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Date: Wed, 26 May 2021 12:11:43 +0000 From: Damien Le Moal <Damien.LeMoal@....com> To: Jan Kara <jack@...e.cz>, "Darrick J. Wong" <djwong@...nel.org> CC: "linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>, "hch@...radead.org" <hch@...radead.org>, Dave Chinner <david@...morbit.com>, "ceph-devel@...r.kernel.org" <ceph-devel@...r.kernel.org>, Chao Yu <yuchao0@...wei.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-cifs@...r.kernel.org>, "linux-ext4@...r.kernel.org" <linux-ext4@...r.kernel.org>, "linux-f2fs-devel@...ts.sourceforge.net" <linux-f2fs-devel@...ts.sourceforge.net>, "linux-mm@...ck.org" <linux-mm@...ck.org>, "linux-xfs@...r.kernel.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 2021/05/26 19:07, Jan Kara wrote: > 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. What about filemap_invalidate_lock_read() and filemap_invalidate_lock_write() ? That reminds the down_read()/down_write() without the slightly confusing down/up. > > 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 >>> -- Damien Le Moal Western Digital Research
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