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Date: Wed, 26 May 2021 12:07:02 +0200 From: Jan Kara <jack@...e.cz> To: "Darrick J. Wong" <djwong@...nel.org> Cc: Jan Kara <jack@...e.cz>, linux-fsdevel@...r.kernel.org, Christoph Hellwig <hch@...radead.org>, Dave Chinner <david@...morbit.com>, ceph-devel@...r.kernel.org, Chao Yu <yuchao0@...wei.com>, Damien Le Moal <damien.lemoal@....com>, "Darrick J. Wong" <darrick.wong@...cle.com>, Jaegeuk Kim <jaegeuk@...nel.org>, Jeff Layton <jlayton@...nel.org>, Johannes Thumshirn <jth@...nel.org>, linux-cifs@...r.kernel.org, linux-ext4@...r.kernel.org, linux-f2fs-devel@...ts.sourceforge.net, linux-mm@...ck.org, linux-xfs@...r.kernel.org, Miklos Szeredi <miklos@...redi.hu>, Steve French <sfrench@...ba.org>, Ted Tso <tytso@....edu>, Matthew Wilcox <willy@...radead.org> Subject: Re: [PATCH 04/13] mm: Add functions to lock invalidate_lock for two mappings On Tue 25-05-21 13:48:05, Darrick J. Wong wrote: > On Tue, May 25, 2021 at 03:50:41PM +0200, Jan Kara wrote: > > 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@...e.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. Honza > To be fair, I've never been able to keep straight that down means lock > and up means unlock. Ah well, at least you didn't use "p" and "v". > > Mechanically, the changes look ok to me. > Acked-by: Darrick J. Wong <djwong@...nel.org> > > --D > > > + struct address_space *mapping2); > > + > > + > > /* > > * NOTE: in a 32bit arch with a preemptable kernel and > > * an UP compile the i_size_read/write must be atomic > > diff --git a/mm/filemap.c b/mm/filemap.c > > index 4d9ec4c6cc34..d3801a9739aa 100644 > > --- a/mm/filemap.c > > +++ b/mm/filemap.c > > @@ -1009,6 +1009,44 @@ struct page *__page_cache_alloc(gfp_t gfp) > > EXPORT_SYMBOL(__page_cache_alloc); > > #endif > > > > +/* > > + * filemap_invalidate_down_write_two - lock invalidate_lock for two mappings > > + * > > + * Lock exclusively invalidate_lock of any passed mapping that is not NULL. > > + * > > + * @mapping1: the first mapping to lock > > + * @mapping2: the second mapping to lock > > + */ > > +void filemap_invalidate_down_write_two(struct address_space *mapping1, > > + struct address_space *mapping2) > > +{ > > + if (mapping1 > mapping2) > > + swap(mapping1, mapping2); > > + if (mapping1) > > + down_write(&mapping1->invalidate_lock); > > + if (mapping2 && mapping1 != mapping2) > > + down_write_nested(&mapping2->invalidate_lock, 1); > > +} > > +EXPORT_SYMBOL(filemap_invalidate_down_write_two); > > + > > +/* > > + * filemap_invalidate_up_write_two - unlock invalidate_lock for two mappings > > + * > > + * Unlock exclusive invalidate_lock of any passed mapping that is not NULL. > > + * > > + * @mapping1: the first mapping to unlock > > + * @mapping2: the second mapping to unlock > > + */ > > +void filemap_invalidate_up_write_two(struct address_space *mapping1, > > + struct address_space *mapping2) > > +{ > > + if (mapping1) > > + up_write(&mapping1->invalidate_lock); > > + if (mapping2 && mapping1 != mapping2) > > + up_write(&mapping2->invalidate_lock); > > +} > > +EXPORT_SYMBOL(filemap_invalidate_up_write_two); > > + > > /* > > * In order to wait for pages to become available there must be > > * waitqueues associated with pages. By using a hash table of > > -- > > 2.26.2 > > -- Jan Kara <jack@...e.com> SUSE Labs, CR
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