1 files changed, 109 insertions, 21 deletions

diff --git a/drivers/block/xen-blkback/blkback.c b/drivers/block/xen-blkback/blkback.c
index 1540792b1e54..15ec4db194d1 100644
--- a/drivers/block/xen-blkback/blkback.c
+++ b/drivers/block/xen-blkback/blkback.c
@@ -39,6 +39,9 @@
 #include <linux/list.h>
 #include <linux/delay.h>
 #include <linux/freezer.h>
+#include <linux/loop.h>
+#include <linux/falloc.h>
+#include <linux/fs.h>
 
 #include <xen/events.h>
 #include <xen/page.h>
@@ -258,13 +261,16 @@ irqreturn_t xen_blkif_be_int(int irq, void *dev_id)
 
 static void print_stats(struct xen_blkif *blkif)
 {
-        pr_info("xen-blkback (%s): oo %3d  |  rd %4d  |  wr %4d  |  f %4d\n",
+        pr_info("xen-blkback (%s): oo %3d  |  rd %4d  |  wr %4d  |  f %4d"
+                 "  |  ds %4d\n",
                  current->comm, blkif->st_oo_req,
-                 blkif->st_rd_req, blkif->st_wr_req, blkif->st_f_req);
+                 blkif->st_rd_req, blkif->st_wr_req,
+                 blkif->st_f_req, blkif->st_ds_req);
         blkif->st_print = jiffies + msecs_to_jiffies(10 * 1000);
         blkif->st_rd_req = 0;
         blkif->st_wr_req = 0;
         blkif->st_oo_req = 0;
+        blkif->st_ds_req = 0;
 }
 
 int xen_blkif_schedule(void *arg)
@@ -410,6 +416,59 @@ static int xen_blkbk_map(struct blkif_request *req,
         return ret;
 }
 
+static void xen_blk_discard(struct xen_blkif *blkif, struct blkif_request *req)
+{
+        int err = 0;
+        int status = BLKIF_RSP_OKAY;
+        struct block_device *bdev = blkif->vbd.bdev;
+
+        if (blkif->blk_backend_type == BLKIF_BACKEND_PHY)
+                /* just forward the discard request */
+                err = blkdev_issue_discard(bdev,
+                                req->u.discard.sector_number,
+                                req->u.discard.nr_sectors,
+                                GFP_KERNEL, 0);
+        else if (blkif->blk_backend_type == BLKIF_BACKEND_FILE) {
+                /* punch a hole in the backing file */
+                struct loop_device *lo = bdev->bd_disk->private_data;
+                struct file *file = lo->lo_backing_file;
+
+                if (file->f_op->fallocate)
+                        err = file->f_op->fallocate(file,
+                                FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE,
+                                req->u.discard.sector_number << 9,
+                                req->u.discard.nr_sectors << 9);
+                else
+                        err = -EOPNOTSUPP;
+        } else
+                err = -EOPNOTSUPP;
+
+        if (err == -EOPNOTSUPP) {
+                pr_debug(DRV_PFX "discard op failed, not supported\n");
+                status = BLKIF_RSP_EOPNOTSUPP;
+        } else if (err)
+                status = BLKIF_RSP_ERROR;
+
+        make_response(blkif, req->id, req->operation, status);
+}
+
+static void xen_blk_drain_io(struct xen_blkif *blkif)
+{
+        atomic_set(&blkif->drain, 1);
+        do {
+                /* The initial value is one, and one refcnt taken at the
+                 * start of the xen_blkif_schedule thread. */
+                if (atomic_read(&blkif->refcnt) <= 2)
+                        break;
+                wait_for_completion_interruptible_timeout(
+                                &blkif->drain_complete, HZ);
+
+                if (!atomic_read(&blkif->drain))
+                        break;
+        } while (!kthread_should_stop());
+        atomic_set(&blkif->drain, 0);
+}
+
 /*
  * Completion callback on the bio's. Called as bh->b_end_io()
  */
@@ -422,6 +481,11 @@ static void __end_block_io_op(struct pending_req *pending_req, int error)
                 pr_debug(DRV_PFX "flush diskcache op failed, not supported\n");
                 xen_blkbk_flush_diskcache(XBT_NIL, pending_req->blkif->be, 0);
                 pending_req->status = BLKIF_RSP_EOPNOTSUPP;
+        } else if ((pending_req->operation == BLKIF_OP_WRITE_BARRIER) &&
+                    (error == -EOPNOTSUPP)) {
+                pr_debug(DRV_PFX "write barrier op failed, not supported\n");
+                xen_blkbk_barrier(XBT_NIL, pending_req->blkif->be, 0);
+                pending_req->status = BLKIF_RSP_EOPNOTSUPP;
         } else if (error) {
                 pr_debug(DRV_PFX "Buffer not up-to-date at end of operation,"
                          " error=%d\n", error);
@@ -438,6 +502,10 @@ static void __end_block_io_op(struct pending_req *pending_req, int error)
                 make_response(pending_req->blkif, pending_req->id,
                               pending_req->operation, pending_req->status);
                 xen_blkif_put(pending_req->blkif);
+                if (atomic_read(&pending_req->blkif->refcnt) <= 2) {
+                        if (atomic_read(&pending_req->blkif->drain))
+                                complete(&pending_req->blkif->drain_complete);
+                }
                 free_req(pending_req);
         }
 }
@@ -532,7 +600,6 @@ do_block_io_op(struct xen_blkif *blkif)
 
         return more_to_do;
 }
-
 /*
  * Transmutation of the 'struct blkif_request' to a proper 'struct bio'
  * and call the 'submit_bio' to pass it to the underlying storage.
@@ -549,6 +616,7 @@ static int dispatch_rw_block_io(struct xen_blkif *blkif,
         int i, nbio = 0;
         int operation;
         struct blk_plug plug;
+        bool drain = false;
 
