Re: [PATCH RFC v3 for-6.8/block 02/17] xen/blkback: use bdev api in xen_update_blkif_status()
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.
Re: [PATCH RFC v3 for-6.8/block 02/17] xen/blkback: use bdev api in xen_update_blkif_status()
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 > > > > > > Avoid to access bd_inode directly, prepare to remove bd_inode from > > > block_devcie. > > > > > > Signed-off-by: Yu Kuai > > > --- > > > 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 -- Jan Kara SUSE Labs, CR
Re: [PATCH RFC v3 for-6.8/block 02/17] xen/blkback: use bdev api in xen_update_blkif_status()
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 Avoid to access bd_inode directly, prepare to remove bd_inode from block_devcie. Signed-off-by: Yu Kuai --- 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
Re: [PATCH RFC v3 for-6.8/block 02/17] xen/blkback: use bdev api in xen_update_blkif_status()
On Thu 21-12-23 16:56:57, Yu Kuai wrote: > From: Yu Kuai > > Avoid to access bd_inode directly, prepare to remove bd_inode from > block_devcie. > > Signed-off-by: Yu Kuai > --- > 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 -- Jan Kara SUSE Labs, CR
[PATCH RFC v3 for-6.8/block 02/17] xen/blkback: use bdev api in xen_update_blkif_status()
From: Yu Kuai
Avoid to access bd_inode directly, prepare to remove bd_inode from
block_devcie.
Signed-off-by: Yu Kuai
---
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);
for (i = 0; i < blkif->nr_rings; i++) {
ring = >rings[i];
--
2.39.2
