A deadlock can be occurred:
Thread 1] Thread 2]
- f2fs_write_data_pages - f2fs_write_begin
- lock_page(page #0)
- grab_cache_page(page #X)
- get_node_page(inode_page)
- grab_cache_page(page #0)
: to convert inline_data
- f2fs_write_data_page
- f2fs_write_inline_data
- get_node_page(inode_page)
In this case, trying to lock inode_page and page #0 causes deadlock.
In order to avoid this, this patch adds a rule for this locking policy,
which is that page #0 should be locked followed by inode_page lock.
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
5f72739583