1 files changed, 47 insertions, 4 deletions

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 53875ae73ad4..f2a4cc79da61 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -142,6 +142,7 @@ static noinline int run_scheduled_bios(struct btrfs_device *device)
         unsigned long limit;
         unsigned long last_waited = 0;
         int force_reg = 0;
+        int sync_pending = 0;
         struct blk_plug plug;
 
         /*
@@ -229,6 +230,22 @@ loop_lock:
 
                 BUG_ON(atomic_read(&cur->bi_cnt) == 0);
 
+                /*
+                 * if we're doing the sync list, record that our
+                 * plug has some sync requests on it
+                 *
+                 * If we're doing the regular list and there are
+                 * sync requests sitting around, unplug before
+                 * we add more
+                 */
+                if (pending_bios == &device->pending_sync_bios) {
+                        sync_pending = 1;
+                } else if (sync_pending) {
+                        blk_finish_plug(&plug);
+                        blk_start_plug(&plug);
+                        sync_pending = 0;
+                }
+
                 submit_bio(cur->bi_rw, cur);
                 num_run++;
                 batch_run++;
@@ -500,6 +517,9 @@ static int __btrfs_close_devices(struct btrfs_fs_devices *fs_devices)
                         fs_devices->rw_devices--;
                 }
 
+                if (device->can_discard)
+                        fs_devices->num_can_discard--;
+
                 new_device = kmalloc(sizeof(*new_device), GFP_NOFS);
                 BUG_ON(!new_device);
                 memcpy(new_device, device, sizeof(*new_device));
@@ -508,6 +528,7 @@ static int __btrfs_close_devices(struct btrfs_fs_devices *fs_devices)
                 new_device->bdev = NULL;
                 new_device->writeable = 0;
                 new_device->in_fs_metadata = 0;
+                new_device->can_discard = 0;
                 list_replace_rcu(&device->dev_list, &new_device->dev_list);
 
                 call_rcu(&device->rcu, free_device);
@@ -547,6 +568,7 @@ int btrfs_close_devices(struct btrfs_fs_devices *fs_devices)
 static int __btrfs_open_devices(struct btrfs_fs_devices *fs_devices,
                                 fmode_t flags, void *holder)
 {
+        struct request_queue *q;
         struct block_device *bdev;
         struct list_head *head = &fs_devices->devices;
         struct btrfs_device *device;
@@ -603,6 +625,12 @@ static int __btrfs_open_devices(struct btrfs_fs_devices *fs_devices,
                         seeding = 0;
                 }
 
+                q = bdev_get_queue(bdev);
+                if (blk_queue_discard(q)) {
+                        device->can_discard = 1;
+                        fs_devices->num_can_discard++;
+                }
+
                 device->bdev = bdev;
                 device->in_fs_metadata = 0;
                 device->mode = flags;
@@ -835,6 +863,7 @@ int find_free_dev_extent(struct btrfs_trans_handle *trans,
 
         max_hole_start = search_start;
         max_hole_size = 0;
+        hole_size = 0;
 
         if (search_start >= search_end) {
                 ret = -ENOSPC;
@@ -917,7 +946,14 @@ next:
                 cond_resched();
         }
 
-        hole_size = search_end- search_start;
+        /*
+         * At this point, search_start should be the end of
+         * allocated dev extents, and when shrinking the device,
+         * search_end may be smaller than search_start.
+         */
+        if (search_end > search_start)
+                hole_size = search_end - search_start;
+
         if (hole_size > max_hole_size) {
                 max_hole_start = search_start;
                 max_hole_size = hole_size;
@@ -1543,6 +1579,7 @@ error:
 
 int btrfs_init_new_device(struct btrfs_root *root, char *device_path)
 {
+        struct request_queue *q;
         struct btrfs_trans_handle *trans;
         struct btrfs_device *device;
         struct block_device *bdev;
@@ -1612,6 +1649,9 @@ int btrfs_init_new_device(struct btrfs_root *root, char *device_path)
 
         lock_chunks(root);
 
+        q = bdev_get_queue(bdev);
+        if (blk_queue_discard(q))
+                device->can_discard = 1;
         device->writeable = 1;
         device->work.func = pending_bios_fn;
         generate_random_uuid(device->uuid);
@@ -1647,6 +1687,8 @@ int btrfs_init_new_device(struct btrfs_root *root, char *device_path)
         root->fs_info->fs_devices->num_devices++;
         root->fs_info->fs_devices->open_devices++;
         root->fs_info->fs_devices->rw_devices++;
+        if (device->can_discard)
+                root->fs_info->fs_devices->num_can_discard++;
         root->fs_info->fs_devices->total_rw_bytes += device->total_bytes;
 
         if (!blk_queue_nonrot(bdev_get_queue(bdev)))
@@ -2413,9 +2455,10 @@ static int __btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
                         total_avail = device->total_bytes - device->bytes_used;
                 else
                         total_avail = 0;
-                /* avail is off by max(alloc_start, 1MB), but that is the same
-                 * for all devices, so it doesn't hurt the sorting later on
-                 */
+
+                /* If there is no space on this device, skip it. */
+                if (total_avail == 0)
+                        continue;
 
                 ret = find_free_dev_extent(trans, device,
                                            max_stripe_size * dev_stripes,