Btrfs-progs: fix bad extent flag
authorJosef Bacik <jbacik@fb.com>
Thu, 5 Feb 2015 20:41:32 +0000 (15:41 -0500)
committerJosef Bacik <jbacik@fb.com>
Mon, 9 Feb 2015 19:53:16 +0000 (14:53 -0500)
We can have FULL_BACKREF set or not set when we need the opposite, this patch
fixes this problem by setting a bit when the flag is set improperly.  This way
we can either correct the problem when we re-create the extent item if the
backrefs are also wrong, or we can just set the flag properly in the extent
item.  Thanks,

Signed-off-by: Josef Bacik <jbacik@fb.com>
cmds-check.c

index 9c379e6..ce0ac88 100644 (file)
@@ -119,12 +119,13 @@ struct extent_record {
        u64 info_objectid;
        u32 num_duplicates;
        u8 info_level;
+       int flag_block_full_backref;
        unsigned int found_rec:1;
        unsigned int content_checked:1;
        unsigned int owner_ref_checked:1;
        unsigned int is_root:1;
        unsigned int metadata:1;
-       unsigned int flag_block_full_backref:1;
+       unsigned int bad_full_backref:1;
 };
 
 struct inode_backref {
@@ -145,6 +146,7 @@ struct root_item_record {
        struct list_head list;
        u64 objectid;
        u64 bytenr;
+       u64 last_snapshot;
        u8 level;
        u8 drop_level;
        int level_size;
@@ -3679,7 +3681,8 @@ static int maybe_free_extent_rec(struct cache_tree *extent_cache,
 {
        if (rec->content_checked && rec->owner_ref_checked &&
            rec->extent_item_refs == rec->refs && rec->refs > 0 &&
-           rec->num_duplicates == 0 && !all_backpointers_checked(rec, 0)) {
+           rec->num_duplicates == 0 && !all_backpointers_checked(rec, 0) &&
+           !rec->bad_full_backref) {
                remove_cache_extent(extent_cache, &rec->cache);
                free_all_extent_backrefs(rec);
                list_del_init(&rec->list);
@@ -4338,6 +4341,8 @@ static int add_extent_rec(struct cache_tree *extent_cache,
        rec->owner_ref_checked = 0;
        rec->num_duplicates = 0;
        rec->metadata = metadata;
+       rec->flag_block_full_backref = -1;
+       rec->bad_full_backref = 0;
        INIT_LIST_HEAD(&rec->backrefs);
        INIT_LIST_HEAD(&rec->dups);
        INIT_LIST_HEAD(&rec->list);
@@ -5563,27 +5568,41 @@ static int is_dropped_key(struct btrfs_key *key,
        return 0;
 }
 
+/*
+ * Here are the rules for FULL_BACKREF.
+ *
+ * 1) If BTRFS_HEADER_FLAG_RELOC is set then we have FULL_BACKREF set.
+ * 2) If btrfs_header_owner(buf) no longer points to buf then we have
+ *     FULL_BACKREF set.
+ * 3) We cow'ed the block walking down a reloc tree.  This is impossible to tell
+ *    if it happened after the relocation occurred since we'll have dropped the
+ *    reloc root, so it's entirely possible to have FULL_BACKREF set on buf and
+ *    have no real way to know for sure.
+ *
+ * We process the blocks one root at a time, and we start from the lowest root
+ * objectid and go to the highest.  So we can just lookup the owner backref for
+ * the record and if we don't find it then we know it doesn't exist and we have
+ * a FULL BACKREF.
+ *
+ * FIXME: if we ever start reclaiming root objectid's then we need to fix this
+ * assumption and simply indicate that we _think_ that the FULL BACKREF needs to
+ * be set or not and then we can check later once we've gathered all the refs.
+ */
 static int calc_extent_flag(struct btrfs_root *root,
                           struct cache_tree *extent_cache,
                           struct extent_buffer *buf,
                           struct root_item_record *ri,
                           u64 *flags)
 {
-       int i;
-       int nritems = btrfs_header_nritems(buf);
-       struct btrfs_key key;
        struct extent_record *rec;
        struct cache_extent *cache;
-       struct data_backref *dback;
        struct tree_backref *tback;
-       struct extent_buffer *new_buf;
        u64 owner = 0;
-       u64 bytenr;
-       u64 offset;
-       u64 ptr;
-       int size;
-       int ret;
-       u8 level;
+
+       cache = lookup_cache_extent(extent_cache, buf->start, 1);
+       /* we have added this extent before */
+       BUG_ON(!cache);
+       rec = container_of(cache, struct extent_record, cache);
 
