[PATCH v3 11/31] ocfs2: abstract the inline data id_count bound check

[Joseph Qi]

Fold the id_count against ocfs2_max_inline_data_with_xattr() test into a
predicate.

The comparison stays signed.  ocfs2_max_inline_data_with_xattr() returns
int and subtracts the unvalidated on-disk i_xattr_inline_size from the
space available in the inode block, so it can go negative on small block
sizes.  Caching it in an unsigned local would turn a negative maximum
into a huge bound and silently accept the oversized id_count.  The
message keeps its %d for the same reason.

No functional change intended.

Signed-off-by: Joseph Qi <joseph.qi@xxxxxxxxxxxxxxxxx>
---
 fs/ocfs2/inode.c | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/fs/ocfs2/inode.c b/fs/ocfs2/inode.c
index 2aac1918562a..259f44661f37 100644
--- a/fs/ocfs2/inode.c
+++ b/fs/ocfs2/inode.c
@@ -174,6 +174,19 @@ static bool ocfs2_dinode_has_inline_clusters(struct ocfs2_dinode *di)
 	return le32_to_cpu(di->i_clusters) != 0;
 }
 
+static bool ocfs2_dinode_has_oversized_inline_data(struct super_block *sb,
+						   struct ocfs2_dinode *di)
+{
+	/*
+	 * The maximum is a signed int and can go negative, because
+	 * i_xattr_inline_size is itself unvalidated.  Keep the comparison
+	 * signed: an unsigned bound would turn a negative maximum into a
+	 * huge one and let the oversized id_count through.
+	 */
+	return le16_to_cpu(di->id2.i_data.id_count) >
+		ocfs2_max_inline_data_with_xattr(sb, di);
+}
+
 void ocfs2_set_inode_flags(struct inode *inode)
 {
 	unsigned int flags = OCFS2_I(inode)->ip_attr;
@@ -1747,8 +1760,7 @@ int ocfs2_validate_inode_block(struct super_block *sb,
 			goto bail;
 		}
 
-		if (le16_to_cpu(data->id_count) >
-		    ocfs2_max_inline_data_with_xattr(sb, di)) {
+		if (ocfs2_dinode_has_oversized_inline_data(sb, di)) {
 			rc = ocfs2_error(sb,
 					 "Invalid dinode #%llu: inline data id_count %u exceeds max %d\n",
 					 (unsigned long long)bh->b_blocknr,
-- 
2.39.3