On Wed, Mar 26, 2025 at 12:01:45PM +0800, Zhang Yi wrote:
> On 2025/3/26 10:16, Baokun Li wrote:
> > On 2025/3/26 1:57, Ojaswin Mujoo wrote:
> >> On Tue, Mar 18, 2025 at 10:31:29PM -0400, Theodore Ts'o wrote:
> >>> On Tue, Mar 18, 2025 at 01:42:31PM +0530, Ojaswin Mujoo wrote:
> >>>>> So this is something we need to do if the journal is actived, and if
> >>>>> it's active, then sbi->s_journal will be non-NULL, and so we can just
> >>>>> check to see if inode == sbi->s_journal instead. This will simplify
> >>>> I believe you mean inode == sbi->s_journal->j_inode here right?
> >>> Yes, that's what I meant; sorry for the not catching this before I
> >>> sent my reply.
> >>>
> >>> Cheers,
> >>>
> >>> - Ted
> >> Hi Ted, Baokun,
> >>
> >> I got some time to revisit this. Seems like checking against
> >> s_journal->j_inode is not enough. This is because both
> >> ext4_check_blockref() and check_block_validity() can be called even
> >> before journal->j_inode is set:
> >>
> >> ext4_open_inode_journal
> >> ext4_get_journal_inode
> >> __ext4_iget
> >> ext4_ind_check_inode
> >> ext4_check_blockref /* j_inode not set */
> >>
> >> journal = jbd2_journal_init_inode
> >> bmap
> >> ext4_bmap
> >> iomap_bmap
> >> ext4_iomap_begin
> >> ext4_map_blocks
> >> check_block_validity
> >>
> >> journal->j_inode = inode
> >>
> >>
> >> Now, I think in this case the best solution might be to use the extra
> >> field like we do in this patch but set EXT4_SB(sb)->s_journal_ino
> >> sufficiently early.
> >>
> >> Thoughts?
> >
> > Because system zone setup happens after the journal are loaded, I think we
> > can skip the check if the journal haven't been loaded yet, like this:
> >
> > diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> > index d04d8a7f12e7..38dc72ff7e78 100644
> > --- a/fs/ext4/inode.c
> > +++ b/fs/ext4/inode.c
> > @@ -383,9 +383,10 @@ static int __check_block_validity(struct inode *inode, const char *func,
> > unsigned int line,
> > struct ext4_map_blocks *map)
> > {
> > + journal_t *journal = EXT4_SB(inode->i_sb)->s_journal;
> > +
> > if (ext4_has_feature_journal(inode->i_sb) &&
> > - (inode->i_ino ==
> > - le32_to_cpu(EXT4_SB(inode->i_sb)->s_es->s_journal_inum)))
> > + (!journal || inode == journal->j_inode))
> > return 0;
> > if (!ext4_inode_block_valid(inode, map->m_pblk, map->m_len)) {
> > ext4_error_inode(inode, func, line, map->m_pblk,
> >
> > If any part of the journal area overlaps with the system zone, we'll catch
> > it when we add the journal area to the system zone later.
> >
> >
>
> Since the creation of the system zone relies on the journal being
> loaded, I think there is no risk in proceeding to call
> ext4_inode_block_valid() to perform a basic block range check for
> the journal inode, or even better.
>
> Thanks,
> Yi.
Got it Yi, makes sense to me. So I believe you are suggesting something
like:
@@ -384,9 +384,10 @@ static int __check_block_validity(struct inode *inode, const char *func,
unsigned int line,
struct ext4_map_blocks *map)
{
+ journal_t *journal = EXT4_SB(inode->i_sb)->s_journal;
+
if (ext4_has_feature_journal(inode->i_sb) &&
- (inode->i_ino ==
- le32_to_cpu(EXT4_SB(inode->i_sb)->s_es->s_journal_inum)))
+ (journal && journal->j_inode == inode))
return 0;
if (!ext4_inode_block_valid(inode, map->m_pblk, map->m_len)) {
ext4_error_inode(inode, func, line, map->m_pblk,
>
So that even if it is a journal inode we can go ahead and perform some basic checks
as the system zone rbtree will anyways be NULL at this point. From a cursory look,
it seems that __ext4_iget(..., journal_inode) -> ext4_ext_check_inode() already relies
on the fact that system zone is NULL, so we should be okay here as well.
If this looks good, I'll send a v2 with the suggested changes.
Thanks,
ojaswin
