Btrfs: fix max chunk size on raid5/6
[cascardo/linux.git] / fs / btrfs / volumes.c
index 72b1cf1..538c5cf 100644 (file)
@@ -25,6 +25,8 @@
 #include <linux/capability.h>
 #include <linux/ratelimit.h>
 #include <linux/kthread.h>
+#include <linux/raid/pq.h>
+#include <asm/div64.h>
 #include "compat.h"
 #include "ctree.h"
 #include "extent_map.h"
@@ -32,6 +34,7 @@
 #include "transaction.h"
 #include "print-tree.h"
 #include "volumes.h"
+#include "raid56.h"
 #include "async-thread.h"
 #include "check-integrity.h"
 #include "rcu-string.h"
@@ -647,6 +650,7 @@ static int __btrfs_close_devices(struct btrfs_fs_devices *fs_devices)
                new_device->writeable = 0;
                new_device->in_fs_metadata = 0;
                new_device->can_discard = 0;
+               spin_lock_init(&new_device->io_lock);
                list_replace_rcu(&device->dev_list, &new_device->dev_list);
 
                call_rcu(&device->rcu, free_device);
@@ -1465,6 +1469,21 @@ int btrfs_rm_device(struct btrfs_root *root, char *device_path)
                goto out;
        }
 
+       if ((all_avail & BTRFS_BLOCK_GROUP_RAID5) &&
+           root->fs_info->fs_devices->rw_devices <= 2) {
+               printk(KERN_ERR "btrfs: unable to go below two "
+                      "devices on raid5\n");
+               ret = -EINVAL;
+               goto out;
+       }
+       if ((all_avail & BTRFS_BLOCK_GROUP_RAID6) &&
+           root->fs_info->fs_devices->rw_devices <= 3) {
+               printk(KERN_ERR "btrfs: unable to go below three "
+                      "devices on raid6\n");
+               ret = -EINVAL;
+               goto out;
+       }
+
        if (strcmp(device_path, "missing") == 0) {
                struct list_head *devices;
                struct btrfs_device *tmp;
@@ -2726,11 +2745,15 @@ static int chunk_drange_filter(struct extent_buffer *leaf,
                return 0;
 
        if (btrfs_chunk_type(leaf, chunk) & (BTRFS_BLOCK_GROUP_DUP |
-            BTRFS_BLOCK_GROUP_RAID1 | BTRFS_BLOCK_GROUP_RAID10))
-               factor = 2;
-       else
-               factor = 1;
-       factor = num_stripes / factor;
+            BTRFS_BLOCK_GROUP_RAID1 | BTRFS_BLOCK_GROUP_RAID10)) {
+               factor = num_stripes / 2;
+       } else if (btrfs_chunk_type(leaf, chunk) & BTRFS_BLOCK_GROUP_RAID5) {
+               factor = num_stripes - 1;
+       } else if (btrfs_chunk_type(leaf, chunk) & BTRFS_BLOCK_GROUP_RAID6) {
+               factor = num_stripes - 2;
+       } else {
+               factor = num_stripes;
+       }
 
        for (i = 0; i < num_stripes; i++) {
                stripe = btrfs_stripe_nr(chunk, i);
@@ -3090,7 +3113,9 @@ int btrfs_balance(struct btrfs_balance_control *bctl,
                allowed |= (BTRFS_BLOCK_GROUP_RAID0 | BTRFS_BLOCK_GROUP_RAID1);
        else
                allowed |= (BTRFS_BLOCK_GROUP_RAID0 | BTRFS_BLOCK_GROUP_RAID1 |
-                               BTRFS_BLOCK_GROUP_RAID10);
+                               BTRFS_BLOCK_GROUP_RAID10 |
+                               BTRFS_BLOCK_GROUP_RAID5 |
+                               BTRFS_BLOCK_GROUP_RAID6);
 
        if ((bctl->data.flags & BTRFS_BALANCE_ARGS_CONVERT) &&
            (!alloc_profile_is_valid(bctl->data.target, 1) ||
@@ -3130,7 +3155,9 @@ int btrfs_balance(struct btrfs_balance_control *bctl,
 
