1) When we allocated last fragment in ufs_truncate, we read page, check
if block mapped to address, and if not trying to allocate it. This is
wrong behaviour, fragment may be NOT allocated, but mapped, this
happened because of "block map" function not checked allocated fragment
or not, it just take address of the first fragment in the block, add
offset of fragment and return result, this is correct behaviour in
almost all situation except call from ufs_truncate.
2) Almost all implementation of UFS, which I can investigate have such
"defect": if you have full disk, and try truncate file, for example 3GB
to 2MB, and have hole in this region, truncate return -ENOSPC. I tried
evade from this problem, but "block allocation" algorithm is tied to
right value of i_lastfrag, and fix of this corner case may slow down of
ordinaries scenarios, so this patch makes behavior of "truncate"
operations similar to what other UFS implementations do.
Signed-off-by: Evgeniy Dushistov <dushistov@mail.ru>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Evgeniy Dushistov
ecdc639487