[PATCH v2 06/31] ocfs2: abstract the dinode suballoc slot checks

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

The suballoc slot validation is a nested if/else-if whose two arms carry
different error messages.  Split it into two predicates so each message
stays at its own call site without having to re-test the slot value to
work out which arm fired.

The arms were already mutually exclusive, so two sequential tests are
equivalent to the if/else-if.

Keep the OCFS2_INVALID_SLOT exclusion in the range predicate.
OCFS2_INVALID_SLOT is 65535, which is greater than max_slots - 1, so
without it every system inode mkfs.ocfs2 creates from the global
allocator would be rejected.

ocfs2_get_suballoc_slot_bit() in suballoc.c open-codes an identical range
test, and is deliberately not converted.  The dinode validator pairs the
range predicate with ocfs2_dinode_has_invalid_suballoc_slot(), which also
rejects OCFS2_INVALID_SLOT on a non-system inode, so that pair is stricter
than what ocfs2_get_suballoc_slot_bit() accepts.  The range predicate on
its own is not stricter, it is the same test.

No functional change intended.

Signed-off-by: Joseph Qi <joseph.qi@linux.alibaba.com>
---
 fs/ocfs2/inode.c | 31 ++++++++++++++++++++++---------
 1 file changed, 22 insertions(+), 9 deletions(-)

diff --git a/fs/ocfs2/inode.c b/fs/ocfs2/inode.c
index 6b78b3f3c5fa..0929deb3e4b4 100644
--- a/fs/ocfs2/inode.c
+++ b/fs/ocfs2/inode.c
@@ -98,6 +98,19 @@ static bool ocfs2_dinode_has_wrong_fs_generation(struct super_block *sb,
 	return le32_to_cpu(di->i_fs_generation) != OCFS2_SB(sb)->fs_generation;
 }
 
+static bool ocfs2_dinode_has_invalid_suballoc_slot(struct ocfs2_dinode *di)
+{
+	return le16_to_cpu(di->i_suballoc_slot) == (u16)OCFS2_INVALID_SLOT &&
+		!(le32_to_cpu(di->i_flags) & OCFS2_SYSTEM_FL);
+}
+
+static bool ocfs2_dinode_has_out_of_range_suballoc_slot(struct super_block *sb,
+							struct ocfs2_dinode *di)
+{
+	return le16_to_cpu(di->i_suballoc_slot) != (u16)OCFS2_INVALID_SLOT &&
+		(u32)le16_to_cpu(di->i_suballoc_slot) > OCFS2_SB(sb)->max_slots - 1;
+}
+
 static bool ocfs2_valid_inode_mode(umode_t mode)
 {
 	return fs_umode_to_ftype(mode) != FT_UNKNOWN;
@@ -1564,15 +1577,15 @@ int ocfs2_validate_inode_block(struct super_block *sb,
 	 * deleting it would pass the slot to get_local_system_inode() via
 	 * ocfs2_remove_inode() and trigger BUG_ON(slot == OCFS2_INVALID_SLOT).
 	 */
-	if (le16_to_cpu(di->i_suballoc_slot) == (u16)OCFS2_INVALID_SLOT) {
-		if (!(le32_to_cpu(di->i_flags) & OCFS2_SYSTEM_FL)) {
-			rc = ocfs2_error(sb,
-					 "Invalid dinode %llu: suballoc slot %u for non-system inode\n",
-					 (unsigned long long)bh->b_blocknr,
-					 le16_to_cpu(di->i_suballoc_slot));
-			goto bail;
-		}
-	} else if ((u32)le16_to_cpu(di->i_suballoc_slot) > OCFS2_SB(sb)->max_slots - 1) {
+	if (ocfs2_dinode_has_invalid_suballoc_slot(di)) {
+		rc = ocfs2_error(sb,
+				 "Invalid dinode %llu: suballoc slot %u for non-system inode\n",
+				 (unsigned long long)bh->b_blocknr,
+				 le16_to_cpu(di->i_suballoc_slot));
+		goto bail;
+	}
+
+	if (ocfs2_dinode_has_out_of_range_suballoc_slot(sb, di)) {
 		rc = ocfs2_error(sb, "Invalid dinode %llu: suballoc slot %u\n",
 				 (unsigned long long)bh->b_blocknr,
 				 le16_to_cpu(di->i_suballoc_slot));
-- 
2.39.3