        /* allow to reduce meta or sys integrity only if force set */
        allowed = BTRFS_BLOCK_GROUP_DUP | BTRFS_BLOCK_GROUP_RAID1 |
-                       BTRFS_BLOCK_GROUP_RAID10;
+                       BTRFS_BLOCK_GROUP_RAID10 |
+                       BTRFS_BLOCK_GROUP_RAID5 |
+                       BTRFS_BLOCK_GROUP_RAID6;
        do {
                seq = read_seqbegin(&fs_info->profiles_lock);
 
@@ -3204,11 +3231,6 @@ int btrfs_balance(struct btrfs_balance_control *bctl,
                update_ioctl_balance_args(fs_info, 0, bargs);
        }
 
-       if ((ret && ret != -ECANCELED && ret != -ENOSPC) ||
-           balance_need_close(fs_info)) {
-               __cancel_balance(fs_info);
-       }
-
        wake_up(&fs_info->balance_wait_q);
 
        return ret;
@@ -3611,8 +3633,46 @@ struct btrfs_raid_attr btrfs_raid_array[BTRFS_NR_RAID_TYPES] = {
                .devs_increment = 1,
                .ncopies        = 1,
        },
+       [BTRFS_RAID_RAID5] = {
+               .sub_stripes    = 1,
+               .dev_stripes    = 1,
+               .devs_max       = 0,
+               .devs_min       = 2,
+               .devs_increment = 1,
+               .ncopies        = 2,
+       },
+       [BTRFS_RAID_RAID6] = {
+               .sub_stripes    = 1,
+               .dev_stripes    = 1,
+               .devs_max       = 0,
+               .devs_min       = 3,
+               .devs_increment = 1,
+               .ncopies        = 3,
+       },
 };
+
+static u32 find_raid56_stripe_len(u32 data_devices, u32 dev_stripe_target)
+{
+       /* TODO allow them to set a preferred stripe size */
+       return 64 * 1024;
+}
+
+static void check_raid56_incompat_flag(struct btrfs_fs_info *info, u64 type)
+{
+       u64 features;
+
+       if (!(type & (BTRFS_BLOCK_GROUP_RAID5 | BTRFS_BLOCK_GROUP_RAID6)))
+               return;
+
+       features = btrfs_super_incompat_flags(info->super_copy);
+       if (features & BTRFS_FEATURE_INCOMPAT_RAID56)
+               return;
+
+       features |= BTRFS_FEATURE_INCOMPAT_RAID56;
+       btrfs_set_super_incompat_flags(info->super_copy, features);
+       printk(KERN_INFO "btrfs: setting RAID5/6 feature flag\n");
+}
+
 static int __btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
                               struct btrfs_root *extent_root,
                               struct map_lookup **map_ret,
@@ -3628,6 +3688,8 @@ static int __btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
        struct btrfs_device_info *devices_info = NULL;
        u64 total_avail;
        int num_stripes;        /* total number of stripes to allocate */
+       int data_stripes;       /* number of stripes that count for
+                                  block group size */
        int sub_stripes;        /* sub_stripes info for map */
        int dev_stripes;        /* stripes per dev */
        int devs_max;           /* max devs to use */
@@ -3639,6 +3701,7 @@ static int __btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
        u64 max_chunk_size;
        u64 stripe_size;
        u64 num_bytes;
+       u64 raid_stripe_len = BTRFS_STRIPE_LEN;
        int ndevs;
        int i;
        int j;
@@ -3768,16 +3831,48 @@ static int __btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
        stripe_size = devices_info[ndevs-1].max_avail;
        num_stripes = ndevs * dev_stripes;
 
-       if (stripe_size * ndevs > max_chunk_size * ncopies) {
-               stripe_size = max_chunk_size * ncopies;
-               do_div(stripe_size, ndevs);
+       /*
+        * this will have to be fixed for RAID1 and RAID10 over
+        * more drives
+        */
+       data_stripes = num_stripes / ncopies;
+
+       if (type & BTRFS_BLOCK_GROUP_RAID5) {
+               raid_stripe_len = find_raid56_stripe_len(ndevs - 1,
+                                btrfs_super_stripesize(info->super_copy));
+               data_stripes = num_stripes - 1;
+       }
+       if (type & BTRFS_BLOCK_GROUP_RAID6) {
+               raid_stripe_len = find_raid56_stripe_len(ndevs - 2,
+                                btrfs_super_stripesize(info->super_copy));
+               data_stripes = num_stripes - 2;
+       }
+
+       /*
+        * Use the number of data stripes to figure out how big this chunk
+        * is really going to be in terms of logical address space,
+        * and compare that answer with the max chunk size
+        */
+       if (stripe_size * data_stripes > max_chunk_size) {
+               u64 mask = (1ULL << 24) - 1;
+               stripe_size = max_chunk_size;
+               do_div(stripe_size, data_stripes);
+
+               /* bump the answer up to a 16MB boundary */
+               stripe_size = (stripe_size + mask) & ~mask;
+
+               /* but don't go higher than the limits we found
+                * while searching for free extents
+                */
+               if (stripe_size > devices_info[ndevs-1].max_avail)
+                       stripe_size = devices_info[ndevs-1].max_avail;
        }
 
