[PATCH 12/30] ocfs2: abstract the fast symlink dinode guard and size check

[Joseph Qi <joseph.qi@linux.alibaba.com>]

Introduce ocfs2_dinode_is_fast_symlink() for the S_ISLNK with no
allocated clusters test that selects the id2.i_symlink union arm, and
ocfs2_dinode_has_oversized_fast_symlink() for the i_size bound.

The guard is deliberately not shared with the similar test inside
ocfs2_dinode_has_extents(), which additionally requires a non-zero
i_size.  A zero-length, zero-cluster symlink currently falls through to
the extent list checks, and reusing one predicate for both would change
that.

No functional change intended.

Signed-off-by: Joseph Qi <joseph.qi@linux.alibaba.com>
---
 fs/ocfs2/inode.c | 20 +++++++++++++++++---
 1 file changed, 17 insertions(+), 3 deletions(-)

diff --git a/fs/ocfs2/inode.c b/fs/ocfs2/inode.c
index db2a67543c7d..51bfa7643ebd 100644
--- a/fs/ocfs2/inode.c
+++ b/fs/ocfs2/inode.c
@@ -182,6 +182,21 @@ static bool ocfs2_dinode_has_inline_size_over_count(struct ocfs2_dinode *di)
 	return le64_to_cpu(di->i_size) > le16_to_cpu(di->id2.i_data.id_count);
 }
 
+/*
+ * Unlike the similar test in ocfs2_dinode_has_extents(), this does not require
+ * a non-zero i_size: a zero-length fast symlink is still validated here.
+ */
+static bool ocfs2_dinode_is_fast_symlink(struct ocfs2_dinode *di)
+{
+	return S_ISLNK(le16_to_cpu(di->i_mode)) && !le32_to_cpu(di->i_clusters);
+}
+
+static bool ocfs2_dinode_has_oversized_fast_symlink(struct super_block *sb,
+						    struct ocfs2_dinode *di)
+{
+	return le64_to_cpu(di->i_size) >= ocfs2_fast_symlink_chars(sb);
+}
+
 void ocfs2_set_inode_flags(struct inode *inode)
 {
 	unsigned int flags = OCFS2_I(inode)->ip_attr;
@@ -1773,12 +1788,11 @@ int ocfs2_validate_inode_block(struct super_block *sb,
 		}
 	}
 
-	if (S_ISLNK(le16_to_cpu(di->i_mode)) &&
-	    !le32_to_cpu(di->i_clusters)) {
+	if (ocfs2_dinode_is_fast_symlink(di)) {
 		int max_inline = ocfs2_fast_symlink_chars(sb);
 		u64 i_size = le64_to_cpu(di->i_size);
 
-		if (i_size >= max_inline) {
+		if (ocfs2_dinode_has_oversized_fast_symlink(sb, di)) {
 			rc = ocfs2_error(sb,
 					 "Invalid dinode #%llu: fast symlink i_size %llu exceeds max %d\n",
 					 (unsigned long long)bh->b_blocknr,
-- 
2.39.3