On 2020/1/18 5:27, Theodore Y. Ts'o wrote: > On Tue, Jan 14, 2020 at 11:31:19AM +0100, Jan Kara wrote: >> Thanks for the patch! Just some small comments below: >> >> On Sat 11-01-20 10:25:42, Kai Li wrote: >>> Fixes: 85e0c4e89c1b "jbd2: if the journal is aborted then don't allow update of the log tail" >> This tag should come at the bottom of the changelog (close to your >> Signed-off-by). >> >>> If journal is dirty when mount, it will be replayed but jbd2 sb >>> log tail cannot be updated to mark a new start because >>> journal->j_flags has already been set with JBD2_ABORT first >>> in journal_init_common. >>> When a new transaction is committed, it will be recorded in block 1 >>> first(journal->j_tail is set to 1 in journal_reset). If emergency >>> restart again before journal super block is updated unfortunately, >>> the new recorded trans will not be replayed in the next mount. >>> It is danerous which may lead to metadata corruption for file system. >> I'd slightly rephrase the text here so that it is more easily readable and >> correct some grammar mistakes. Something like: >> >> If the journal is dirty when the filesystem is mounted, jbd2 will replay >> the journal but the journal superblock will not be updated by >> journal_reset() because JBD2_ABORT flag is still set (it was set in >> journal_init_common()). This is problematic because when a new transaction >> is then committed, it will be recorded in block 1 (journal->j_tail was set >> to 1 in journal_reset()). If unclean shutdown happens again before the >> journal superblock is updated, the new recorded transaction will not be >> replayed during the next mount (because of stale sb->s_start and >> sb->s_sequence values) which can lead to filesystem corruption. >> >> Otherwise the patch looks good to me so feel free to add: >> >> Reviewed-by: Jan Kara <jack@xxxxxxx> >> >> (again this is added to the bottom of the changelog like the 'Fixes' tag or >> 'Signed-off-by' tag). > Thanks, applied with a fixed up commit description. > > - Ted > Sorry for reply so late due to my business trip recently. This new comment is ok and more clear. Thanks. - Kai