        do_div(stripe_size, dev_stripes);
 
        /* align to BTRFS_STRIPE_LEN */
-       do_div(stripe_size, BTRFS_STRIPE_LEN);
-       stripe_size *= BTRFS_STRIPE_LEN;
+       do_div(stripe_size, raid_stripe_len);
+       stripe_size *= raid_stripe_len;
 
        map = kmalloc(map_lookup_size(num_stripes), GFP_NOFS);
        if (!map) {
@@ -3795,14 +3890,14 @@ static int __btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
                }
        }
        map->sector_size = extent_root->sectorsize;
-       map->stripe_len = BTRFS_STRIPE_LEN;
-       map->io_align = BTRFS_STRIPE_LEN;
-       map->io_width = BTRFS_STRIPE_LEN;
+       map->stripe_len = raid_stripe_len;
+       map->io_align = raid_stripe_len;
+       map->io_width = raid_stripe_len;
        map->type = type;
        map->sub_stripes = sub_stripes;
 
        *map_ret = map;
-       num_bytes = stripe_size * (num_stripes / ncopies);
+       num_bytes = stripe_size * data_stripes;
 
        *stripe_size_out = stripe_size;
        *num_bytes_out = num_bytes;
@@ -3853,6 +3948,8 @@ static int __btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
        }
 
        free_extent_map(em);
+       check_raid56_incompat_flag(extent_root->fs_info, type);
+
        kfree(devices_info);
        return 0;
 
@@ -4136,6 +4233,10 @@ int btrfs_num_copies(struct btrfs_fs_info *fs_info, u64 logical, u64 len)
                ret = map->num_stripes;
        else if (map->type & BTRFS_BLOCK_GROUP_RAID10)
                ret = map->sub_stripes;
+       else if (map->type & BTRFS_BLOCK_GROUP_RAID5)
+               ret = 2;
+       else if (map->type & BTRFS_BLOCK_GROUP_RAID6)
+               ret = 3;
        else
                ret = 1;
        free_extent_map(em);
@@ -4148,6 +4249,52 @@ int btrfs_num_copies(struct btrfs_fs_info *fs_info, u64 logical, u64 len)
        return ret;
 }
 
+unsigned long btrfs_full_stripe_len(struct btrfs_root *root,
+                                   struct btrfs_mapping_tree *map_tree,
+                                   u64 logical)
+{
+       struct extent_map *em;
+       struct map_lookup *map;
+       struct extent_map_tree *em_tree = &map_tree->map_tree;
+       unsigned long len = root->sectorsize;
+
+       read_lock(&em_tree->lock);
+       em = lookup_extent_mapping(em_tree, logical, len);
+       read_unlock(&em_tree->lock);
+       BUG_ON(!em);
+
+       BUG_ON(em->start > logical || em->start + em->len < logical);
+       map = (struct map_lookup *)em->bdev;
+       if (map->type & (BTRFS_BLOCK_GROUP_RAID5 |
+                        BTRFS_BLOCK_GROUP_RAID6)) {
+               len = map->stripe_len * nr_data_stripes(map);
+       }
+       free_extent_map(em);
+       return len;
+}
+
+int btrfs_is_parity_mirror(struct btrfs_mapping_tree *map_tree,
+                          u64 logical, u64 len, int mirror_num)
+{
+       struct extent_map *em;
+       struct map_lookup *map;
+       struct extent_map_tree *em_tree = &map_tree->map_tree;
+       int ret = 0;
+
+       read_lock(&em_tree->lock);
+       em = lookup_extent_mapping(em_tree, logical, len);
+       read_unlock(&em_tree->lock);
+       BUG_ON(!em);
+
+       BUG_ON(em->start > logical || em->start + em->len < logical);
+       map = (struct map_lookup *)em->bdev;
+       if (map->type & (BTRFS_BLOCK_GROUP_RAID5 |
+                        BTRFS_BLOCK_GROUP_RAID6))
+               ret = 1;
+       free_extent_map(em);
+       return ret;
+}
+
 static int find_live_mirror(struct btrfs_fs_info *fs_info,
                            struct map_lookup *map, int first, int num,
                            int optimal, int dev_replace_is_ongoing)
@@ -4185,10 +4332,39 @@ static int find_live_mirror(struct btrfs_fs_info *fs_info,
        return optimal;
 }
 
