tree 7a2e010060b6233cd02e2e36b62f5dcaa96c2c36
parent fbdcf18df73758b2e187ab94678b30cd5f6ff9f9
author Jun'ichi Nomura <j-nomura@ce.jp.nec.com> 1197555325 +0000
committer Alasdair G Kergon <agk@redhat.com> 1198171928 +0000

dm: table detect io beyond device

This patch fixes a panic on shrinking a DM device if there is
outstanding I/O to the part of the device that is being removed.
(Normally this doesn't happen - a filesystem would be resized first,
for example.)

The bug is that __clone_and_map() assumes dm_table_find_target()
always returns a valid pointer.  It may fail if a bio arrives from the
block layer but its target sector is no longer included in the DM
btree.

This patch appends an empty entry to table->targets[] which will
be returned by a lookup beyond the end of the device.

After calling dm_table_find_target(), __clone_and_map() and target_message()
check for this condition using
dm_target_is_valid().

Sample test script to trigger oops: