[PATCH v2] xfs_db: use correct inode to set inode type

[Zorro Lang <zlang@redhat.com>]

A test fails as:
  # xfs_db -c "inode 133" -c "addr" -c "p core.size" -c "type inode" -c "addr" -c "p core.size" /dev/sdb1
  current
          byte offset 68096, length 512
          buffer block 128 (fsbno 16), 32 bbs
          inode 133, dir inode -1, type inode
  core.size = 123142
  current
          byte offset 65536, length 512
          buffer block 128 (fsbno 16), 32 bbs
          inode 128, dir inode 128, type inode
  core.size = 42

The "type inode" command accidentally moves the io cursor because it
forgets to include the io cursor's buffer offset when it computes the
inode number from the io cursor's location.

Fixes: 533d1d229a88 ("xfs_db: properly set inode type")

Reported-by: Jianhong Yin <jiyin@redhat.com>
Signed-off-by: Zorro Lang <zlang@redhat.com>
---

V2 did below changes:
0) git commit log is changed.
1) Separate out several clear steps to calculate inode.
2) Remove improper comment which describe inode calculation.

Thanks,
Zorro

 db/io.c | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/db/io.c b/db/io.c
index 6628d061..884da599 100644
--- a/db/io.c
+++ b/db/io.c
@@ -588,18 +588,20 @@ set_iocur_type(
 {
 	struct xfs_buf	*bp = iocur_top->bp;
 
-	/* Inodes are special; verifier checks all inodes in the chunk */
+	/*
+	 * Inodes are special; verifier checks all inodes in the chunk, the
+	 * set_cur_inode() will help that
+	 */
 	if (type->typnm == TYP_INODE) {
 		xfs_daddr_t	b = iocur_top->bb;
+		xfs_agblock_t	agbno;
+		xfs_agino_t	agino;
 		xfs_ino_t	ino;
 
-		/*
-		 * Note that this will back up to the beginning of the inode
- 		 * which contains the current disk location; daddr may change.
- 		 */
-		ino = XFS_AGINO_TO_INO(mp, xfs_daddr_to_agno(mp, b),
-			((b << BBSHIFT) >> mp->m_sb.sb_inodelog) %
-			XFS_AGB_TO_AGINO(mp, mp->m_sb.sb_agblocks));
+		agbno = xfs_daddr_to_agbno(mp, b);
+		agino = XFS_OFFBNO_TO_AGINO(mp, agbno,
+				iocur_top->boff / mp->m_sb.sb_inodesize);
+		ino = XFS_AGINO_TO_INO(mp, xfs_daddr_to_agno(mp, b), agino);
 		set_cur_inode(ino);
 		return;
 	}
-- 
2.20.1