         switch (req->operation) {
         case BLKIF_OP_READ:
@@ -559,11 +627,16 @@ static int dispatch_rw_block_io(struct xen_blkif *blkif,
                 blkif->st_wr_req++;
                 operation = WRITE_ODIRECT;
                 break;
+        case BLKIF_OP_WRITE_BARRIER:
+                drain = true;
         case BLKIF_OP_FLUSH_DISKCACHE:
                 blkif->st_f_req++;
                 operation = WRITE_FLUSH;
                 break;
-        case BLKIF_OP_WRITE_BARRIER:
+        case BLKIF_OP_DISCARD:
+                blkif->st_ds_req++;
+                operation = REQ_DISCARD;
+                break;
         default:
                 operation = 0; /* make gcc happy */
                 goto fail_response;
@@ -572,7 +645,8 @@ static int dispatch_rw_block_io(struct xen_blkif *blkif,
 
         /* Check that the number of segments is sane. */
         nseg = req->nr_segments;
-        if (unlikely(nseg == 0 && operation != WRITE_FLUSH) ||
+        if (unlikely(nseg == 0 && operation != WRITE_FLUSH &&
+                                operation != REQ_DISCARD) ||
             unlikely(nseg > BLKIF_MAX_SEGMENTS_PER_REQUEST)) {
                 pr_debug(DRV_PFX "Bad number of segments in request (%d)\n",
                          nseg);
@@ -621,16 +695,25 @@ static int dispatch_rw_block_io(struct xen_blkif *blkif,
                 }
         }
 
+        /* Wait on all outstanding I/O's and once that has been completed
+         * issue the WRITE_FLUSH.
+         */
+        if (drain)
+                xen_blk_drain_io(pending_req->blkif);
+
         /*
          * If we have failed at this point, we need to undo the M2P override,
          * set gnttab_set_unmap_op on all of the grant references and perform
          * the hypercall to unmap the grants - that is all done in
          * xen_blkbk_unmap.
          */
-        if (xen_blkbk_map(req, pending_req, seg))
+        if (operation != REQ_DISCARD && xen_blkbk_map(req, pending_req, seg))
                 goto fail_flush;
 
-        /* This corresponding xen_blkif_put is done in __end_block_io_op */
+        /*
+         * This corresponding xen_blkif_put is done in __end_block_io_op, or
+         * below (in "!bio") if we are handling a BLKIF_OP_DISCARD.
+         */
         xen_blkif_get(blkif);
 
         for (i = 0; i < nseg; i++) {
@@ -654,18 +737,25 @@ static int dispatch_rw_block_io(struct xen_blkif *blkif,
                 preq.sector_number += seg[i].nsec;
         }
 
-        /* This will be hit if the operation was a flush. */
+        /* This will be hit if the operation was a flush or discard. */
         if (!bio) {
-                BUG_ON(operation != WRITE_FLUSH);
+                BUG_ON(operation != WRITE_FLUSH && operation != REQ_DISCARD);
 
-                bio = bio_alloc(GFP_KERNEL, 0);
-                if (unlikely(bio == NULL))
-                        goto fail_put_bio;
+                if (operation == WRITE_FLUSH) {
+                        bio = bio_alloc(GFP_KERNEL, 0);
+                        if (unlikely(bio == NULL))
+                                goto fail_put_bio;
 
-                biolist[nbio++] = bio;
-                bio->bi_bdev    = preq.bdev;
-                bio->bi_private = pending_req;
-                bio->bi_end_io  = end_block_io_op;
+                        biolist[nbio++] = bio;
+                        bio->bi_bdev    = preq.bdev;
+                        bio->bi_private = pending_req;
+                        bio->bi_end_io  = end_block_io_op;
+                } else if (operation == REQ_DISCARD) {
+                        xen_blk_discard(blkif, req);
+                        xen_blkif_put(blkif);
+                        free_req(pending_req);
+                        return 0;
+                }
         }
 
         /*
@@ -685,7 +775,7 @@ static int dispatch_rw_block_io(struct xen_blkif *blkif,
 
         if (operation == READ)
                 blkif->st_rd_sect += preq.nr_sects;
-        else if (operation == WRITE || operation == WRITE_FLUSH)
+        else if (operation & WRITE)
                 blkif->st_wr_sect += preq.nr_sects;
 
         return 0;
@@ -765,9 +855,9 @@ static int __init xen_blkif_init(void)
 
         mmap_pages = xen_blkif_reqs * BLKIF_MAX_SEGMENTS_PER_REQUEST;
 
-        blkbk->pending_reqs          = kmalloc(sizeof(blkbk->pending_reqs[0]) *
+        blkbk->pending_reqs          = kzalloc(sizeof(blkbk->pending_reqs[0]) *
                                         xen_blkif_reqs, GFP_KERNEL);
-        blkbk->pending_grant_handles = kzalloc(sizeof(blkbk->pending_grant_handles[0]) *
+        blkbk->pending_grant_handles = kmalloc(sizeof(blkbk->pending_grant_handles[0]) *
                                         mmap_pages, GFP_KERNEL);
         blkbk->pending_pages         = kzalloc(sizeof(blkbk->pending_pages[0]) *
                                         mmap_pages, GFP_KERNEL);
@@ -790,8 +880,6 @@ static int __init xen_blkif_init(void)
         if (rc)
                 goto failed_init;
 
-        memset(blkbk->pending_reqs, 0, sizeof(blkbk->pending_reqs));
-
         INIT_LIST_HEAD(&blkbk->pending_free);
         spin_lock_init(&blkbk->pending_free_lock);
         init_waitqueue_head(&blkbk->pending_free_wq);