btrfs-progs: Add fixing function for inodes whose nlink dismatch
authorQu Wenruo <quwenruo@cn.fujitsu.com>
Tue, 9 Dec 2014 08:27:29 +0000 (16:27 +0800)
committerDavid Sterba <dsterba@suse.cz>
Wed, 10 Dec 2014 12:44:53 +0000 (13:44 +0100)
[BUG]
At least two users have already hit a bug in btrfs causing file
missing(Chromium config file).
The missing file's nlink is still 1 but its backref points to non-exist
parent inode.

This should be a kernel bug, but btrfsck fix is needed anyway.

[FIX]
For such nlink mismatch inode, we will reset all the inode_ref with its
dir_index/item (including valid one), and re-add the valids.
If there is no valid backref for it, create 'lost+found' under the root
of the subvolume and add link to the directory.

Reported-by: Mike Gavrilov <mikhail.v.gavrilov@gmail.com>
Reported-by: Ed Tomlinson <edt@aei.ca>
Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.cz>
cmds-check.c

index 9c0189d..2ea273c 100644 (file)
@@ -1837,6 +1837,18 @@ static int repair_inode_backrefs(struct btrfs_root *root,
                        struct btrfs_trans_handle *trans;
                        struct btrfs_key location;
 
+                       ret = check_dir_conflict(root, backref->name,
+                                                backref->namelen,
+                                                backref->dir,
+                                                backref->index);
+                       if (ret) {
+                               /*
+                                * let nlink fixing routine to handle it,
+                                * which can do it better.
+                                */
+                               ret = 0;
+                               break;
+                       }
                        location.objectid = rec->ino;
                        location.type = BTRFS_INODE_ITEM_KEY;
                        location.offset = 0;
@@ -1915,20 +1927,191 @@ static int find_file_name(struct inode_record *rec,
        return -ENOENT;
 }
 
+/* Reset the nlink of the inode to the correct one */
+static int reset_nlink(struct btrfs_trans_handle *trans,
+                      struct btrfs_root *root,
+                      struct btrfs_path *path,
+                      struct inode_record *rec)
+{
+       struct inode_backref *backref;
+       struct inode_backref *tmp;
+       struct btrfs_key key;
+       struct btrfs_inode_item *inode_item;
+       int ret = 0;
+
+       /* Remove all backref including the valid ones */
+       list_for_each_entry_safe(backref, tmp, &rec->backrefs, list) {
+               ret = btrfs_unlink(trans, root, rec->ino, backref->dir,
+                                  backref->index, backref->name,
+                                  backref->namelen, 0);
+               if (ret < 0)
+                       goto out;
+
+               /* remove invalid backref, so it won't be added back */
+               if (!(backref->found_dir_index &&
+                     backref->found_dir_item &&
+                     backref->found_inode_ref)) {
+                       list_del(&backref->list);
+                       free(backref);
+               }
+       }
+
+       /* Set nlink to 0 */
+       key.objectid = rec->ino;
+       key.type = BTRFS_INODE_ITEM_KEY;
+       key.offset = 0;
+       ret = btrfs_search_slot(trans, root, &key, path, 0, 1);
+       if (ret < 0)
+               goto out;
+       if (ret > 0) {
+               ret = -ENOENT;
+               goto out;
+       }
+       inode_item = btrfs_item_ptr(path->nodes[0], path->slots[0],
+                                   struct btrfs_inode_item);
+       btrfs_set_inode_nlink(path->nodes[0], inode_item, 0);
+       btrfs_mark_buffer_dirty(path->nodes[0]);
+       btrfs_release_path(path);
+
+       /*
+        * Add back valid inode_ref/dir_item/dir_index,
+        * add_link() will handle the nlink inc, so new nlink must be correct
+        */
+       list_for_each_entry(backref, &rec->backrefs, list) {
+               ret = btrfs_add_link(trans, root, rec->ino, backref->dir,
+                                    backref->name, backref->namelen,
+                                    backref->ref_type, &backref->index, 1);
+               if (ret < 0)
+                       goto out;
+       }
+out:
+       btrfs_release_path(path);
+       return ret;
+}
+
+static int repair_inode_nlinks(struct btrfs_trans_handle *trans,
+                              struct btrfs_root *root,
+                              struct btrfs_path *path,
+                              struct inode_record *rec)
+{
+       char *dir_name = "lost+found";
+       char namebuf[BTRFS_NAME_LEN] = {0};
+       u64 lost_found_ino;
+       u32 mode = 0700;
+       u8 type = 0;
+       int namelen = 0;
+       int name_recovered = 0;
+       int type_recovered = 0;
+       int ret = 0;
+
+       /*
+        * Get file name and type first before these invalid inode ref
+        * are deleted by remove_all_invalid_backref()
+        */
+       name_recovered = !find_file_name(rec, namebuf, &namelen);
+       type_recovered = !find_file_type(rec, &type);
+
+       if (!name_recovered) {
+               printf("Can't get file name for inode %llu, using '%llu' as fallback\n",
+                      rec->ino, rec->ino);
+               namelen = count_digits(rec->ino);
+               sprintf(namebuf, "%llu", rec->ino);
+               name_recovered = 1;
+       }
+       if (!type_recovered) {
+               printf("Can't get file type for inode %llu, using FILE as fallback\n",
+                      rec->ino);
+               type = BTRFS_FT_REG_FILE;
+               type_recovered = 1;
+       }
+
+       ret = reset_nlink(trans, root, path, rec);
+       if (ret < 0) {
+               fprintf(stderr,
+                       "Failed to reset nlink for inode %llu: %s\n",
+                       rec->ino, strerror(-ret));
+               goto out;
+       }
+
+       if (rec->found_link == 0) {
+               lost_found_ino = root->highest_inode;
+               if (lost_found_ino >= BTRFS_LAST_FREE_OBJECTID) {
+                       ret = -EOVERFLOW;
+                       goto out;
+               }
+               lost_found_ino++;
+               ret = btrfs_mkdir(trans, root, dir_name, strlen(dir_name),
+                                 BTRFS_FIRST_FREE_OBJECTID, &lost_found_ino,
+                                 mode);
+               if (ret < 0) {
+                       fprintf(stderr, "Failed to create '%s' dir: %s",
+                               dir_name, strerror(-ret));
+                       goto out;
+               }
+               ret = btrfs_add_link(trans, root, rec->ino, lost_found_ino,
+                                    namebuf, namelen, type, NULL, 1);
+               if (ret == -EEXIST) {
+                       /*
+                        * Conflicting file name, add ".INO" as suffix * +1 for '.'
+                        */
+                       if (namelen + count_digits(rec->ino) + 1 >
+                           BTRFS_NAME_LEN) {
+                               ret = -EFBIG;
+                               goto out;
+                       }
+                       snprintf(namebuf + namelen, BTRFS_NAME_LEN - namelen,
+                                ".%llu", rec->ino);
+                       namelen += count_digits(rec->ino) + 1;
+                       ret = btrfs_add_link(trans, root, rec->ino,
+                                            lost_found_ino, namebuf,
+                                            namelen, type, NULL, 1);
+               }
+               if (ret < 0) {
+                       fprintf(stderr,
+                               "Failed to link the inode %llu to %s dir: %s",
+                               rec->ino, dir_name, strerror(-ret));
+                       goto out;
+               }
+               /*
+                * Just increase the found_link, don't actually add the
+                * backref. This will make things easier and this inode
+                * record will be freed after the repair is done.
+                * So fsck will not report problem about this inode.
+                */
+               rec->found_link++;
+               printf("Moving file '%.*s' to '%s' dir since it has no valid backref\n",
+                      namelen, namebuf, dir_name);
+       }
+       rec->errors &= ~I_ERR_LINK_COUNT_WRONG;
+       printf("Fixed the nlink of inode %llu\n", rec->ino);
+out:
+       btrfs_release_path(path);
+       return ret;
+}
+
 static int try_repair_inode(struct btrfs_root *root, struct inode_record *rec)
 {
        struct btrfs_trans_handle *trans;
        struct btrfs_path *path;
        int ret = 0;
 
