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From:   Jiachen Zhang <zhangjiachen.jaycee@bytedance.com>
To:     Chandan Babu R <chandan.babu@oracle.com>,
        "Darrick J. Wong" <djwong@kernel.org>
Cc:     Dave Chinner <dchinner@redhat.com>,
        Allison Henderson <allison.henderson@oracle.com>,
        Zhang Tianci <zhangtianci.1997@bytedance.com>,
        Brian Foster <bfoster@redhat.com>, linux-xfs@vger.kernel.org,
        linux-kernel@vger.kernel.org, xieyongji@bytedance.com, me@jcix.top,
        Jiachen Zhang <zhangjiachen.jaycee@bytedance.com>,
        Christoph Hellwig <hch@lst.de>
Subject: [PATCH v3 1/3] xfs: ensure logflagsp is initialized in xfs_bmap_del_extent_real
Date:   Thu, 30 Nov 2023 12:05:14 +0800
Message-Id: <20231130040516.35677-2-zhangjiachen.jaycee@bytedance.com>
In-Reply-To: <20231130040516.35677-1-zhangjiachen.jaycee@bytedance.com>
References: <20231130040516.35677-1-zhangjiachen.jaycee@bytedance.com>
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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 | 73 +++++++++++++++++-----------------------
 1 file changed, 31 insertions(+), 42 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
index be62acffad6c..eacd7f43c952 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);
 
@@ -5035,7 +5036,6 @@ xfs_bmap_del_extent_real(
 	ASSERT(got_endoff >= del_endoff);
 	ASSERT(!isnullstartblock(got.br_startblock));
 	qfield = 0;
-	error = 0;
 
 	/*
 	 * If it's the case where the directory code is running with no block
@@ -5051,13 +5051,13 @@ xfs_bmap_del_extent_real(
 	    del->br_startoff > got.br_startoff && del_endoff < got_endoff)
 		return -ENOSPC;
 
-	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,
 					del->br_blockcount);
 			if (error)
-				goto done;
+				return error;
 		}
 
 		do_fx = 0;
@@ -5072,11 +5072,9 @@ xfs_bmap_del_extent_real(
 	if (cur) {
 		error = xfs_bmbt_lookup_eq(cur, &got, &i);
 		if (error)
-			goto done;
-		if (XFS_IS_CORRUPT(mp, i != 1)) {
-			error = -EFSCORRUPTED;
-			goto done;
-		}
+			return error;
+		if (XFS_IS_CORRUPT(mp, i != 1))
+			return -EFSCORRUPTED;
 	}
 
 	if (got.br_startoff == del->br_startoff)
@@ -5093,17 +5091,15 @@ 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)))
-			goto done;
-		if (XFS_IS_CORRUPT(mp, i != 1)) {
-			error = -EFSCORRUPTED;
-			goto done;
-		}
+			return error;
+		if (XFS_IS_CORRUPT(mp, i != 1))
+			return -EFSCORRUPTED;
 		break;
 	case BMAP_LEFT_FILLING:
 		/*
@@ -5114,12 +5110,12 @@ 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);
 		if (error)
-			goto done;
+			return error;
 		break;
 	case BMAP_RIGHT_FILLING:
 		/*
@@ -5128,12 +5124,12 @@ 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);
 		if (error)
-			goto done;
+			return error;
 		break;
 	case 0:
 		/*
@@ -5150,18 +5146,18 @@ 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)
-				goto done;
+				return error;
 			error = xfs_btree_increment(cur, 0, &i);
 			if (error)
-				goto done;
+				return error;
 			cur->bc_rec.b = new;
 			error = xfs_btree_insert(cur, &i);
 			if (error && error != -ENOSPC)
-				goto done;
+				return error;
 			/*
 			 * If get no-space back from btree insert, it tried a
 			 * split, and we have a zero block reservation.  Fix up
@@ -5174,33 +5170,28 @@ xfs_bmap_del_extent_real(
 				 */
 				error = xfs_bmbt_lookup_eq(cur, &got, &i);
 				if (error)
-					goto done;
-				if (XFS_IS_CORRUPT(mp, i != 1)) {
-					error = -EFSCORRUPTED;
-					goto done;
-				}
+					return error;
+				if (XFS_IS_CORRUPT(mp, i != 1))
+					return -EFSCORRUPTED;
 				/*
 				 * Update the btree record back
 				 * to the original value.
 				 */
 				error = xfs_bmbt_update(cur, &old);
 				if (error)
-					goto done;
+					return error;
 				/*
 				 * Reset the extent record back
 				 * to the original value.
 				 */
 				xfs_iext_update_extent(ip, state, icur, &old);
-				flags = 0;
-				error = -ENOSPC;
-				goto done;
-			}
-			if (XFS_IS_CORRUPT(mp, i != 1)) {
-				error = -EFSCORRUPTED;
-				goto done;
+				*logflagsp = 0;
+				return -ENOSPC;
 			}
+			if (XFS_IS_CORRUPT(mp, i != 1))
+				return -EFSCORRUPTED;
 		} else
-			flags |= xfs_ilog_fext(whichfork);
+			*logflagsp |= xfs_ilog_fext(whichfork);
 
 		ifp->if_nextents++;
 		xfs_iext_next(ifp, icur);
@@ -5224,7 +5215,7 @@ xfs_bmap_del_extent_real(
 					((bflags & XFS_BMAPI_NODISCARD) ||
 					del->br_state == XFS_EXT_UNWRITTEN));
 			if (error)
-				goto done;
+				return error;
 		}
 	}
 
@@ -5239,9 +5230,7 @@ xfs_bmap_del_extent_real(
 	if (qfield && !(bflags & XFS_BMAPI_REMAP))
 		xfs_trans_mod_dquot_byino(tp, ip, qfield, (long)-nblks);
 
-done:
-	*logflagsp = flags;
-	return error;
+	return 0;
 }
 
 /*
-- 
2.20.1