[PATCH 04/14] mm: Add functions to lock invalidate_lock for two mappings
From: Jan Kara <jack@suse.cz>
Date: 2021-06-07 14:52:42
Also in:
ceph-devel, linux-cifs, linux-f2fs-devel, linux-fsdevel, linux-mm, linux-xfs
Subsystem:
filesystems (vfs and infrastructure), memory management, page cache, the rest · Maintainers:
Alexander Viro, Christian Brauner, Andrew Morton, Matthew Wilcox, Jan Kara, Linus Torvalds
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 d8afbc9661d7..ddc11bafc183 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h@@ -849,6 +849,12 @@ static inline void filemap_invalidate_unlock_shared( void lock_two_nondirectories(struct inode *, struct inode*); void unlock_two_nondirectories(struct inode *, struct inode*); +void filemap_invalidate_lock_two(struct address_space *mapping1, + struct address_space *mapping2); +void filemap_invalidate_unlock_two(struct address_space *mapping1, + 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 c8e7e451d81e..b8e9bccecd9f 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_lock_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_lock_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_lock_two); + +/* + * filemap_invalidate_unlock_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_unlock_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_unlock_two); + /* * In order to wait for pages to become available there must be * waitqueues associated with pages. By using a hash table of
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2.26.2