Merge branch 'master' of git://git.ipfire.org/ipfire-2.x

[people/teissler/ipfire-2.x.git] / src / patches / suse-2.6.27.31 / patches.drivers / blk-request-based-multipath-update

From: Kiyoshi Ueda <k-ueda@ct.jp.nec.com>
Subject: Block layer fixes for request-based multipathing
References: References: FATE#302108

This is a combined patch from linux-2.6.git. Commit-IDs:

d6c578ec08b3f07050401ed83193b3f21729213b
afac32f0c9c68698eaf7688d52de859301a0539f
ebd2bf40e9cfa4ebfa614703944f4eafdf0d2c64
509395182b6b7cf7e3c1ca2cd669506d8f43ee01
88171cad9ace4b67c5298e6504d70454296afb76

Signed-off-by: Hannes Reinecke <hare@suse.de>

---
 block/blk-core.c        |  169 +++++++++++++++++++++++++++++++++++++++++++++---
 block/blk-settings.c    |    6 +
 drivers/scsi/scsi_lib.c |   32 +++++++++
 include/linux/blkdev.h  |   12 +++
 4 files changed, 209 insertions(+), 10 deletions(-)

--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -592,7 +592,8 @@ blk_init_queue_node(request_fn_proc *rfn
        q->request_fn           = rfn;
        q->prep_rq_fn           = NULL;
        q->unplug_fn            = generic_unplug_device;
-       q->queue_flags          = (1 << QUEUE_FLAG_CLUSTER);
+       q->queue_flags          = (1 << QUEUE_FLAG_CLUSTER |
+                                  1 << QUEUE_FLAG_STACKABLE);
        q->queue_lock           = lock;
 
        blk_queue_segment_boundary(q, 0xffffffff);
@@ -1586,6 +1587,87 @@ void blkdev_dequeue_request(struct reque
 EXPORT_SYMBOL(blkdev_dequeue_request);
 
 /**
+ * blk_rq_check_limits - Helper function to check a request for the queue limit
+ * @q:  the queue
+ * @rq: the request being checked
+ *
+ * Description:
+ *    @rq may have been made based on weaker limitations of upper-level queues
+ *    in request stacking drivers, and it may violate the limitation of @q.
+ *    Since the block layer and the underlying device driver trust @rq
+ *    after it is inserted to @q, it should be checked against @q before
+ *    the insertion using this generic function.
+ *
+ *    This function should also be useful for request stacking drivers
+ *    in some cases below, so export this fuction.
+ *    Request stacking drivers like request-based dm may change the queue
+ *    limits while requests are in the queue (e.g. dm's table swapping).
+ *    Such request stacking drivers should check those requests agaist
+ *    the new queue limits again when they dispatch those requests,
+ *    although such checkings are also done against the old queue limits
+ *    when submitting requests.
+ */
+int blk_rq_check_limits(struct request_queue *q, struct request *rq)
+{
+       if (rq->nr_sectors > q->max_sectors ||
+           rq->data_len > q->max_hw_sectors << 9) {
+               printk(KERN_ERR "%s: over max size limit.\n", __func__);
+               return -EIO;
+       }
+
+       /*
+        * queue's settings related to segment counting like q->bounce_pfn
+        * may differ from that of other stacking queues.
+        * Recalculate it to check the request correctly on this queue's
+        * limitation.
+        */
+       blk_recalc_rq_segments(rq);
+       if (rq->nr_phys_segments > q->max_phys_segments ||
+           rq->nr_phys_segments > q->max_hw_segments) {
+               printk(KERN_ERR "%s: over max segments limit.\n", __func__);
+               return -EIO;
+       }
+
+       return 0;
+}
+EXPORT_SYMBOL_GPL(blk_rq_check_limits);
+
+/**
+ * blk_insert_cloned_request - Helper for stacking drivers to submit a request
+ * @q:  the queue to submit the request
+ * @rq: the request being queued
+ */
+int blk_insert_cloned_request(struct request_queue *q, struct request *rq)
+{
+       unsigned long flags;
+
+       if (blk_rq_check_limits(q, rq))
+               return -EIO;
+
+#ifdef CONFIG_FAIL_MAKE_REQUEST
+       if (rq->rq_disk && rq->rq_disk->part0.make_it_fail &&
+           should_fail(&fail_make_request, blk_rq_bytes(rq)))
+               return -EIO;
+#endif
+
+       spin_lock_irqsave(q->queue_lock, flags);
+
+       /*
+        * Submitting request must be dequeued before calling this function
+        * because it will be linked to another request_queue
+        */
+       BUG_ON(blk_queued_rq(rq));
+
+       drive_stat_acct(rq, 1);
+       __elv_add_request(q, rq, ELEVATOR_INSERT_BACK, 0);
+
+       spin_unlock_irqrestore(q->queue_lock, flags);
+
+       return 0;
+}
+EXPORT_SYMBOL_GPL(blk_insert_cloned_request);
+
+/**
  * __end_that_request_first - end I/O on a request
  * @req:      the request being processed
  * @error:    %0 for success, < %0 for error
@@ -1857,6 +1939,22 @@ void end_request(struct request *req, in
 }
 EXPORT_SYMBOL(end_request);
 
