Btrfs: deal with free space cache errors while replaying log

So everybody who got hit by my fsync bug will still continue to hit this
BUG_ON() in the free space cache, which is pretty heavy handed.  So I took a
file system that had this bug and fixed up all the BUG_ON()'s and leaks that
popped up when I tried to mount a broken file system like this.  With this patch
we just fail to mount instead of panicing.  Thanks,

Signed-off-by: Josef Bacik <jbacik@fusionio.com>

3 files changed, 59 insertions, 32 deletions

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index ef4ce2c026d6..b0a3fab98713 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -5210,9 +5210,11 @@ int btrfs_pin_extent_for_log_replay(struct btrfs_root *root,
                                     u64 bytenr, u64 num_bytes)
 {
         struct btrfs_block_group_cache *cache;
+        int ret;
 
         cache = btrfs_lookup_block_group(root->fs_info, bytenr);
-        BUG_ON(!cache); /* Logic error */
+        if (!cache)
+                return -EINVAL;
 
         /*
          * pull in the free space cache (if any) so that our pin
@@ -5225,9 +5227,9 @@ int btrfs_pin_extent_for_log_replay(struct btrfs_root *root,
         pin_down_extent(root, cache, bytenr, num_bytes, 0);
 
         /* remove us from the free space cache (if we're there at all) */
-        btrfs_remove_free_space(cache, bytenr, num_bytes);
+        ret = btrfs_remove_free_space(cache, bytenr, num_bytes);
         btrfs_put_block_group(cache);
-        return 0;
+        return ret;
 }
 
 /**
@@ -6611,40 +6613,42 @@ int btrfs_alloc_logged_file_extent(struct btrfs_trans_handle *trans,
         if (!caching_ctl) {
                 BUG_ON(!block_group_cache_done(block_group));
                 ret = btrfs_remove_free_space(block_group, start, num_bytes);
-                BUG_ON(ret); /* -ENOMEM */
+                if (ret)
+                        goto out;
         } else {
                 mutex_lock(&caching_ctl->mutex);
 
                 if (start >= caching_ctl->progress) {
                         ret = add_excluded_extent(root, start, num_bytes);
-                        BUG_ON(ret); /* -ENOMEM */
                 } else if (start + num_bytes <= caching_ctl->progress) {
                         ret = btrfs_remove_free_space(block_group,
                                                       start, num_bytes);
-                        BUG_ON(ret); /* -ENOMEM */
                 } else {
                         num_bytes = caching_ctl->progress - start;
                         ret = btrfs_remove_free_space(block_group,
                                                       start, num_bytes);
-                        BUG_ON(ret); /* -ENOMEM */
+                        if (ret)
+                                goto out_lock;
 
                         start = caching_ctl->progress;
                         num_bytes = ins->objectid + ins->offset -
                                     caching_ctl->progress;
                         ret = add_excluded_extent(root, start, num_bytes);
-                        BUG_ON(ret); /* -ENOMEM */
                 }
-
+out_lock:
                 mutex_unlock(&caching_ctl->mutex);
                 put_caching_control(caching_ctl);
+                if (ret)
+                        goto out;
         }
 
         ret = btrfs_update_reserved_bytes(block_group, ins->offset,
                                           RESERVE_ALLOC_NO_ACCOUNT);
         BUG_ON(ret); /* logic error */
-        btrfs_put_block_group(block_group);
         ret = alloc_reserved_file_extent(trans, root, 0, root_objectid,
                                          0, owner, offset, ins, 1);
+out:
+        btrfs_put_block_group(block_group);
         return ret;
 }
 
diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c
index fa1a8140bfb5..37b2b89a28f6 100644
--- a/fs/btrfs/free-space-cache.c
+++ b/fs/btrfs/free-space-cache.c
@@ -1567,7 +1567,8 @@ again:
         search_bytes = ctl->unit;
         search_bytes = min(search_bytes, end - search_start + 1);
         ret = search_bitmap(ctl, bitmap_info, &search_start, &search_bytes);
-        BUG_ON(ret < 0 || search_start != *offset);
+        if (ret < 0 || search_start != *offset)
+                return -EINVAL;
 
         /* We may have found more bits than what we need */
         search_bytes = min(search_bytes, *bytes);
@@ -1973,7 +1974,6 @@ again:
                 re_search = true;
                 goto again;
         }
-        BUG_ON(ret); /* logic error */
 out_lock:
         spin_unlock(&ctl->tree_lock);
 out:
diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index f50137a98fb1..aebfb2d7b7d2 100644
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -277,17 +277,19 @@ static int process_one_buffer(struct btrfs_root *log,
                               struct extent_buffer *eb,
                               struct walk_control *wc, u64 gen)
 {
+        int ret = 0;
+
         if (wc->pin)
-                btrfs_pin_extent_for_log_replay(log->fs_info->extent_root,
-                                                eb->start, eb->len);
+                ret = btrfs_pin_extent_for_log_replay(log->fs_info->extent_root,
+                                                      eb->start, eb->len);
 
-        if (btrfs_buffer_uptodate(eb, gen, 0)) {
+        if (!ret && btrfs_buffer_uptodate(eb, gen, 0)) {
                 if (wc->write)
                         btrfs_write_tree_block(eb);
                 if (wc->wait)
                         btrfs_wait_tree_block_writeback(eb);
         }
-        return 0;
+        return ret;
 }
 