-       if (!(rec->errors & (I_ERR_DIR_ISIZE_WRONG | I_ERR_NO_ORPHAN_ITEM)))
+       if (!(rec->errors & (I_ERR_DIR_ISIZE_WRONG |
+                            I_ERR_NO_ORPHAN_ITEM |
+                            I_ERR_LINK_COUNT_WRONG)))
                return rec->errors;
 
        path = btrfs_alloc_path();
        if (!path)
                return -ENOMEM;
 
-       trans = btrfs_start_transaction(root, 1);
+       /*
+        * For nlink repair, it may create a dir and add link, so
+        * 2 for parent(256)'s dir_index and dir_item
+        * 2 for lost+found dir's inode_item and inode_ref
+        * 1 for the new inode_ref of the file
+        * 2 for lost+found dir's dir_index and dir_item for the file
+        */
+       trans = btrfs_start_transaction(root, 7);
        if (IS_ERR(trans)) {
                btrfs_free_path(path);
                return PTR_ERR(trans);
@@ -1938,6 +2121,8 @@ static int try_repair_inode(struct btrfs_root *root, struct inode_record *rec)
                ret = repair_inode_isize(trans, root, path, rec);
        if (!ret && rec->errors & I_ERR_NO_ORPHAN_ITEM)
                ret = repair_inode_orphan_item(trans, root, path, rec);
+       if (!ret && rec->errors & I_ERR_LINK_COUNT_WRONG)
+               ret = repair_inode_nlinks(trans, root, path, rec);
        btrfs_commit_transaction(trans, root);
        btrfs_free_path(path);
        return ret;
@@ -2088,6 +2273,8 @@ static int check_inode_recs(struct btrfs_root *root,
                        }
                }
 
+               if (rec->found_link != rec->nlink)
+                       rec->errors |= I_ERR_LINK_COUNT_WRONG;
                if (repair) {
                        ret = try_repair_inode(root, rec);
                        if (ret == 0 && can_free_inode_rec(rec)) {
@@ -2100,8 +2287,6 @@ static int check_inode_recs(struct btrfs_root *root,
                error++;
                if (!rec->found_inode_item)
                        rec->errors |= I_ERR_NO_INODE_ITEM;
-               if (rec->found_link != rec->nlink)
-                       rec->errors |= I_ERR_LINK_COUNT_WRONG;
                print_inode_error(root, rec);
                list_for_each_entry(backref, &rec->backrefs, list) {
                        if (!backref->found_dir_item)