1 files changed, 459 insertions, 167 deletions

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 1718e1a5c320..d158530233b7 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -22,6 +22,7 @@
 #include <linux/blkdev.h>
 #include <linux/random.h>
 #include <linux/iocontext.h>
+#include <linux/capability.h>
 #include <asm/div64.h>
 #include "compat.h"
 #include "ctree.h"
@@ -600,8 +601,10 @@ static int __btrfs_open_devices(struct btrfs_fs_devices *fs_devices,
                 set_blocksize(bdev, 4096);
 
                 bh = btrfs_read_dev_super(bdev);
-                if (!bh)
+                if (!bh) {
+                        ret = -EINVAL;
                         goto error_close;
+                }
 
                 disk_super = (struct btrfs_super_block *)bh->b_data;
                 devid = btrfs_stack_device_id(&disk_super->dev_item);
@@ -703,7 +706,7 @@ int btrfs_scan_one_device(const char *path, fmode_t flags, void *holder,
                 goto error_close;
         bh = btrfs_read_dev_super(bdev);
         if (!bh) {
-                ret = -EIO;
+                ret = -EINVAL;
                 goto error_close;
         }
         disk_super = (struct btrfs_super_block *)bh->b_data;
@@ -729,59 +732,167 @@ error:
         return ret;
 }
 
+/* helper to account the used device space in the range */
+int btrfs_account_dev_extents_size(struct btrfs_device *device, u64 start,
+                                   u64 end, u64 *length)
+{
+        struct btrfs_key key;
+        struct btrfs_root *root = device->dev_root;
+        struct btrfs_dev_extent *dev_extent;
+        struct btrfs_path *path;
+        u64 extent_end;
+        int ret;
+        int slot;
+        struct extent_buffer *l;
+
+        *length = 0;
+
+        if (start >= device->total_bytes)
+                return 0;
+
+        path = btrfs_alloc_path();
+        if (!path)
+                return -ENOMEM;
+        path->reada = 2;
+
+        key.objectid = device->devid;
+        key.offset = start;
+        key.type = BTRFS_DEV_EXTENT_KEY;
+
+        ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
+        if (ret < 0)
+                goto out;
+        if (ret > 0) {
+                ret = btrfs_previous_item(root, path, key.objectid, key.type);
+                if (ret < 0)
+                        goto out;
+        }
+
+        while (1) {
+                l = path->nodes[0];
+                slot = path->slots[0];
+                if (slot >= btrfs_header_nritems(l)) {
+                        ret = btrfs_next_leaf(root, path);
+                        if (ret == 0)
+                                continue;
+                        if (ret < 0)
+                                goto out;
+
+                        break;
+                }
+                btrfs_item_key_to_cpu(l, &key, slot);
+
+                if (key.objectid < device->devid)
+                        goto next;
+
+                if (key.objectid > device->devid)
+                        break;
+
+                if (btrfs_key_type(&key) != BTRFS_DEV_EXTENT_KEY)
+                        goto next;
+
+                dev_extent = btrfs_item_ptr(l, slot, struct btrfs_dev_extent);
+                extent_end = key.offset + btrfs_dev_extent_length(l,
+                                                                  dev_extent);
+                if (key.offset <= start && extent_end > end) {
+                        *length = end - start + 1;
+                        break;
+                } else if (key.offset <= start && extent_end > start)
+                        *length += extent_end - start;
+                else if (key.offset > start && extent_end <= end)
+                        *length += extent_end - key.offset;
+                else if (key.offset > start && key.offset <= end) {
+                        *length += end - key.offset + 1;
+                        break;
+                } else if (key.offset > end)
+                        break;
+
+next:
+                path->slots[0]++;
+        }
+        ret = 0;
+out:
+        btrfs_free_path(path);
+        return ret;
+}
+
 /*
+ * find_free_dev_extent - find free space in the specified device
+ * @trans:      transaction handler
+ * @device:     the device which we search the free space in
+ * @num_bytes:  the size of the free space that we need
+ * @start:      store the start of the free space.
+ * @len:        the size of the free space. that we find, or the size of the max
+ *              free space if we don't find suitable free space
+ *
  * this uses a pretty simple search, the expectation is that it is
  * called very infrequently and that a given device has a small number
  * of extents
+ *
+ * @start is used to store the start of the free space if we find. But if we
+ * don't find suitable free space, it will be used to store the start position
+ * of the max free space.
+ *
+ * @len is used to store the size of the free space that we find.
+ * But if we don't find suitable free space, it is used to store the size of
+ * the max free space.
  */
 int find_free_dev_extent(struct btrfs_trans_handle *trans,
                          struct btrfs_device *device, u64 num_bytes,
-                         u64 *start, u64 *max_avail)
+                         u64 *start, u64 *len)
 {
         struct btrfs_key key;
         struct btrfs_root *root = device->dev_root;
-        struct btrfs_dev_extent *dev_extent = NULL;
+        struct btrfs_dev_extent *dev_extent;
         struct btrfs_path *path;
-        u64 hole_size = 0;
-        u64 last_byte = 0;
-        u64 search_start = 0;
+        u64 hole_size;
+        u64 max_hole_start;
+        u64 max_hole_size;
+        u64 extent_end;
+        u64 search_start;
         u64 search_end = device->total_bytes;
         int ret;
-        int slot = 0;
-        int start_found;
+        int slot;
         struct extent_buffer *l;
 