+static int end_that_request_data(struct request *rq, int error,
+                                unsigned int nr_bytes, unsigned int bidi_bytes)
+{
+       if (rq->bio) {
+               if (__end_that_request_first(rq, error, nr_bytes))
+                       return 1;
+
+               /* Bidi request must be completed as a whole */
+               if (blk_bidi_rq(rq) &&
+                   __end_that_request_first(rq->next_rq, error, bidi_bytes))
+                       return 1;
+       }
+
+       return 0;
+}
+
 /**
  * blk_end_io - Generic end_io function to complete a request.
  * @rq:           the request being processed
@@ -1883,15 +1981,8 @@ static int blk_end_io(struct request *rq
        struct request_queue *q = rq->q;
        unsigned long flags = 0UL;
 
-       if (rq->bio) {
-               if (__end_that_request_first(rq, error, nr_bytes))
-                       return 1;
-
-               /* Bidi request must be completed as a whole */
-               if (blk_bidi_rq(rq) &&
-                   __end_that_request_first(rq->next_rq, error, bidi_bytes))
-                       return 1;
-       }
+       if (end_that_request_data(rq, error, nr_bytes, bidi_bytes))
+               return 1;
 
        /* Special feature for tricky drivers */
        if (drv_callback && drv_callback(rq))
@@ -1974,6 +2065,36 @@ int blk_end_bidi_request(struct request 
 EXPORT_SYMBOL_GPL(blk_end_bidi_request);
 
 /**
+ * blk_update_request - Special helper function for request stacking drivers
+ * @rq:           the request being processed
+ * @error:        %0 for success, < %0 for error
+ * @nr_bytes:     number of bytes to complete @rq
+ *
+ * Description:
+ *     Ends I/O on a number of bytes attached to @rq, but doesn't complete
+ *     the request structure even if @rq doesn't have leftover.
+ *     If @rq has leftover, sets it up for the next range of segments.
+ *
+ *     This special helper function is only for request stacking drivers
+ *     (e.g. request-based dm) so that they can handle partial completion.
+ *     Actual device drivers should use blk_end_request instead.
+ */
+void blk_update_request(struct request *rq, int error, unsigned int nr_bytes)
+{
+       if (!end_that_request_data(rq, error, nr_bytes, 0)) {
+               /*
+                * These members are not updated in end_that_request_data()
+                * when all bios are completed.
+                * Update them so that the request stacking driver can find
+                * how many bytes remain in the request later.
+                */
+               rq->nr_sectors = rq->hard_nr_sectors = 0;
+               rq->current_nr_sectors = rq->hard_cur_sectors = 0;
+       }
+}
+EXPORT_SYMBOL_GPL(blk_update_request);
+
+/**
  * blk_end_request_callback - Special helper function for tricky drivers
  * @rq:           the request being processed
  * @error:        %0 for success, < %0 for error
@@ -2028,6 +2149,34 @@ void blk_rq_bio_prep(struct request_queu
                rq->rq_disk = bio->bi_bdev->bd_disk;
 }
 
+/**
+ * blk_lld_busy - Check if underlying low-level drivers of a device are busy
+ * @q : the queue of the device being checked
+ *
+ * Description:
+ *    Check if underlying low-level drivers of a device are busy.
+ *    If the drivers want to export their busy state, they must set own
+ *    exporting function using blk_queue_lld_busy() first.
+ *
+ *    Basically, this function is used only by request stacking drivers
+ *    to stop dispatching requests to underlying devices when underlying
+ *    devices are busy.  This behavior helps more I/O merging on the queue
+ *    of the request stacking driver and prevents I/O throughput regression
+ *    on burst I/O load.
+ *
+ * Return:
+ *    0 - Not busy (The request stacking driver should dispatch request)
+ *    1 - Busy (The request stacking driver should stop dispatching request)
+ */
+int blk_lld_busy(struct request_queue *q)
+{
+       if (q->lld_busy_fn)
+               return q->lld_busy_fn(q);
+
+       return 0;
+}
+EXPORT_SYMBOL_GPL(blk_lld_busy);
+
 int kblockd_schedule_work(struct request_queue *q, struct work_struct *work)
 {
        return queue_work(kblockd_workqueue, work);
--- a/block/blk-settings.c
+++ b/block/blk-settings.c
@@ -89,6 +89,12 @@ void blk_queue_rq_timed_out(struct reque
 }
 EXPORT_SYMBOL_GPL(blk_queue_rq_timed_out);
 
+void blk_queue_lld_busy(struct request_queue *q, lld_busy_fn *fn)
+{
+       q->lld_busy_fn = fn;
+}
+EXPORT_SYMBOL_GPL(blk_queue_lld_busy);
+
 /**
  * blk_queue_make_request - define an alternate make_request function for a device
  * @q:  the request queue for the device to be affected
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1465,6 +1465,37 @@ static inline int scsi_host_queue_ready(
 }
 
