Btrfs: Add locking around volume management (device add/remove/balance)

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

diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index c6759fc..bbf9bf3 100644 (file)
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -1251,10 +1251,6 @@ int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root
        WARN_ON(p->nodes[0] != NULL);
        WARN_ON(cow && root == root->fs_info->extent_root &&
                !mutex_is_locked(&root->fs_info->alloc_mutex));
-       WARN_ON(root == root->fs_info->chunk_root &&
-               !mutex_is_locked(&root->fs_info->chunk_mutex));
-       WARN_ON(root == root->fs_info->dev_root &&
-               !mutex_is_locked(&root->fs_info->chunk_mutex));
        if (ins_len < 0)
                lowest_unlock = 2;
 again:

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index a287964..f3783db 100644 (file)
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -523,6 +523,7 @@ struct btrfs_fs_info {
        struct mutex alloc_mutex;
        struct mutex chunk_mutex;
        struct mutex drop_mutex;
+       struct mutex volume_mutex;
        struct list_head trans_list;
        struct list_head hashers;
        struct list_head dead_roots;

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 4cdc0b6..8f4c400 100644 (file)
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -1287,6 +1287,7 @@ struct btrfs_root *open_ctree(struct super_block *sb,
        mutex_init(&fs_info->chunk_mutex);
        mutex_init(&fs_info->transaction_kthread_mutex);
        mutex_init(&fs_info->cleaner_mutex);
+       mutex_init(&fs_info->volume_mutex);
 
 #if 0
        ret = add_hasher(fs_info, "crc32c");

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 5e0857f..8ebfa6b 100644 (file)
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -245,6 +245,7 @@ static int noinline find_search_start(struct btrfs_root *root,
        u64 search_start = *start_ret;
        int wrapped = 0;
 
+       WARN_ON(!mutex_is_locked(&root->fs_info->alloc_mutex));
        total_fs_bytes = btrfs_super_total_bytes(&root->fs_info->super_copy);
        free_space_cache = &root->fs_info->free_space_cache;
 
@@ -1242,6 +1243,7 @@ static int update_block_group(struct btrfs_trans_handle *trans,
        u64 start;
        u64 end;
 
+       WARN_ON(!mutex_is_locked(&root->fs_info->alloc_mutex));
        while(total) {
                cache = btrfs_lookup_block_group(info, bytenr);
                if (!cache) {
@@ -1297,6 +1299,7 @@ static int update_pinned_extents(struct btrfs_root *root,
        struct btrfs_block_group_cache *cache;
        struct btrfs_fs_info *fs_info = root->fs_info;
 
+       WARN_ON(!mutex_is_locked(&root->fs_info->alloc_mutex));
        if (pin) {
                set_extent_dirty(&fs_info->pinned_extents,
                                bytenr, bytenr + num - 1, GFP_NOFS);
@@ -1391,6 +1394,7 @@ static int finish_current_insert(struct btrfs_trans_handle *trans,
        int level;
        int err = 0;
 
+       WARN_ON(!mutex_is_locked(&extent_root->fs_info->alloc_mutex));
        btrfs_set_stack_extent_refs(&extent_item, 1);
        btrfs_set_key_type(&ins, BTRFS_EXTENT_ITEM_KEY);
        path = btrfs_alloc_path();
@@ -1437,6 +1441,7 @@ static int pin_down_bytes(struct btrfs_root *root, u64 bytenr, u32 num_bytes,
 {
        int err = 0;
 
+       WARN_ON(!mutex_is_locked(&root->fs_info->alloc_mutex));
        if (!pending) {
                struct extent_buffer *buf;
                buf = btrfs_find_tree_block(root, bytenr, num_bytes);
@@ -1490,6 +1495,7 @@ static int __free_extent(struct btrfs_trans_handle *trans, struct btrfs_root
        struct btrfs_extent_item *ei;
        u32 refs;
 
+       WARN_ON(!mutex_is_locked(&root->fs_info->alloc_mutex));
        key.objectid = bytenr;
        btrfs_set_key_type(&key, BTRFS_EXTENT_ITEM_KEY);
        key.offset = num_bytes;
@@ -1619,6 +1625,7 @@ static int del_pending_extents(struct btrfs_trans_handle *trans, struct
        struct extent_io_tree *pending_del;
        struct extent_io_tree *pinned_extents;
 
