Messages in this thread | | | Date | Fri, 17 Feb 2023 09:43:11 +0800 | Subject | Re: [PATCH v3 1/2] ext4: commit super block if fs record error when journal record without error | From | Baokun Li <> |
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On 2023/2/17 1:31, Jan Kara wrote: > On Tue 14-02-23 10:29:04, Ye Bin wrote: >> From: Ye Bin <yebin10@huawei.com> >> >> Now, 'es->s_state' maybe covered by recover journal. And journal errno >> maybe not recorded in journal sb as IO error. ext4_update_super() only >> update error information when 'sbi->s_add_error_count' large than zero. >> Then 'EXT4_ERROR_FS' flag maybe lost. >> To solve above issue commit error information after recover journal. >> >> Signed-off-by: Ye Bin <yebin10@huawei.com> >> --- >> fs/ext4/super.c | 12 ++++++++++++ >> 1 file changed, 12 insertions(+) > Hum, I'm not sure I follow here. If journal replay has overwritten the > superblock (and thus the stored error info), then I'd expect > es->s_error_count got overwritten (possibly to 0) as well. And this is > actually relatively realistic scenario with errors=remount-ro behavior when > the first fs error happens. > > What I intended in my original suggestion was to save es->s_error_count, > es->s_state & EXT4_ERROR_FS, es->s_first_error_*, es->s_last_error_* before > doing journal replay in ext4_load_journal() and then after journal replay > merge this info back to the superblock - if EXT4_ERROR_FS was set, set it > now as well, take max of old and new s_error_count, set s_first_error_* if > it is now unset, set s_last_error_* if stored timestamp is newer than > current timestamp. > > Or am I overengineering it now? :) > > Honza This is exactly how the code is designed now! The code has now saved all the above information except EXT4_ERROR_FS by the following two pieces of logic, as follows:
---------------- In struct ext4_super_block ---------------- 1412 #define EXT4_S_ERR_START offsetof(struct ext4_super_block, s_error_count) 1413 __le32 s_error_count; /* number of fs errors */ 1414 __le32 s_first_error_time; /* first time an error happened */ 1415 __le32 s_first_error_ino; /* inode involved in first error */ 1416 __le64 s_first_error_block; /* block involved of first error */ 1417 __u8 s_first_error_func[32] __nonstring; /* function where the error happened */ 1418 __le32 s_first_error_line; /* line number where error happened */ 1419 __le32 s_last_error_time; /* most recent time of an error */ 1420 __le32 s_last_error_ino; /* inode involved in last error */ 1421 __le32 s_last_error_line; /* line number where error happened */ 1422 __le64 s_last_error_block; /* block involved of last error */ 1423 __u8 s_last_error_func[32] __nonstring; /* function where the error happened */ 1424 #define EXT4_S_ERR_END offsetof(struct ext4_super_block, s_mount_opts) -----------------------------------------------------------
---------------- In ext4_load_journal() ---------------- 5929 char *save = kmalloc(EXT4_S_ERR_LEN, GFP_KERNEL); 5930 if (save) 5931 memcpy(save, ((char *) es) + 5932 EXT4_S_ERR_START, EXT4_S_ERR_LEN); 5933 err = jbd2_journal_load(journal); 5934 if (save) 5935 memcpy(((char *) es) + EXT4_S_ERR_START, 5936 save, EXT4_S_ERR_LEN); 5937 kfree(save); --------------------------------------------------------
As you said, we should also save EXT4_ERROR_FS to es->s_state. But we are not saving this now, so I think we just need to add
`es->s_state |= cpu_to_le16(EXT4_SB(sb)->s_mount_state & EXT4_ERROR_FS);`
to save the possible EXT4_ERROR_FS flag after copying the error area data to es.
-- With Best Regards, Baokun Li .
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