew Wilcox , Christoph Hellwig Cc: David Howells , Paulo Alcantara , Jens Axboe , Leon Romanovsky , Steve French , ChenXiaoSong , 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-erofs@lists.ozlabs.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH v7 07/29] mm: Make readahead store folio count in readahead_control Date: Wed, 22 Jul 2026 14:01:54 +0100 Message-ID: <20260722130218.78958-8-dhowells@redhat.com> In-Reply-To: <20260722130218.78958-1-dhowells@redhat.com> References: <20260722130218.78958-1-dhowells@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 X-Mimecast-MFC-PROC-ID: HK3UiJ8vRZrrl5TqYXf6sGOCxPBy7H8MGHqIISa8geU_1784725412 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: 8bit content-type: text/plain; charset="US-ASCII"; x-default=true X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 3D4292000D X-Rspam-User: X-Stat-Signature: hykjq569kt4pxgta41iyat1g53mxm8q9 X-HE-Tag: 1784725421-341363 X-HE-Meta: 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 VR7u5Ngl 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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 cc: 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 2c3718d592d6..e1e51bace388 100644 --- a/include/linux/pagemap.h +++ b/include/linux/pagemap.h @@ -1348,6 +1348,7 @@ 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; @@ -1527,6 +1528,15 @@ 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 558c92957518..069ded56fd80 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;