-        path = btrfs_alloc_path();
-        if (!path)
-                return -ENOMEM;
-        path->reada = 2;
-        start_found = 0;
-
         /* FIXME use last free of some kind */
 
         /* we don't want to overwrite the superblock on the drive,
          * so we make sure to start at an offset of at least 1MB
          */
-        search_start = max((u64)1024 * 1024, search_start);
+        search_start = 1024 * 1024;
 
-        if (root->fs_info->alloc_start + num_bytes <= device->total_bytes)
+        if (root->fs_info->alloc_start + num_bytes <= search_end)
                 search_start = max(root->fs_info->alloc_start, search_start);
 
+        max_hole_start = search_start;
+        max_hole_size = 0;
+
+        if (search_start >= search_end) {
+                ret = -ENOSPC;
+                goto error;
+        }
+
+        path = btrfs_alloc_path();
+        if (!path) {
+                ret = -ENOMEM;
+                goto error;
+        }
+        path->reada = 2;
+
         key.objectid = device->devid;
         key.offset = search_start;
         key.type = BTRFS_DEV_EXTENT_KEY;
+
         ret = btrfs_search_slot(trans, root, &key, path, 0, 0);
         if (ret < 0)
-                goto error;
+                goto out;
         if (ret > 0) {
                 ret = btrfs_previous_item(root, path, key.objectid, key.type);
                 if (ret < 0)
-                        goto error;
-                if (ret > 0)
-                        start_found = 1;
+                        goto out;
         }
-        l = path->nodes[0];
-        btrfs_item_key_to_cpu(l, &key, path->slots[0]);
+
         while (1) {
                 l = path->nodes[0];
                 slot = path->slots[0];
@@ -790,24 +901,9 @@ int find_free_dev_extent(struct btrfs_trans_handle *trans,
                         if (ret == 0)
                                 continue;
                         if (ret < 0)
-                                goto error;
-no_more_items:
-                        if (!start_found) {
-                                if (search_start >= search_end) {
-                                        ret = -ENOSPC;
-                                        goto error;
-                                }
-                                *start = search_start;
-                                start_found = 1;
-                                goto check_pending;
-                        }
-                        *start = last_byte > search_start ?
-                                last_byte : search_start;
-                        if (search_end <= *start) {
-                                ret = -ENOSPC;
-                                goto error;
-                        }
-                        goto check_pending;
+                                goto out;
+
+                        break;
                 }
                 btrfs_item_key_to_cpu(l, &key, slot);
 
@@ -815,48 +911,62 @@ no_more_items:
                         goto next;
 
                 if (key.objectid > device->devid)
-                        goto no_more_items;
+                        break;
 
