Commit 7506ae6a authored by Jan Kara's avatar Jan Kara
Browse files

mm: Add functions to lock invalidate_lock for two mappings 



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

Reviewed-by: default avatarDarrick J. Wong <djwong@kernel.org>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarJan Kara <jack@suse.cz>
parent 730633f0

include/linux/fs.h

+6 −0
Original line number Diff line number Diff line
@@ -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

mm/filemap.c

+38 −0
Original line number Diff line number Diff line
@@ -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