| Message ID | 20231221085712.1766333-3-yukuai1@huaweicloud.com |
|---|---|
| State | New |
| Headers | show |
| Series | block: don't access bd_inode directly from other modules | expand |
On Thu 21-12-23 16:56:57, Yu Kuai wrote: > From: Yu Kuai <yukuai3@huawei.com> > > Avoid to access bd_inode directly, prepare to remove bd_inode from > block_devcie. > > Signed-off-by: Yu Kuai <yukuai3@huawei.com> > --- > drivers/block/xen-blkback/xenbus.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > > diff --git a/drivers/block/xen-blkback/xenbus.c b/drivers/block/xen-blkback/xenbus.c > index e34219ea2b05..e645afa4af57 100644 > --- a/drivers/block/xen-blkback/xenbus.c > +++ b/drivers/block/xen-blkback/xenbus.c > @@ -104,8 +104,7 @@ static void xen_update_blkif_status(struct xen_blkif *blkif) > xenbus_dev_error(blkif->be->dev, err, "block flush"); > return; > } > - invalidate_inode_pages2( > - blkif->vbd.bdev_handle->bdev->bd_inode->i_mapping); > + invalidate_bdev(blkif->vbd.bdev_handle->bdev); This function uses invalidate_inode_pages2() while invalidate_bdev() ends up using mapping_try_invalidate() and there are subtle behavioral differences between these two (for example invalidate_inode_pages2() tries to clean dirty pages using the ->launder_folio method). So I think you'll need helper like invalidate_bdev2() for this. Honza
Hi, Jan! 在 2024/01/04 19:06, Jan Kara 写道: > On Thu 21-12-23 16:56:57, Yu Kuai wrote: >> From: Yu Kuai <yukuai3@huawei.com> >> >> Avoid to access bd_inode directly, prepare to remove bd_inode from >> block_devcie. >> >> Signed-off-by: Yu Kuai <yukuai3@huawei.com> >> --- >> drivers/block/xen-blkback/xenbus.c | 3 +-- >> 1 file changed, 1 insertion(+), 2 deletions(-) >> >> diff --git a/drivers/block/xen-blkback/xenbus.c b/drivers/block/xen-blkback/xenbus.c >> index e34219ea2b05..e645afa4af57 100644 >> --- a/drivers/block/xen-blkback/xenbus.c >> +++ b/drivers/block/xen-blkback/xenbus.c >> @@ -104,8 +104,7 @@ static void xen_update_blkif_status(struct xen_blkif *blkif) >> xenbus_dev_error(blkif->be->dev, err, "block flush"); >> return; >> } >> - invalidate_inode_pages2( >> - blkif->vbd.bdev_handle->bdev->bd_inode->i_mapping); >> + invalidate_bdev(blkif->vbd.bdev_handle->bdev); > > This function uses invalidate_inode_pages2() while invalidate_bdev() ends > up using mapping_try_invalidate() and there are subtle behavioral > differences between these two (for example invalidate_inode_pages2() tries > to clean dirty pages using the ->launder_folio method). So I think you'll > need helper like invalidate_bdev2() for this. Thanks for reviewing this patch, I know the differenct between then, what I don't understand is that why using invalidate_inode_pages2() here. sync_blockdev() is just called and 0 is returned, I think in this case it's safe to call invalidate_bdev() directly, or am I missing other things? Thanks, Kuai > > Honza >
Hi Kuai! On Thu 04-01-24 20:19:05, Yu Kuai wrote: > 在 2024/01/04 19:06, Jan Kara 写道: > > On Thu 21-12-23 16:56:57, Yu Kuai wrote: > > > From: Yu Kuai <yukuai3@huawei.com> > > > > > > Avoid to access bd_inode directly, prepare to remove bd_inode from > > > block_devcie. > > > > > > Signed-off-by: Yu Kuai <yukuai3@huawei.com> > > > --- > > > drivers/block/xen-blkback/xenbus.c | 3 +-- > > > 1 file changed, 1 insertion(+), 2 deletions(-) > > > > > > diff --git a/drivers/block/xen-blkback/xenbus.c b/drivers/block/xen-blkback/xenbus.c > > > index e34219ea2b05..e645afa4af57 100644 > > > --- a/drivers/block/xen-blkback/xenbus.c > > > +++ b/drivers/block/xen-blkback/xenbus.c > > > @@ -104,8 +104,7 @@ static void xen_update_blkif_status(struct xen_blkif *blkif) > > > xenbus_dev_error(blkif->be->dev, err, "block flush"); > > > return; > > > } > > > - invalidate_inode_pages2( > > > - blkif->vbd.bdev_handle->bdev->bd_inode->i_mapping); > > > + invalidate_bdev(blkif->vbd.bdev_handle->bdev); > > > > This function uses invalidate_inode_pages2() while invalidate_bdev() ends > > up using mapping_try_invalidate() and there are subtle behavioral > > differences between these two (for example invalidate_inode_pages2() tries > > to clean dirty pages using the ->launder_folio method). So I think you'll > > need helper like invalidate_bdev2() for this. > > Thanks for reviewing this patch, I know the differenct between then, > what I don't understand is that why using invalidate_inode_pages2() > here. Well, then the change in behavior should be at least noted in the changelog. > sync_blockdev() is just called and 0 is returned, I think in this > case it's safe to call invalidate_bdev() directly, or am I missing > other things? I still think there's a difference. invalidate_inode_pages2() also unmaps memory mappings which mapping_try_invalidate() does not do. That being said in xen_update_blkif_status() we seem to be bringing up a virtual block device so before this function is called, anybody would have hard time using anything in it. But this definitely needs a confirmation from Xen maintainers and a good documentation of the behavioral change in the changelog. Honza
On Thu, Jan 04, 2024 at 12:06:31PM +0100, Jan Kara wrote: > This function uses invalidate_inode_pages2() while invalidate_bdev() ends > up using mapping_try_invalidate() and there are subtle behavioral > differences between these two (for example invalidate_inode_pages2() tries > to clean dirty pages using the ->launder_folio method). So I think you'll > need helper like invalidate_bdev2() for this. That assues that the existing code actually does this intentionally, which seems doubtful. But the change in behavior does not to be documented and explained.
diff --git a/drivers/block/xen-blkback/xenbus.c b/drivers/block/xen-blkback/xenbus.c index e34219ea2b05..e645afa4af57 100644 --- a/drivers/block/xen-blkback/xenbus.c +++ b/drivers/block/xen-blkback/xenbus.c @@ -104,8 +104,7 @@ static void xen_update_blkif_status(struct xen_blkif *blkif) xenbus_dev_error(blkif->be->dev, err, "block flush"); return; } - invalidate_inode_pages2( - blkif->vbd.bdev_handle->bdev->bd_inode->i_mapping); + invalidate_bdev(blkif->vbd.bdev_handle->bdev); for (i = 0; i < blkif->nr_rings; i++) { ring = &blkif->rings[i];