-                if (key.offset >= search_start && key.offset > last_byte &&
-                    start_found) {
-                        if (last_byte < search_start)
-                                last_byte = search_start;
-                        hole_size = key.offset - last_byte;
+                if (btrfs_key_type(&key) != BTRFS_DEV_EXTENT_KEY)
+                        goto next;
 
-                        if (hole_size > *max_avail)
-                                *max_avail = hole_size;
+                if (key.offset > search_start) {
+                        hole_size = key.offset - search_start;
 
-                        if (key.offset > last_byte &&
-                            hole_size >= num_bytes) {
-                                *start = last_byte;
-                                goto check_pending;
+                        if (hole_size > max_hole_size) {
+                                max_hole_start = search_start;
+                                max_hole_size = hole_size;
+                        }
+
+                        /*
+                         * If this free space is greater than which we need,
+                         * it must be the max free space that we have found
+                         * until now, so max_hole_start must point to the start
+                         * of this free space and the length of this free space
+                         * is stored in max_hole_size. Thus, we return
+                         * max_hole_start and max_hole_size and go back to the
+                         * caller.
+                         */
+                        if (hole_size >= num_bytes) {
+                                ret = 0;
+                                goto out;
                         }
                 }
-                if (btrfs_key_type(&key) != BTRFS_DEV_EXTENT_KEY)
-                        goto next;
 
-                start_found = 1;
                 dev_extent = btrfs_item_ptr(l, slot, struct btrfs_dev_extent);
-                last_byte = key.offset + btrfs_dev_extent_length(l, dev_extent);
+                extent_end = key.offset + btrfs_dev_extent_length(l,
+                                                                  dev_extent);
+                if (extent_end > search_start)
+                        search_start = extent_end;
 next:
                 path->slots[0]++;
                 cond_resched();
         }
-check_pending:
-        /* we have to make sure we didn't find an extent that has already
-         * been allocated by the map tree or the original allocation
-         */
-        BUG_ON(*start < search_start);
 
-        if (*start + num_bytes > search_end) {
-                ret = -ENOSPC;
-                goto error;
+        hole_size = search_end- search_start;
+        if (hole_size > max_hole_size) {
+                max_hole_start = search_start;
+                max_hole_size = hole_size;
         }
-        /* check for pending inserts here */
-        ret = 0;
 
-error:
+        /* See above. */
+        if (hole_size < num_bytes)
+                ret = -ENOSPC;
+        else
+                ret = 0;
+
+out:
         btrfs_free_path(path);
+error:
+        *start = max_hole_start;
+        if (len)
+                *len = max_hole_size;
         return ret;
 }
 
@@ -1196,7 +1306,7 @@ int btrfs_rm_device(struct btrfs_root *root, char *device_path)
                 set_blocksize(bdev, 4096);
                 bh = btrfs_read_dev_super(bdev);
                 if (!bh) {
-                        ret = -EIO;
+                        ret = -EINVAL;
                         goto error_close;
                 }
                 disk_super = (struct btrfs_super_block *)bh->b_data;
@@ -1916,6 +2026,9 @@ int btrfs_balance(struct btrfs_root *dev_root)
         if (dev_root->fs_info->sb->s_flags & MS_RDONLY)
                 return -EROFS;
 
+        if (!capable(CAP_SYS_ADMIN))
+                return -EPERM;
+
         mutex_lock(&dev_root->fs_info->volume_mutex);
         dev_root = dev_root->fs_info->dev_root;
 
@@ -2154,66 +2267,67 @@ static noinline u64 chunk_bytes_by_type(u64 type, u64 calc_size,
                 return calc_size * num_stripes;
 }
 