 /*
@@ -623,7 +625,8 @@ static noinline int replay_one_extent(struct btrfs_trans_handle *trans,
                                                 ins.objectid, ins.offset,
                                                 0, root->root_key.objectid,
                                                 key->objectid, offset, 0);
-                                BUG_ON(ret);
+                                if (ret)
+                                        goto out;
                         } else {
                                 /*
                                  * insert the extent pointer in the extent
@@ -632,7 +635,8 @@ static noinline int replay_one_extent(struct btrfs_trans_handle *trans,
                                 ret = btrfs_alloc_logged_file_extent(trans,
                                                 root, root->root_key.objectid,
                                                 key->objectid, offset, &ins);
-                                BUG_ON(ret);
+                                if (ret)
+                                        goto out;
                         }
                         btrfs_release_path(path);
 
@@ -1952,11 +1956,13 @@ static int replay_one_buffer(struct btrfs_root *log, struct extent_buffer *eb,
                         if (S_ISDIR(mode)) {
                                 ret = replay_dir_deletes(wc->trans,
                                          root, log, path, key.objectid, 0);
-                                BUG_ON(ret);
+                                if (ret)
+                                        break;
                         }
                         ret = overwrite_item(wc->trans, root, path,
                                              eb, i, &key);
-                        BUG_ON(ret);
+                        if (ret)
+                                break;
 
                         /* for regular files, make sure corresponding
                          * orhpan item exist. extents past the new EOF
@@ -1965,12 +1971,14 @@ static int replay_one_buffer(struct btrfs_root *log, struct extent_buffer *eb,
                         if (S_ISREG(mode)) {
                                 ret = insert_orphan_item(wc->trans, root,
                                                          key.objectid);
-                                BUG_ON(ret);
+                                if (ret)
+                                        break;
                         }
 
                         ret = link_to_fixup_dir(wc->trans, root,
                                                 path, key.objectid);
-                        BUG_ON(ret);
+                        if (ret)
+                                break;
                 }
                 if (wc->stage < LOG_WALK_REPLAY_ALL)
                         continue;
@@ -1979,28 +1987,35 @@ static int replay_one_buffer(struct btrfs_root *log, struct extent_buffer *eb,
                 if (key.type == BTRFS_XATTR_ITEM_KEY) {
                         ret = overwrite_item(wc->trans, root, path,
                                              eb, i, &key);
-                        BUG_ON(ret);
+                        if (ret)
+                                break;
                 } else if (key.type == BTRFS_INODE_REF_KEY) {
                         ret = add_inode_ref(wc->trans, root, log, path,
                                             eb, i, &key);
-                        BUG_ON(ret && ret != -ENOENT);
+                        if (ret && ret != -ENOENT)
+                                break;
+                        ret = 0;
                 } else if (key.type == BTRFS_INODE_EXTREF_KEY) {
                         ret = add_inode_ref(wc->trans, root, log, path,
                                             eb, i, &key);
-                        BUG_ON(ret && ret != -ENOENT);
+                        if (ret && ret != -ENOENT)
+                                break;
+                        ret = 0;
                 } else if (key.type == BTRFS_EXTENT_DATA_KEY) {
                         ret = replay_one_extent(wc->trans, root, path,
                                                 eb, i, &key);
-                        BUG_ON(ret);
+                        if (ret)
+                                break;
                 } else if (key.type == BTRFS_DIR_ITEM_KEY ||
                            key.type == BTRFS_DIR_INDEX_KEY) {
                         ret = replay_one_dir_item(wc->trans, root, path,
                                                   eb, i, &key);
-                        BUG_ON(ret);
+                        if (ret)
+                                break;
                 }
         }
         btrfs_free_path(path);
-        return 0;
+        return ret;
 }
 
 static noinline int walk_down_log_tree(struct btrfs_trans_handle *trans,
@@ -2045,8 +2060,10 @@ static noinline int walk_down_log_tree(struct btrfs_trans_handle *trans,
 
                 if (*level == 1) {
                         ret = wc->process_func(root, next, wc, ptr_gen);
-                        if (ret)
+                        if (ret) {
+                                free_extent_buffer(next);
                                 return ret;
+                        }
 
                         path->slots[*level]++;
                         if (wc->free) {
@@ -3970,6 +3987,9 @@ again:
                 wc.replay_dest = btrfs_read_fs_root_no_name(fs_info, &tmp_key);
                 if (IS_ERR(wc.replay_dest)) {
                         ret = PTR_ERR(wc.replay_dest);
+                        free_extent_buffer(log->node);
+                        free_extent_buffer(log->commit_root);
+                        kfree(log);
                         btrfs_error(fs_info, ret, "Couldn't read target root "
                                     "for tree log recovery.");
                         goto error;
@@ -3978,12 +3998,10 @@ again:
                 wc.replay_dest->log_root = log;
                 btrfs_record_root_in_trans(trans, wc.replay_dest);
                 ret = walk_log_tree(trans, log, &wc);
-                BUG_ON(ret);
 
-                if (wc.stage == LOG_WALK_REPLAY_ALL) {
+                if (!ret && wc.stage == LOG_WALK_REPLAY_ALL) {
                         ret = fixup_inode_link_counts(trans, wc.replay_dest,
                                                       path);
-                        BUG_ON(ret);
                 }
 
                 key.offset = found_key.offset - 1;
@@ -3992,6 +4010,9 @@ again:
                 free_extent_buffer(log->commit_root);
                 kfree(log);
 
+                if (ret)
+                        goto error;
+
                 if (found_key.offset == 0)
                         break;
         }
@@ -4024,6 +4045,8 @@ again:
 
         return 0;
 error:
+        if (wc.trans)
+                btrfs_end_transaction(wc.trans, fs_info->tree_root);
         btrfs_free_path(path);
         return ret;
 }