        /*
         * Except file/reloc tree, we can not have
@@ -5596,91 +5615,28 @@ static int calc_extent_flag(struct btrfs_root *root,
         */
        if (buf->start == ri->bytenr)
                goto normal;
-       if (btrfs_is_leaf(buf)) {
-               /*
-                * we are searching from original root, world
-                * peace is achieved, we use normal backref.
-                */
-               owner = btrfs_header_owner(buf);
-               if (owner == ri->objectid)
-                       goto normal;
-               /*
-                * we check every eb here, and if any of
-                * eb dosen't have original root refers
-                * to this eb, we set full backref flag for
-                * this extent, otherwise normal backref.
-                */
-               for (i = 0; i < nritems; i++) {
-                       struct btrfs_file_extent_item *fi;
-                       btrfs_item_key_to_cpu(buf, &key, i);
 
-                       if (key.type != BTRFS_EXTENT_DATA_KEY)
-                               continue;
-                       fi = btrfs_item_ptr(buf, i,
-                                           struct btrfs_file_extent_item);
-                       if (btrfs_file_extent_type(buf, fi) ==
-                           BTRFS_FILE_EXTENT_INLINE)
-                               continue;
-                       if (btrfs_file_extent_disk_bytenr(buf, fi) == 0)
-                               continue;
-                       bytenr = btrfs_file_extent_disk_bytenr(buf, fi);
-                       cache = lookup_cache_extent(extent_cache, bytenr, 1);
-                       if (!cache)
-                               goto full_backref;
-                       offset = btrfs_file_extent_offset(buf, fi);
-                       rec = container_of(cache, struct extent_record, cache);
-                       dback = find_data_backref(rec, 0, ri->objectid, owner,
-                                       key.offset - offset, 1, bytenr, bytenr);
-                       if (!dback)
-                               goto full_backref;
-               }
+       if (btrfs_header_flag(buf, BTRFS_HEADER_FLAG_RELOC))
                goto full_backref;
-       } else {
-               level = btrfs_header_level(buf);
-               for (i = 0; i < nritems; i++) {
-                       ptr = btrfs_node_blockptr(buf, i);
-                       size = btrfs_level_size(root, level);
-                       if (i == 0) {
-                               new_buf = read_tree_block(root, ptr, size, 0);
-                               if (!extent_buffer_uptodate(new_buf)) {
-                                       free_extent_buffer(new_buf);
-                                       ret = -EIO;
-                                       return ret;
-                               }
-                               /*
-                                * we are searching from origin root, world
-                                * peace is achieved, we use normal backref.
-                                */
-                               owner = btrfs_header_owner(new_buf);
-                               free_extent_buffer(new_buf);
-                               if (owner == ri->objectid)
-                                       goto normal;
-                       }
-                       cache = lookup_cache_extent(extent_cache, ptr, size);
-                       if (!cache)
-                               goto full_backref;
-                       rec = container_of(cache, struct extent_record, cache);
-                       tback = find_tree_backref(rec, 0, owner);
-                       if (!tback)
-                               goto full_backref;
-               }
 
-       }
+       owner = btrfs_header_owner(buf);
+       if (owner == ri->objectid)
+               goto normal;
+
+       tback = find_tree_backref(rec, 0, owner);
+       if (!tback)
+               goto full_backref;
 normal:
        *flags = 0;
-       cache = lookup_cache_extent(extent_cache, buf->start, 1);
-       /* we have added this extent before */
-       BUG_ON(!cache);
-       rec = container_of(cache, struct extent_record, cache);
-       rec->flag_block_full_backref = 0;
+       if (rec->flag_block_full_backref != -1 &&
+           rec->flag_block_full_backref != 0)
+               rec->bad_full_backref = 1;
        return 0;
 full_backref:
        *flags |= BTRFS_BLOCK_FLAG_FULL_BACKREF;
-       cache = lookup_cache_extent(extent_cache, buf->start, 1);
-       /* we have added this extent before */
-       BUG_ON(!cache);
-       rec = container_of(cache, struct extent_record, cache);
-       rec->flag_block_full_backref = 1;
+       if (rec->flag_block_full_backref != -1 &&
+           rec->flag_block_full_backref != 1)
+               rec->bad_full_backref = 1;
        return 0;
 }
 
@@ -5767,10 +5723,6 @@ static int run_next_block(struct btrfs_root *root,
 
        nritems = btrfs_header_nritems(buf);
 
