[RFC PATCH 7/8] fs/xfs: handle CoW for fsdax write() path

From: Shiyang Ruan
Date: Mon Apr 27 2020 - 04:49:04 EST


In fsdax mode, WRITE and ZERO on a shared extent need CoW mechanism
performed. After CoW, new extents needs to be remapped to the file.

Signed-off-by: Shiyang Ruan <ruansy.fnst@xxxxxxxxxxxxxx>

fs/dax.c: fix nrexceptional count error.
---
fs/xfs/xfs_bmap_util.c | 6 +++++-
fs/xfs/xfs_file.c | 10 +++++++---
fs/xfs/xfs_iomap.c | 3 ++-
fs/xfs/xfs_iops.c | 11 ++++++++---
fs/xfs/xfs_reflink.c | 2 ++
5 files changed, 24 insertions(+), 8 deletions(-)

diff --git a/fs/xfs/xfs_bmap_util.c b/fs/xfs/xfs_bmap_util.c
index 4f800f7fe888..8980120415ba 100644
--- a/fs/xfs/xfs_bmap_util.c
+++ b/fs/xfs/xfs_bmap_util.c
@@ -969,10 +969,14 @@ xfs_free_file_space(
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);
+ IS_DAX(VFS_I(ip)) ?
+ &xfs_direct_write_iomap_ops : &xfs_buffered_write_iomap_ops);
if (error)
return error;

+ if (xfs_is_reflink_inode(ip))
+ xfs_reflink_end_cow(ip, offset, len);
+
/*
* If we zeroed right up to EOF and EOF straddles a page boundary we
* must make sure that the post-EOF area is also zeroed because the
diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index 4b8bdecc3863..2f8a83b2605d 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -588,9 +588,13 @@ xfs_file_dax_write(

trace_xfs_file_dax_write(ip, count, pos);
ret = dax_iomap_rw(iocb, from, &xfs_direct_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);
+ if (ret > 0) {
+ if (iocb->ki_pos > i_size_read(inode)) {
+ i_size_write(inode, iocb->ki_pos);
+ error = xfs_setfilesize(ip, pos, ret);
+ }
+ if (xfs_is_cow_inode(ip))
+ xfs_reflink_end_cow(ip, pos, ret);
}
out:
xfs_iunlock(ip, iolock);
diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
index bb590a267a7f..ca92f76498c9 100644
--- a/fs/xfs/xfs_iomap.c
+++ b/fs/xfs/xfs_iomap.c
@@ -754,13 +754,14 @@ xfs_direct_write_iomap_begin(
goto out_unlock;

if (imap_needs_cow(ip, flags, &imap, nimaps)) {
+ bool need_convert = flags & IOMAP_DIRECT || IS_DAX(inode);
error = -EAGAIN;
if (flags & IOMAP_NOWAIT)
goto out_unlock;

/* may drop and re-acquire the ilock */
error = xfs_reflink_allocate_cow(ip, &imap, &cmap, &shared,
- &lockmode, flags & IOMAP_DIRECT);
+ &lockmode, need_convert);
if (error)
goto out_unlock;
if (shared)
diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c
index f7a99b3bbcf7..92b58ae06c0e 100644
--- a/fs/xfs/xfs_iops.c
+++ b/fs/xfs/xfs_iops.c
@@ -864,6 +864,7 @@ xfs_setattr_size(
int error;
uint lock_flags = 0;
bool did_zeroing = false;
+ const struct iomap_ops *ops;

ASSERT(xfs_isilocked(ip, XFS_IOLOCK_EXCL));
ASSERT(xfs_isilocked(ip, XFS_MMAPLOCK_EXCL));
@@ -910,13 +911,17 @@ xfs_setattr_size(
* extension, or zeroing out the rest of the block on a downward
* truncate.
*/
+ if (IS_DAX(inode))
+ ops = &xfs_direct_write_iomap_ops;
+ else
+ ops = &xfs_buffered_write_iomap_ops;
+
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);
+ &did_zeroing, ops);
} else {
- error = iomap_truncate_page(inode, newsize, &did_zeroing,
- &xfs_buffered_write_iomap_ops);
+ error = iomap_truncate_page(inode, newsize, &did_zeroing, ops);
}

if (error)
diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
index 792217cd1e64..f87ab78dd421 100644
--- a/fs/xfs/xfs_reflink.c
+++ b/fs/xfs/xfs_reflink.c
@@ -1269,6 +1269,8 @@ xfs_reflink_zero_posteof(

trace_xfs_zero_eof(ip, isize, pos - isize);
return iomap_zero_range(VFS_I(ip), isize, pos - isize, NULL,
+ IS_DAX(VFS_I(ip)) ?
+ &xfs_direct_write_iomap_ops :
&xfs_buffered_write_iomap_ops);
}

--
2.26.2