Hi Alison, Thanks for the heads-up. The Sashiko complaint in v3 is about a pre-existing bug in dax_range_compare_iter() — the size parameter passed to dax_iomap_direct_access() is an absolute file offset (ALIGN(pos1 + len, PAGE_SIZE)) rather than a relative length.
This is indeed a real bug, but it is a separate issue from what this patch fixes (wrong error code propagation). I have already addressed it in a separate patch: "dax: fix dax_range_compare_iter() to use correct size and address offset" That patch fixes both the size parameter and the memcmp() addresses (missing offset_in_page()). The two patches fix independent bugs and can be applied separately. I've also replied to Sashiko. Thanks, Jianyun On Fri, Oct 16, 2026 at 9:23 AM Alison Schofield <[email protected]> wrote: > > On Thu, Oct 15, 2026 at 10:34:25PM +0800, [email protected] wrote: > > From: Jianyun Gao <[email protected]> > > > > When dax_range_compare_iter() returns a negative error code (e.g. -EIO), > > dax_dedupe_file_range_compare() incorrectly returns 'ret' which holds the > > positive return value from iomap_iter() indicating more iterations remain. > > This positive value leaks to the caller, where vfs_dedupe_file_range() > > interprets it as success (bytes_deduped = len), causing userspace to > > incorrectly believe deduplication completed. > > > > Return 'status' instead to propagate the actual error code. > > Hi Jianyun, > > I looked at merging this today but the Sashiko response stopped me. > > I do see you addressed Sashiko in v1, ignored Sashiko in v2. > If this v3 Sashiko complaint is one you've already addressed, please > reply saying so. Thanks! > > -- Alison > > > > > Fixes: 0e79e3736d54 ("fsdax: dedupe: iter two files at the same time") > > Cc: [email protected] > > Signed-off-by: Jianyun Gao <[email protected]> > > Reviewed-by: Jan Kara <[email protected]> > > Reviewed-by: "Darrick J. Wong" <[email protected]> > > --- > > Changes in v3: > > - Fix the Fixes tag to point to the commit that actually introduced > > the bug (0e79e3736d54), not the one that renamed the variable > > - Add Reviewed-by from Darrick J. Wong > > > > Link: > > https://lore.kernel.org/lkml/[email protected]/ > > # v2 > > fs/dax.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/fs/dax.c b/fs/dax.c > > index 6ba50142eeb2..1f6a4fbb97bd 100644 > > --- a/fs/dax.c > > +++ b/fs/dax.c > > @@ -2261,7 +2261,7 @@ int dax_dedupe_file_range_compare(struct inode *src, > > loff_t srcoff, > > status = dax_range_compare_iter(&src_iter, &dst_iter, > > min(src_iter.len, dst_iter.len), same); > > if (status < 0) > > - return ret; > > + return status; > > src_iter.status = dst_iter.status = status; > > } > > return ret; > > -- > > 2.34.1 > > > >
