diff options
| -rw-r--r-- | fs/btrfs/send.c | 140 |
1 files changed, 134 insertions, 6 deletions
diff --git a/fs/btrfs/send.c b/fs/btrfs/send.c index f618224d2326..6926546939f6 100644 --- a/fs/btrfs/send.c +++ b/fs/btrfs/send.c @@ -1067,6 +1067,7 @@ static int __clone_root_cmp_sort(const void *e1, const void *e2) /* * Called for every backref that is found for the current extent. + * Results are collected in sctx->clone_roots->ino/offset/found_refs */ static int __iterate_backrefs(u64 ino, u64 offset, u64 root, void *ctx_) { @@ -1090,7 +1091,7 @@ static int __iterate_backrefs(u64 ino, u64 offset, u64 root, void *ctx_) } /* - * There are inodes that have extents that lie behind it's i_size. Don't + * There are inodes that have extents that lie behind its i_size. Don't * accept clones from these extents. */ ret = get_inode_info(found->root, ino, &i_size, NULL, NULL, NULL, NULL, @@ -1137,6 +1138,12 @@ static int __iterate_backrefs(u64 ino, u64 offset, u64 root, void *ctx_) } /* + * Given an inode, offset and extent item, it finds a good clone for a clone + * instruction. Returns -ENOENT when none could be found. The function makes + * sure that the returned clone is usable at the point where sending is at the + * moment. This means, that no clones are accepted which lie behind the current + * inode+offset. + * * path must point to the extent item when called. */ static int find_extent_clone(struct send_ctx *sctx, @@ -1529,6 +1536,10 @@ out: return ret; } +/* + * Looks up the first btrfs_inode_ref of a given ino. It returns the parent dir, + * generation of the parent dir and the name of the dir entry. + */ static int get_first_ref(struct send_ctx *sctx, struct btrfs_root *root, u64 ino, u64 *dir, u64 *dir_gen, struct fs_path *name) @@ -1615,6 +1626,16 @@ out: return ret; } +/* + * Used by process_recorded_refs to determine if a new ref would overwrite an + * already existing ref. In case it detects an overwrite, it returns the + * inode/gen in who_ino/who_gen. + * When an overwrite is detected, process_recorded_refs does proper orphanizing + * to make sure later references to the overwritten inode are possible. + * Orphanizing is however only required for the first ref of an inode. + * process_recorded_refs does an additional is_first_ref check to see if + * orphanizing is really required. + */ static int will_overwrite_ref(struct send_ctx *sctx, u64 dir, u64 dir_gen, const char *name, int name_len, u64 *who_ino, u64 *who_gen) @@ -1639,6 +1660,11 @@ static int will_overwrite_ref(struct send_ctx *sctx, u64 dir, u64 dir_gen, goto out; } + /* + * Check if the overwritten ref was already processed. If yes, the ref + * was already unlinked/moved, so we can safely assume that we will not + * overwrite anything at this point in time. + */ if (other_inode > sctx->send_progress) { ret = get_inode_info(sctx->parent_root, other_inode, NULL, who_gen, NULL, NULL, NULL, NULL); @@ -1655,6 +1681,13 @@ out: return ret; } +/* + * Checks if the ref was overwritten by an already processed inode. This is + * used by __get_cur_name_and_parent to find out if the ref was orphanized and + * thus the orphan name needs be used. + * process_recorded_refs also uses it to avoid unlinking of refs that were + * overwritten. + */ static int did_overwrite_ref(struct send_ctx *sctx, u64 dir, u64 dir_gen, u64 ino, u64 ino_gen, @@ -1703,6 +1736,11 @@ out: return ret; } +/* + * Same as did_overwrite_ref, but also checks if it is the first ref of an inode + * that got overwritten. This is used by process_recorded_refs to determine + * if it has to use the path as returned by get_cur_path or the orphan name. + */ static int did_overwrite_first_ref(struct send_ctx *sctx, u64 ino, u64 gen) { int ret = 0; @@ -1731,6 +1769,11 @@ out: return ret; } +/* + * Insert a name cache entry. On 32bit kernels the radix tree index is 32bit, + * so we need to do some special handling in case we have clashes. This function + * takes care of this with the help of name_cache_entry::radix_list. + */ static int name_cache_insert(struct send_ctx *sctx, struct name_cache_entry *nce) { @@ -1792,12 +1835,19 @@ static struct name_cache_entry *name_cache_search(struct send_ctx *sctx, return NULL; } +/* + * Removes the entry from the list and adds it back to the end. This marks the + * entry as recently used so that name_cache_clean_unused does not remove it. + */ static void name_cache_used(struct send_ctx *sctx, struct name_cache_entry *nce) { list_del(&nce->list); list_add_tail(&nce->list, &sctx->name_cache_list); } +/* + * Remove some entries from the beginning of name_cache_list. + */ static void name_cache_clean_unused(struct send_ctx *sctx) { struct name_cache_entry *nce; @@ -1824,6 +1874,14 @@ static void name_cache_free(struct send_ctx *sctx) } } +/* + * Used by get_cur_path for each ref up to the root. + * Returns 0 if it succeeded. + * Returns 1 if the inode is not existent or got overwritten. In that case, the + * name is an orphan name. This instructs get_cur_path to stop iterating. If 1 + * is returned, parent_ino/parent_gen are not guaranteed to be valid. + * Returns <0 in case of error. + */ static int __get_cur_name_and_parent(struct send_ctx *sctx, u64 ino, u64 gen, u64 *parent_ino, @@ -1835,6 +1893,11 @@ static int __get_cur_name_and_parent(struct send_ctx *sctx, struct btrfs_path *path = NULL; struct name_cache_entry *nce = NULL; + /* + * First check if we already did a call to this function with the same + * ino/gen. If yes, check if the cache entry is still up-to-date. If yes + * return the cached result. + */ nce = name_cache_search(sctx, ino, gen); if (nce) { if (ino < sctx->send_progress && nce->need_later_update) { @@ -1857,6 +1920,11 @@ static int __get_cur_name_and_parent(struct send_ctx *sctx, if (!path) return -ENOMEM; + /* + * If the inode is not existent yet, add the orphan name and return 1. + * This should only happen for the parent dir that we determine in + * __record_new_ref + */ ret = is_inode_existent(sctx, ino, gen); if (ret < 0) goto out; @@ -1869,6 +1937,10 @@ static int __get_cur_name_and_parent(struct send_ctx *sctx, goto out_cache; } + /* + * Depending on whether the inode was already processed or not, use + * send_root or parent_root for ref lookup. + */ if (ino < sctx->send_progress) ret = get_first_ref(sctx, sctx->send_root, ino, parent_ino, parent_gen, dest); @@ -1878,6 +1950,10 @@ static int __get_cur_name_and_parent(struct send_ctx *sctx, if (ret < 0) goto out; + /* + * Check if the ref was overwritten by an inode's ref that was processed + * earlier. If yes, treat as orphan and return 1. + */ ret = did_overwrite_ref(sctx, *parent_ino, *parent_gen, ino, gen, dest->start, dest->end - dest->start); if (ret < 0) @@ -1891,6 +1967,9 @@ static int __get_cur_name_and_parent(struct send_ctx *sctx, } out_cache: + /* + * Store the result of the lookup in the name cache. + */ nce = kmalloc(sizeof(*nce) + fs_path_len(dest) + 1, GFP_NOFS); if (!nce) { ret = -ENOMEM; @@ -2278,7 +2357,7 @@ verbose_printk("btrfs: send_utimes %llu\n", ino); btrfs_inode_mtime(ii)); TLV_PUT_BTRFS_TIMESPEC(sctx, BTRFS_SEND_A_CTIME, eb, btrfs_inode_ctime(ii)); - /* TODO otime? */ + /* TODO Add otime support when the otime patches get into upstream */ ret = send_cmd(sctx); @@ -2520,7 +2599,7 @@ static void free_recorded_refs(struct send_ctx *sctx) } /* - * Renames/moves a file/dir to it's orphan name. Used when the first + * Renames/moves a file/dir to its orphan name. Used when the first * ref of an unprocessed inode gets overwritten and for all non empty * directories. */ @@ -2840,7 +2919,9 @@ verbose_printk("btrfs: process_recorded_refs %llu\n", sctx->cur_ino); * If the inode is still orphan, unlink the orphan. This may * happen when a previous inode did overwrite the first ref * of this inode and no new refs were added for the current - * inode. + * inode. Unlinking does