+static inline int parity_smaller(u64 a, u64 b)
+{
+       return a > b;
+}
+
+/* Bubble-sort the stripe set to put the parity/syndrome stripes last */
+static void sort_parity_stripes(struct btrfs_bio *bbio, u64 *raid_map)
+{
+       struct btrfs_bio_stripe s;
+       int i;
+       u64 l;
+       int again = 1;
+
+       while (again) {
+               again = 0;
+               for (i = 0; i < bbio->num_stripes - 1; i++) {
+                       if (parity_smaller(raid_map[i], raid_map[i+1])) {
+                               s = bbio->stripes[i];
+                               l = raid_map[i];
+                               bbio->stripes[i] = bbio->stripes[i+1];
+                               raid_map[i] = raid_map[i+1];
+                               bbio->stripes[i+1] = s;
+                               raid_map[i+1] = l;
+                               again = 1;
+                       }
+               }
+       }
+}
+
 static int __btrfs_map_block(struct btrfs_fs_info *fs_info, int rw,
                             u64 logical, u64 *length,
                             struct btrfs_bio **bbio_ret,
-                            int mirror_num)
+                            int mirror_num, u64 **raid_map_ret)
 {
        struct extent_map *em;
        struct map_lookup *map;
@@ -4200,6 +4376,8 @@ static int __btrfs_map_block(struct btrfs_fs_info *fs_info, int rw,
        u64 stripe_nr;
        u64 stripe_nr_orig;
        u64 stripe_nr_end;
+       u64 stripe_len;
+       u64 *raid_map = NULL;
        int stripe_index;
        int i;
        int ret = 0;
@@ -4211,6 +4389,7 @@ static int __btrfs_map_block(struct btrfs_fs_info *fs_info, int rw,
        int num_alloc_stripes;
        int patch_the_first_stripe_for_dev_replace = 0;
        u64 physical_to_patch_in_first_stripe = 0;
+       u64 raid56_full_stripe_start = (u64)-1;
 
        read_lock(&em_tree->lock);
        em = lookup_extent_mapping(em_tree, logical, *length);
@@ -4227,29 +4406,63 @@ static int __btrfs_map_block(struct btrfs_fs_info *fs_info, int rw,
        map = (struct map_lookup *)em->bdev;
        offset = logical - em->start;
 
+       if (mirror_num > map->num_stripes)
+               mirror_num = 0;
+
+       stripe_len = map->stripe_len;
        stripe_nr = offset;
        /*
         * stripe_nr counts the total number of stripes we have to stride
         * to get to this block
         */
-       do_div(stripe_nr, map->stripe_len);
+       do_div(stripe_nr, stripe_len);
 
-       stripe_offset = stripe_nr * map->stripe_len;
+       stripe_offset = stripe_nr * stripe_len;
        BUG_ON(offset < stripe_offset);
 
        /* stripe_offset is the offset of this block in its stripe*/
        stripe_offset = offset - stripe_offset;
 
