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Subject[PATCH v2.1 08/14] fsdax: Output address in dax_iomap_pfn() and rename it
Date
Add address output in dax_iomap_pfn() in order to perform a memcpy() in
CoW case. Since this function both output address and pfn, rename it to
dax_iomap_direct_access().

Signed-off-by: Shiyang Ruan <ruansy.fnst@fujitsu.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ritesh Harjani <riteshh@linux.ibm.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>

==
Hi Andrew,

As Dan mentioned[1], the rc should be initialized. I fixed it and resend this patch.

[1] https://lore.kernel.org/linux-fsdevel/Yp8FUZnO64Qvyx5G@kili/

---
fs/dax.c | 18 +++++++++++++-----
1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/fs/dax.c b/fs/dax.c
index b59b864017ad..7a8eb1e30a1b 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -1026,20 +1026,22 @@ int dax_writeback_mapping_range(struct address_space *mapping,
}
EXPORT_SYMBOL_GPL(dax_writeback_mapping_range);

-static int dax_iomap_pfn(const struct iomap *iomap, loff_t pos, size_t size,
- pfn_t *pfnp)
+static int dax_iomap_direct_access(const struct iomap *iomap, loff_t pos,
+ size_t size, void **kaddr, pfn_t *pfnp)
{
pgoff_t pgoff = dax_iomap_pgoff(iomap, pos);
- int id, rc;
+ int id, rc = 0;
long length;

id = dax_read_lock();
length = dax_direct_access(iomap->dax_dev, pgoff, PHYS_PFN(size),
- DAX_ACCESS, NULL, pfnp);
+ DAX_ACCESS, kaddr, pfnp);
if (length < 0) {
rc = length;
goto out;
}
+ if (!pfnp)
+ goto out_check_addr;
rc = -EINVAL;
if (PFN_PHYS(length) < size)
goto out;
@@ -1049,6 +1051,12 @@ static int dax_iomap_pfn(const struct iomap *iomap, loff_t pos, size_t size,
if (length > 1 && !pfn_t_devmap(*pfnp))
goto out;
rc = 0;
+
+out_check_addr:
+ if (!kaddr)
+ goto out;
+ if (!*kaddr)
+ rc = -EFAULT;
out:
dax_read_unlock(id);
return rc;
@@ -1456,7 +1464,7 @@ static vm_fault_t dax_fault_iter(struct vm_fault *vmf,
return pmd ? VM_FAULT_FALLBACK : VM_FAULT_SIGBUS;
}

- err = dax_iomap_pfn(&iter->iomap, pos, size, &pfn);
+ err = dax_iomap_direct_access(&iter->iomap, pos, size, NULL, &pfn);
if (err)
return pmd ? VM_FAULT_FALLBACK : dax_fault_return(err);

--
2.36.1


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