JBD2 makes sure journal data is fallen on fs device by sync_blockdev(),
however, other process could intercept the EIO information from bdev's
mapping, which leads journal recovering successful even EIO occurs during
data written back to fs device.
We found this problem in our product, iscsi + multipath is chosen for block
device of ext4. Unstable network may trigger kpartx to rescan partitions in
device mapper layer. Detailed process is shown as following:
mount kpartx irq
jbd2_journal_recover
do_one_pass
memcpy(nbh->b_data, obh->b_data) // copy data to fs dev from journal
mark_buffer_dirty // mark bh dirty
vfs_read
generic_file_read_iter // dio
filemap_write_and_wait_range
__filemap_fdatawrite_range
do_writepages
block_write_full_folio
submit_bh_wbc
>> EIO occurs in disk <<
end_buffer_async_write
mark_buffer_write_io_error
mapping_set_error
set_bit(AS_EIO, &mapping->flags) // set!
filemap_check_errors
test_and_clear_bit(AS_EIO, &mapping->flags) // clear!
err2 = sync_blockdev
filemap_write_and_wait
filemap_check_errors
test_and_clear_bit(AS_EIO, &mapping->flags) // false
err2 = 0
Filesystem is mounted successfully even data from journal is failed written
into disk, and ext4/ocfs2 could become corrupted.
Fix it by comparing the wb_err state in fs block device before recovering
and after recovering.
Fetch a reproducer in [Link].
Link: https://bugzilla.kernel.org/show_bug.cgi?id=217888
Cc: [email protected]
Signed-off-by: Zhihao Cheng <[email protected]>
Signed-off-by: Zhang Yi <[email protected]>
---
fs/jbd2/recovery.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/fs/jbd2/recovery.c b/fs/jbd2/recovery.c
index c269a7d29a46..0fecaa6a3ac6 100644
--- a/fs/jbd2/recovery.c
+++ b/fs/jbd2/recovery.c
@@ -289,6 +289,8 @@ int jbd2_journal_recover(journal_t *journal)
journal_superblock_t * sb;
struct recovery_info info;
+ errseq_t wb_err;
+ struct address_space *mapping;
memset(&info, 0, sizeof(info));
sb = journal->j_superblock;
@@ -306,6 +308,8 @@ int jbd2_journal_recover(journal_t *journal)
return 0;
}
+ mapping = journal->j_fs_dev->bd_inode->i_mapping;
+ errseq_check_and_advance(&mapping->wb_err, &wb_err);
err = do_one_pass(journal, &info, PASS_SCAN);
if (!err)
err = do_one_pass(journal, &info, PASS_REVOKE);
@@ -327,6 +331,9 @@ int jbd2_journal_recover(journal_t *journal)
jbd2_journal_clear_revoke(journal);
err2 = sync_blockdev(journal->j_fs_dev);
+ if (!err)
+ err = err2;
+ err2 = errseq_check_and_advance(&mapping->wb_err, &wb_err);
if (!err)
err = err2;
/* Make sure all replayed data is on permanent storage */
--
2.39.2
?? 2023/9/8 19:14, Jan Kara ะด??:
Hi Jan,
> On Fri 08-09-23 17:28:08, Zhihao Cheng wrote:
>> JBD2 makes sure journal data is fallen on fs device by sync_blockdev(),
>> however, other process could intercept the EIO information from bdev's
>> mapping, which leads journal recovering successful even EIO occurs during
>> data written back to fs device.
>>
>> We found this problem in our product, iscsi + multipath is chosen for block
>> device of ext4. Unstable network may trigger kpartx to rescan partitions in
>> device mapper layer. Detailed process is shown as following:
>>
>> mount kpartx irq
>> jbd2_journal_recover
>> do_one_pass
>> memcpy(nbh->b_data, obh->b_data) // copy data to fs dev from journal
>> mark_buffer_dirty // mark bh dirty
>> vfs_read
>> generic_file_read_iter // dio
>> filemap_write_and_wait_range
>> __filemap_fdatawrite_range
>> do_writepages
>> block_write_full_folio
>> submit_bh_wbc
>> >> EIO occurs in disk <<
>> end_buffer_async_write
>> mark_buffer_write_io_error
>> mapping_set_error
>> set_bit(AS_EIO, &mapping->flags) // set!
>> filemap_check_errors
>> test_and_clear_bit(AS_EIO, &mapping->flags) // clear!
>> err2 = sync_blockdev
>> filemap_write_and_wait
>> filemap_check_errors
>> test_and_clear_bit(AS_EIO, &mapping->flags) // false
>> err2 = 0
>>
>> Filesystem is mounted successfully even data from journal is failed written
>> into disk, and ext4/ocfs2 could become corrupted.
