tree 3aeca5bc6bd3976552077909509e3a7e2be9542b
parent 1d7095c72d35eee4ebc28e66563e636b9adafeb2
author Al Viro <viro@zeniv.linux.org.uk> 1368859132 -0400
committer Al Viro <viro@zeniv.linux.org.uk> 1370027863 -0400

hpfs: deadlock and race in directory lseek()

For one thing, there's an ABBA deadlock on hpfs fs-wide lock and i_mutex
in hpfs_dir_lseek() - there's a lot of methods that grab the former with
the caller already holding the latter, so it must take i_mutex first.

For another, locking the damn thing, carefully validating the offset,
then dropping locks and assigning the offset is obviously racy.

Moreover, we _must_ do hpfs_add_pos(), or the machinery in dnode.c
won't modify the sucker on B-tree surgeries.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>