linux-kernel - [PATCH v3 3/3] ext4: add check pending tree when evict inode

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Date:   Sat,  3 Dec 2022 10:59:41 +0800
From:   Ye Bin <yebin@...weicloud.com>
To:     tytso@....edu, adilger.kernel@...ger.ca, linux-ext4@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, jack@...e.cz,
        Ye Bin <yebin10@...wei.com>,
        syzbot+05a0f0ccab4a25626e38@...kaller.appspotmail.com
Subject: [PATCH v3 3/3] ext4: add check pending tree when evict inode

From: Ye Bin <yebin10@...wei.com>

Syzbot found the following issue:
BUG: memory leak
unreferenced object 0xffff8881bde17420 (size 32):
  comm "rep", pid 2327, jiffies 4295381963 (age 32.265s)
  hex dump (first 32 bytes):
    01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace:
    [<00000000ac6d38f8>] __insert_pending+0x13c/0x2d0
    [<00000000d717de3b>] ext4_es_insert_delayed_block+0x399/0x4e0
    [<000000004be03913>] ext4_da_map_blocks.constprop.0+0x739/0xfa0
    [<00000000885a832a>] ext4_da_get_block_prep+0x10c/0x440
    [<0000000029b7f8ef>] __block_write_begin_int+0x28d/0x860
    [<00000000e182ebc3>] ext4_da_write_inline_data_begin+0x2d1/0xf30
    [<00000000ced0c8a2>] ext4_da_write_begin+0x612/0x860
    [<000000008d5f27fa>] generic_perform_write+0x215/0x4d0
    [<00000000552c1cde>] ext4_buffered_write_iter+0x101/0x3b0
    [<0000000052177ae8>] do_iter_readv_writev+0x19f/0x340
    [<000000004b9de834>] do_iter_write+0x13b/0x650
    [<00000000e2401b9b>] iter_file_splice_write+0x5a5/0xab0
    [<0000000023aa5d90>] direct_splice_actor+0x103/0x1e0
    [<0000000089e00fc1>] splice_direct_to_actor+0x2c9/0x7b0
    [<000000004386851e>] do_splice_direct+0x159/0x280
    [<00000000b567e609>] do_sendfile+0x932/0x1200

Above issue fixed by 1b8f787ef547 "ext4: fix warning in 'ext4_da_release_space'"
in this scene. To make things better add check pending tree when evit inode.
According to Eric Whitney's suggestion, bigalloc + inline is still in development
so we just add test for this situation, there isn't need to add code to free
pending tree entry.

Reported-by: syzbot+05a0f0ccab4a25626e38@...kaller.appspotmail.com
Signed-off-by: Ye Bin <yebin10@...wei.com>
---
 fs/ext4/super.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 41413338c05b..2e2fbc4a832c 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -1391,6 +1391,11 @@ static void ext4_destroy_inode(struct inode *inode)
 			"Inode %lu (%p): i_reserved_data_blocks (%u) not cleared!",
 			inode->i_ino, EXT4_I(inode),
 			EXT4_I(inode)->i_reserved_data_blocks);
+
+	if (!RB_EMPTY_ROOT(&EXT4_I(inode)->i_pending_tree.root))
+		ext4_error(inode->i_sb,
+			"Inode %lu (%p): i_pending_tree not empty!",
+			inode->i_ino, EXT4_I(inode));
 }
 
 static void init_once(void *foo)
-- 
2.31.1