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Mon, 6 Jul 2026 15:28:06 +0000 (UTC) Received: from warthog.procyon.org.com (unknown [10.44.33.159]) by mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 9039E18005A5; Mon, 6 Jul 2026 15:27:57 +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 v5 01/21] mm: Make readahead store folio count in readahead_control Date: Mon, 6 Jul 2026 16:27:16 +0100 Message-ID: <20260706152737.1231312-2-dhowells@redhat.com> In-Reply-To: <20260706152737.1231312-1-dhowells@redhat.com> References: <20260706152737.1231312-1-dhowells@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.93 X-Mimecast-MFC-PROC-ID: aebgUEpHBKY-M6Tl0_h9foO8_HNrjbmj5j32KcjnVCA_1783351689 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: 8bit content-type: text/plain; charset="US-ASCII"; x-default=true X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 1243E180015 X-Stat-Signature: 9b3o4t8h6mtjcd75mqj9nnr3ni1txynu X-Rspam-User: X-HE-Tag: 1783351696-950531 X-HE-Meta: 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 Zr+YWxXu idvCCYt6kuGpNcv4VXum/ddpc9d0bnJhLKvdL9AviKIyx0QokhosAYiuC3TdAp1+6tIP6gg/V/ea/2wf58lrkbeIf4Q3qshdLMfBb2lH01+cxdel7D4K1MdNvyKPeL1uyKUZn87gBZEh/Ypltegg7mZkehxhxVzH9ERG8G0c3b5OOe82nTEP7YGqCBa/62n2UDHxRju7BvP04SDd7eyflnAys4dwimYx9z5Cus1NtSQfrDHdj+XR2COV430IXLHTrhtX7YeP5WNJTMXNtYgLdHITT+VeAbq2V7JtmoOayezQZVzuVgrg8TkPnQuhmsT5S5WtZ+CtvJD7HH/G/HdPByLs/3q43uDbm5AZtSr5HFEae7PMJF+RuF27kgNrrCQviPkk7jvCsjQEsKvd0+rD3PfM+IAsHEw0vqvTw+UK1wHpLghAyd2T1uy/kB4MfsDBkCjp1jUBB3HJvN8TgMpZ2T3u0/DVEri8g8RuPEPEm1WtxU5IRmGME32AvJWNLxnTeXGmKorNFe+cK2ZyMxIFcONsRfUATumoAU8UMMW7x6qeKA20zTC0io3gaTxJvz7fbCTEyo3+9q3gBUqu0i6kIp9OFfQ== 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;