Btrfs: Implement raid0 when multiple devices are present

Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 100 insertions, 30 deletions

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 263f01cc3db4..d8fce32a3bbc 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -18,6 +18,7 @@
 #include <linux/sched.h>
 #include <linux/bio.h>
 #include <linux/buffer_head.h>
+#include <asm/div64.h>
 #include "ctree.h"
 #include "extent_map.h"
 #include "disk-io.h"
@@ -25,10 +26,24 @@
 #include "print-tree.h"
 #include "volumes.h"
 
-struct map_lookup {
+struct stripe {
         struct btrfs_device *dev;
         u64 physical;
 };
+
+struct map_lookup {
+        u64 type;
+        int io_align;
+        int io_width;
+        int stripe_len;
+        int sector_size;
+        int num_stripes;
+        struct stripe stripes[];
+};
+
+#define map_lookup_size(n) (sizeof(struct map_lookup) + \
+                            (sizeof(struct stripe) * (n)))
+
 static DEFINE_MUTEX(uuid_mutex);
 static LIST_HEAD(fs_uuids);
 
@@ -592,6 +607,7 @@ int btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
                       u64 *num_bytes, u64 type)
 {
         u64 dev_offset;
+        struct btrfs_fs_info *info = extent_root->fs_info;
         struct btrfs_root *chunk_root = extent_root->fs_info->chunk_root;
         struct btrfs_stripe *stripes;
         struct btrfs_device *device = NULL;
@@ -610,10 +626,18 @@ int btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
         int looped = 0;
         int ret;
         int index;
+        int stripe_len = 64 * 1024;
         struct btrfs_key key;
 
         if (list_empty(dev_list))
                 return -ENOSPC;
+
+        if (type & BTRFS_BLOCK_GROUP_RAID0)
+                num_stripes = btrfs_super_num_devices(&info->super_copy);
+        if (type & BTRFS_BLOCK_GROUP_DATA)
+                stripe_len = 64 * 1024;
+        if (type & (BTRFS_BLOCK_GROUP_METADATA | BTRFS_BLOCK_GROUP_SYSTEM))
+                stripe_len = 32 * 1024;
 again:
         INIT_LIST_HEAD(&private_devs);
         cur = dev_list->next;
@@ -650,9 +674,15 @@ again:
         if (!chunk)
                 return -ENOMEM;
 
+        map = kmalloc(map_lookup_size(num_stripes), GFP_NOFS);
+        if (!map) {
+                kfree(chunk);
+                return -ENOMEM;
+        }
+
         stripes = &chunk->stripe;
 
-        *num_bytes = calc_size;
+        *num_bytes = calc_size * num_stripes;
         index = 0;
         while(index < num_stripes) {
                 BUG_ON(list_empty(&private_devs));
@@ -669,6 +699,8 @@ printk("alloc chunk size %Lu from dev %Lu\n", calc_size, device->devid);
                 ret = btrfs_update_device(trans, device);
                 BUG_ON(ret);
 
+                map->stripes[index].dev = device;
+                map->stripes[index].physical = dev_offset;
                 btrfs_set_stack_stripe_devid(stripes + index, device->devid);
                 btrfs_set_stack_stripe_offset(stripes + index, dev_offset);
                 physical = dev_offset;
@@ -680,12 +712,18 @@ printk("alloc chunk size %Lu from dev %Lu\n", calc_size, device->devid);
         key.offset = *num_bytes;
         key.type = BTRFS_CHUNK_ITEM_KEY;
         btrfs_set_stack_chunk_owner(chunk, extent_root->root_key.objectid);
-        btrfs_set_stack_chunk_stripe_len(chunk, 64 * 1024);
+        btrfs_set_stack_chunk_stripe_len(chunk, stripe_len);
         btrfs_set_stack_chunk_type(chunk, type);
         btrfs_set_stack_chunk_num_stripes(chunk, num_stripes);
-        btrfs_set_stack_chunk_io_align(chunk, extent_root->sectorsize);
-        btrfs_set_stack_chunk_io_width(chunk, extent_root->sectorsize);
+        btrfs_set_stack_chunk_io_align(chunk, stripe_len);
+        btrfs_set_stack_chunk_io_width(chunk, stripe_len);
         btrfs_set_stack_chunk_sector_size(chunk, extent_root->sectorsize);
+        map->sector_size = extent_root->sectorsize;
+        map->stripe_len = stripe_len;
+        map->io_align = stripe_len;
+        map->io_width = stripe_len;
+        map->type = type;
+        map->num_stripes = num_stripes;
 
         ret = btrfs_insert_item(trans, chunk_root, &key, chunk,
                                 btrfs_chunk_item_size(num_stripes));
@@ -695,25 +733,11 @@ printk("alloc chunk size %Lu from dev %Lu\n", calc_size, device->devid);
         em = alloc_extent_map(GFP_NOFS);
         if (!em)
                 return -ENOMEM;
-        map = kmalloc(sizeof(*map), GFP_NOFS);
-        if (!map) {
-                free_extent_map(em);
-                return -ENOMEM;
-        }
-
         em->bdev = (struct block_device *)map;
         em->start = key.objectid;
         em->len = key.offset;
         em->block_start = 0;
 
