On 07.05.19 22:35, Max Reitz wrote: > Hi, > > This series adds a --salvage option to qemu-img convert. With this, > qemu-img will not abort when it encounters an I/O error. Instead, it > tries to narrow it down and will treat the affected sectors as being > completely 0 (and print a warning). > > Testing this is not so easy, because while real I/O errors during read > operations should be treated as described above, errors encountered > during bdrv_block_status() should just be ignored and the affected > sectors should be considered allocated. But blkdebug does not yet have > a way to intercept this, and: > > (1) Just adding a new block-status event would be silly, because I don't > want an event, I want it to fail on a certain kind of operation, on > a certain sector range, independently of any events, so why can't we > just do that? See patch 4. > > (2) If we just make blkdebug intercept .bdrv_co_block_status() like all > other kinds of operations, at least iotest 041 fails, which does > exactly that silly thing: It uses the read_aio event to wait for any > read. But it turns out that there may be a bdrv_*block_status() > call in between, so suddenly the wrong operation yields an error. > As I said, the real fault here is that it does not really make sense > to pray that the operation you want to fail is the one that is > immediately executed after some event that you hope will trigger > that operation. > See patch 3. > > So patch 3 allows blkdebug users to select which kind of I/O operation > they actually want to make fail, and patch 4 allows them to not use any > event, but to have a rule active all the time. > > Together, we can then enable error injection for block-status in patch 5 > and make use of event=none iotype=block-status in patch 6.
Applied the series to my block branch, and fixed _filter_offsets in patch 6 as suggested by Vladimir. Max
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