On Wed 26-05-21 12:11:43, Damien Le Moal wrote:

On 2021/05/26 19:07, Jan Kara wrote:

quoted

On Tue 25-05-21 13:48:05, Darrick J. Wong wrote:

quoted

On Tue, May 25, 2021 at 03:50:41PM +0200, Jan Kara wrote:

quoted

Some operations such as reflinking blocks among files will need to lock
invalidate_lock for two mappings. Add helper functions to do that.

Signed-off-by: Jan Kara <jack@suse.cz>
---
 include/linux/fs.h |  6 ++++++
 mm/filemap.c       | 38 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 44 insertions(+)

diff --git a/include/linux/fs.h b/include/linux/fs.h
index 897238d9f1e0..e6f7447505f5 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h

@@ -822,6 +822,12 @@ static inline void inode_lock_shared_nested(struct inode *inode, unsigned subcla
 void lock_two_nondirectories(struct inode *, struct inode*);
 void unlock_two_nondirectories(struct inode *, struct inode*);
 
+void filemap_invalidate_down_write_two(struct address_space *mapping1,
+				       struct address_space *mapping2);
+void filemap_invalidate_up_write_two(struct address_space *mapping1,

TBH I find myself wishing that the invalidate_lock used the same
lock/unlock style wrappers that we use for i_rwsem.

filemap_invalidate_lock(inode1->mapping);
filemap_invalidate_lock_two(inode1->i_mapping, inode2->i_mapping);

OK, and filemap_invalidate_lock_shared() for down_read()? I guess that
works for me.

What about filemap_invalidate_lock_read() and filemap_invalidate_lock_write() ?
That reminds the down_read()/down_write() without the slightly confusing down/up.

Well, if we go for lock wrappers as Darrick suggested, I'd mirror naming
used for inode_lock(). That is IMO the least confusing option... And that
naming has _lock and _lock_shared suffixes.

								Honza

-- 
Jan Kara [off-list ref]
SUSE Labs, CR