> -----Original Message-----
> From: Darrick J. Wong <djw...@kernel.org>
> Subject: Re: [PATCH v5 3/7] fsdax: Add dax_iomap_cow_copy() for
> dax_iomap_zero
>
> On Tue, May 11, 2021 at 11:09:29AM +0800, Shiyang Ruan wrote:
> > Punch hole on a reflinked file needs dax_copy_edge() too. Otherwise,
> > data in not aligned area will be not correct. So, add the srcmap to
> > dax_iomap_zero() and replace memset() as dax_copy_edge().
> >
> > Signed-off-by: Shiyang Ruan <ruansy.f...@fujitsu.com>
> > Reviewed-by: Ritesh Harjani <rite...@linux.ibm.com>
> > ---
> > fs/dax.c | 25 +++++++++++++++----------
> > fs/iomap/buffered-io.c | 2 +-
> > include/linux/dax.h | 3 ++-
> > 3 files changed, 18 insertions(+), 12 deletions(-)
> >
> > diff --git a/fs/dax.c b/fs/dax.c
> > index ef0e564e7904..ee9d28a79bfb 100644
> > --- a/fs/dax.c
> > +++ b/fs/dax.c
> > @@ -1186,7 +1186,8 @@ static vm_fault_t dax_pmd_load_hole(struct
> > xa_state *xas, struct vm_fault *vmf, } #endif /* CONFIG_FS_DAX_PMD
> > */
> >
> > -s64 dax_iomap_zero(loff_t pos, u64 length, struct iomap *iomap)
> > +s64 dax_iomap_zero(loff_t pos, u64 length, struct iomap *iomap,
> > + struct iomap *srcmap)
> > {
> > sector_t sector = iomap_sector(iomap, pos & PAGE_MASK);
> > pgoff_t pgoff;
> > @@ -1208,19 +1209,23 @@ s64 dax_iomap_zero(loff_t pos, u64 length,
> > struct iomap *iomap)
> >
> > if (page_aligned)
> > rc = dax_zero_page_range(iomap->dax_dev, pgoff, 1);
> > - else
> > + else {
> > rc = dax_direct_access(iomap->dax_dev, pgoff, 1, &kaddr, NULL);
> > - if (rc < 0) {
> > - dax_read_unlock(id);
> > - return rc;
> > - }
> > -
> > - if (!page_aligned) {
> > - memset(kaddr + offset, 0, size);
> > + if (rc < 0)
> > + goto out;
> > + if (iomap->addr != srcmap->addr) {
>
> Why isn't this "if (srcmap->type != IOMAP_HOLE)" ?
>
> I suppose it has the same effect, since @iomap should never be a hole and we
> should never have a @srcmap that's the same as @iomap, but still, we use
> IOMAP_HOLE checks in most other parts of fs/iomap/.
According to its caller `iomap_zero_range_actor()`, whether srcmap->type is
IOMAP_HOLE has already been checked before `dax_iomap_zero()`. So the check
you suggested will always be true...
--
Thanks,
Ruan Shiyang.
>
> Other than that, the logic looks decent to me.
>
> --D
>
> > + rc = dax_iomap_cow_copy(offset, size, PAGE_SIZE, srcmap,
> > + kaddr);
> > + if (rc < 0)
> > + goto out;
> > + } else
> > + memset(kaddr + offset, 0, size);
> > dax_flush(iomap->dax_dev, kaddr + offset, size);
> > }
> > +
> > +out:
> > dax_read_unlock(id);
> > - return size;
> > + return rc < 0 ? rc : size;
> > }
> >
> > static loff_t
> > diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c index
> > f2cd2034a87b..2734955ea67f 100644
> > --- a/fs/iomap/buffered-io.c
> > +++ b/fs/iomap/buffered-io.c
> > @@ -933,7 +933,7 @@ static loff_t iomap_zero_range_actor(struct inode
> *inode, loff_t pos,
> > s64 bytes;
> >
> > if (IS_DAX(inode))
> > - bytes = dax_iomap_zero(pos, length, iomap);
> > + bytes = dax_iomap_zero(pos, length, iomap, srcmap);
> > else
> > bytes = iomap_zero(inode, pos, length, iomap, srcmap);
> > if (bytes < 0)
> > diff --git a/include/linux/dax.h b/include/linux/dax.h index
> > b52f084aa643..3275e01ed33d 100644
> > --- a/include/linux/dax.h
> > +++ b/include/linux/dax.h
> > @@ -237,7 +237,8 @@ vm_fault_t dax_finish_sync_fault(struct vm_fault
> > *vmf, int dax_delete_mapping_entry(struct address_space *mapping,
> > pgoff_t index); int dax_invalidate_mapping_entry_sync(struct
> address_space *mapping,
> > pgoff_t index);
> > -s64 dax_iomap_zero(loff_t pos, u64 length, struct iomap *iomap);
> > +s64 dax_iomap_zero(loff_t pos, u64 length, struct iomap *iomap,
> > + struct iomap *srcmap);
> > static inline bool dax_mapping(struct address_space *mapping) {
> > return mapping->host && IS_DAX(mapping->host);
> > --
> > 2.31.1
> >
> >
> >
>
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