[PATCH v2 1/2] xfs: ensure logflagsp is initialized in xfs_bmap_del_extent_real

[Jiachen Zhang <zhangjiachen.jaycee@bytedance.com>]

In the case of returning -ENOSPC, ensure logflagsp is initialized by 0.
Otherwise the caller __xfs_bunmapi will set uninitialized illegal
tmp_logflags value into xfs log, which might cause unpredictable error
in the log recovery procedure.

Also, remove the flags variable and set the *logflagsp directly, so that
the code should be more robust in the long run.

Fixes: 1b24b633aafe ("xfs: move some more code into xfs_bmap_del_extent_real")
Signed-off-by: Jiachen Zhang <zhangjiachen.jaycee@bytedance.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
 fs/xfs/libxfs/xfs_bmap.c | 26 ++++++++++++++------------
 1 file changed, 14 insertions(+), 12 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
index be62acffad6c..9435bd6c950b 100644
--- a/fs/xfs/libxfs/xfs_bmap.c
+++ b/fs/xfs/libxfs/xfs_bmap.c
@@ -5010,7 +5010,6 @@ xfs_bmap_del_extent_real(
 	xfs_fileoff_t		del_endoff;	/* first offset past del */
 	int			do_fx;	/* free extent at end of routine */
 	int			error;	/* error return value */
-	int			flags = 0;/* inode logging flags */
 	struct xfs_bmbt_irec	got;	/* current extent entry */
 	xfs_fileoff_t		got_endoff;	/* first offset past got */
 	int			i;	/* temp state */
@@ -5023,6 +5022,8 @@ xfs_bmap_del_extent_real(
 	uint32_t		state = xfs_bmap_fork_to_state(whichfork);
 	struct xfs_bmbt_irec	old;
 
+	*logflagsp = 0;
+
 	mp = ip->i_mount;
 	XFS_STATS_INC(mp, xs_del_exlist);
 
@@ -5048,10 +5049,12 @@ xfs_bmap_del_extent_real(
 	if (tp->t_blk_res == 0 &&
 	    ifp->if_format == XFS_DINODE_FMT_EXTENTS &&
 	    ifp->if_nextents >= XFS_IFORK_MAXEXT(ip, whichfork) &&
-	    del->br_startoff > got.br_startoff && del_endoff < got_endoff)
-		return -ENOSPC;
+	    del->br_startoff > got.br_startoff && del_endoff < got_endoff) {
+		error = -ENOSPC;
+		goto done;
+	}
 
-	flags = XFS_ILOG_CORE;
+	*logflagsp = XFS_ILOG_CORE;
 	if (whichfork == XFS_DATA_FORK && XFS_IS_REALTIME_INODE(ip)) {
 		if (!(bflags & XFS_BMAPI_REMAP)) {
 			error = xfs_rtfree_blocks(tp, del->br_startblock,
@@ -5093,9 +5096,9 @@ xfs_bmap_del_extent_real(
 		xfs_iext_prev(ifp, icur);
 		ifp->if_nextents--;
 
-		flags |= XFS_ILOG_CORE;
+		*logflagsp |= XFS_ILOG_CORE;
 		if (!cur) {
-			flags |= xfs_ilog_fext(whichfork);
+			*logflagsp |= xfs_ilog_fext(whichfork);
 			break;
 		}
 		if ((error = xfs_btree_delete(cur, &i)))
@@ -5114,7 +5117,7 @@ xfs_bmap_del_extent_real(
 		got.br_blockcount -= del->br_blockcount;
 		xfs_iext_update_extent(ip, state, icur, &got);
 		if (!cur) {
-			flags |= xfs_ilog_fext(whichfork);
+			*logflagsp |= xfs_ilog_fext(whichfork);
 			break;
 		}
 		error = xfs_bmbt_update(cur, &got);
@@ -5128,7 +5131,7 @@ xfs_bmap_del_extent_real(
 		got.br_blockcount -= del->br_blockcount;
 		xfs_iext_update_extent(ip, state, icur, &got);
 		if (!cur) {
-			flags |= xfs_ilog_fext(whichfork);
+			*logflagsp |= xfs_ilog_fext(whichfork);
 			break;
 		}
 		error = xfs_bmbt_update(cur, &got);
@@ -5150,7 +5153,7 @@ xfs_bmap_del_extent_real(
 		new.br_state = got.br_state;
 		new.br_startblock = del_endblock;
 
-		flags |= XFS_ILOG_CORE;
+		*logflagsp |= XFS_ILOG_CORE;
 		if (cur) {
 			error = xfs_bmbt_update(cur, &got);
 			if (error)
@@ -5191,7 +5194,7 @@ xfs_bmap_del_extent_real(
 				 * to the original value.
 				 */
 				xfs_iext_update_extent(ip, state, icur, &old);
-				flags = 0;
+				*logflagsp = 0;
 				error = -ENOSPC;
 				goto done;
 			}
@@ -5200,7 +5203,7 @@ xfs_bmap_del_extent_real(
 				goto done;
 			}
 		} else
-			flags |= xfs_ilog_fext(whichfork);
+			*logflagsp |= xfs_ilog_fext(whichfork);
 
 		ifp->if_nextents++;
 		xfs_iext_next(ifp, icur);
@@ -5240,7 +5243,6 @@ xfs_bmap_del_extent_real(
 		xfs_trans_mod_dquot_byino(tp, ip, qfield, (long)-nblks);
 
 done:
-	*logflagsp = flags;
 	return error;
 }
 
-- 
2.20.1