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Registered in England and Wales under Company Registration No. 3798903 Subject: [PATCH v2 4/6] folio: Add a function to get the host inode for a folio From: David Howells To: "Matthew Wilcox (Oracle)" Cc: dhowells@redhat.com, Jeff Layton , Ilya Dryomov , linux-fsdevel@vger.kernel.org, linux-cachefs@redhat.com, linux-afs@lists.infradead.org, linux-nfs@vger.kernel.org, linux-cifs@vger.kernel.org, ceph-devel@vger.kernel.org, v9fs-developer@lists.sourceforge.net, devel@lists.orangefs.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Date: Fri, 27 Aug 2021 10:44:03 +0100 Message-ID: <163005744370.2472992.18324470937328925723.stgit@warthog.procyon.org.uk> In-Reply-To: <163005740700.2472992.12365214290752300378.stgit@warthog.procyon.org.uk> References: <163005740700.2472992.12365214290752300378.stgit@warthog.procyon.org.uk> User-Agent: StGit/0.23 MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Precedence: bulk List-ID: X-Mailing-List: linux-cifs@vger.kernel.org Add a convenience function, folio_inode() that will get the host inode from a folio's mapping. Changes: ver #2: - Fix contradiction between doc and implementation by disallowing use with swap caches[1]. Signed-off-by: David Howells Link: https://lore.kernel.org/r/YST8OcVNy02Rivbm@casper.infradead.org/ [1] Link: https://lore.kernel.org/r/162880453171.3369675.3704943108660112470.stgit@warthog.procyon.org.uk/ # rfc Link: https://lore.kernel.org/r/162981151155.1901565.7010079316994382707.stgit@warthog.procyon.org.uk/ --- include/linux/pagemap.h | 14 ++++++++++++++ mm/page-writeback.c | 2 +- 2 files changed, 15 insertions(+), 1 deletion(-) diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h index c8d336e62177..320f1f4db1a5 100644 --- a/include/linux/pagemap.h +++ b/include/linux/pagemap.h @@ -203,6 +203,20 @@ static inline struct address_space *page_mapping_file(struct page *page) return folio_mapping(folio); } +/** + * folio_inode - Get the host inode for this folio. + * @folio: The folio. + * + * For folios which are in the page cache, return the inode that is hosting + * this folio belongs to. + * + * Do not call this for folios which aren't in the page cache. + */ +static inline struct inode *folio_inode(struct folio *folio) +{ + return folio->mapping->host; +} + static inline bool page_cache_add_speculative(struct page *page, int count) { VM_BUG_ON_PAGE(PageTail(page), page); diff --git a/mm/page-writeback.c b/mm/page-writeback.c index 86b90173baf8..f750946d11f7 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -2918,7 +2918,7 @@ EXPORT_SYMBOL_GPL(folio_wait_writeback_killable); */ void folio_wait_stable(struct folio *folio) { - if (folio->mapping->host->i_sb->s_iflags & SB_I_STABLE_WRITES) + if (folio_inode(folio)->i_sb->s_iflags & SB_I_STABLE_WRITES) folio_wait_writeback(folio); } EXPORT_SYMBOL_GPL(folio_wait_stable);