[PATCH v8 6/7] xfs: support CoW in fsdax mode

From: Shiyang Ruan
Date: Sun Aug 29 2021 - 08:26:12 EST

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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.fnst@xxxxxxxxxxx>
---
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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