-static int __btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
-                               struct btrfs_root *extent_root,
-                               struct map_lookup **map_ret,
-                               u64 *num_bytes, u64 *stripe_size,
-                               u64 start, u64 type)
+/* Used to sort the devices by max_avail(descending sort) */
+int btrfs_cmp_device_free_bytes(const void *dev_info1, const void *dev_info2)
 {
-        struct btrfs_fs_info *info = extent_root->fs_info;
-        struct btrfs_device *device = NULL;
-        struct btrfs_fs_devices *fs_devices = info->fs_devices;
-        struct list_head *cur;
-        struct map_lookup *map = NULL;
-        struct extent_map_tree *em_tree;
-        struct extent_map *em;
-        struct list_head private_devs;
-        int min_stripe_size = 1 * 1024 * 1024;
-        u64 calc_size = 1024 * 1024 * 1024;
-        u64 max_chunk_size = calc_size;
-        u64 min_free;
-        u64 avail;
-        u64 max_avail = 0;
-        u64 dev_offset;
-        int num_stripes = 1;
-        int min_stripes = 1;
-        int sub_stripes = 0;
-        int looped = 0;
-        int ret;
-        int index;
-        int stripe_len = 64 * 1024;
+        if (((struct btrfs_device_info *)dev_info1)->max_avail >
+            ((struct btrfs_device_info *)dev_info2)->max_avail)
+                return -1;
+        else if (((struct btrfs_device_info *)dev_info1)->max_avail <
+                 ((struct btrfs_device_info *)dev_info2)->max_avail)
+                return 1;
+        else
+                return 0;
+}
 
-        if ((type & BTRFS_BLOCK_GROUP_RAID1) &&
-            (type & BTRFS_BLOCK_GROUP_DUP)) {
-                WARN_ON(1);
-                type &= ~BTRFS_BLOCK_GROUP_DUP;
-        }
-        if (list_empty(&fs_devices->alloc_list))
-                return -ENOSPC;
+static int __btrfs_calc_nstripes(struct btrfs_fs_devices *fs_devices, u64 type,
+                                 int *num_stripes, int *min_stripes,
+                                 int *sub_stripes)
+{
+        *num_stripes = 1;
+        *min_stripes = 1;
+        *sub_stripes = 0;
 
         if (type & (BTRFS_BLOCK_GROUP_RAID0)) {
-                num_stripes = fs_devices->rw_devices;
-                min_stripes = 2;
+                *num_stripes = fs_devices->rw_devices;
+                *min_stripes = 2;
         }
         if (type & (BTRFS_BLOCK_GROUP_DUP)) {
-                num_stripes = 2;
-                min_stripes = 2;
+                *num_stripes = 2;
+                *min_stripes = 2;
         }
         if (type & (BTRFS_BLOCK_GROUP_RAID1)) {
                 if (fs_devices->rw_devices < 2)
                         return -ENOSPC;
-                num_stripes = 2;
-                min_stripes = 2;
+                *num_stripes = 2;
+                *min_stripes = 2;
         }
         if (type & (BTRFS_BLOCK_GROUP_RAID10)) {
-                num_stripes = fs_devices->rw_devices;
-                if (num_stripes < 4)
+                *num_stripes = fs_devices->rw_devices;
+                if (*num_stripes < 4)
                         return -ENOSPC;
-                num_stripes &= ~(u32)1;
-                sub_stripes = 2;
-                min_stripes = 4;
+                *num_stripes &= ~(u32)1;
+                *sub_stripes = 2;
+                *min_stripes = 4;
         }
 
+        return 0;
+}
+
+static u64 __btrfs_calc_stripe_size(struct btrfs_fs_devices *fs_devices,
+                                    u64 proposed_size, u64 type,
+                                    int num_stripes, int small_stripe)
+{
+        int min_stripe_size = 1 * 1024 * 1024;
+        u64 calc_size = proposed_size;
+        u64 max_chunk_size = calc_size;
+        int ncopies = 1;
+
+        if (type & (BTRFS_BLOCK_GROUP_RAID1 |
+                    BTRFS_BLOCK_GROUP_DUP |
+                    BTRFS_BLOCK_GROUP_RAID10))
+                ncopies = 2;
+
         if (type & BTRFS_BLOCK_GROUP_DATA) {
                 max_chunk_size = 10 * calc_size;
                 min_stripe_size = 64 * 1024 * 1024;
@@ -2230,51 +2344,209 @@ static int __btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
         max_chunk_size = min(div_factor(fs_devices->total_rw_bytes, 1),
                              max_chunk_size);
 
