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From: David Howells <dhowells@redhat.com>
To: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: dhowells@redhat.com, Jeff Layton <jlayton@kernel.org>,
	Ilya Dryomov <idryomov@gmail.com>,
	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
Subject: [PATCH v2 4/6] folio: Add a function to get the host inode for a folio
Date: Fri, 27 Aug 2021 10:44:03 +0100	[thread overview]
Message-ID: <163005744370.2472992.18324470937328925723.stgit@warthog.procyon.org.uk> (raw)
In-Reply-To: <163005740700.2472992.12365214290752300378.stgit@warthog.procyon.org.uk>

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 <dhowells@redhat.com>
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);



  parent reply	other threads:[~2021-08-27  9:46 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-27  9:43 [PATCH v2 0/6] netfs, afs, ceph: Support folios, at least partially David Howells
2021-08-27  9:43 ` [PATCH v2 1/6] afs: Fix afs_launder_page() to set correct start file position David Howells
2021-08-27  9:43 ` [PATCH v2 2/6] afs: Sort out symlink reading David Howells
2021-08-27  9:43 ` [PATCH v2 3/6] folio: Add a function to change the private data attached to a folio David Howells
2021-08-27  9:44 ` David Howells [this message]
2021-08-27  9:44 ` [PATCH v2 5/6] netfs, afs, ceph: Use folios David Howells
2021-09-08 19:06   ` Jeff Layton
2021-08-27  9:44 ` [PATCH v2 6/6] afs: Use folios in directory handling David Howells

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