In fsdax mode, WRITE and ZERO on a shared extent need CoW performed.
After that, new allocated extents needs to be remapped to the file.  Add
an implementation of ->iomap_end() for dax write ops to do the remapping
work.

Signed-off-by: Shiyang Ruan <ruansy.f...@fujitsu.com>
---
 fs/dax.c               | 39 ++++++++++++++++++++++++++++++++++++---
 fs/iomap/buffered-io.c |  3 ++-
 fs/xfs/xfs_bmap_util.c |  3 +--
 fs/xfs/xfs_file.c      |  4 ++--
 fs/xfs/xfs_iomap.c     | 32 +++++++++++++++++++++++++++++++-
 fs/xfs/xfs_iomap.h     | 32 ++++++++++++++++++++++++++++++++
 fs/xfs/xfs_iops.c      |  7 +++----
 fs/xfs/xfs_reflink.c   |  3 +--
 include/linux/dax.h    |  4 ++++
 include/linux/iomap.h  |  1 +
 10 files changed, 113 insertions(+), 15 deletions(-)

diff --git a/fs/dax.c b/fs/dax.c
index a1232d6b7e37..88541b734f97 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -1401,6 +1401,39 @@ dax_iomap_rw(struct kiocb *iocb, struct iov_iter *iter,
 }
 EXPORT_SYMBOL_GPL(dax_iomap_rw);
 
+int
+dax_iomap_zero_range(struct inode *inode, loff_t pos, loff_t len,
+               bool *did_zero, const struct iomap_ops *ops)
+{
+       struct iomap_iter iomi = {
+               .inode          = inode,
+               .pos            = pos,
+               .len            = len,
+               .flags          = IOMAP_ZERO,
+       };
+       int ret;
+
+       while ((ret = iomap_iter(&iomi, ops)) > 0)
+               iomi.processed = iomap_zero_iter(&iomi, did_zero);
+
+       return ret;
+}
+EXPORT_SYMBOL_GPL(dax_iomap_zero_range);
+
+int
+dax_iomap_truncate_page(struct inode *inode, loff_t pos, bool *did_zero,
+               const struct iomap_ops *ops)
+{
+       unsigned int blocksize = i_blocksize(inode);
+       unsigned int off = pos & (blocksize - 1);
+
+       /* Block boundary? Nothing to do */
+       if (!off)
+               return 0;
+       return dax_iomap_zero_range(inode, pos, blocksize - off, did_zero, ops);
+}
+EXPORT_SYMBOL_GPL(dax_iomap_truncate_page);
+
 static vm_fault_t dax_fault_return(int error)
 {
        if (error == 0)
@@ -1521,7 +1554,7 @@ static vm_fault_t dax_fault_iter(struct vm_fault *vmf,
 }
 
 static vm_fault_t dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp,
-                              int *iomap_errp, const struct iomap_ops *ops)
+               int *iomap_errp, const struct iomap_ops *ops)
 {
        struct address_space *mapping = vmf->vma->vm_file->f_mapping;
        XA_STATE(xas, &mapping->i_pages, vmf->pgoff);
@@ -1631,7 +1664,7 @@ static bool dax_fault_check_fallback(struct vm_fault 
*vmf, struct xa_state *xas,
 }
 
 static vm_fault_t dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp,
-                              const struct iomap_ops *ops)
+               const struct iomap_ops *ops)
 {
        struct address_space *mapping = vmf->vma->vm_file->f_mapping;
        XA_STATE_ORDER(xas, &mapping->i_pages, vmf->pgoff, PMD_ORDER);
@@ -1732,7 +1765,7 @@ static vm_fault_t dax_iomap_pmd_fault(struct vm_fault 
*vmf, pfn_t *pfnp,
  * successfully.
  */
 vm_fault_t dax_iomap_fault(struct vm_fault *vmf, enum page_entry_size pe_size,
-                   pfn_t *pfnp, int *iomap_errp, const struct iomap_ops *ops)
+               pfn_t *pfnp, int *iomap_errp, const struct iomap_ops *ops)
 {
        switch (pe_size) {
        case PE_SIZE_PTE:
diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index 6e8d40877d01..6341a1328def 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -887,7 +887,7 @@ static s64 __iomap_zero_iter(struct iomap_iter *iter, 
loff_t pos, u64 length)
        return iomap_write_end(iter, pos, bytes, bytes, page);
 }
 
