On Wed 15-02-23 16:51:23, zhanchengbin wrote:
>
> On 2023/2/14 19:48, Jan Kara wrote:
> > On Mon 13-02-23 12:05:21, zhanchengbin wrote:
> > > If ENOMEM fails when the extent is splitting, we need to restore the length
> > > of the split extent.
> > > In the call stack of the ext4_split_extent_at function, only in
> > > ext4_ext_create_new_leaf will it alloc memory and change the shape of the
> > > extent tree,even if an ENOMEM is returned at this time, the extent tree is
> > > still self-consistent, Just restore the split extent lens in the function
> > > ext4_split_extent_at.
> > >
> > > ext4_split_extent_at
> > > ext4_ext_insert_extent
> > > ext4_ext_create_new_leaf
> > > 1)ext4_ext_split
> > > ext4_find_extent
> > > 2)ext4_ext_grow_indepth
> > > ext4_find_extent
> > >
> > > Signed-off-by: zhanchengbin <zhanchengbin1@xxxxxxxxxx>
> > > ---
> > > fs/ext4/extents.c | 3 ++-
> > > 1 file changed, 2 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
> > > index 9de1c9d1a13d..0f95e857089e 100644
> > > --- a/fs/ext4/extents.c
> > > +++ b/fs/ext4/extents.c
> > > @@ -935,6 +935,7 @@ ext4_find_extent(struct inode *inode, ext4_lblk_t block,
> > > bh = read_extent_tree_block(inode, path[ppos].p_idx, --i, flags);
> > > if (IS_ERR(bh)) {
> > > + EXT4_ERROR_INODE(inode, "IO error reading extent block");
> >
> > Why have you added this? Usually we don't log any additional errors for IO
> > errors because the storage layer already reports it... Furthermore this
> > would potentialy panic the system / remount the fs RO which we also usually
> > don't do in case of IO errors, only in case of FS corruption.
> >
> > Honza
>
> Because failure of read_extent_tree_block indirectly leads to filesystem
> inconsistency in ext4_split_extent_at, I want the filesystem to become
> read-only after failure.
Can you please describe how exactly? Because I'd rather declare the error
directly in ext4_split_extent_at() than in ext4_find_extent() unless it
gets too complicated...
Honza
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
