From: Shiyang Ruan ruansy.fnst@fujitsu.com
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@fujitsu.... Fixes: 0e79e3736d54 ("fsdax: dedupe: iter two files at the same time") Signed-off-by: Shiyang Ruan ruansy.fnst@fujitsu.com Reviewed-by: Darrick J. Wong djwong@kernel.org Cc: Dan Williams dan.j.williams@intel.com Cc: Jan Kara jack@suse.cz Cc: Matthew Wilcox (Oracle) willy@infradead.org Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- 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;