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Message-ID: <20210525221751.GQ202121@locust>
Date: Tue, 25 May 2021 15:17:51 -0700
From: "Darrick J. Wong" <djwong@...nel.org>
To: "ruansy.fnst@...itsu.com" <ruansy.fnst@...itsu.com>
Cc: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"linux-xfs@...r.kernel.org" <linux-xfs@...r.kernel.org>,
"linux-nvdimm@...ts.01.org" <linux-nvdimm@...ts.01.org>,
"linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>,
"darrick.wong@...cle.com" <darrick.wong@...cle.com>,
"dan.j.williams@...el.com" <dan.j.williams@...el.com>,
"willy@...radead.org" <willy@...radead.org>,
"viro@...iv.linux.org.uk" <viro@...iv.linux.org.uk>,
"david@...morbit.com" <david@...morbit.com>,
"hch@....de" <hch@....de>, "rgoldwyn@...e.de" <rgoldwyn@...e.de>,
Ritesh Harjani <riteshh@...ux.ibm.com>
Subject: Re: [PATCH v5 3/7] fsdax: Add dax_iomap_cow_copy() for dax_iomap_zero
On Wed, May 12, 2021 at 01:37:24AM +0000, ruansy.fnst@...itsu.com wrote:
> > -----Original Message-----
> > From: Darrick J. Wong <djwong@...nel.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.fnst@...itsu.com>
> > > Reviewed-by: Ritesh Harjani <riteshh@...ux.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...
Ah right, so it is. I'll go review the newest version of this patch.
--D
>
>
> --
> 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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