Add a convenience function, folio_inode() that will get the host inode from
a folio's mapping.
Changes:
ver #3:
- Fix mistake in function description[2].
ver #2:
- Fix contradiction between doc and implementation by disallowing use
with swap caches[1].
Signed-off-by: David Howells <[email protected]>
Reviewed-by: Matthew Wilcox (Oracle) <[email protected]>
Tested-by: Jeff Layton <[email protected]>
Tested-by: Dominique Martinet <[email protected]>
Tested-by: [email protected]
Link: https://lore.kernel.org/r/[email protected]/ [1]
Link: https://lore.kernel.org/r/[email protected]/ [2]
Link:
https://lore.kernel.org/r/162880453171.3369675.3704943108660112470.st...@warthog.procyon.org.uk/
# rfc
Link:
https://lore.kernel.org/r/162981151155.1901565.7010079316994382707.st...@warthog.procyon.org.uk/
Link:
https://lore.kernel.org/r/163005744370.2472992.18324470937328925723.st...@warthog.procyon.org.uk/
# v2
Link:
https://lore.kernel.org/r/163584184628.4023316.9386282630968981869.st...@warthog.procyon.org.uk/
# v3
---
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 1f560aecd9b5..1a0c646eb6ff 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -253,6 +253,20 @@ 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 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 2d498bb62248..a613f8ef6a02 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -2967,7 +2967,7 @@ 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);
--
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