+       WARN_ON(!mutex_is_locked(&extent_root->fs_info->alloc_mutex));
        pending_del = &extent_root->fs_info->pending_del;
        pinned_extents = &extent_root->fs_info->pinned_extents;
 
@@ -2428,6 +2435,10 @@ int btrfs_drop_snapshot(struct btrfs_trans_handle *trans, struct btrfs_root
                btrfs_node_key(node, &found_key, path->slots[level]);
                WARN_ON(memcmp(&found_key, &root_item->drop_progress,
                               sizeof(found_key)));
+               /*
+                * unlock our path, this is safe because only this
+                * function is allowed to delete this snapshot
+                */
                for (i = 0; i < BTRFS_MAX_LEVEL; i++) {
                        if (path->nodes[i] && path->locks[i]) {
                                path->locks[i] = 0;
@@ -2611,7 +2622,6 @@ static int find_root_for_ref(struct btrfs_root *root,
        u64 root_search_start = BTRFS_FS_TREE_OBJECTID;
        u64 found_bytenr;
        int ret;
-       int i;
 
        root_location.offset = (u64)-1;
        root_location.type = BTRFS_ROOT_ITEM_KEY;
@@ -2635,12 +2645,6 @@ static int find_root_for_ref(struct btrfs_root *root,
                                found_bytenr = path->nodes[level]->start;
                }
 
-               for (i = level; i < BTRFS_MAX_LEVEL; i++) {
-                       if (!path->nodes[i])
-                               break;
-                       free_extent_buffer(path->nodes[i]);
-                       path->nodes[i] = NULL;
-               }
                btrfs_release_path(cur_root, path);
 
                if (found_bytenr == bytenr) {
@@ -2689,6 +2693,8 @@ static int noinline relocate_one_reference(struct btrfs_root *extent_root,
        int ret;
        int level;
 
+       WARN_ON(!mutex_is_locked(&extent_root->fs_info->alloc_mutex));
+
        ref = btrfs_item_ptr(path->nodes[0], path->slots[0],
                             struct btrfs_extent_ref);
        ref_root = btrfs_ref_root(path->nodes[0], ref);
@@ -2707,6 +2713,7 @@ static int noinline relocate_one_reference(struct btrfs_root *extent_root,
        found_root = btrfs_read_fs_root_no_name(extent_root->fs_info,
                                                &root_location);
        BUG_ON(!found_root);
+       mutex_unlock(&extent_root->fs_info->alloc_mutex);
 
        if (ref_objectid >= BTRFS_FIRST_FREE_OBJECTID) {
                found_key.objectid = ref_objectid;
@@ -2748,9 +2755,9 @@ static int noinline relocate_one_reference(struct btrfs_root *extent_root,
                /* this can happen if the reference is not against
                 * the latest version of the tree root
                 */
-               if (is_bad_inode(inode)) {
+               if (is_bad_inode(inode))
                        goto out;
-               }
+
                *last_file_objectid = inode->i_ino;
                *last_file_root = found_root->root_key.objectid;
                *last_file_offset = ref_offset;
@@ -2760,7 +2767,7 @@ static int noinline relocate_one_reference(struct btrfs_root *extent_root,
        } else {
                struct btrfs_trans_handle *trans;
                struct extent_buffer *eb;
-               int i;
+               int needs_lock = 0;
 
                eb = read_tree_block(found_root, extent_key->objectid,
                                     extent_key->offset, 0);
@@ -2782,26 +2789,40 @@ static int noinline relocate_one_reference(struct btrfs_root *extent_root,
                if (ret)
                        goto out;
 
+               /*
+                * right here almost anything could happen to our key,
+                * but that's ok.  The cow below will either relocate it
+                * or someone else will have relocated it.  Either way,
+                * it is in a different spot than it was before and
+                * we're happy.
+                */
+
                trans = btrfs_start_transaction(found_root, 1);
 
