Btrfs: fix a bug in parsing return value in logical resolve

In logical resolve, we parse extent_from_logical()'s 'ret' as a kind of flag.

It is possible to lose our errors because
(-EXXXX & BTRFS_EXTENT_FLAG_TREE_BLOCK) is true.

I'm not sure if it is on purpose, it just looks too hacky if it is.
I'd rather use a real flag and a 'ret' to catch errors.

Acked-by: Jan Schmidt <list.btrfs@jan-o-sch.net>
Signed-off-by: Liu Bo <liub.liubo@gmail.com>

5 files changed, 34 insertions, 20 deletions

diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c
index e600857d3ca4..ab286e5bfe33 100644
--- a/fs/btrfs/backref.c
+++ b/fs/btrfs/backref.c
@@ -1193,7 +1193,8 @@ char *btrfs_iref_to_path(struct btrfs_root *fs_root, struct btrfs_path *path,
  * tree blocks and <0 on error.
  */
 int extent_from_logical(struct btrfs_fs_info *fs_info, u64 logical,
-                        struct btrfs_path *path, struct btrfs_key *found_key)
+                        struct btrfs_path *path, struct btrfs_key *found_key,
+                        u64 *flags_ret)
 {
         int ret;
         u64 flags;
@@ -1237,10 +1238,17 @@ int extent_from_logical(struct btrfs_fs_info *fs_info, u64 logical,
                  (unsigned long long)found_key->objectid,
                  (unsigned long long)found_key->offset,
                  (unsigned long long)flags, item_size);
-        if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
-                return BTRFS_EXTENT_FLAG_TREE_BLOCK;
-        if (flags & BTRFS_EXTENT_FLAG_DATA)
-                return BTRFS_EXTENT_FLAG_DATA;
+
+        WARN_ON(!flags_ret);
+        if (flags_ret) {
+                if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
+                        *flags_ret = BTRFS_EXTENT_FLAG_TREE_BLOCK;
+                else if (flags & BTRFS_EXTENT_FLAG_DATA)
+                        *flags_ret = BTRFS_EXTENT_FLAG_DATA;
+                else
+                        BUG_ON(1);
+                return 0;
+        }
 
         return -EIO;
 }
@@ -1433,15 +1441,15 @@ int iterate_inodes_from_logical(u64 logical, struct btrfs_fs_info *fs_info,
 {
         int ret;
         u64 extent_item_pos;
+        u64 flags = 0;
         struct btrfs_key found_key;
         int search_commit_root = path->search_commit_root;
 
-        ret = extent_from_logical(fs_info, logical, path,
-                                        &found_key);
+        ret = extent_from_logical(fs_info, logical, path, &found_key, &flags);
         btrfs_release_path(path);
         if (ret < 0)
                 return ret;
-        if (ret & BTRFS_EXTENT_FLAG_TREE_BLOCK)
+        if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
                 return -EINVAL;
 
         extent_item_pos = logical - found_key.objectid;
diff --git a/fs/btrfs/backref.h b/fs/btrfs/backref.h
index 032f4dc7eab8..4fda5d8029a7 100644
--- a/fs/btrfs/backref.h
+++ b/fs/btrfs/backref.h
@@ -40,7 +40,8 @@ int inode_item_info(u64 inum, u64 ioff, struct btrfs_root *fs_root,
                         struct btrfs_path *path);
 
 int extent_from_logical(struct btrfs_fs_info *fs_info, u64 logical,
-                        struct btrfs_path *path, struct btrfs_key *found_key);
+                        struct btrfs_path *path, struct btrfs_key *found_key,
+                        u64 *flags);
 
 int tree_backref_for_extent(unsigned long *ptr, struct extent_buffer *eb,
                                 struct btrfs_extent_item *ei, u32 item_size,
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index de886ac7ba0f..48ff3f7317b0 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -3211,6 +3211,7 @@ static long btrfs_ioctl_logical_to_ino(struct btrfs_root *root,
         int ret = 0;
         int size;
         u64 extent_item_pos;
+        u64 flags = 0;
         struct btrfs_ioctl_logical_ino_args *loi;
         struct btrfs_data_container *inodes = NULL;
         struct btrfs_path *path = NULL;
@@ -3240,10 +3241,11 @@ static long btrfs_ioctl_logical_to_ino(struct btrfs_root *root,
                 goto out;
         }
 
-        ret = extent_from_logical(root->fs_info, loi->logical, path, &key);
+        ret = extent_from_logical(root->fs_info, loi->logical, path, &key,
+                                  &flags);
         btrfs_release_path(path);
 
-        if (ret & BTRFS_EXTENT_FLAG_TREE_BLOCK)
+        if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
                 ret = -ENOENT;
         if (ret < 0)
                 goto out;
diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c
index 4e9eafe01c55..d3bb901ade42 100644
--- a/fs/btrfs/scrub.c
+++ b/fs/btrfs/scrub.c
@@ -352,13 +352,14 @@ static void scrub_print_warning(const char *errstr, struct scrub_block *sblock)
         struct extent_buffer *eb;
         struct btrfs_extent_item *ei;
         struct scrub_warning swarn;
-        u32 item_size;
-        int ret;
+        unsigned long ptr = 0;
+        u64 extent_item_pos;
+        u64 flags = 0;
         u64 ref_root;
+        u32 item_size;
         u8 ref_level;
-        unsigned long ptr = 0;
         const int bufsize = 4096;
-        u64 extent_item_pos;
+        int ret;
 
         path = btrfs_alloc_path();
 
@@ -375,7 +376,8 @@ static void scrub_print_warning(const char *errstr, struct scrub_block *sblock)
         if (!path || !swarn.scratch_buf || !swarn.msg_buf)
                 goto out;
 
-        ret = extent_from_logical(fs_info, swarn.logical, path, &found_key);
+        ret = extent_from_logical(fs_info, swarn.logical, path, &found_key,
+                                  &flags);
         if (ret < 0)
                 goto out;
 
@@ -387,7 +389,7 @@ static void scrub_print_warning(const char *errstr, struct scrub_block *sblock)
         item_size = btrfs_item_size_nr(eb, path->slots[0]);
         btrfs_release_path(path);
 
-        if (ret & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
+        if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
                 do {
                         ret = tree_backref_for_extent(&ptr, eb, ei, item_size,
                                                         &ref_root, &ref_level);
diff --git a/fs/btrfs/send.c b/fs/btrfs/send.c
index e5c867996aa0..c6ef070a8dca 100644
--- a/fs/btrfs/send.c
+++ b/fs/btrfs/send.c
@@ -1152,6 +1152,7 @@ static int find_extent_clone(struct send_ctx *sctx,
         u64 disk_byte;
         u64 num_bytes;
         u64 extent_item_pos;
+        u64 flags = 0;
         struct btrfs_file_extent_item *fi;
         struct extent_buffer *eb = path->nodes[0];
         struct backref_ctx *backref_ctx = NULL;
@@ -1198,13 +1199,13 @@ static int find_extent_clone(struct send_ctx *sctx,
         }
         logical = disk_byte + btrfs_file_extent_offset(eb, fi);
 
-        ret = extent_from_logical(sctx->send_root->fs_info,
-                        disk_byte, tmp_path, &found_key);
+        ret = extent_from_logical(sctx->send_root->fs_info, disk_byte, tmp_path,
+                                  &found_key, &flags);
         btrfs_release_path(tmp_path);
 
         if (ret < 0)
                 goto out;
-        if (ret & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
+        if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
                 ret = -EIO;
                 goto out;
         }