-       if (rw & REQ_DISCARD)
+       /* if we're here for raid56, we need to know the stripe aligned start */
+       if (map->type & (BTRFS_BLOCK_GROUP_RAID5 | BTRFS_BLOCK_GROUP_RAID6)) {
+               unsigned long full_stripe_len = stripe_len * nr_data_stripes(map);
+               raid56_full_stripe_start = offset;
+
+               /* allow a write of a full stripe, but make sure we don't
+                * allow straddling of stripes
+                */
+               do_div(raid56_full_stripe_start, full_stripe_len);
+               raid56_full_stripe_start *= full_stripe_len;
+       }
+
+       if (rw & REQ_DISCARD) {
+               /* we don't discard raid56 yet */
+               if (map->type &
+                   (BTRFS_BLOCK_GROUP_RAID5 | BTRFS_BLOCK_GROUP_RAID6)) {
+                       ret = -EOPNOTSUPP;
+                       goto out;
+               }
                *length = min_t(u64, em->len - offset, *length);
-       else if (map->type & BTRFS_BLOCK_GROUP_PROFILE_MASK) {
-               /* we limit the length of each bio to what fits in a stripe */
-               *length = min_t(u64, em->len - offset,
-                               map->stripe_len - stripe_offset);
+       } else if (map->type & BTRFS_BLOCK_GROUP_PROFILE_MASK) {
+               u64 max_len;
+               /* For writes to RAID[56], allow a full stripeset across all disks.
+                  For other RAID types and for RAID[56] reads, just allow a single
+                  stripe (on a single disk). */
+               if (map->type & (BTRFS_BLOCK_GROUP_RAID5 | BTRFS_BLOCK_GROUP_RAID6) &&
+                   (rw & REQ_WRITE)) {
+                       max_len = stripe_len * nr_data_stripes(map) -
+                               (offset - raid56_full_stripe_start);
+               } else {
+                       /* we limit the length of each bio to what fits in a stripe */
+                       max_len = stripe_len - stripe_offset;
+               }
+               *length = min_t(u64, em->len - offset, max_len);
        } else {
                *length = em->len - offset;
        }
 
+       /* This is for when we're called from btrfs_merge_bio_hook() and all
+          it cares about is the length */
        if (!bbio_ret)
                goto out;
 
@@ -4282,7 +4495,7 @@ static int __btrfs_map_block(struct btrfs_fs_info *fs_info, int rw,
                u64 physical_of_found = 0;
 
                ret = __btrfs_map_block(fs_info, REQ_GET_READ_MIRRORS,
-                            logical, &tmp_length, &tmp_bbio, 0);
+                            logical, &tmp_length, &tmp_bbio, 0, NULL);
                if (ret) {
                        WARN_ON(tmp_bbio != NULL);
                        goto out;
@@ -4348,6 +4561,7 @@ static int __btrfs_map_block(struct btrfs_fs_info *fs_info, int rw,
        do_div(stripe_nr_end, map->stripe_len);
        stripe_end_offset = stripe_nr_end * map->stripe_len -
                            (offset + *length);
+
        if (map->type & BTRFS_BLOCK_GROUP_RAID0) {
                if (rw & REQ_DISCARD)
                        num_stripes = min_t(u64, map->num_stripes,
@@ -4398,6 +4612,65 @@ static int __btrfs_map_block(struct btrfs_fs_info *fs_info, int rw,
                                              dev_replace_is_ongoing);
                        mirror_num = stripe_index - old_stripe_index + 1;
                }
+
+       } else if (map->type & (BTRFS_BLOCK_GROUP_RAID5 |
+                               BTRFS_BLOCK_GROUP_RAID6)) {
+               u64 tmp;
+
+               if (bbio_ret && ((rw & REQ_WRITE) || mirror_num > 1)
+                   && raid_map_ret) {
+                       int i, rot;
+
+                       /* push stripe_nr back to the start of the full stripe */
+                       stripe_nr = raid56_full_stripe_start;
+                       do_div(stripe_nr, stripe_len);
+
+                       stripe_index = do_div(stripe_nr, nr_data_stripes(map));
+
+                       /* RAID[56] write or recovery. Return all stripes */
+                       num_stripes = map->num_stripes;
+                       max_errors = nr_parity_stripes(map);
+
+                       raid_map = kmalloc(sizeof(u64) * num_stripes,
+                                          GFP_NOFS);
+                       if (!raid_map) {
+                               ret = -ENOMEM;
+                               goto out;
+                       }
+
+                       /* Work out the disk rotation on this stripe-set */
+                       tmp = stripe_nr;
+                       rot = do_div(tmp, num_stripes);
+
+                       /* Fill in the logical address of each stripe */
+                       tmp = stripe_nr * nr_data_stripes(map);
+                       for (i = 0; i < nr_data_stripes(map); i++)
+                               raid_map[(i+rot) % num_stripes] =
+                                       em->start + (tmp + i) * map->stripe_len;
+
+                       raid_map[(i+rot) % map->num_stripes] = RAID5_P_STRIPE;
+                       if (map->type & BTRFS_BLOCK_GROUP_RAID6)
+                               raid_map[(i+rot+1) % num_stripes] =
+                                       RAID6_Q_STRIPE;
+
+                       *length = map->stripe_len;
+                       stripe_index = 0;
+                       stripe_offset = 0;
+               } else {
+                       /*
+                        * Mirror #0 or #1 means the original data block.
+                        * Mirror #2 is RAID5 parity block.
+                        * Mirror #3 is RAID6 Q block.
+                        */
+                       stripe_index = do_div(stripe_nr, nr_data_stripes(map));
+                       if (mirror_num > 1)
+                               stripe_index = nr_data_stripes(map) +
+                                               mirror_num - 2;
+
+                       /* We distribute the parity blocks across stripes */
+                       tmp = stripe_nr + stripe_index;
+                       stripe_index = do_div(tmp, map->num_stripes);
+               }
        } else {
                /*
                 * after this do_div call, stripe_nr is the number of stripes
@@ -4506,8 +4779,11 @@ static int __btrfs_map_block(struct btrfs_fs_info *fs_info, int rw,
        if (rw & (REQ_WRITE | REQ_GET_READ_MIRRORS)) {
                if (map->type & (BTRFS_BLOCK_GROUP_RAID1 |
                                 BTRFS_BLOCK_GROUP_RAID10 |
+                                BTRFS_BLOCK_GROUP_RAID5 |
                                 BTRFS_BLOCK_GROUP_DUP)) {
                        max_errors = 1;
+               } else if (map->type & BTRFS_BLOCK_GROUP_RAID6) {
+                       max_errors = 2;
                }
        }
 