+               if (found_root == extent_root->fs_info->extent_root ||
+                   found_root == extent_root->fs_info->chunk_root ||
+                   found_root == extent_root->fs_info->dev_root) {
+                       needs_lock = 1;
+                       mutex_lock(&extent_root->fs_info->alloc_mutex);
+               }
+
                path->lowest_level = level;
                path->reada = 2;
                ret = btrfs_search_slot(trans, found_root, &found_key, path,
                                        0, 1);
                path->lowest_level = 0;
-               for (i = level; i < BTRFS_MAX_LEVEL; i++) {
-                       if (!path->nodes[i])
-                               break;
-                       free_extent_buffer(path->nodes[i]);
-                       path->nodes[i] = NULL;
-               }
                btrfs_release_path(found_root, path);
+
                if (found_root == found_root->fs_info->extent_root)
                        btrfs_extent_post_op(trans, found_root);
+               if (needs_lock)
+                       mutex_unlock(&extent_root->fs_info->alloc_mutex);
+
                btrfs_end_transaction(trans, found_root);
-       }
 
+       }
 out:
+       mutex_lock(&extent_root->fs_info->alloc_mutex);
        return 0;
 }
 
@@ -2943,7 +2964,10 @@ int __alloc_chunk_for_shrink(struct btrfs_root *root,
 
        if (btrfs_block_group_used(&shrink_block_group->item) > 0) {
 
+               mutex_unlock(&root->fs_info->alloc_mutex);
                trans = btrfs_start_transaction(root, 1);
+               mutex_lock(&root->fs_info->alloc_mutex);
+
                new_alloc_flags = update_block_group_flags(root,
                                                   shrink_block_group->flags);
                if (new_alloc_flags != shrink_block_group->flags) {
@@ -2954,7 +2978,10 @@ int __alloc_chunk_for_shrink(struct btrfs_root *root,
                }
                do_chunk_alloc(trans, root->fs_info->extent_root,
                               calc + 2 * 1024 * 1024, new_alloc_flags, force);
+
+               mutex_unlock(&root->fs_info->alloc_mutex);
                btrfs_end_transaction(trans, root);
+               mutex_lock(&root->fs_info->alloc_mutex);
        }
        return 0;
 }
@@ -3031,9 +3058,9 @@ again:
                if (ret < 0)
                        goto out;
 
+next:
                leaf = path->nodes[0];
                nritems = btrfs_header_nritems(leaf);
-next:
                if (path->slots[0] >= nritems) {
                        ret = btrfs_next_leaf(root, path);
                        if (ret < 0)
@@ -3083,6 +3110,7 @@ next:
                printk("btrfs relocate found %llu last extent was %llu\n",
                       (unsigned long long)total_found,
                       (unsigned long long)found_key.objectid);
+               mutex_unlock(&root->fs_info->alloc_mutex);
                trans = btrfs_start_transaction(tree_root, 1);
                btrfs_commit_transaction(trans, tree_root);
 
@@ -3090,6 +3118,7 @@ next:
 
                trans = btrfs_start_transaction(tree_root, 1);
                btrfs_commit_transaction(trans, tree_root);
+               mutex_lock(&root->fs_info->alloc_mutex);
                goto again;
        }
 
@@ -3097,7 +3126,10 @@ next:
         * we've freed all the extents, now remove the block
         * group item from the tree
         */
+       mutex_unlock(&root->fs_info->alloc_mutex);
+
        trans = btrfs_start_transaction(root, 1);
+       mutex_lock(&root->fs_info->alloc_mutex);
        memcpy(&key, &shrink_block_group->key, sizeof(key));
 
        ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
@@ -3119,8 +3151,12 @@ next:
        kfree(shrink_block_group);
 
        btrfs_del_item(trans, root, path);
+       btrfs_release_path(root, path);
+       mutex_unlock(&root->fs_info->alloc_mutex);
        btrfs_commit_transaction(trans, root);
 
+       mutex_lock(&root->fs_info->alloc_mutex);
+
        /* the code to unpin extents might set a few bits in the free
         * space cache for this range again
         */
@@ -3263,6 +3299,7 @@ int btrfs_make_block_group(struct btrfs_trans_handle *trans,
        struct btrfs_block_group_cache *cache;
        struct extent_io_tree *block_group_cache;
 
