Re: [PATCH v2 12/12] btrfs-progs: cmds-check.c: walk_down_tree_v2 break cause of leaf process

[Qu Wenruo]

At 02/06/2017 01:47 PM, Qu Wenruo wrote:

From: Su Yue <suy.f...@cn.fujitsu.com>

In lowmem mode, 'walk_down_tree_v2' returns negative values wheather
the error is fatal or not. It causes the loop where 'walk_down_tree_v2'
is to break even the error is tolerated and then subsequent nodes process
will be skipped.

Fix it by redefining meanings of values 'walk_down_tree_v2' returns.
Do a similar fix for 'process_one_leaf_v2'.

Signed-off-by: Su Yue <suy.f...@cn.fujitsu.com>
---
 cmds-check.c | 37 ++++++++++++++++++++++---------------
 1 file changed, 22 insertions(+), 15 deletions(-)

diff --git a/cmds-check.c b/cmds-check.c
index 7d273623..fae18e00 100644
--- a/cmds-check.c
+++ b/cmds-check.c
@@ -1868,6 +1868,11 @@ static int update_nodes_refs(struct btrfs_root *root, 
u64 bytenr,
 static int check_inode_item(struct btrfs_root *root, struct btrfs_path *path,
                            unsigned int ext_ref);

+/*
+ * Returns >0  Found error, not fatal, should continue process
+ * Returns <0  Fata error, must exit the whole check
+ * returns 0   No error is found
+ */
 static int process_one_leaf_v2(struct btrfs_root *root, struct btrfs_path 
*path,
                               struct node_refs *nrefs, int *level, int ext_ref)
 {
@@ -1937,13 +1942,8 @@ again:
        }
 out:
        err &= ~LAST_ITEM;
-       /*
-        * Convert any error bitmap to -EIO, as we should avoid
-        * mixing positive and negative return value to represent
-        * error
-        */
        if (err && !ret)
-               ret = -EIO;
+               ret = err;
        return ret;
 }

@@ -2213,6 +2213,11 @@ out:
 static int check_inode_item(struct btrfs_root *root, struct btrfs_path *path,
                            unsigned int ext_ref);

+/*
+ * Returns >0  Found error, should continue
+ * Returns 0   No error is found
+ * Returns <0  Fatal error, must exit the whole check
+ */
 static int walk_down_tree_v2(struct btrfs_root *root, struct btrfs_path *path,
                             int *level, struct node_refs *nrefs, int ext_ref)
 {
@@ -5028,8 +5033,9 @@ static int check_fs_root_v2(struct btrfs_root *root, 
unsigned int ext_ref)
        struct btrfs_path path;
        struct node_refs nrefs;
        struct btrfs_root_item *root_item = &root->root_item;
-       int ret, wret;
+       int ret;
        int level;
+       int err = 0;

        /*
         * We need to manually check the first inode item(256)
@@ -5063,16 +5069,17 @@ static int check_fs_root_v2(struct btrfs_root *root, 
unsigned int ext_ref)
        }

        while (1) {
-               wret = walk_down_tree_v2(root, &path, &level, &nrefs, ext_ref);
-               if (wret < 0)
-                       ret = wret;
-               if (wret != 0)
+               ret = walk_down_tree_v2(root, &path, &level, &nrefs, ext_ref);
+               err |= !!ret;
+
+               /* if ret is negative, walk shall stop */
+               if (ret < 0) {
+                       ret = err;
                        break;
+               }

-               wret = walk_up_tree_v2(root, &path, &level);
-               if (wret < 0)
-                       ret = wret;
-               if (wret != 0)
+               ret = walk_up_tree_v2(root, &path, &level);
+               if (ret != 0)
                        break;

Here @ret can be 1, to indicate a normal traversal end.

In that case we need to change @ret to 0, as it's a normal end.

Or it will be caught as error.

Updated in github repo.

Thanks,
Qu

        }

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