Commits
Dmitry Monakhov committed 1c9114f9c0f
ext4: serialize unlocked dio reads with truncate
Current serialization will works only for DIO which holds
i_mutex, but nonlocked DIO following race is possible:
dio_nolock_read_task truncate_task
->ext4_setattr()
->inode_dio_wait()
->ext4_ext_direct_IO
->ext4_ind_direct_IO
->__blockdev_direct_IO
->ext4_get_block
->truncate_setsize()
->ext4_truncate()
#alloc truncated blocks
#to other inode
->submit_io()
#INFORMATION LEAK
In order to serialize with unlocked DIO reads we have to
rearrange wait sequence
1) update i_size first
2) if i_size about to be reduced wait for outstanding DIO requests
3) and only after that truncate inode blocks
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>