+       WARN_ON(!mutex_is_locked(&root->fs_info->alloc_mutex));
        extent_root = root->fs_info->extent_root;
        block_group_cache = &root->fs_info->block_group_cache;
 

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 026039a..83f17a5 100644 (file)
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -307,8 +307,7 @@ static int btrfs_ioctl_resize(struct btrfs_root *root, void __user *arg)
                goto out;
        }
 
-       mutex_lock(&root->fs_info->alloc_mutex);
-       mutex_lock(&root->fs_info->chunk_mutex);
+       mutex_lock(&root->fs_info->volume_mutex);
        sizestr = vol_args->name;
        devstr = strchr(sizestr, ':');
        if (devstr) {
@@ -378,8 +377,7 @@ static int btrfs_ioctl_resize(struct btrfs_root *root, void __user *arg)
        }
 
 out_unlock:
-       mutex_lock(&root->fs_info->alloc_mutex);
-       mutex_lock(&root->fs_info->chunk_mutex);
+       mutex_unlock(&root->fs_info->volume_mutex);
 out:
        kfree(vol_args);
        return ret;

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 4e7cee2..5e6ee7a 100644 (file)
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -56,6 +56,18 @@ void btrfs_unlock_volumes(void)
        mutex_unlock(&uuid_mutex);
 }
 
+static void lock_chunks(struct btrfs_root *root)
+{
+       mutex_lock(&root->fs_info->alloc_mutex);
+       mutex_lock(&root->fs_info->chunk_mutex);
+}
+
+static void unlock_chunks(struct btrfs_root *root)
+{
+       mutex_unlock(&root->fs_info->alloc_mutex);
+       mutex_unlock(&root->fs_info->chunk_mutex);
+}
+
 int btrfs_cleanup_fs_uuids(void)
 {
        struct btrfs_fs_devices *fs_devices;
@@ -822,6 +834,7 @@ static int btrfs_rm_dev_item(struct btrfs_root *root,
        key.objectid = BTRFS_DEV_ITEMS_OBJECTID;
        key.type = BTRFS_DEV_ITEM_KEY;
        key.offset = device->devid;
+       lock_chunks(root);
 
        ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
        if (ret < 0)
@@ -856,6 +869,7 @@ static int btrfs_rm_dev_item(struct btrfs_root *root,
                                    total_bytes - 1);
 out:
        btrfs_free_path(path);
+       unlock_chunks(root);
        btrfs_commit_transaction(trans, root);
        return ret;
 }
@@ -870,9 +884,8 @@ int btrfs_rm_device(struct btrfs_root *root, char *device_path)
        u64 devid;
        int ret = 0;
 
-       mutex_lock(&root->fs_info->alloc_mutex);
-       mutex_lock(&root->fs_info->chunk_mutex);
        mutex_lock(&uuid_mutex);
+       mutex_lock(&root->fs_info->volume_mutex);
 
        all_avail = root->fs_info->avail_data_alloc_bits |
                root->fs_info->avail_system_alloc_bits |
@@ -988,9 +1001,8 @@ error_close:
        if (bdev)
                close_bdev_excl(bdev);
 out:
+       mutex_unlock(&root->fs_info->volume_mutex);
        mutex_unlock(&uuid_mutex);
-       mutex_unlock(&root->fs_info->chunk_mutex);
-       mutex_unlock(&root->fs_info->alloc_mutex);
        return ret;
 }
 
@@ -1010,10 +1022,10 @@ int btrfs_init_new_device(struct btrfs_root *root, char *device_path)
                return -EIO;
        }
 
-       mutex_lock(&root->fs_info->alloc_mutex);
-       mutex_lock(&root->fs_info->chunk_mutex);
+       mutex_lock(&root->fs_info->volume_mutex);
 
        trans = btrfs_start_transaction(root, 1);
+       lock_chunks(root);
        devices = &root->fs_info->fs_devices->devices;
        list_for_each(cur, devices) {
                device = list_entry(cur, struct btrfs_device, dev_list);
@@ -1065,9 +1077,9 @@ 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++;
 out:
+       unlock_chunks(root);
        btrfs_end_transaction(trans, root);
-       mutex_unlock(&root->fs_info->chunk_mutex);
-       mutex_unlock(&root->fs_info->alloc_mutex);
+       mutex_unlock(&root->fs_info->volume_mutex);
 
        return ret;
 
