Commits
Jaegeuk Kim committed bd43df021ac
f2fs: cover global locks for reserve_new_block
The fill_zero() from fallocate() calls get_new_data_page() in which calls
reserve_new_block().
The reserve_new_block() should be covered by *DATA_NEW*, one of global locks.
And also, before getting the lock, we should check free sections by calling
f2fs_balance_fs().
If we break this rule, f2fs is able to face with out-of-control free space
management and fall into infinite loop like the following scenario as well.
[f2fs_sync_fs()] [fallocate()]
- write_checkpoint() - fill_zero()
- block_operations() - get_new_data_page()
: grab NODE_NEW - get_dnode_of_data()
: get locked dirty node page
- sync_node_pages()
: try to grab NODE_NEW for data allocation
: trylock and skip the dirty node page
: call sync_node_pages() repeatedly in order to flush all the dirty node
pages!
In order to avoid this, we should grab another global lock such as DATA_NEW
before calling get_new_data_page() in fill_zero().
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>