linux-kernel - [PATCH 5.16 0896/1039] ext4: use ext4_ext_remove_space() for fast commit replay delete range

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Message-Id: <20220124184155.406199813@linuxfoundation.org>
Date:   Mon, 24 Jan 2022 19:44:45 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Xin Yin <yinxin.x@...edance.com>,
        Harshad Shirwadkar <harshadshirwadkar@...il.com>,
        Theodore Tso <tytso@....edu>, stable@...nel.org
Subject: [PATCH 5.16 0896/1039] ext4: use ext4_ext_remove_space() for fast commit replay delete range

From: Xin Yin <yinxin.x@...edance.com>

commit 0b5b5a62b945a141e64011b2f90ee7e46f14be98 upstream.

For now ,we use ext4_punch_hole() during fast commit replay delete range
procedure. But it will be affected by inode->i_size, which may not
correct during fast commit replay procedure. The following test will
failed.

-create & write foo (len 1000K)
-falloc FALLOC_FL_ZERO_RANGE foo (range 400K - 600K)
-create & fsync bar
-falloc FALLOC_FL_PUNCH_HOLE foo (range 300K-500K)
-fsync foo
-crash before a full commit

After the fast_commit reply procedure, the range 400K-500K will not be
removed. Because in this case, when calling ext4_punch_hole() the
inode->i_size is 0, and it just retruns with doing nothing.

Change to use ext4_ext_remove_space() instead of ext4_punch_hole()
to remove blocks of inode directly.

Signed-off-by: Xin Yin <yinxin.x@...edance.com>
Reviewed-by: Harshad Shirwadkar <harshadshirwadkar@...il.com>
Link: https://lore.kernel.org/r/20211223032337.5198-2-yinxin.x@bytedance.com
Signed-off-by: Theodore Ts'o <tytso@....edu>
Cc: stable@...nel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 fs/ext4/fast_commit.c |   13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

--- a/fs/ext4/fast_commit.c
+++ b/fs/ext4/fast_commit.c
@@ -1812,11 +1812,14 @@ ext4_fc_replay_del_range(struct super_bl
 		}
 	}
 
-	ret = ext4_punch_hole(inode,
-		le32_to_cpu(lrange.fc_lblk) << sb->s_blocksize_bits,
-		le32_to_cpu(lrange.fc_len) <<  sb->s_blocksize_bits);
-	if (ret)
-		jbd_debug(1, "ext4_punch_hole returned %d", ret);
+	down_write(&EXT4_I(inode)->i_data_sem);
+	ret = ext4_ext_remove_space(inode, lrange.fc_lblk,
+				lrange.fc_lblk + lrange.fc_len - 1);
+	up_write(&EXT4_I(inode)->i_data_sem);
+	if (ret) {
+		iput(inode);
+		return 0;
+	}
 	ext4_ext_replay_shrink_inode(inode,
 		i_size_read(inode) >> sb->s_blocksize_bits);
 	ext4_mark_inode_dirty(NULL, inode);