-again:
-        max_avail = 0;
-        if (!map || map->num_stripes != num_stripes) {
-                kfree(map);
-                map = kmalloc(map_lookup_size(num_stripes), GFP_NOFS);
-                if (!map)
-                        return -ENOMEM;
-                map->num_stripes = num_stripes;
-        }
-
-        if (calc_size * num_stripes > max_chunk_size) {
-                calc_size = max_chunk_size;
+        if (calc_size * num_stripes > max_chunk_size * ncopies) {
+                calc_size = max_chunk_size * ncopies;
                 do_div(calc_size, num_stripes);
-                do_div(calc_size, stripe_len);
-                calc_size *= stripe_len;
+                do_div(calc_size, BTRFS_STRIPE_LEN);
+                calc_size *= BTRFS_STRIPE_LEN;
         }
 
         /* we don't want tiny stripes */
-        if (!looped)
+        if (!small_stripe)
                 calc_size = max_t(u64, min_stripe_size, calc_size);
 
         /*
-         * we're about to do_div by the stripe_len so lets make sure
+         * we're about to do_div by the BTRFS_STRIPE_LEN so lets make sure
          * we end up with something bigger than a stripe
          */
-        calc_size = max_t(u64, calc_size, stripe_len * 4);
+        calc_size = max_t(u64, calc_size, BTRFS_STRIPE_LEN);
+
+        do_div(calc_size, BTRFS_STRIPE_LEN);
+        calc_size *= BTRFS_STRIPE_LEN;
+
+        return calc_size;
+}
+
+static struct map_lookup *__shrink_map_lookup_stripes(struct map_lookup *map,
+                                                      int num_stripes)
+{
+        struct map_lookup *new;
+        size_t len = map_lookup_size(num_stripes);
+
+        BUG_ON(map->num_stripes < num_stripes);
+
+        if (map->num_stripes == num_stripes)
+                return map;
+
+        new = kmalloc(len, GFP_NOFS);
+        if (!new) {
+                /* just change map->num_stripes */
+                map->num_stripes = num_stripes;
+                return map;
+        }
+
+        memcpy(new, map, len);
+        new->num_stripes = num_stripes;
+        kfree(map);
+        return new;
+}
+
+/*
+ * helper to allocate device space from btrfs_device_info, in which we stored
+ * max free space information of every device. It is used when we can not
+ * allocate chunks by default size.
+ *
+ * By this helper, we can allocate a new chunk as larger as possible.
+ */
+static int __btrfs_alloc_tiny_space(struct btrfs_trans_handle *trans,
+                                    struct btrfs_fs_devices *fs_devices,
+                                    struct btrfs_device_info *devices,
+                                    int nr_device, u64 type,
+                                    struct map_lookup **map_lookup,
+                                    int min_stripes, u64 *stripe_size)
+{
+        int i, index, sort_again = 0;
+        int min_devices = min_stripes;
+        u64 max_avail, min_free;
+        struct map_lookup *map = *map_lookup;
+        int ret;
+
+        if (nr_device < min_stripes)
+                return -ENOSPC;
+
+        btrfs_descending_sort_devices(devices, nr_device);
+
+        max_avail = devices[0].max_avail;
+        if (!max_avail)
+                return -ENOSPC;
+
+        for (i = 0; i < nr_device; i++) {
+                /*
+                 * if dev_offset = 0, it means the free space of this device
+                 * is less than what we need, and we didn't search max avail
+                 * extent on this device, so do it now.
+                 */
+                if (!devices[i].dev_offset) {
+                        ret = find_free_dev_extent(trans, devices[i].dev,
+                                                   max_avail,
+                                                   &devices[i].dev_offset,
+                                                   &devices[i].max_avail);
+                        if (ret != 0 && ret != -ENOSPC)
+                                return ret;
+                        sort_again = 1;
+                }
+        }
+
+        /* we update the max avail free extent of each devices, sort again */
+        if (sort_again)
+                btrfs_descending_sort_devices(devices, nr_device);
+
+        if (type & BTRFS_BLOCK_GROUP_DUP)
+                min_devices = 1;
+
+        if (!devices[min_devices - 1].max_avail)
+                return -ENOSPC;
+
+        max_avail = devices[min_devices - 1].max_avail;
+        if (type & BTRFS_BLOCK_GROUP_DUP)
+                do_div(max_avail, 2);
+
+        max_avail = __btrfs_calc_stripe_size(fs_devices, max_avail, type,
+                                             min_stripes, 1);
+        if (type & BTRFS_BLOCK_GROUP_DUP)
+                min_free = max_avail * 2;
+        else
+                min_free = max_avail;
+
+        if (min_free > devices[min_devices - 1].max_avail)
+                return -ENOSPC;
+
+        map = __shrink_map_lookup_stripes(map, min_stripes);
+        *stripe_size = max_avail;
+
+        index = 0;
+        for (i = 0; i < min_stripes; i++) {
+                map->stripes[i].dev = devices[index].dev;
+                map->stripes[i].physical = devices[index].dev_offset;
+                if (type & BTRFS_BLOCK_GROUP_DUP) {
+                        i++;
+                        map->stripes[i].dev = devices[index].dev;
+                        map->stripes[i].physical = devices[index].dev_offset +
+                                                   max_avail;
+                }
+                index++;
+        }
+        *map_lookup = map;
+
+        return 0;
+}
 