-static loff_t iomap_zero_iter(struct iomap_iter *iter, bool *did_zero)
+loff_t iomap_zero_iter(struct iomap_iter *iter, bool *did_zero)
 {
        const struct iomap *iomap = &iter->iomap;
        const struct iomap *srcmap = iomap_iter_srcmap(iter);
@@ -918,6 +918,7 @@ static loff_t iomap_zero_iter(struct iomap_iter *iter, bool 
*did_zero)
 
        return written;
 }
+EXPORT_SYMBOL_GPL(iomap_zero_iter);
 
 int
 iomap_zero_range(struct inode *inode, loff_t pos, loff_t len, bool *did_zero,
diff --git a/fs/xfs/xfs_bmap_util.c b/fs/xfs/xfs_bmap_util.c
index 213a97a921bb..f1b7a2637a1d 100644
--- a/fs/xfs/xfs_bmap_util.c
+++ b/fs/xfs/xfs_bmap_util.c
@@ -1009,8 +1009,7 @@ xfs_free_file_space(
                return 0;
        if (offset + len > XFS_ISIZE(ip))
                len = XFS_ISIZE(ip) - offset;
-       error = iomap_zero_range(VFS_I(ip), offset, len, NULL,
-                       &xfs_buffered_write_iomap_ops);
+       error = xfs_iomap_zero_range(ip, offset, len, NULL);
        if (error)
                return error;
 
diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index cc3cfb12df53..d57f94c523c7 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -704,7 +704,7 @@ xfs_file_dax_write(
        pos = iocb->ki_pos;
 
        trace_xfs_file_dax_write(iocb, from);
-       ret = dax_iomap_rw(iocb, from, &xfs_direct_write_iomap_ops);
+       ret = dax_iomap_rw(iocb, from, &xfs_dax_write_iomap_ops);
        if (ret > 0 && iocb->ki_pos > i_size_read(inode)) {
                i_size_write(inode, iocb->ki_pos);
                error = xfs_setfilesize(ip, pos, ret);
@@ -1329,7 +1329,7 @@ __xfs_filemap_fault(
 
                ret = dax_iomap_fault(vmf, pe_size, &pfn, NULL,
                                (write_fault && !vmf->cow_page) ?
-                                &xfs_direct_write_iomap_ops :
+                                &xfs_dax_write_iomap_ops :
                                 &xfs_read_iomap_ops);
                if (ret & VM_FAULT_NEEDDSYNC)
                        ret = dax_finish_sync_fault(vmf, pe_size, pfn);
diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
index d8cd2583dedb..c037a47004f9 100644
--- a/fs/xfs/xfs_iomap.c
+++ b/fs/xfs/xfs_iomap.c
@@ -761,7 +761,8 @@ xfs_direct_write_iomap_begin(
 
                /* may drop and re-acquire the ilock */
                error = xfs_reflink_allocate_cow(ip, &imap, &cmap, &shared,
-                               &lockmode, flags & IOMAP_DIRECT);
+                               &lockmode,
+                               (flags & IOMAP_DIRECT) || IS_DAX(inode));
                if (error)
                        goto out_unlock;
                if (shared)
@@ -854,6 +855,35 @@ const struct iomap_ops xfs_direct_write_iomap_ops = {
        .iomap_begin            = xfs_direct_write_iomap_begin,
 };
 
+static int
+xfs_dax_write_iomap_end(
+       struct inode            *inode,
+       loff_t                  pos,
+       loff_t                  length,
+       ssize_t                 written,
+       unsigned                flags,
+       struct iomap            *iomap)
+{
+       int                     error = 0;
+       struct xfs_inode        *ip = XFS_I(inode);
+       bool                    cow = xfs_is_cow_inode(ip);
+       const struct iomap_iter *iter =
+                               container_of(iomap, typeof(*iter), iomap);
+
+       if (cow) {
+               if (iter->processed <= 0)
+                       xfs_reflink_cancel_cow_range(ip, pos, length, true);
+               else
+                       error = xfs_reflink_end_cow(ip, pos, iter->processed);
+       }
+       return error ?: iter->processed;
+}
+
+const struct iomap_ops xfs_dax_write_iomap_ops = {
+       .iomap_begin    = xfs_direct_write_iomap_begin,
+       .iomap_end      = xfs_dax_write_iomap_end,
+};
+
 static int
 xfs_buffered_write_iomap_begin(
        struct inode            *inode,
diff --git a/fs/xfs/xfs_iomap.h b/fs/xfs/xfs_iomap.h
index 7d3703556d0e..1ca9f9102523 100644
--- a/fs/xfs/xfs_iomap.h
+++ b/fs/xfs/xfs_iomap.h
@@ -45,5 +45,37 @@ extern const struct iomap_ops xfs_direct_write_iomap_ops;
 extern const struct iomap_ops xfs_read_iomap_ops;
 extern const struct iomap_ops xfs_seek_iomap_ops;
 extern const struct iomap_ops xfs_xattr_iomap_ops;
+extern const struct iomap_ops xfs_dax_write_iomap_ops;
+
+static inline int
+xfs_iomap_zero_range(
+       struct xfs_inode        *ip,
+       loff_t                  pos,
+       loff_t                  len,
+       bool                    *did_zero)
+{
+       struct inode            *inode = VFS_I(ip);
+
+       return IS_DAX(inode)
+                       ? dax_iomap_zero_range(inode, pos, len, did_zero,
+                                              &xfs_dax_write_iomap_ops)
+                       : iomap_zero_range(inode, pos, len, did_zero,
+                                              &xfs_buffered_write_iomap_ops);
+}
+
+static inline int
+xfs_iomap_truncate_page(
+       struct xfs_inode        *ip,
+       loff_t                  pos,
+       bool                    *did_zero)
+{
+       struct inode            *inode = VFS_I(ip);
+
+       return IS_DAX(inode)
+                       ? dax_iomap_truncate_page(inode, pos, did_zero,
+                                              &xfs_dax_write_iomap_ops)
+                       : iomap_truncate_page(inode, pos, did_zero,
+                                              &xfs_buffered_write_iomap_ops);
+}
 