 /*
+ * Busy state exporting function for request stacking drivers.
+ *
+ * For efficiency, no lock is taken to check the busy state of
+ * shost/starget/sdev, since the returned value is not guaranteed and
+ * may be changed after request stacking drivers call the function,
+ * regardless of taking lock or not.
+ *
+ * When scsi can't dispatch I/Os anymore and needs to kill I/Os
+ * (e.g. !sdev), scsi needs to return 'not busy'.
+ * Otherwise, request stacking drivers may hold requests forever.
+ */
+static int scsi_lld_busy(struct request_queue *q)
+{
+       struct scsi_device *sdev = q->queuedata;
+       struct Scsi_Host *shost;
+       struct scsi_target *starget;
+
+       if (!sdev)
+               return 0;
+
+       shost = sdev->host;
+       starget = scsi_target(sdev);
+
+       if (scsi_host_in_recovery(shost) || scsi_host_is_busy(shost) ||
+           scsi_target_is_busy(starget) || scsi_device_is_busy(sdev))
+               return 1;
+
+       return 0;
+}
+
+/*
  * Kill a request for a dead device
  */
 static void scsi_kill_request(struct request *req, struct request_queue *q)
@@ -1778,6 +1809,7 @@ 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;
 }
 
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -272,6 +272,7 @@ typedef int (merge_bvec_fn) (struct requ
 typedef void (prepare_flush_fn) (struct request_queue *, struct request *);
 typedef void (softirq_done_fn)(struct request *);
 typedef int (dma_drain_needed_fn)(struct request *);
+typedef int (lld_busy_fn) (struct request_queue *q);
 
 enum blk_eh_timer_return {
        BLK_EH_NOT_HANDLED,
@@ -328,6 +329,7 @@ struct request_queue
        softirq_done_fn         *softirq_done_fn;
        rq_timed_out_fn         *rq_timed_out_fn;
        dma_drain_needed_fn     *dma_drain_needed;
+       lld_busy_fn             *lld_busy_fn;
 
        /*
         * Dispatch queue sorting
@@ -443,6 +445,7 @@ struct request_queue
 #define QUEUE_FLAG_BIDI                9       /* queue supports bidi requests */
 #define QUEUE_FLAG_NOMERGES    10      /* disable merge attempts */
 #define QUEUE_FLAG_SAME_COMP   11      /* force complete on same CPU */
+#define QUEUE_FLAG_STACKABLE   13      /* supports request stacking */
 
 static inline int queue_is_locked(struct request_queue *q)
 {
@@ -549,6 +552,8 @@ enum {
 #define blk_queue_stopped(q)   test_bit(QUEUE_FLAG_STOPPED, &(q)->queue_flags)
 #define blk_queue_nomerges(q)  test_bit(QUEUE_FLAG_NOMERGES, &(q)->queue_flags)
 #define blk_queue_flushing(q)  ((q)->ordseq)
+#define blk_queue_stackable(q) \
+       test_bit(QUEUE_FLAG_STACKABLE, &(q)->queue_flags)
 
 #define blk_fs_request(rq)     ((rq)->cmd_type == REQ_TYPE_FS)
 #define blk_pc_request(rq)     ((rq)->cmd_type == REQ_TYPE_BLOCK_PC)
@@ -695,6 +700,10 @@ extern void __blk_put_request(struct req
 extern struct request *blk_get_request(struct request_queue *, int, gfp_t);
 extern void blk_insert_request(struct request_queue *, struct request *, int, void *);
 extern void blk_requeue_request(struct request_queue *, struct request *);
+extern int blk_rq_check_limits(struct request_queue *q, struct request *rq);
+extern int blk_lld_busy(struct request_queue *q);
+extern int blk_insert_cloned_request(struct request_queue *q,
+                                    struct request *rq);
 extern void blk_plug_device(struct request_queue *);
 extern void blk_plug_device_unlocked(struct request_queue *);
 extern int blk_remove_plug(struct request_queue *);
@@ -792,6 +801,8 @@ extern void blk_complete_request(struct 
 extern void __blk_complete_request(struct request *);
 extern void blk_abort_request(struct request *);
 extern void blk_abort_queue(struct request_queue *);
+extern void blk_update_request(struct request *rq, int error,
+                              unsigned int nr_bytes);
 
 /*
  * blk_end_request() takes bytes instead of sectors as a complete size.
@@ -821,6 +832,7 @@ extern void blk_queue_update_dma_pad(str
 extern int blk_queue_dma_drain(struct request_queue *q,
                               dma_drain_needed_fn *dma_drain_needed,
                               void *buf, unsigned int size);
+extern void blk_queue_lld_busy(struct request_queue *q, lld_busy_fn *fn);
 extern void blk_queue_segment_boundary(struct request_queue *, unsigned long);
 extern void blk_queue_prep_rq(struct request_queue *, prep_rq_fn *pfn);
 extern void blk_queue_merge_bvec(struct request_queue *, merge_bvec_fn *);