-        do_div(calc_size, stripe_len);
-        calc_size *= stripe_len;
+static int __btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
+                               struct btrfs_root *extent_root,
+                               struct map_lookup **map_ret,
+                               u64 *num_bytes, u64 *stripe_size,
+                               u64 start, u64 type)
+{
+        struct btrfs_fs_info *info = extent_root->fs_info;
+        struct btrfs_device *device = NULL;
+        struct btrfs_fs_devices *fs_devices = info->fs_devices;
+        struct list_head *cur;
+        struct map_lookup *map;
+        struct extent_map_tree *em_tree;
+        struct extent_map *em;
+        struct btrfs_device_info *devices_info;
+        struct list_head private_devs;
+        u64 calc_size = 1024 * 1024 * 1024;
+        u64 min_free;
+        u64 avail;
+        u64 dev_offset;
+        int num_stripes;
+        int min_stripes;
+        int sub_stripes;
+        int min_devices;        /* the min number of devices we need */
+        int i;
+        int ret;
+        int index;
+
+        if ((type & BTRFS_BLOCK_GROUP_RAID1) &&
+            (type & BTRFS_BLOCK_GROUP_DUP)) {
+                WARN_ON(1);
+                type &= ~BTRFS_BLOCK_GROUP_DUP;
+        }
+        if (list_empty(&fs_devices->alloc_list))
+                return -ENOSPC;
+
+        ret = __btrfs_calc_nstripes(fs_devices, type, &num_stripes,
+                                    &min_stripes, &sub_stripes);
+        if (ret)
+                return ret;
+
+        devices_info = kzalloc(sizeof(*devices_info) * fs_devices->rw_devices,
+                               GFP_NOFS);
+        if (!devices_info)
+                return -ENOMEM;
+
+        map = kmalloc(map_lookup_size(num_stripes), GFP_NOFS);
+        if (!map) {
+                ret = -ENOMEM;
+                goto error;
+        }
+        map->num_stripes = num_stripes;
 
         cur = fs_devices->alloc_list.next;
         index = 0;
+        i = 0;
 
-        if (type & BTRFS_BLOCK_GROUP_DUP)
+        calc_size = __btrfs_calc_stripe_size(fs_devices, calc_size, type,
+                                             num_stripes, 0);
+
+        if (type & BTRFS_BLOCK_GROUP_DUP) {
                 min_free = calc_size * 2;
-        else
+                min_devices = 1;
+        } else {
                 min_free = calc_size;
-
-        /*
-         * we add 1MB because we never use the first 1MB of the device, unless
-         * we've looped, then we are likely allocating the maximum amount of
-         * space left already
-         */
-        if (!looped)
-                min_free += 1024 * 1024;
+                min_devices = min_stripes;
+        }
 
