Re: [PATCH RFC] ext4:record error information when insert extent failed in 'ext4_split_extent_at'
From: zhanchengbin
Date: Thu Oct 27 2022 - 21:42:05 EST
There have been a lot of problems here before, but the problem has not
been fundamentally solved.
On 2022/10/24 20:27, Ye Bin wrote:
From: Ye Bin <yebin10@xxxxxxxxxx>
There's issue as follows when do test with memory fault injection:
[localhost]# fsck.ext4 -a image
image: clean, 45595/655360 files, 466841/2621440 blocks
[localhost]# fsck.ext4 -fn image
Pass 1: Checking inodes, blocks, and sizes
Pass 2: Checking directory structure
Pass 3: Checking directory connectivity
Pass 4: Checking reference counts
Pass 5: Checking group summary information
Block bitmap differences: -(1457230--1457256)
Fix? no
image: ********** WARNING: Filesystem still has errors **********
image: 45595/655360 files (12.4% non-contiguous), 466841/2621440 blocks
Inject context:
-----------------------------------------------------------
Inject function:kmem_cache_alloc (pid:177858) (return: 0)
Calltrace Context:
mem_cache_allock+0x73/0xcc
ext4_mb_new_blocks+0x32e/0x540 [ext4]
ext4_new_meta_blocks+0xc4/0x110 [ext4]
ext4_ext_grow_indepth+0x68/0x250 [ext4]
ext4_ext_create_new_leaf+0xc5/0x120 [ext4]
ext4_ext_insert_extent+0x1bf/0x670 [ext4]
ext4_split_extent_at+0x212/0x530 [ext4]
ext4_split_extent+0x13a/0x1a0 [ext4]
ext4_ext_handle_unwritten_extents+0x13d/0x240 [ext4]
ext4_ext_map_blocks+0x459/0x8f0 [ext4]
ext4_map_blocks+0x18e/0x5a0 [ext4]
ext4_iomap_alloc+0xb0/0x1b0 [ext4]
ext4_iomap_begin+0xb0/0x130 [ext4]
iomap_apply+0x95/0x2e0
__iomap_dio_rw+0x1cc/0x4b0
iomap_dio_rw+0xe/0x40
ext4_dio_write_iter+0x1a9/0x390 [ext4]
new_sync_write+0x113/0x1b0
vfs_write+0x1b7/0x250
ksys_write+0x5f/0xe0
do_syscall_64+0x33/0x40
entry_SYSCALL_64_after_hwframe+0x61/0xc6
Compare extent change in journal:
Start:
ee_block ee_len ee_start
75 32798 1457227 -> unwritten len=30
308 12 434489
355 5 442492
=>
ee_block ee_len ee_start
11 2 951584
74 32769 951647 -> unwritten len=1
75 32771 1457227 -> unwritten len=3, length decreased 27
211 15 960906
308 12 434489
355 5 442492
Acctually, above issue can repaired by 'fsck -fa'. But file system is 'clean',
'fsck' will not do deep repair.
Obviously, final lost 27 blocks. Above issue may happens as follows:
ext4_split_extent_at
...
err = ext4_ext_insert_extent(handle, inode, ppath, &newex, flags); -> return -ENOMEM
if (err != -ENOSPC && err != -EDQUOT）
goto out; -> goto 'out' will not fix extent length, will
...
fix_extent_len:
ex->ee_len = orig_ex.ee_len;
/*
* Ignore ext4_ext_dirty return value since we are already in error path
* and err is a non-zero error code.
*/
ext4_ext_dirty(handle, inode, path + path->p_depth);
return err;
out:
ext4_ext_show_leaf(inode, path);
return err;
If 'ext4_ext_insert_extent' return '-ENOMEM' which will not fix 'ex->ee_len' by
old length. 'ext4_ext_insert_extent' will trigger extent tree merge, fix like
'ex->ee_len = orig_ex.ee_len' may lead to new issues.
To solve above issue, record error messages when 'ext4_ext_insert_extent' return
'err' not equal '(-ENOSPC && -EDQUOT)'. If filesysten is mounted with 'errors=continue'
as filesystem is not clean 'fsck' will repair issue. If filesystem is mounted with
'errors=remount-ro' filesystem will be remounted by read-only.
Signed-off-by: Ye Bin <yebin10@xxxxxxxxxx>
---
fs/ext4/extents.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index f1956288307f..582a7d59d6e3 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -3252,8 +3252,13 @@ static int ext4_split_extent_at(handle_t *handle,
ext4_ext_mark_unwritten(ex2);
err = ext4_ext_insert_extent(handle, inode, ppath, &newex, flags);
- if (err != -ENOSPC && err != -EDQUOT)
+ if (err != -ENOSPC && err != -EDQUOT) {
+ if (err)
+ EXT4_ERROR_INODE_ERR(inode, -err,
+ "insert extent failed block = %d len = %d",
+ ex2->ee_block, ex2->ee_len);
goto out;
+ }
if (EXT4_EXT_MAY_ZEROOUT & split_flag) {
if (split_flag & (EXT4_EXT_DATA_VALID1|EXT4_EXT_DATA_VALID2)) {