search for: nbd_internal_is_state_readi

All accesses to the h->state field are redirected through these macros (except when we create the handle). This is simple refactoring. --- generator/generator | 18 +++++++++--------- lib/connect.c | 10 +++++----- lib/disconnect.c | 8 ++++---- lib/internal.h | 3 +++ lib/is-state.c | 12 ++++++------ lib/rw.c | 4 ++-- 6 files changed, 29 insertions(+), 26

I need to think about this patch series a bit more, but it does at least pass the tests. Rich.

Split h->state into: - h->public_state = the state on entry to the locked region This is also the atomically, publicly visible state. - h->state = the real current state of the handle When we leave the locked region we update h->public_state with h->state, so that from outside the lock the handle appears to move atomically from its previous state to the final state without

For each nbd_(unlocked_)?aio_is_* function, split it into an internal function that tests the state and a public visible API function. For calls within the library, use the internal function. This is simple refactoring. As a side effect this fixes a race condition identified by Eric Blake: Thread A Thread B (in a call that holds h->lock) (calling nbd_aio_pread)

Split h->state into: - h->state = the state on entry to the locked region - h->next_state = the current state and what the "publicly visible" state will become when we leave the locked region Some calls to get_state become calls to get_next_state depending on which of these they are trying to read. Calls to set_state become set_next_state because that is what gets

v1 was here: https://www.redhat.com/archives/libguestfs/2019-June/thread.html#00055 v2 was here: https://www.redhat.com/archives/libguestfs/2019-June/thread.html#00067 v3: - Fix atomicly -> atomically in commit message. - Fix a comment. - Fix TOCTTOU: There is now an inline function generated called <name>_is_permitted_state, and this is called twice, first outside the

Split h->state into: - h->public_state = the state on entry to the locked region This is also the atomicly, publicly visible state. - h->state = the real current state of the handle When we leave the locked region we update h->public_state with h->state, so that from outside the lock the handle appears to move atomically from its previous state to the final state without

On 6/5/19 6:15 AM, Richard W.M. Jones wrote: > For each nbd_(unlocked_)?aio_is_* function, split it into an internal > function that tests the state and a public visible API function. > > For calls within the library, use the internal function. > > This is simple refactoring. > > As a side effect this fixes a race condition identified by Eric Blake: > > Thread A

Once the client has requested NBD_CMD_DISC, the protocol states that it must not send any further information to the server (further writes may still be needed for a clean TLS shutdown, but that's a different matter requiring more states). Our state machine can prevent some of this if we have moved to CLOSED, but that's not foolproof because we can queue commands that can't be written

This is the bare minimum needed to allow the user to take control over the rest of option negotiating. This patch adds several new API: nbd_set_opt_mode() - called during Created to enable the new mode nbd_get_opt_mode() - query whether opt mode is enabled nbd_opt_go() - used in Negotiating state to attempt to use export nbd_opt_abort() - used in Negotiating state to skip Connected state

As mentioned in commits 176fc4ea and 609c25f0, our original plan in adding a flags argument to nbd_shutdown was to let us specify different behaviors at the libnbd level, rather than NBD protocol flags (for that, the user has nbd_aio_disconnect). But when we later parameterized OFlags to accept various bitmasks (commit f891340b), we failed to mark nbd_shutdown as using a different bitmask than

Although rare, it is possible that nbd_internal_run(cmd_issue) will report failure (perhaps because the server disconnected at the wrong time), even though we have queued the user's command. If we have a valid cookie, we MUST return it for the sake of users that will be calling nbd_aio_command_complete, as otherwise the user has no idea what cookie to wait on. Ignoring the state machine

On Fri, Sep 11, 2020 at 09:31:11AM -0500, Eric Blake wrote: > As mentioned in commits 176fc4ea and 609c25f0, our original plan in > adding a flags argument to nbd_shutdown was to let us specify > different behaviors at the libnbd level, rather than NBD protocol > flags (for that, the user has nbd_aio_disconnect). But when we later > parameterized OFlags to accept various bitmasks

I think this needs extra documentation in docs/libnbd.pod because it's definitely not clear just from the rather thin manual page for set_opt_mode how it works. docs/libnbd.pod is a good place for a broader description of how it works. IIUC let me try to explain: we get through as far as the end of group OPT_STRUCTURED_REPLY before we check the opt flag, and then the remainder of opt

We have no control over the user piling up lots of commands faster than the server can accept (h->cmds_to_issue), or delaying retiring those batched commands (h->cmds_in_flight), hence our use of O(n) list insertion can be noticeable, since the growth of n can be unbounded from our viewpoint. It's easy enough to track a tail pointer to keep insertion O(1), to match that these two lists

Noticed while thinking about the recent threads wondering if we need a more efficient lookup from cookie back to command. Both of these fix bugs, but are tricky enough that I'm posting for review. Eric Blake (2): lib: Decrement in_flight at response, not retirement lib: Do O(1) rather than O(n) queue insertion generator/states-issue-command.c | 2 ++ generator/states-reply.c |

On 8/11/20 12:12 PM, Richard W.M. Jones wrote: > I think this needs extra documentation in docs/libnbd.pod because it's > definitely not clear just from the rather thin manual page for > set_opt_mode how it works. docs/libnbd.pod is a good place for a > broader description of how it works. Yes, good idea. State-wise, the existing flow was: Created - Progress only by command

Well, I'm not quite done (I still want to get nbdinfo to work on a single nbd connection for all cases when reading the heads of the file is not required), but I'm happy with patches 1-11, and 12-13 show where I'm headed for getting NBD_OPT_INFO to work. Posting now to see if some of the earlier patches are ready to commit while I continue working on the latter half. Eric Blake (13):