         INIT_LIST_HEAD(&private_devs);
         while (index < num_stripes) {
@@ -2287,27 +2559,39 @@ again:
                 cur = cur->next;
 
                 if (device->in_fs_metadata && avail >= min_free) {
-                        ret = find_free_dev_extent(trans, device,
-                                                   min_free, &dev_offset,
-                                                   &max_avail);
+                        ret = find_free_dev_extent(trans, device, min_free,
+                                                   &devices_info[i].dev_offset,
+                                                   &devices_info[i].max_avail);
                         if (ret == 0) {
                                 list_move_tail(&device->dev_alloc_list,
                                                &private_devs);
                                 map->stripes[index].dev = device;
-                                map->stripes[index].physical = dev_offset;
+                                map->stripes[index].physical =
+                                                devices_info[i].dev_offset;
                                 index++;
                                 if (type & BTRFS_BLOCK_GROUP_DUP) {
                                         map->stripes[index].dev = device;
                                         map->stripes[index].physical =
-                                                dev_offset + calc_size;
+                                                devices_info[i].dev_offset +
+                                                calc_size;
                                         index++;
                                 }
-                        }
-                } else if (device->in_fs_metadata && avail > max_avail)
-                        max_avail = avail;
+                        } else if (ret != -ENOSPC)
+                                goto error;
+
+                        devices_info[i].dev = device;
+                        i++;
+                } else if (device->in_fs_metadata &&
+                           avail >= BTRFS_STRIPE_LEN) {
+                        devices_info[i].dev = device;
+                        devices_info[i].max_avail = avail;
+                        i++;
+                }
+
                 if (cur == &fs_devices->alloc_list)
                         break;
         }
+
         list_splice(&private_devs, &fs_devices->alloc_list);
         if (index < num_stripes) {
                 if (index >= min_stripes) {
@@ -2316,34 +2600,36 @@ again:
                                 num_stripes /= sub_stripes;
                                 num_stripes *= sub_stripes;
                         }
-                        looped = 1;
-                        goto again;
-                }
-                if (!looped && max_avail > 0) {
-                        looped = 1;
-                        calc_size = max_avail;
-                        goto again;
+
+                        map = __shrink_map_lookup_stripes(map, num_stripes);
+                } else if (i >= min_devices) {
+                        ret = __btrfs_alloc_tiny_space(trans, fs_devices,
+                                                       devices_info, i, type,
+                                                       &map, min_stripes,
+                                                       &calc_size);
+                        if (ret)
+                                goto error;
+                } else {
+                        ret = -ENOSPC;
+                        goto error;
                 }
-                kfree(map);
-                return -ENOSPC;
         }
         map->sector_size = extent_root->sectorsize;
-        map->stripe_len = stripe_len;
-        map->io_align = stripe_len;
-        map->io_width = stripe_len;
+        map->stripe_len = BTRFS_STRIPE_LEN;
+        map->io_align = BTRFS_STRIPE_LEN;
+        map->io_width = BTRFS_STRIPE_LEN;
         map->type = type;
-        map->num_stripes = num_stripes;
         map->sub_stripes = sub_stripes;
 
         *map_ret = map;
         *stripe_size = calc_size;
         *num_bytes = chunk_bytes_by_type(type, calc_size,
-                                         num_stripes, sub_stripes);
+                                         map->num_stripes, sub_stripes);
 
         em = alloc_extent_map(GFP_NOFS);
         if (!em) {
-                kfree(map);
-                return -ENOMEM;
+                ret = -ENOMEM;
+                goto error;
         }
         em->bdev = (struct block_device *)map;
         em->start = start;
@@ -2376,7 +2662,13 @@ again:
                 index++;
         }
 
+        kfree(devices_info);
         return 0;
+
+error:
+        kfree(map);
+        kfree(devices_info);
+        return ret;
 }
 
 static int __finish_chunk_alloc(struct btrfs_trans_handle *trans,