On 24/02/2025 20:32, Darrick J. Wong wrote:
On Thu, Feb 13, 2025 at 01:56:14PM +0000, John Garry wrote:
For CoW-based atomic write support, always allocate a cow hole in
xfs_reflink_allocate_cow() to write the new data.
The semantics is that if @atomic is set, we will be passed a CoW fork
extent mapping for no error returned.
Signed-off-by: John Garry <john.g.garry@xxxxxxxxxx>
---
fs/xfs/xfs_iomap.c | 2 +-
fs/xfs/xfs_reflink.c | 12 +++++++-----
fs/xfs/xfs_reflink.h | 2 +-
3 files changed, 9 insertions(+), 7 deletions(-)
diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
index d61460309a78..ab79f0080288 100644
--- a/fs/xfs/xfs_iomap.c
+++ b/fs/xfs/xfs_iomap.c
@@ -865,7 +865,7 @@ 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) || IS_DAX(inode));
+ (flags & IOMAP_DIRECT) || IS_DAX(inode), false);
Now I'm /really/ think it's time for some reflink allocation flags,
because the function signature now involves two booleans...
ok, but the @convert_now arg is passed to other functions from
xfs_reflink_allocate_cow() - so would you prefer to create a bool
@convert_now inside xfs_reflink_allocate_cow() and pass that bool as
before? Or pass the flags all the way down to end users of @convert_now?
if (error)
goto out_unlock;
if (shared)
diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
index 8428f7b26ee6..3dab3ba900a3 100644
--- a/fs/xfs/xfs_reflink.c
+++ b/fs/xfs/xfs_reflink.c
@@ -435,7 +435,8 @@ xfs_reflink_fill_cow_hole(
struct xfs_bmbt_irec *cmap,
bool *shared,
uint *lockmode,
- bool convert_now)
+ bool convert_now,
+ bool atomic)
...but this can come later.
Do you mean that this would just be a new flag to set?
> Also, is atomic==true only for the> ATOMIC_SW operation?
Right, so I think that the variable (or new flag) can be renamed for that.
I think so, but that's the unfortunate thing about
booleans.
{
struct xfs_mount *mp = ip->i_mount;
struct xfs_trans *tp;
@@ -466,7 +467,7 @@ xfs_reflink_fill_cow_hole(
*lockmode = XFS_ILOCK_EXCL;
error = xfs_find_trim_cow_extent(ip, imap, cmap, shared, &found);
- if (error || !*shared)
+ if (error || (!*shared && !atomic))
goto out_trans_cancel;
if (found) {
@@ -566,7 +567,8 @@ xfs_reflink_allocate_cow(
struct xfs_bmbt_irec *cmap,
bool *shared,
uint *lockmode,
- bool convert_now)
+ bool convert_now,
+ bool atomic)
Nit: ^ space before tab.
ok
If the answer to the question above is 'yes' then with that nit fixed,
Reviewed-by: "Darrick J. Wong" <djwong@xxxxxxxxxx>
Thanks, but I will wait for your feedback to decide whether to pick that up.
John
