btrfs-progs: check: lowmem: Fix false alert on inline compressed extent

Old lowmem check doesn't check if the inline extent is compressed and
always checks extent numbytes against inline item size.

And when it finds the extent numbytes mismatch with inline item size it
doesn't output any error message, just return error silently, making it
quite hard to debug.

Fix it by only checking extent numbytes against inline item size when
the extent is not compressed, and output error message.

Reported-by: Christoph Anton Mitterer <calestyo@scientia.net>
Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/cmds-check.c b/cmds-check.c
index 29c532b..3d0b123 100644 (file)
--- a/cmds-check.c
+++ b/cmds-check.c
@@ -4711,17 +4711,28 @@ static int check_file_extent(struct btrfs_root *root, struct btrfs_key *fkey,
 
        fi = btrfs_item_ptr(node, slot, struct btrfs_file_extent_item);
 
+       /* Check inline extent */
        extent_type = btrfs_file_extent_type(node, fi);
-       /* Skip if file extent is inline */
        if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
                struct btrfs_item *e = btrfs_item_nr(slot);
                u32 item_inline_len;
 
                item_inline_len = btrfs_file_extent_inline_item_len(node, e);
                extent_num_bytes = btrfs_file_extent_inline_len(node, slot, fi);
-               if (extent_num_bytes == 0 ||
-                   extent_num_bytes != item_inline_len)
+               compressed = btrfs_file_extent_compression(node, fi);
+               if (extent_num_bytes == 0) {
+                       error(
+               "root %llu EXTENT_DATA[%llu %llu] has empty inline extent",
+                               root->objectid, fkey->objectid, fkey->offset);
                        err |= FILE_EXTENT_ERROR;
+               }
+               if (!compressed && extent_num_bytes != item_inline_len) {
+                       error(
+               "root %llu EXTENT_DATA[%llu %llu] wrong inline size, have: %llu, expected: %u",
+                               root->objectid, fkey->objectid, fkey->offset,
+                               extent_num_bytes, item_inline_len);
+                       err |= FILE_EXTENT_ERROR;
+               }
                *size += extent_num_bytes;
                return err;
        }