@@ -4608,6 +4884,10 @@ static int __btrfs_map_block(struct btrfs_fs_info *fs_info, int rw,
                bbio->stripes[0].physical = physical_to_patch_in_first_stripe;
                bbio->mirror_num = map->num_stripes + 1;
        }
+       if (raid_map) {
+               sort_parity_stripes(bbio, raid_map);
+               *raid_map_ret = raid_map;
+       }
 out:
        if (dev_replace_is_ongoing)
                btrfs_dev_replace_unlock(dev_replace);
@@ -4620,7 +4900,7 @@ int btrfs_map_block(struct btrfs_fs_info *fs_info, int rw,
                      struct btrfs_bio **bbio_ret, int mirror_num)
 {
        return __btrfs_map_block(fs_info, rw, logical, length, bbio_ret,
-                                mirror_num);
+                                mirror_num, NULL);
 }
 
 int btrfs_rmap_block(struct btrfs_mapping_tree *map_tree,
@@ -4634,6 +4914,7 @@ int btrfs_rmap_block(struct btrfs_mapping_tree *map_tree,
        u64 bytenr;
        u64 length;
        u64 stripe_nr;
+       u64 rmap_len;
        int i, j, nr = 0;
 
        read_lock(&em_tree->lock);
@@ -4644,10 +4925,17 @@ int btrfs_rmap_block(struct btrfs_mapping_tree *map_tree,
        map = (struct map_lookup *)em->bdev;
 
        length = em->len;
+       rmap_len = map->stripe_len;
+
        if (map->type & BTRFS_BLOCK_GROUP_RAID10)
                do_div(length, map->num_stripes / map->sub_stripes);
        else if (map->type & BTRFS_BLOCK_GROUP_RAID0)
                do_div(length, map->num_stripes);
+       else if (map->type & (BTRFS_BLOCK_GROUP_RAID5 |
+                             BTRFS_BLOCK_GROUP_RAID6)) {
+               do_div(length, nr_data_stripes(map));
+               rmap_len = map->stripe_len * nr_data_stripes(map);
+       }
 
        buf = kzalloc(sizeof(u64) * map->num_stripes, GFP_NOFS);
        BUG_ON(!buf); /* -ENOMEM */
@@ -4667,8 +4955,11 @@ int btrfs_rmap_block(struct btrfs_mapping_tree *map_tree,
                        do_div(stripe_nr, map->sub_stripes);
                } else if (map->type & BTRFS_BLOCK_GROUP_RAID0) {
                        stripe_nr = stripe_nr * map->num_stripes + i;
-               }
-               bytenr = chunk_start + stripe_nr * map->stripe_len;
+               } /* else if RAID[56], multiply by nr_data_stripes().
+                  * Alternatively, just use rmap_len below instead of
+                  * map->stripe_len */
+
+               bytenr = chunk_start + stripe_nr * rmap_len;
                WARN_ON(nr >= map->num_stripes);
                for (j = 0; j < nr; j++) {
                        if (buf[j] == bytenr)
@@ -4682,7 +4973,7 @@ int btrfs_rmap_block(struct btrfs_mapping_tree *map_tree,
 
