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SubjectRe: [PATCH -next v2] ext4: fix bug_on in ext4_writepages
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On 2022/5/11 21:47, Jan Kara wrote:
> On Tue 10-05-22 18:02:28, Ye Bin wrote:
>> we got issue as follows:
>> EXT4-fs error (device loop0): ext4_mb_generate_buddy:1141: group 0, block bitmap and bg descriptor inconsistent: 25 vs 31513 free cls
>> ------------[ cut here ]------------
>> kernel BUG at fs/ext4/inode.c:2708!
>> invalid opcode: 0000 [#1] PREEMPT SMP KASAN PTI
>> CPU: 2 PID: 2147 Comm: rep Not tainted 5.18.0-rc2-next-20220413+ #155
>> RIP: 0010:ext4_writepages+0x1977/0x1c10
>> RSP: 0018:ffff88811d3e7880 EFLAGS: 00010246
>> RAX: 0000000000000000 RBX: 0000000000000001 RCX: ffff88811c098000
>> RDX: 0000000000000000 RSI: ffff88811c098000 RDI: 0000000000000002
>> RBP: ffff888128140f50 R08: ffffffffb1ff6387 R09: 0000000000000000
>> R10: 0000000000000007 R11: ffffed10250281ea R12: 0000000000000001
>> R13: 00000000000000a4 R14: ffff88811d3e7bb8 R15: ffff888128141028
>> FS: 00007f443aed9740(0000) GS:ffff8883aef00000(0000) knlGS:0000000000000000
>> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>> CR2: 0000000020007200 CR3: 000000011c2a4000 CR4: 00000000000006e0
>> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
>> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
>> Call Trace:
>> <TASK>
>> do_writepages+0x130/0x3a0
>> filemap_fdatawrite_wbc+0x83/0xa0
>> filemap_flush+0xab/0xe0
>> ext4_alloc_da_blocks+0x51/0x120
>> __ext4_ioctl+0x1534/0x3210
>> __x64_sys_ioctl+0x12c/0x170
>> do_syscall_64+0x3b/0x90
>>
>> It may happen as follows:
>> 1. write inline_data inode
>> vfs_write
>> new_sync_write
>> ext4_file_write_iter
>> ext4_buffered_write_iter
>> generic_perform_write
>> ext4_da_write_begin
>> ext4_da_write_inline_data_begin -> If inline data size too
>> small will allocate block to write, then mapping will has
>> dirty page
>> ext4_da_convert_inline_data_to_extent ->clear EXT4_STATE_MAY_INLINE_DATA
>> 2. fallocate
>> do_vfs_ioctl
>> ioctl_preallocate
>> vfs_fallocate
>> ext4_fallocate
>> ext4_convert_inline_data
>> ext4_convert_inline_data_nolock
>> ext4_map_blocks -> fail will goto restore data
>> ext4_restore_inline_data
>> ext4_create_inline_data
>> ext4_write_inline_data
>> ext4_set_inode_state -> set inode EXT4_STATE_MAY_INLINE_DATA
>> 3. writepages
>> __ext4_ioctl
>> ext4_alloc_da_blocks
>> filemap_flush
>> filemap_fdatawrite_wbc
>> do_writepages
>> ext4_writepages
>> if (ext4_has_inline_data(inode))
>> BUG_ON(ext4_test_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA))
>>
>> The root cause of this issue is we destory inline data until call ext4_writepages
>> under delay allocation mode. But there maybe already covert from inline to extent.
>> To solved this issue, we call filemap_flush firstly.
>>
>> Signed-off-by: Ye Bin <yebin10@huawei.com>
>> ---
>> fs/ext4/inline.c | 8 ++++++++
>> 1 file changed, 8 insertions(+)
>>
>> diff --git a/fs/ext4/inline.c b/fs/ext4/inline.c
>> index 6d253edebf9f..130ed5d83734 100644
>> --- a/fs/ext4/inline.c
>> +++ b/fs/ext4/inline.c
>> @@ -2002,6 +2002,14 @@ int ext4_convert_inline_data(struct inode *inode)
>> if (!ext4_has_inline_data(inode)) {
>> ext4_clear_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA);
>> return 0;
>> + } else if (test_opt(inode->i_sb, DELALLOC) && !S_ISDIR(inode->i_mode)) {
>> + error = filemap_flush(inode->i_mapping);
> This is actually an interesting option and I kind of like it but shouldn't
> we restrict this to the situation when EXT4_STATE_MAY_INLINE_DATA is clear?
> Otherwise we would be writing out inline data to the inode unnecessarily
> for each ext4_convert_inline_data() call.
>
> Honza
Acctually, this issue only exist in delay allocate mode. Do we need to
restrict this to
“test_opt(inode->i_sb, DELALLOC)” as follows ?
@@ -2002,6 +2002,13 @@ int ext4_convert_inline_data(struct inode *inode)
if (!ext4_has_inline_data(inode)) {
ext4_clear_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA);
return 0;
+ } else if (test_opt(inode->i_sb, DELALLOC) &&
+ !ext4_test_inode_state(inode,
EXT4_STATE_MAY_INLINE_DATA)) {
+ error = filemap_flush(inode->i_mapping);
+ if (error)
+ return error;
+ if (!ext4_has_inline_data(inode))
+ return 0;
}


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