The patch titled scsi: export busy state via q->lld_busy_fn() has been removed from the -mm tree. Its filename was scsi-export-busy-state-via-q-lld_busy_fn.patch This patch was dropped because an updated version will be merged The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: scsi: export busy state via q->lld_busy_fn() From: Kiyoshi Ueda <k-ueda@xxxxxxxxxxxxx> This patch implements q->lld_busy_fn() for scsi mid layer to export its busy state. Please note that it checks the cached information (sdev->lld_busy) for efficiency, instead of checking the actual state of sdev/starget/shost everytime. So the care must be taken not to leave sdev->lld_busy = 1 for the following cases: - when there is no request in the sdev queue - when scsi can't dispatch I/Os anymore and needs to kill I/Os Otherwise, request stacking drivers may not submit any request, and then, nobody sets back lld_busy = 0 and that causes deadlock. OTOH, it has no major problem in setting sdev->lld_busy = 0 even when the starget/shost is actually busy, because newly submitted request will soon turn it to 1 in scsi_request_fn(). Signed-off-by: Kiyoshi Ueda <k-ueda@xxxxxxxxxxxxx> Signed-off-by: Jun'ichi Nomura <j-nomura@xxxxxxxxxxxxx> Cc: James Bottomley <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx> Cc: Jens Axboe <jens.axboe@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- drivers/scsi/scsi.c | 4 ++-- drivers/scsi/scsi_lib.c | 20 +++++++++++++++++++- include/scsi/scsi_device.h | 13 +++++++++++++ 3 files changed, 34 insertions(+), 3 deletions(-) diff -puN drivers/scsi/scsi.c~scsi-export-busy-state-via-q-lld_busy_fn drivers/scsi/scsi.c --- a/drivers/scsi/scsi.c~scsi-export-busy-state-via-q-lld_busy_fn +++ a/drivers/scsi/scsi.c @@ -804,8 +804,6 @@ void scsi_finish_command(struct scsi_cmn struct scsi_driver *drv; unsigned int good_bytes; - scsi_device_unbusy(sdev); - /* * Clear the flags which say that the device/host is no longer * capable of accepting new commands. These are set in scsi_queue.c @@ -817,6 +815,8 @@ void scsi_finish_command(struct scsi_cmn shost->host_blocked = 0; sdev->device_blocked = 0; + scsi_device_unbusy(sdev); + /* * If we have valid sense information, then some kind of recovery * must have taken place. Make a note of this. diff -puN drivers/scsi/scsi_lib.c~scsi-export-busy-state-via-q-lld_busy_fn drivers/scsi/scsi_lib.c --- a/drivers/scsi/scsi_lib.c~scsi-export-busy-state-via-q-lld_busy_fn +++ a/drivers/scsi/scsi_lib.c @@ -470,6 +470,8 @@ void scsi_device_unbusy(struct scsi_devi spin_unlock(shost->host_lock); spin_lock(sdev->request_queue->queue_lock); sdev->device_busy--; + if (sdev->device_busy < sdev->queue_depth && !sdev->device_blocked) + sdev->lld_busy = 0; spin_unlock_irqrestore(sdev->request_queue->queue_lock, flags); } @@ -1463,6 +1465,13 @@ static void scsi_softirq_done(struct req } } +static int scsi_lld_busy(struct request_queue *q) +{ + struct scsi_device *sdev = q->queuedata; + + return sdev ? sdev->lld_busy : 0; +} + /* * Function: scsi_request_fn() * @@ -1505,9 +1514,14 @@ static void scsi_request_fn(struct reque * accept it. */ req = elv_next_request(q); - if (!req || !scsi_dev_queue_ready(q, sdev)) + if (!req) break; + if (!scsi_dev_queue_ready(q, sdev)) { + sdev->lld_busy = 1; + break; + } + if (unlikely(!scsi_device_online(sdev))) { sdev_printk(KERN_ERR, sdev, "rejecting I/O to offline device\n"); @@ -1578,6 +1592,8 @@ static void scsi_request_fn(struct reque rtn = scsi_dispatch_cmd(cmd); spin_lock_irq(q->queue_lock); if(rtn) { + sdev->lld_busy = 1; + /* we're refusing the command; because of * the way locks get dropped, we need to * check here if plugging is required */ @@ -1602,6 +1618,7 @@ static void scsi_request_fn(struct reque * later time. */ spin_lock_irq(q->queue_lock); + sdev->lld_busy = 1; blk_requeue_request(q, req); sdev->device_busy--; if(sdev->device_busy == 0) @@ -1685,6 +1702,7 @@ struct request_queue *scsi_alloc_queue(s blk_queue_prep_rq(q, scsi_prep_fn); blk_queue_softirq_done(q, scsi_softirq_done); blk_queue_rq_timed_out(q, scsi_times_out); + blk_queue_lld_busy(q, scsi_lld_busy); return q; } diff -puN include/scsi/scsi_device.h~scsi-export-busy-state-via-q-lld_busy_fn include/scsi/scsi_device.h --- a/include/scsi/scsi_device.h~scsi-export-busy-state-via-q-lld_busy_fn +++ a/include/scsi/scsi_device.h @@ -145,6 +145,19 @@ struct scsi_device { unsigned retry_hwerror:1; /* Retry HARDWARE_ERROR */ unsigned last_sector_bug:1; /* do not use multisector accesses on SD_LAST_BUGGY_SECTORS */ + unsigned lld_busy:1; /* Exporting busy state for stacking + * drivers. + * + * 1 - There is one or more requests + * in the device's queue, + * and the device (or target/host) + * can not dispatch any request + * immediately. + * 0 - The device can dispatch + * (or kill) requests immediately, + * or there is no request in + * the device's queue even though + * target/host may busy. */ DECLARE_BITMAP(supported_events, SDEV_EVT_MAXBITS); /* supported events */ struct list_head event_list; /* asserted events */ _ Patches currently in -mm which might be from k-ueda@xxxxxxxxxxxxx are git-block.patch scsi-export-busy-state-via-q-lld_busy_fn.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html