not mean that the inode is deleted in + * all cases. There may still be links to this inode in other + * places. */ if (is_orphan) { ret = send_unlink(sctx, valid_path); @@ -2857,6 +2938,11 @@ verbose_printk("btrfs: process_recorded_refs %llu\n", sctx->cur_ino); */ ULIST_ITER_INIT(&uit); while ((un = ulist_next(check_dirs, &uit))) { + /* + * In case we had refs into dirs that were not processed yet, + * we don't need to do the utime and rmdir logic for these dirs. + * The dir will be processed later. + */ if (un->val > sctx->cur_ino) continue; @@ -4048,7 +4134,17 @@ static int changed_inode(struct send_ctx *sctx, sctx->cur_inode_mode = btrfs_inode_mode( sctx->right_path->nodes[0], right_ii); } else if (result == BTRFS_COMPARE_TREE_CHANGED) { + /* + * We need to do some special handling in case the inode was + * reported as changed with a changed generation number. This + * means that the original inode was deleted and new inode + * reused the same inum. So we have to treat the old inode as + * deleted and the new one as new. + */ if (sctx->cur_inode_new_gen) { + /* + * First, process the inode as if it was deleted. + */ sctx->cur_inode_gen = right_gen; sctx->cur_inode_new = 0; sctx->cur_inode_deleted = 1; @@ -4061,6 +4157,9 @@ static int changed_inode(struct send_ctx *sctx, if (ret < 0) goto out; + /* + * Now process the inode as if it was new. + */ sctx->cur_inode_gen = left_gen; sctx->cur_inode_new = 1; sctx->cur_inode_deleted = 0; @@ -4080,6 +4179,11 @@ static int changed_inode(struct send_ctx *sctx, * process_recorded_refs_if_needed in the new_gen case. */ sctx->send_progress = sctx->cur_ino + 1; + + /* + * Now process all extents and xattrs of the inode as if + * they were all new. + */ ret = process_all_extents(sctx); if (ret < 0) goto out; @@ -4102,6 +4206,16 @@ out: return ret; } +/* + * We have to process new refs before deleted refs, but compare_trees gives us + * the new and deleted refs mixed. To fix this, we record the new/deleted refs + * first and later process them in process_recorded_refs. + * For the cur_inode_new_gen case, we skip recording completely because + * changed_inode did already initiate processing of refs. The reason for this is + * that in this case, compare_tree actually compares the refs of 2 different + * inodes. To fix this, process_all_refs is used in changed_inode to handle all + * refs of the right tree as deleted and all refs of the left tree as new. + */ static int changed_ref(struct send_ctx *sctx, enum btrfs_compare_tree_result result) { @@ -4122,6 +4236,11 @@ static int changed_ref(struct send_ctx *sctx, return ret; } +/* + * Process new/deleted/changed xattrs. We skip processing in the + * cur_inode_new_gen case because changed_inode did already initiate processing + * of xattrs. The reason is the same as in changed_ref + */ static int changed_xattr(struct send_ctx *sctx, enum btrfs_compare_tree_result result) { @@ -4141,6 +4260,11 @@ static int changed_xattr(struct send_ctx *sctx, return ret; } +/* + * Process new/deleted/changed extents. We skip processing in the + * cur_inode_new_gen case because changed_inode did already initiate processing + * of extents. The reason is the same as in changed_ref + */ static int changed_extent(struct send_ctx *sctx, enum btrfs_compare_tree_result result) { @@ -4157,7 +4281,10 @@ static int changed_extent(struct send_ctx *sctx, return ret; } - +/* + * Updates compare related fields in sctx and simply forwards to the actual + * changed_xxx functions. + */ static int changed_cb(struct btrfs_root *left_root, struct btrfs_root *right_root, struct btrfs_path *left_path, @@ -4229,7 +4356,8 @@ join_trans: } /* - * Make sure the tree has not changed + * Make sure the tree has not changed after re-joining. We detect this + * by comparing start_ctransid and ctransid. They should always match. */ spin_lock(&send_root->root_times_lock); ctransid = btrfs_root_ctransid(&send_root->root_item); |