From: Shiyang Ruan <ruansy.fnst@xxxxxxxxxxx> commit e900ba10d15041a6236cc75778cc6e06c3590a58 upstream. In an dedupe comparison iter loop, the length of iomap_iter decreases because it implies the remaining length after each iteration. The dedupe command will fail with -EIO if the range is larger than one page size and not aligned to the page size. Also report warning in dmesg: [ 4338.498374] ------------[ cut here ]------------ [ 4338.498689] WARNING: CPU: 3 PID: 1415645 at fs/iomap/iter.c:16 ... The compare function should use the min length of the current iters, not the total length. Link: https://lkml.kernel.org/r/1679469958-2-1-git-send-email-ruansy.fnst@xxxxxxxxxxx Fixes: 0e79e3736d54 ("fsdax: dedupe: iter two files at the same time") Signed-off-by: Shiyang Ruan <ruansy.fnst@xxxxxxxxxxx> Reviewed-by: Darrick J. Wong <djwong@xxxxxxxxxx> Cc: Dan Williams <dan.j.williams@xxxxxxxxx> Cc: Jan Kara <jack@xxxxxxx> Cc: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- fs/dax.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/fs/dax.c +++ b/fs/dax.c @@ -2022,8 +2022,8 @@ int dax_dedupe_file_range_compare(struct while ((ret = iomap_iter(&src_iter, ops)) > 0 && (ret = iomap_iter(&dst_iter, ops)) > 0) { - compared = dax_range_compare_iter(&src_iter, &dst_iter, len, - same); + compared = dax_range_compare_iter(&src_iter, &dst_iter, + min(src_iter.len, dst_iter.len), same); if (compared < 0) return ret; src_iter.processed = dst_iter.processed = compared;
