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Thu, 8 Oct 2026 08:47:37 +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 v16 1/8] mm: Make readahead store folio count in readahead_control Date: Thu, 8 Oct 2026 09:47:13 +0100 Message-ID: <20261008084722.963948-2-dhowells@redhat.com> In-Reply-To: <20261008084722.963948-1-dhowells@redhat.com> References: <20261008084722.963948-1-dhowells@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 X-Mimecast-MFC-PROC-ID: 4E5eqaXeMG0g74HlR3Dvpz6uI_DPv3jBwH8m89C_M8E_1791449265 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: 8bit content-type: text/plain; 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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;