 #endif /* __XFS_IOMAP_H__*/
diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c
index 93c082db04b7..0380f6942bc0 100644
--- a/fs/xfs/xfs_iops.c
+++ b/fs/xfs/xfs_iops.c
@@ -911,8 +911,8 @@ xfs_setattr_size(
         */
        if (newsize > oldsize) {
                trace_xfs_zero_eof(ip, oldsize, newsize - oldsize);
-               error = iomap_zero_range(inode, oldsize, newsize - oldsize,
-                               &did_zeroing, &xfs_buffered_write_iomap_ops);
+               error = xfs_iomap_zero_range(ip, oldsize, newsize - oldsize,
+                               &did_zeroing);
        } else {
                /*
                 * iomap won't detect a dirty page over an unwritten block (or a
@@ -924,8 +924,7 @@ xfs_setattr_size(
                                                     newsize);
                if (error)
                        return error;
-               error = iomap_truncate_page(inode, newsize, &did_zeroing,
-                               &xfs_buffered_write_iomap_ops);
+               error = xfs_iomap_truncate_page(ip, newsize, &did_zeroing);
        }
 
        if (error)
diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
index 28effe537d07..13e461cf2055 100644
--- a/fs/xfs/xfs_reflink.c
+++ b/fs/xfs/xfs_reflink.c
@@ -1269,8 +1269,7 @@ xfs_reflink_zero_posteof(
                return 0;
 
        trace_xfs_zero_eof(ip, isize, pos - isize);
-       return iomap_zero_range(VFS_I(ip), isize, pos - isize, NULL,
-                       &xfs_buffered_write_iomap_ops);
+       return xfs_iomap_zero_range(ip, isize, pos - isize, NULL);
 }
 
 /*
diff --git a/include/linux/dax.h b/include/linux/dax.h
index 8ecd125434ef..96b1f0bb4ab8 100644
--- a/include/linux/dax.h
+++ b/include/linux/dax.h
@@ -237,6 +237,10 @@ 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);
+int dax_iomap_zero_range(struct inode *inode, loff_t pos, loff_t len,
+               bool *did_zero, const struct iomap_ops *ops);
+int dax_iomap_truncate_page(struct inode *inode, loff_t pos, bool *did_zero,
+               const struct iomap_ops *ops);
 s64 dax_iomap_zero(loff_t pos, u64 length, const struct iomap *iomap,
                const struct iomap *srcmap);
 int dax_dedupe_file_range_compare(struct inode *src, loff_t srcoff,
diff --git a/include/linux/iomap.h b/include/linux/iomap.h
index 24f8489583ca..b32cbdb74c49 100644
--- a/include/linux/iomap.h
+++ b/include/linux/iomap.h
@@ -235,6 +235,7 @@ int iomap_migrate_page(struct address_space *mapping, 
struct page *newpage,
 #endif
 int iomap_file_unshare(struct inode *inode, loff_t pos, loff_t len,
                const struct iomap_ops *ops);
+loff_t iomap_zero_iter(struct iomap_iter *iter, bool *did_zero);
 int iomap_zero_range(struct inode *inode, loff_t pos, loff_t len,
                bool *did_zero, const struct iomap_ops *ops);
 int iomap_truncate_page(struct inode *inode, loff_t pos, bool *did_zero,
-- 
2.32.0




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