[PATCH v4 2/5] folio: Add a function to get the host inode for a folio
From: David Howells <dhowells@redhat.com>
Date: 2021-11-09 21:30:06
Also in:
ceph-devel, linux-cifs, linux-fsdevel, linux-nfs, lkml
Subsystem:
memory management, page cache, the rest · Maintainers:
Andrew Morton, Matthew Wilcox, Linus Torvalds
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 <dhowells@redhat.com>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Tested-by: Jeff Layton <jlayton@kernel.org>
Tested-by: Dominique Martinet <asmadeus@codewreck.org>
Tested-by: kafs-testing@auristor.com
Link: https://lore.kernel.org/r/YST8OcVNy02Rivbm@casper.infradead.org/ (local) [1]
Link: https://lore.kernel.org/r/YYKLkBwQdtn4ja+i@casper.infradead.org/ (local) [2]
Link: https://lore.kernel.org/r/162880453171.3369675.3704943108660112470.stgit@warthog.procyon.org.uk/ (local) # rfc
Link: https://lore.kernel.org/r/162981151155.1901565.7010079316994382707.stgit@warthog.procyon.org.uk/ (local)
Link: https://lore.kernel.org/r/163005744370.2472992.18324470937328925723.stgit@warthog.procyon.org.uk/ (local) # v2
Link: https://lore.kernel.org/r/163584184628.4023316.9386282630968981869.stgit@warthog.procyon.org.uk/ (local) # 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);