-        map->physical = physical;
-        map->dev = device;
-
-        if (!map->dev) {
-                kfree(map);
-                free_extent_map(em);
-                return -EIO;
-        }
         kfree(chunk);
 
         em_tree = &extent_root->fs_info->mapping_tree.map_tree;
@@ -758,6 +782,9 @@ int btrfs_map_block(struct btrfs_mapping_tree *map_tree,
         struct map_lookup *map;
         struct extent_map_tree *em_tree = &map_tree->map_tree;
         u64 offset;
+        u64 stripe_offset;
+        u64 stripe_nr;
+        int stripe_index;
 
 
         spin_lock(&em_tree->lock);
@@ -767,9 +794,40 @@ int btrfs_map_block(struct btrfs_mapping_tree *map_tree,
         BUG_ON(em->start > logical || em->start + em->len < logical);
         map = (struct map_lookup *)em->bdev;
         offset = logical - em->start;
-        *phys = map->physical + offset;
-        *length = em->len - offset;
-        *dev = map->dev;
+
+        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);
+
+        stripe_offset = stripe_nr * map->stripe_len;
+        BUG_ON(offset < stripe_offset);
+
+        /* stripe_offset is the offset of this block in its stripe*/
+        stripe_offset = offset - stripe_offset;
+
+        /*
+         * after this do_div call, stripe_nr is the number of stripes
+         * on this device we have to walk to find the data, and
+         * stripe_index is the number of our device in the stripe array
+         */
+        stripe_index = do_div(stripe_nr, map->num_stripes);
+
+        BUG_ON(stripe_index >= map->num_stripes);
+
+        *phys = map->stripes[stripe_index].physical + stripe_offset +
+                stripe_nr * map->stripe_len;
+
+        if (map->type & BTRFS_BLOCK_GROUP_RAID0) {
+                /* 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 {
+                *length = em->len - offset;
+        }
+        *dev = map->stripes[stripe_index].dev;
         free_extent_map(em);
         spin_unlock(&em_tree->lock);
         return 0;
@@ -822,7 +880,9 @@ static int read_one_chunk(struct btrfs_root *root, struct btrfs_key *key,
         u64 logical;
         u64 length;
         u64 devid;
+        int num_stripes;
         int ret;
+        int i;
 
         logical = key->objectid;
         length = key->offset;
@@ -846,7 +906,8 @@ static int read_one_chunk(struct btrfs_root *root, struct btrfs_key *key,
         em = alloc_extent_map(GFP_NOFS);
         if (!em)
                 return -ENOMEM;
-        map = kmalloc(sizeof(*map), GFP_NOFS);
+        num_stripes = btrfs_chunk_num_stripes(leaf, chunk);
+        map = kmalloc(map_lookup_size(num_stripes), GFP_NOFS);
         if (!map) {
                 free_extent_map(em);
                 return -ENOMEM;
@@ -857,13 +918,22 @@ static int read_one_chunk(struct btrfs_root *root, struct btrfs_key *key,
         em->len = length;
         em->block_start = 0;
 
-        map->physical = btrfs_stripe_offset_nr(leaf, chunk, 0);
-        devid = btrfs_stripe_devid_nr(leaf, chunk, 0);
-        map->dev = btrfs_find_device(root, devid);
-        if (!map->dev) {
-                kfree(map);
-                free_extent_map(em);
-                return -EIO;
+        map->num_stripes = num_stripes;
+        map->io_width = btrfs_chunk_io_width(leaf, chunk);
+        map->io_align = btrfs_chunk_io_align(leaf, chunk);
+        map->sector_size = btrfs_chunk_sector_size(leaf, chunk);
+        map->stripe_len = btrfs_chunk_stripe_len(leaf, chunk);
+        map->type = btrfs_chunk_type(leaf, chunk);
+        for (i = 0; i < num_stripes; i++) {
+                map->stripes[i].physical =
+                        btrfs_stripe_offset_nr(leaf, chunk, i);
+                devid = btrfs_stripe_devid_nr(leaf, chunk, i);
+                map->stripes[i].dev = btrfs_find_device(root, devid);
+                if (!map->stripes[i].dev) {
+                        kfree(map);
+                        free_extent_map(em);
+                        return -EIO;
+                }
         }
 
         spin_lock(&map_tree->map_tree.lock);