kernel/drivers/target/target_core_user.c, branch linux-4.16.y

tcmu: Fix trailing semicolon

2018-01-18T09:21:24Z

The trailing semicolon is an empty statement that does no operation. It is completely stripped out by the compiler. Removing it since it doesn't do anything. Signed-off-by: Luis de Bethencourt Acked-by: Mike Christie Signed-off-by: Nicholas Bellinger

tcmu: fix cmd user after free

2018-01-18T09:21:23Z

If we are failing the command due to a qfull timeout we are also freeing the tcmu command, so we cannot access it later to get the se_cmd. Note: The clearing of cmd->se_cmd is not needed. We do not check it later for something like determining if the command was failed due to a timeout. As a result I am dropping it. Signed-off-by: Mike Christie Signed-off-by: Nicholas Bellinger

tcmu: allow userspace to reset ring

2018-01-17T02:05:04Z

This patch adds 2 tcmu attrs to block/unblock a device and reset the ring buffer. They are used when the userspace daemon has crashed or forced to shutdown while IO is executing. On restart, the daemon can block the device so new IO is not sent to userspace while it puts the ring in a clean state. Notes: The reset ring opreation is specific to tcmu, but the block one could be generic. I kept it tcmu specific, because it requires some extra locking/state checks in the main IO path and since other backend modules did not need this functionality I thought only tcmu should take the perf hit. Signed-off-by: Mike Christie Signed-off-by: Nicholas Bellinger

tcmu: fix error return code in tcmu_configure_device()

2018-01-13T05:17:35Z

Fix to return error code -ENOMEM from the kzalloc() error handling case instead of 0, as done elsewhere in this function. Fixes: 80eb876 ("tcmu: allow max block and global max blocks to be settable") Signed-off-by: Wei Yongjun Acked-by: Mike Christie Signed-off-by: Nicholas Bellinger

target_core_user: add cmd id to broken ring message

2018-01-12T23:07:30Z

Log cmd id that was not found in the tcmu_handle_completions lookup failure path. Signed-off-by: Mike Christie Signed-off-by: Nicholas Bellinger

tcmu: prevent corruption when invalid data page requested

2018-01-12T23:07:29Z

We will always have a page mapped for cmd data if it is valid command. If the mapping does not exist then something bad happened in userspace and it should not proceed. This has us return VM_FAULT_SIGBUS when this happens instead of returning a freshly allocated paged. The latter can cause corruption because userspace might write the pages data overwriting valid data or return it to the initiator. Signed-off-by: Mike Christie Signed-off-by: Nicholas Bellinger

tcmu: allow max block and global max blocks to be settable

2018-01-12T23:07:20Z

Users might have a physical system to a target so they could have a lot more than 2 gigs of memory they want to devote to tcmu. OTOH, we could be running in a vm and so a 2 gig global and 1 gig per dev limit might be too high. This patch allows the user to specify the limits. Signed-off-by: Mike Christie Signed-off-by: Nicholas Bellinger

tcmu: make ring buffer timer configurable

2018-01-12T23:07:19Z

This adds a timer, qfull_time_out, that controls how long a device will wait for ring buffer space to open before failing the commands in the queue. It is useful to separate this timer from the cmd_time_out and default 30 sec one, because for HA setups cmd_time_out may be disbled and 30 seconds is too long to wait when some OSs like ESX will timeout commands after as little as 8 - 15 seconds. Signed-off-by: Mike Christie Signed-off-by: Nicholas Bellinger

tcmu: don't block submitting context for block waits

2018-01-12T23:07:19Z

This patch has tcmu internally queue cmds if its ring buffer is full. It also makes the TCMU_GLOBAL_MAX_BLOCKS limit a hint instead of a hard limit, so we do not have to add any new locks/atomics in the main IO path except when IO is not running. This fixes the following bugs: 1. We cannot sleep from the submitting context because it might be called from a target recv context. This results in transport level commands timing out. For example if the ring is full, we would sleep, and a iscsi initiator would send a iscsi ping/nop which times out because the target's recv thread is sleeping here. 2. Devices were not fairly scheduled to run when they hit the global limit so they could time out waiting for ring space while others got run. Signed-off-by: Mike Christie Signed-off-by: Nicholas Bellinger

tcmu: simplify dbi thresh handling

2018-01-12T23:07:18Z

We do not really save a lot by trying to increase thresh a multiple of the existing value. This just simplifies the code by increasing it to whatever is needed for the command being executed. Signed-off-by: Mike Christie Signed-off-by: Nicholas Bellinger