| Message ID | 1669908701-93-1-git-send-email-ruansy.fnst@fujitsu.com (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 0e79e3736d54bb8efbc9fb29cc3b54a132783565 |
| Headers | show |
| Series | fsdax,xfs: fix warning messages | expand |
On Thu, Dec 01, 2022 at 03:31:41PM +0000, Shiyang Ruan wrote: > The iomap_iter() on a range of one file may loop more than once. In > this case, the inner dst_iter can update its iomap but the outer > src_iter can't. This may cause the wrong remapping in filesystem. Let > them called at the same time. > > Signed-off-by: Shiyang Ruan <ruansy.fnst@fujitsu.com> Thank you for adding that explanation, it makes the problem much more obvious. :) Reviewed-by: Darrick J. Wong <djwong@kernel.org> --D > --- > fs/dax.c | 16 ++++++++-------- > 1 file changed, 8 insertions(+), 8 deletions(-) > > diff --git a/fs/dax.c b/fs/dax.c > index f1eb59bee0b5..354be56750c2 100644 > --- a/fs/dax.c > +++ b/fs/dax.c > @@ -1964,15 +1964,15 @@ int dax_dedupe_file_range_compare(struct inode *src, loff_t srcoff, > .len = len, > .flags = IOMAP_DAX, > }; > - int ret; > + int ret, compared = 0; > > - while ((ret = iomap_iter(&src_iter, ops)) > 0) { > - while ((ret = iomap_iter(&dst_iter, ops)) > 0) { > - dst_iter.processed = dax_range_compare_iter(&src_iter, > - &dst_iter, len, same); > - } > - if (ret <= 0) > - src_iter.processed = ret; > + 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); > + if (compared < 0) > + return ret; > + src_iter.processed = dst_iter.processed = compared; > } > return ret; > } > -- > 2.38.1 >
diff --git a/fs/dax.c b/fs/dax.c index f1eb59bee0b5..354be56750c2 100644 --- a/fs/dax.c +++ b/fs/dax.c @@ -1964,15 +1964,15 @@ int dax_dedupe_file_range_compare(struct inode *src, loff_t srcoff, .len = len, .flags = IOMAP_DAX, }; - int ret; + int ret, compared = 0; - while ((ret = iomap_iter(&src_iter, ops)) > 0) { - while ((ret = iomap_iter(&dst_iter, ops)) > 0) { - dst_iter.processed = dax_range_compare_iter(&src_iter, - &dst_iter, len, same); - } - if (ret <= 0) - src_iter.processed = ret; + 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); + if (compared < 0) + return ret; + src_iter.processed = dst_iter.processed = compared; } return ret; }
The iomap_iter() on a range of one file may loop more than once. In this case, the inner dst_iter can update its iomap but the outer src_iter can't. This may cause the wrong remapping in filesystem. Let them called at the same time. Signed-off-by: Shiyang Ruan <ruansy.fnst@fujitsu.com> --- fs/dax.c | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-)