-       /*
-        * FIXME, this only works only if we don't have any full
-        * backref mode.
-        */
        flags = 0;
        if (!init_extent_tree) {
                ret = btrfs_lookup_extent_info(NULL, root, bytenr,
@@ -5793,11 +5745,37 @@ static int run_next_block(struct btrfs_root *root,
        }
 
        if (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF) {
-               if (rec)
-                       rec->flag_block_full_backref = 1;
+               if (ri != NULL &&
+                   ri->objectid != BTRFS_TREE_RELOC_OBJECTID &&
+                   ri->objectid == btrfs_header_owner(buf)) {
+                       /*
+                        * Ok we got to this block from it's original owner and
+                        * we have FULL_BACKREF set.  Relocation can leave
+                        * converted blocks over so this is altogether possible,
+                        * however it's not possible if the generation > the
+                        * last snapshot, so check for this case.
+                        */
+                       if (!btrfs_header_flag(buf, BTRFS_HEADER_FLAG_RELOC) &&
+                           btrfs_header_generation(buf) > ri->last_snapshot) {
+                               flags &= ~BTRFS_BLOCK_FLAG_FULL_BACKREF;
+                               rec->bad_full_backref = 1;
+                       }
+               }
+       } else {
+               if (ri != NULL &&
+                   (ri->objectid == BTRFS_TREE_RELOC_OBJECTID ||
+                    btrfs_header_flag(buf, BTRFS_HEADER_FLAG_RELOC))) {
+                       flags |= BTRFS_BLOCK_FLAG_FULL_BACKREF;
+                       rec->bad_full_backref = 1;
+               }
+       }
+
+       if (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF) {
+               rec->flag_block_full_backref = 1;
                parent = bytenr;
                owner = 0;
        } else {
+               rec->flag_block_full_backref = 0;
                parent = 0;
                owner = btrfs_header_owner(buf);
        }
@@ -6283,7 +6261,7 @@ static int record_extent(struct btrfs_trans_handle *trans,
                                           parent, tback->root, 0, 0);
                fprintf(stderr, "adding new tree backref on "
                        "start %llu len %llu parent %llu root %llu\n",
-                       rec->start, rec->max_size, tback->parent, tback->root);
+                       rec->start, rec->max_size, parent, tback->root);
        }
        if (ret)
                goto fail;
@@ -7121,6 +7099,7 @@ static int fixup_extent_refs(struct btrfs_fs_info *info,
                if (!back->found_ref)
                        continue;
 
+               rec->bad_full_backref = 0;
                ret = record_extent(trans, info, path, rec, back, allocated, flags);
                allocated = 1;
 
@@ -7138,6 +7117,67 @@ out:
        return ret;
 }
 
+static int fixup_extent_flags(struct btrfs_fs_info *fs_info,
+                             struct extent_record *rec)
+{
+       struct btrfs_trans_handle *trans;
+       struct btrfs_root *root = fs_info->extent_root;
+       struct btrfs_path *path;
+       struct btrfs_extent_item *ei;
+       struct btrfs_key key;
+       u64 flags;
+       int ret = 0;
+
+       key.objectid = rec->start;
+       if (rec->metadata) {
+               key.type = BTRFS_METADATA_ITEM_KEY;
+               key.offset = rec->info_level;
+       } else {
+               key.type = BTRFS_EXTENT_ITEM_KEY;
+               key.offset = rec->max_size;
+       }
+
+       path = btrfs_alloc_path();
+       if (!path)
+               return -ENOMEM;
+
+       trans = btrfs_start_transaction(root, 0);
+       if (IS_ERR(trans)) {
+               btrfs_free_path(path);
+               return PTR_ERR(trans);
+       }
+
+       ret = btrfs_search_slot(trans, root, &key, path, 0, 1);
+       if (ret < 0) {
+               btrfs_free_path(path);
+               btrfs_commit_transaction(trans, root);
+               return ret;
+       } else if (ret) {
+               fprintf(stderr, "Didn't find extent for %llu\n",
+                       (unsigned long long)rec->start);
+               btrfs_free_path(path);
+               btrfs_commit_transaction(trans, root);
+               return -ENOENT;
+       }
+
+       ei = btrfs_item_ptr(path->nodes[0], path->slots[0],
+                           struct btrfs_extent_item);
+       flags = btrfs_extent_flags(path->nodes[0], ei);
+       if (rec->flag_block_full_backref) {
+               fprintf(stderr, "setting full backref on %llu\n",
+                       (unsigned long long)key.objectid);
+               flags |= BTRFS_BLOCK_FLAG_FULL_BACKREF;
+       } else {
+               fprintf(stderr, "clearing full backref on %llu\n",
+                       (unsigned long long)key.objectid);
+               flags &= ~BTRFS_BLOCK_FLAG_FULL_BACKREF;
+       }
+       btrfs_set_extent_flags(path->nodes[0], ei, flags);
+       btrfs_mark_buffer_dirty(path->nodes[0]);
+       btrfs_free_path(path);
+       return btrfs_commit_transaction(trans, root);
+}
+
 /* right now we only prune from the extent allocation tree */
 static int prune_one_block(struct btrfs_trans_handle *trans,
                           struct btrfs_fs_info *info,
@@ -7408,6 +7448,18 @@ static int check_extent_refs(struct btrfs_root *root,
                        err = 1;
                        cur_err = 1;
                }
+               if (rec->bad_full_backref) {
+                       fprintf(stderr, "bad full backref, on [%llu]\n",
+                               (unsigned long long)rec->start);
+                       if (repair) {
+                               ret = fixup_extent_flags(root->fs_info, rec);
+                               if (ret)
+                                       goto repair_abort;
+                               fixed = 1;
+                       }
+                       err = 1;
+                       cur_err = 1;
+               }
 