@@ -1122,7 +1134,7 @@ out:
        return ret;
 }
 
-int btrfs_grow_device(struct btrfs_trans_handle *trans,
+static int __btrfs_grow_device(struct btrfs_trans_handle *trans,
                      struct btrfs_device *device, u64 new_size)
 {
        struct btrfs_super_block *super_copy =
@@ -1134,6 +1146,16 @@ int btrfs_grow_device(struct btrfs_trans_handle *trans,
        return btrfs_update_device(trans, device);
 }
 
+int btrfs_grow_device(struct btrfs_trans_handle *trans,
+                     struct btrfs_device *device, u64 new_size)
+{
+       int ret;
+       lock_chunks(device->dev_root);
+       ret = __btrfs_grow_device(trans, device, new_size);
+       unlock_chunks(device->dev_root);
+       return ret;
+}
+
 static int btrfs_free_chunk(struct btrfs_trans_handle *trans,
                            struct btrfs_root *root,
                            u64 chunk_tree, u64 chunk_objectid,
@@ -1234,6 +1256,8 @@ int btrfs_relocate_chunk(struct btrfs_root *root,
        trans = btrfs_start_transaction(root, 1);
        BUG_ON(!trans);
 
+       lock_chunks(root);
+
        /*
         * step two, delete the device extents and the
         * chunk tree entries
@@ -1278,6 +1302,7 @@ int btrfs_relocate_chunk(struct btrfs_root *root,
        /* once for us */
        free_extent_map(em);
 
+       unlock_chunks(root);
        btrfs_end_transaction(trans, root);
        return 0;
 }
@@ -1308,8 +1333,7 @@ int btrfs_balance(struct btrfs_root *dev_root)
        struct btrfs_key found_key;
 
 
-       BUG(); /* FIXME, needs locking */
-
+       mutex_lock(&dev_root->fs_info->volume_mutex);
        dev_root = dev_root->fs_info->dev_root;
 
        /* step one make some room on all the devices */
@@ -1355,13 +1379,14 @@ int btrfs_balance(struct btrfs_root *dev_root)
 
                ret = btrfs_previous_item(chunk_root, path, 0,
                                          BTRFS_CHUNK_ITEM_KEY);
-               if (ret) {
+               if (ret)
                        break;
-               }
+
                btrfs_item_key_to_cpu(path->nodes[0], &found_key,
                                      path->slots[0]);
                if (found_key.objectid != key.objectid)
                        break;
+
                chunk = btrfs_item_ptr(path->nodes[0],
                                       path->slots[0],
                                       struct btrfs_chunk);
@@ -1370,16 +1395,17 @@ int btrfs_balance(struct btrfs_root *dev_root)
                if (key.offset == 0)
                        break;
 
+               btrfs_release_path(chunk_root, path);
                ret = btrfs_relocate_chunk(chunk_root,
                                           chunk_root->root_key.objectid,
                                           found_key.objectid,
                                           found_key.offset);
                BUG_ON(ret);
-               btrfs_release_path(chunk_root, path);
        }
        ret = 0;
 error:
        btrfs_free_path(path);
+       mutex_unlock(&dev_root->fs_info->volume_mutex);
        return ret;
 }
 
@@ -1419,14 +1445,18 @@ int btrfs_shrink_device(struct btrfs_device *device, u64 new_size)
 
        path->reada = 2;
 
+       lock_chunks(root);
+
        device->total_bytes = new_size;
        ret = btrfs_update_device(trans, device);
        if (ret) {
+               unlock_chunks(root);
                btrfs_end_transaction(trans, root);
                goto done;
        }
        WARN_ON(diff > old_total);
        btrfs_set_super_total_bytes(super_copy, old_total - diff);
+       unlock_chunks(root);
        btrfs_end_transaction(trans, root);
 
        key.objectid = device->devid;