linux-ext4 - Re: [RFC PATCH 0/3] ext4: enhance extent consistency check

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Date:   Mon, 27 Sep 2021 22:22:42 +0800
From:   Zhang Yi <yi.zhang@...wei.com>
To:     <linux-ext4@...r.kernel.org>
CC:     <tytso@....edu>, <adilger.kernel@...ger.ca>, <jack@...e.cz>,
        <yukuai3@...wei.com>
Subject: Re: [RFC PATCH 0/3] ext4: enhance extent consistency check

Gentle ping.

On 2021/9/8 20:08, Zhang Yi wrote:
> Now that in the error patch of extent updating procedure cannot handle
> error and roll-back partial updates properly, so we could access the
> left inconsistent extent buffer later and lead to BUGON in
> errors=continue mode. For example, we could get below BUGON if we
> update leaf extent but failed to update index extent in
> ext4_ext_insert_extent() and try to alloc block again.
> 
>   kernel BUG at fs/ext4/mballoc.c:4085!
>   invalid opcode: 0000 [#1] SMP PTI
>   CPU: 30 PID: 1177 Comm: xfs_io Not tainted 5.14.0-00006-g555c93b65a81 #543
>   RIP: 0010:ext4_mb_normalize_request.constprop.0+0x72c/0x8a0
>   RSP: 0018:ffffb398c0abb8d8 EFLAGS: 00010202
>   RAX: 0000000000000000 RBX: ffff8d79d3125000 RCX: 0000000000001500
>   RDX: 0000000000001500 RSI: 0000000000000000 RDI: ffffb398c0abba50
>   RBP: 0000000000001500 R08: 0000000000000001 R09: 00000000000015c0
>   R10: 0000000000660000 R11: ffff8d79e21212d8 R12: ffff8d79e21215b8
>   R13: 0000000000001500 R14: ffffb398c0abba50 R15: ffff8d79e21215b8
>   FS:  00007f1bf519f800(0000) GS:ffff8d80e5d80000(0000) knlGS:0000000000000000
>   CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>   CR2: 0000560c5b96d000 CR3: 000000010f170000 CR4: 00000000000006e0
>   DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
>   DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
>   Call Trace:
>    ext4_mb_new_blocks+0x8f3/0x1c90
>    ? __read_extent_tree_block+0x20a/0x260
>    ext4_ext_map_blocks+0xb7c/0x1d30
>    ext4_map_blocks+0x15d/0xa30
>    ? __cond_resched+0x1d/0x50
>    ? kmem_cache_alloc+0x206/0x400
>    _ext4_get_block+0xa8/0x170
>    ext4_get_block+0x1a/0x30
>    ext4_block_write_begin+0x179/0x8c0
>    ? ext4_get_block_unwritten+0x20/0x20
>    ? __ext4_journal_start_sb+0x179/0x1d0
>    ext4_write_begin+0x42d/0x910
>    ext4_da_write_begin+0x2eb/0x750
>    generic_perform_write+0xcb/0x280
>    ext4_buffered_write_iter+0xc3/0x1e0
>    ext4_file_write_iter+0x70/0xac0
>    ? _raw_spin_unlock+0x12/0x30
>    ? __handle_mm_fault+0x13e1/0x2520
>    new_sync_write+0x166/0x220
>    vfs_write+0x1d7/0x3b0
>    ksys_pwrite64+0x85/0xf0
>    __x64_sys_pwrite64+0x22/0x30
>    do_syscall_64+0x3b/0x90
>    entry_SYSCALL_64_after_hwframe+0x44/0xae
>   RIP: 0033:0x7f1bf5760378
> 
> This patch set address to enhance extent check in __ext4_ext_check() and
> force check buffer again through clear buffer's verified bit if we
> breaks off extent updating.
> 
> Thanks,
> Yi.
> 
> 
> Zhang Yi (3):
>   ext4: check for out-of-order index extents in
>     ext4_valid_extent_entries()
>   ext4: check for inconsistent extents between index and leaf block
>   ext4: prevent partial update of the extent blocks
> 
>  fs/ext4/extents.c | 95 +++++++++++++++++++++++++++++++----------------
>  1 file changed, 64 insertions(+), 31 deletions(-)
>