>>
>> Fix it by comparing the wb_err state in fs block device before recovering
>> and after recovering.
>>
>> Fetch a reproducer in [Link].
>>
>> Link: https://bugzilla.kernel.org/show_bug.cgi?id=217888
>> Cc: [email protected]
>> Signed-off-by: Zhihao Cheng <[email protected]>
>> Signed-off-by: Zhang Yi <[email protected]>
>
> Thanks for the patch! It makes sense but it is somewhat inconsistent with
> how we deal with other checks for metadata IO errors in ext4. We do those
> checks in ext4 through ext4_check_bdev_write_error(). So I wonder if in
> this case we shouldn't move the errseq_check_and_advance() in
> __ext4_fill_super() earlier (before journal setup) and then use it in
> ext4_load_and_init_journal() to detect errors during background metadata
> writeback. What do you think?
>
Do you mean that modify like this?
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 38217422f938..3f6239f8cc4e 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -4907,6 +4907,13 @@ static int ext4_load_and_init_journal(struct
super_block *sb,
if (err)
return err;
+ err =
errseq_check_and_advance(&sb->s_bdev->bd_inode->i_mapping->wb_err,
+ &sbi->s_bdev_wb_err);
+ if (err) {
+ ext4_msg(sb, KERN_ERR, "Failed to sync fs block device");
+ goto out;
+ }
+
if (ext4_has_feature_64bit(sb) &&
!jbd2_journal_set_features(EXT4_SB(sb)->s_journal, 0, 0,
JBD2_FEATURE_INCOMPAT_64BIT)) {
@@ -5365,6 +5372,13 @@ static int __ext4_fill_super(struct fs_context
*fc, struct super_block *sb)
goto failed_mount3a;
}
+ /*
+ * Save the original bdev mapping's wb_err value which could be
+ * used to detect the metadata async write error.
+ */
+ spin_lock_init(&sbi->s_bdev_wb_lock);
+ errseq_check_and_advance(&sb->s_bdev->bd_inode->i_mapping->wb_err,
+ &sbi->s_bdev_wb_err);
err = -EINVAL;
/*
* The first inode we look at is the journal inode. Don't try
@@ -5571,13 +5585,6 @@ static int __ext4_fill_super(struct fs_context
*fc, struct super_block *sb)
}
#endif /* CONFIG_QUOTA */
- /*
- * Save the original bdev mapping's wb_err value which could be
- * used to detect the metadata async write error.
- */
- spin_lock_init(&sbi->s_bdev_wb_lock);
- errseq_check_and_advance(&sb->s_bdev->bd_inode->i_mapping->wb_err,
- &sbi->s_bdev_wb_err);
EXT4_SB(sb)->s_mount_state |= EXT4_ORPHAN_FS;
ext4_orphan_cleanup(sb, es);
EXT4_SB(sb)->s_mount_state &= ~EXT4_ORPHAN_FS;
If so, there are two points:
1. ocfs2 also uses jbd2, we only fix ext4.
2. EIO from ext4_commit_super() in ext4_load_journal is ignored, now
ext4 will fail mounting.
> Honza
>
>> ---
>> fs/jbd2/recovery.c | 7 +++++++
>> 1 file changed, 7 insertions(+)
>>
>> diff --git a/fs/jbd2/recovery.c b/fs/jbd2/recovery.c
>> index c269a7d29a46..0fecaa6a3ac6 100644
>> --- a/fs/jbd2/recovery.c
>> +++ b/fs/jbd2/recovery.c
>> @@ -289,6 +289,8 @@ int jbd2_journal_recover(journal_t *journal)
>> journal_superblock_t * sb;
>>
>> struct recovery_info info;
>> + errseq_t wb_err;
>> + struct address_space *mapping;
>>
>> memset(&info, 0, sizeof(info));
>> sb = journal->j_superblock;
>> @@ -306,6 +308,8 @@ int jbd2_journal_recover(journal_t *journal)
>> return 0;
>> }
>>
>> + mapping = journal->j_fs_dev->bd_inode->i_mapping;
>> + errseq_check_and_advance(&mapping->wb_err, &wb_err);
>> err = do_one_pass(journal, &info, PASS_SCAN);
>> if (!err)
>> err = do_one_pass(journal, &info, PASS_REVOKE);
>> @@ -327,6 +331,9 @@ int jbd2_journal_recover(journal_t *journal)
>>
>> jbd2_journal_clear_revoke(journal);
>> err2 = sync_blockdev(journal->j_fs_dev);
>> + if (!err)
>> + err = err2;
>> + err2 = errseq_check_and_advance(&mapping->wb_err, &wb_err);
>> if (!err)
>> err = err2;
>> /* Make sure all replayed data is on permanent storage */
>> --
>> 2.39.2
>>