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Wed, 7 Oct 2026 14:20:22 +0000 (UTC) Received: from warthog.com (unknown [10.44.32.90]) by mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 018DC3004195; Wed, 7 Oct 2026 14:20:13 +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 v14 1/8] mm: Make readahead store folio count in readahead_control Date: Wed, 7 Oct 2026 15:19:52 +0100 Message-ID: <20261007142001.851620-2-dhowells@redhat.com> In-Reply-To: <20261007142001.851620-1-dhowells@redhat.com> References: <20261007142001.851620-1-dhowells@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.4 X-Mimecast-MFC-PROC-ID: _BBEyAd-FRThoeOnqWoUUXGVxNFPGtb1TOUNRZ77hPc_1791382847 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: 8bit content-type: text/plain; charset="US-ASCII"; x-default=true X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: D7792140005 X-Rspam-User: X-Stat-Signature: da1t36sor3aq3yt4s4y46fceirn7xk39 X-HE-Tag: 1791382853-728946 X-HE-Meta: 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 NmJfj88C 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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;