                remove_cache_extent(extent_cache, cache);
                free_all_extent_backrefs(rec);
@@ -7702,7 +7754,7 @@ static int check_devices(struct rb_root *dev_cache,
 }
 
 static int add_root_item_to_list(struct list_head *head,
-                                 u64 objectid, u64 bytenr,
+                                 u64 objectid, u64 bytenr, u64 last_snapshot,
                                  u8 level, u8 drop_level,
                                  int level_size, struct btrfs_key *drop_key)
 {
@@ -7716,6 +7768,7 @@ static int add_root_item_to_list(struct list_head *head,
        ri_rec->level = level;
        ri_rec->level_size = level_size;
        ri_rec->drop_level = drop_level;
+       ri_rec->last_snapshot = last_snapshot;
        if (drop_key)
                memcpy(&ri_rec->drop_key, drop_key, sizeof(*drop_key));
        list_add_tail(&ri_rec->list, head);
@@ -7863,14 +7916,14 @@ again:
        root1 = root->fs_info->tree_root;
        level = btrfs_header_level(root1->node);
        ret = add_root_item_to_list(&normal_trees, root1->root_key.objectid,
-                                   root1->node->start, level, 0,
+                                   root1->node->start, 0, level, 0,
                                    btrfs_level_size(root1, level), NULL);
        if (ret < 0)
                goto out;
        root1 = root->fs_info->chunk_root;
        level = btrfs_header_level(root1->node);
        ret = add_root_item_to_list(&normal_trees, root1->root_key.objectid,
-                                   root1->node->start, level, 0,
+                                   root1->node->start, 0, level, 0,
                                    btrfs_level_size(root1, level), NULL);
        if (ret < 0)
                goto out;
@@ -7895,15 +7948,18 @@ again:
                btrfs_item_key_to_cpu(leaf, &found_key, path.slots[0]);
                if (btrfs_key_type(&found_key) == BTRFS_ROOT_ITEM_KEY) {
                        unsigned long offset;
+                       u64 last_snapshot;
 
                        offset = btrfs_item_ptr_offset(leaf, path.slots[0]);
                        read_extent_buffer(leaf, &ri, offset, sizeof(ri));
+                       last_snapshot = btrfs_root_last_snapshot(&ri);
                        if (btrfs_disk_key_objectid(&ri.drop_progress) == 0) {
                                level = btrfs_root_level(&ri);
                                level_size = btrfs_level_size(root, level);
                                ret = add_root_item_to_list(&normal_trees,
                                                found_key.objectid,
-                                               btrfs_root_bytenr(&ri), level,
+                                               btrfs_root_bytenr(&ri),
+                                               last_snapshot, level,
                                                0, level_size, NULL);
                                if (ret < 0)
                                        goto out;
@@ -7916,7 +7972,8 @@ again:
                                ret = add_root_item_to_list(&dropping_trees,
                                                objectid,
                                                btrfs_root_bytenr(&ri),
-                                               level, ri.drop_level,
+                                               last_snapshot, level,
+                                               ri.drop_level,
                                                level_size, &found_key);
                                if (ret < 0)
                                        goto out;