        *logical = buf;
        *naddrs = nr;
-       *stripe_len = map->stripe_len;
+       *stripe_len = rmap_len;
 
        free_extent_map(em);
        return 0;
@@ -4756,7 +5047,7 @@ static void btrfs_end_bio(struct bio *bio, int err)
                bio->bi_bdev = (struct block_device *)
                                        (unsigned long)bbio->mirror_num;
                /* only send an error to the higher layers if it is
-                * beyond the tolerance of the multi-bio
+                * beyond the tolerance of the btrfs bio
                 */
                if (atomic_read(&bbio->error) > bbio->max_errors) {
                        err = -EIO;
@@ -4790,13 +5081,18 @@ struct async_sched {
  * This will add one bio to the pending list for a device and make sure
  * the work struct is scheduled.
  */
-static noinline void schedule_bio(struct btrfs_root *root,
+noinline void btrfs_schedule_bio(struct btrfs_root *root,
                                 struct btrfs_device *device,
                                 int rw, struct bio *bio)
 {
        int should_queue = 1;
        struct btrfs_pending_bios *pending_bios;
 
+       if (device->missing || !device->bdev) {
+               bio_endio(bio, -EIO);
+               return;
+       }
+
        /* don't bother with additional async steps for reads, right now */
        if (!(rw & REQ_WRITE)) {
                bio_get(bio);
@@ -4894,7 +5190,7 @@ static void submit_stripe_bio(struct btrfs_root *root, struct btrfs_bio *bbio,
 #endif
        bio->bi_bdev = dev->bdev;
        if (async)
-               schedule_bio(root, dev, rw, bio);
+               btrfs_schedule_bio(root, dev, rw, bio);
        else
                btrfsic_submit_bio(rw, bio);
 }
@@ -4953,6 +5249,7 @@ int btrfs_map_bio(struct btrfs_root *root, int rw, struct bio *bio,
        u64 logical = (u64)bio->bi_sector << 9;
        u64 length = 0;
        u64 map_length;
+       u64 *raid_map = NULL;
        int ret;
        int dev_nr = 0;
        int total_devs = 1;
@@ -4961,12 +5258,30 @@ int btrfs_map_bio(struct btrfs_root *root, int rw, struct bio *bio,
        length = bio->bi_size;
        map_length = length;
 
-       ret = btrfs_map_block(root->fs_info, rw, logical, &map_length, &bbio,
-                             mirror_num);
-       if (ret)
+       ret = __btrfs_map_block(root->fs_info, rw, logical, &map_length, &bbio,
+                             mirror_num, &raid_map);
+       if (ret) /* -ENOMEM */
                return ret;
 
        total_devs = bbio->num_stripes;
+       bbio->orig_bio = first_bio;
+       bbio->private = first_bio->bi_private;
+       bbio->end_io = first_bio->bi_end_io;
+       atomic_set(&bbio->stripes_pending, bbio->num_stripes);
+
+       if (raid_map) {
+               /* In this case, map_length has been set to the length of
+                  a single stripe; not the whole write */
+               if (rw & WRITE) {
+                       return raid56_parity_write(root, bio, bbio,
+                                                  raid_map, map_length);
+               } else {
+                       return raid56_parity_recover(root, bio, bbio,
+                                                    raid_map, map_length,
+                                                    mirror_num);
+               }
+       }
+
        if (map_length < length) {
                printk(KERN_CRIT "btrfs: mapping failed logical %llu bio len %llu "
                       "len %llu\n", (unsigned long long)logical,
@@ -4975,11 +5290,6 @@ int btrfs_map_bio(struct btrfs_root *root, int rw, struct bio *bio,
                BUG();
        }
 
-       bbio->orig_bio = first_bio;
-       bbio->private = first_bio->bi_private;
-       bbio->end_io = first_bio->bi_end_io;
-       atomic_set(&bbio->stripes_pending, bbio->num_stripes);
-
        while (dev_nr < total_devs) {
                dev = bbio->stripes[dev_nr].dev;
                if (!dev || !dev->bdev || (rw & WRITE && !dev->writeable)) {