2016-08-23 22:04:11

by Ross Zwisler

[permalink] [raw]
Subject: [PATCH v2 1/9] ext4: allow DAX writeback for hole punch

Currently when doing a DAX hole punch with ext4 we fail to do a writeback.
This is because the logic around filemap_write_and_wait_range() in
ext4_punch_hole() only looks for dirty page cache pages in the radix tree,
not for dirty DAX exceptional entries.

Signed-off-by: Ross Zwisler <ross.zwisler-VuQAYsv1563Yd54FQh9/[email protected]>
Reviewed-by: Jan Kara <[email protected]>
Cc: <[email protected]>
---
fs/ext4/inode.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 3131747..0900cb4 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3890,7 +3890,7 @@ int ext4_update_disksize_before_punch(struct inode *inode, loff_t offset,
}

/*
- * ext4_punch_hole: punches a hole in a file by releaseing the blocks
+ * ext4_punch_hole: punches a hole in a file by releasing the blocks
* associated with the given offset and length
*
* @inode: File inode
@@ -3919,7 +3919,7 @@ int ext4_punch_hole(struct inode *inode, loff_t offset, loff_t length)
* Write out all dirty pages to avoid race conditions
* Then release them.
*/
- if (mapping->nrpages && mapping_tagged(mapping, PAGECACHE_TAG_DIRTY)) {
+ if (mapping_tagged(mapping, PAGECACHE_TAG_DIRTY)) {
ret = filemap_write_and_wait_range(mapping, offset,
offset + length - 1);
if (ret)
--
2.9.0


2016-09-21 15:22:44

by Ross Zwisler

[permalink] [raw]
Subject: Re: [PATCH v2 1/9] ext4: allow DAX writeback for hole punch

On Tue, Aug 23, 2016 at 04:04:11PM -0600, Ross Zwisler wrote:
> Currently when doing a DAX hole punch with ext4 we fail to do a writeback.
> This is because the logic around filemap_write_and_wait_range() in
> ext4_punch_hole() only looks for dirty page cache pages in the radix tree,
> not for dirty DAX exceptional entries.
>
> Signed-off-by: Ross Zwisler <[email protected]>
> Reviewed-by: Jan Kara <[email protected]>
> Cc: <[email protected]>

Ted & Jan,

I'm still working on the latest version of the PMD work which integrates with
the new struct iomap faults. At this point it doesn't look like I'm going to
make v4.9, but I think that this bug fix at least should probably go in alone?

Thanks,
- Ross

> ---
> fs/ext4/inode.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index 3131747..0900cb4 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -3890,7 +3890,7 @@ int ext4_update_disksize_before_punch(struct inode *inode, loff_t offset,
> }
>
> /*
> - * ext4_punch_hole: punches a hole in a file by releaseing the blocks
> + * ext4_punch_hole: punches a hole in a file by releasing the blocks
> * associated with the given offset and length
> *
> * @inode: File inode
> @@ -3919,7 +3919,7 @@ int ext4_punch_hole(struct inode *inode, loff_t offset, loff_t length)
> * Write out all dirty pages to avoid race conditions
> * Then release them.
> */
> - if (mapping->nrpages && mapping_tagged(mapping, PAGECACHE_TAG_DIRTY)) {
> + if (mapping_tagged(mapping, PAGECACHE_TAG_DIRTY)) {
> ret = filemap_write_and_wait_range(mapping, offset,
> offset + length - 1);
> if (ret)
> --
> 2.9.0
>

2016-09-22 06:59:43

by Jan Kara

[permalink] [raw]
Subject: Re: [PATCH v2 1/9] ext4: allow DAX writeback for hole punch

On Wed 21-09-16 09:22:44, Ross Zwisler wrote:
> On Tue, Aug 23, 2016 at 04:04:11PM -0600, Ross Zwisler wrote:
> > Currently when doing a DAX hole punch with ext4 we fail to do a writeback.
> > This is because the logic around filemap_write_and_wait_range() in
> > ext4_punch_hole() only looks for dirty page cache pages in the radix tree,
> > not for dirty DAX exceptional entries.
> >
> > Signed-off-by: Ross Zwisler <[email protected]>
> > Reviewed-by: Jan Kara <[email protected]>
> > Cc: <[email protected]>
>
> Ted & Jan,
>
> I'm still working on the latest version of the PMD work which integrates with
> the new struct iomap faults. At this point it doesn't look like I'm going to
> make v4.9, but I think that this bug fix at least should probably go in alone?

Yeah. Ted, feel free to add:

Reviewed-by: Jan Kara <[email protected]>

and merge this change. Thanks!

Honza
> > fs/ext4/inode.c | 4 ++--
> > 1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> > index 3131747..0900cb4 100644
> > --- a/fs/ext4/inode.c
> > +++ b/fs/ext4/inode.c
> > @@ -3890,7 +3890,7 @@ int ext4_update_disksize_before_punch(struct inode *inode, loff_t offset,
> > }
> >
> > /*
> > - * ext4_punch_hole: punches a hole in a file by releaseing the blocks
> > + * ext4_punch_hole: punches a hole in a file by releasing the blocks
> > * associated with the given offset and length
> > *
> > * @inode: File inode
> > @@ -3919,7 +3919,7 @@ int ext4_punch_hole(struct inode *inode, loff_t offset, loff_t length)
> > * Write out all dirty pages to avoid race conditions
> > * Then release them.
> > */
> > - if (mapping->nrpages && mapping_tagged(mapping, PAGECACHE_TAG_DIRTY)) {
> > + if (mapping_tagged(mapping, PAGECACHE_TAG_DIRTY)) {
> > ret = filemap_write_and_wait_range(mapping, offset,
> > offset + length - 1);
> > if (ret)
> > --
> > 2.9.0
> >
--
Jan Kara <[email protected]>
SUSE Labs, CR

2016-09-22 15:51:03

by Theodore Ts'o

[permalink] [raw]
Subject: Re: [PATCH v2 1/9] ext4: allow DAX writeback for hole punch

On Wed, Sep 21, 2016 at 09:22:44AM -0600, Ross Zwisler wrote:
>
> Ted & Jan,
>
> I'm still working on the latest version of the PMD work which integrates with
> the new struct iomap faults. At this point it doesn't look like I'm going to
> make v4.9, but I think that this bug fix at least should probably go in alone?

Thanks, applied.

- Ted

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