[PATCH v2 5/7] btrfs: check/lowmem: Check and repair free space cache inode mode

[Qu Wenruo <wqu@suse.com>]

Unlike inodes in fs roots, we don't really check the inode items in root
tree, in fact we just skip everything other than ROOT_ITEM and ROOT_REF.

This makes invalid inode items sneak into root tree.
For example:
        item 9 key (256 INODE_ITEM 0) itemoff 13702 itemsize 160
                generation 30 transid 30 size 65536 nbytes 1507328
                block group 0 mode 0 links 1 uid 0 gid 0 rdev 0
				   ^ Should be 100600
                sequence 23 flags 0x1b(NODATASUM|NODATACOW|NOCOMPRESS|PREALLOC)
                atime 0.0 (1970-01-01 08:00:00)
                ctime 1553491158.189771625 (2019-03-25 13:19:18)
                mtime 0.0 (1970-01-01 08:00:00)
                otime 0.0 (1970-01-01 08:00:00)

There is a report of such problem in the mail list.

This patch will check and repair inode items of free space cache inodes in
lowmem mode.

Since free space cache inodes doesn't have INODE_REF but still has 1
link, we can't use check_inode_item() directly.
Instead we only check the inode mode, as that's the important part.

The check and repair function: check_repair_free_space_inode() is also
exported for original mode.

Signed-off-by: Qu Wenruo <wqu@suse.com>
---
 check/mode-common.c | 35 +++++++++++++++++++++++++++++++++++
 check/mode-common.h |  4 +++-
 check/mode-lowmem.c | 11 +++++++++++
 check/mode-lowmem.h |  2 ++
 4 files changed, 51 insertions(+), 1 deletion(-)

diff --git a/check/mode-common.c b/check/mode-common.c
index 466e7a8d09a7..95dc32d875e6 100644
--- a/check/mode-common.c
+++ b/check/mode-common.c
@@ -21,6 +21,7 @@
 #include "transaction.h"
 #include "utils.h"
 #include "disk-io.h"
+#include "repair.h"
 #include "check/mode-common.h"
 
 /*
@@ -889,3 +890,37 @@ abort:
 	btrfs_abort_transaction(trans, ret);
  	return ret;
 }
+
+/*
+ * For free space inodes, we can't call check_inode_item() as free space
+ * cache inode doesn't have INODE_REF.
+ * We just check its inode mode.
+ */
+int check_repair_free_space_inode(struct btrfs_fs_info *fs_info,
+				  struct btrfs_path *path)
+{
+	struct btrfs_inode_item *iitem;
+	struct btrfs_key key;
+	u32 mode;
+	int ret = 0;
+
+	btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
+	ASSERT(key.type == BTRFS_INODE_ITEM_KEY && is_fstree(key.objectid));
+	iitem = btrfs_item_ptr(path->nodes[0], path->slots[0],
+			       struct btrfs_inode_item);
+	mode = btrfs_inode_mode(path->nodes[0], iitem);
+	if (mode != FREE_SPACE_CACHE_INODE_MODE) {
+		error(
+	"free space cache inode %llu has invalid mode: has 0%o expect 0%o",
+			key.objectid, mode, FREE_SPACE_CACHE_INODE_MODE);
+		ret = -EUCLEAN;
+		if (repair) {
+			ret = repair_imode_common(fs_info->tree_root,
+						  path);
+			if (ret < 0)
+				return ret;
+			return ret;
+		}
+	}
+	return ret;
+}
diff --git a/check/mode-common.h b/check/mode-common.h
index 5aaf3aaa389b..4c169c6e3b29 100644
--- a/check/mode-common.h
+++ b/check/mode-common.h
@@ -24,6 +24,7 @@
 #include <sys/stat.h>
 #include "ctree.h"
 
+#define FREE_SPACE_CACHE_INODE_MODE	(0100600)
 /*
  * Use for tree walk to walk through trees whose leaves/nodes can be shared
  * between different trees. (Namely subvolume/fs trees)
@@ -128,7 +129,8 @@ int delete_corrupted_dir_item(struct btrfs_trans_handle *trans,
 int reset_imode(struct btrfs_trans_handle *trans, struct btrfs_root *root,
 		struct btrfs_path *path, u64 ino, u32 mode);
 int repair_imode_common(struct btrfs_root *root, struct btrfs_path *path);
-
+int check_repair_free_space_inode(struct btrfs_fs_info *fs_info,
+				  struct btrfs_path *path);
 /*
  * Check if the inode mode @imode is valid
  *
diff --git a/check/mode-lowmem.c b/check/mode-lowmem.c
index 8ecf27795c36..6665a7b07e0f 100644
--- a/check/mode-lowmem.c
+++ b/check/mode-lowmem.c
@@ -5088,6 +5088,17 @@ int check_fs_roots_lowmem(struct btrfs_fs_info *fs_info)
 		btrfs_item_key_to_cpu(node, &key, slot);
 		if (key.objectid > BTRFS_LAST_FREE_OBJECTID)
 			goto out;
+		if (key.type == BTRFS_INODE_ITEM_KEY &&
+		    is_fstree(key.objectid)) {
+			ret = check_repair_free_space_inode(fs_info, &path);
+			/* Check if we still have a valid path to continue */
+			if (ret < 0 && path.nodes[0]) {
+				err |= ret;
+				goto next;
+			}
+			if (ret < 0 && !path.nodes[0])
+				goto out;
+		}
 		if (key.type == BTRFS_ROOT_ITEM_KEY &&
 		    fs_root_objectid(key.objectid)) {
 			if (key.objectid == BTRFS_TREE_RELOC_OBJECTID) {
diff --git a/check/mode-lowmem.h b/check/mode-lowmem.h
index e0ab30b770d5..d2983fd12eb4 100644
--- a/check/mode-lowmem.h
+++ b/check/mode-lowmem.h
@@ -67,5 +67,7 @@
 
 int check_fs_roots_lowmem(struct btrfs_fs_info *fs_info);
 int check_chunks_and_extents_lowmem(struct btrfs_fs_info *fs_info);
+int check_repair_free_space_inode(struct btrfs_fs_info *fs_info,
+				  struct btrfs_path *path);
 
 #endif
-- 
2.21.0