| Message ID | 3545034.1619392490@warthog.procyon.org.uk (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | iov_iter: Four fixes for ITER_XARRAY | expand |
On Mon, Apr 26, 2021 at 12:14:50AM +0100, David Howells wrote: > Hi Al, > > I think this patch should include all the fixes necessary. I could merge > it in, but I think it might be better to tag it on the end as an additional > patch. Looks sane, but I wonder if it would've been better to deal with this > @@ -791,6 +791,8 @@ size_t _copy_mc_to_iter(const void *addr, size_t bytes, struct iov_iter *i) > curr_addr = (unsigned long) from; > bytes = curr_addr - s_addr - rem; > rcu_read_unlock(); > + i->iov_offset += bytes; > + i->count -= bytes; > return bytes; > } > }) by having your iterator check the return value of X callback and, having decremented .bv_len by return value, broke out of the loop. __label__ __bugger_off; xas_for_each(&xas, head, ULONG_MAX) { \ if (xas_retry(&xas, head)) \ continue; \ if (WARN_ON(xa_is_value(head))) \ break; \ if (WARN_ON(PageHuge(head))) \ break; \ for (j = (head->index < index) ? index - head->index : 0; \ j < thp_nr_pages(head); j++) { \ __v.bv_page = head + j; \ size_t left; offset = (i->xarray_start + skip) & ~PAGE_MASK; \ seg = PAGE_SIZE - offset; \ __v.bv_offset = offset; \ __v.bv_len = min(n, seg); \ left = (STEP); __v.bv_len -= left; n -= __v.bv_len; \ skip += __v.bv_len; \ if (!n || left) goto __bugger_off; } \ if (n == 0) \ break; \ } \ __bugger_off: Then rename iterate_and_advance() to __iterate_and_advance() and have #define iterate_and_advance(....., X) __iterate_and_advance(....., ((void)(X),0)) with iterate_all_kinds() using iterate_xarray(....,((void)(X),0) Then _copy_mc_to_iter() could use __iterate_and_advance(), getting rid of the need of doing anything special in case of short copy. OTOH, I can do that myself in a followup - not a problem.
On Mon, 2021-04-26 at 00:14 +0100, David Howells wrote: > Hi Al, > > I think this patch should include all the fixes necessary. I could merge > it in, but I think it might be better to tag it on the end as an additional > patch. > > David > --- > iov_iter: Four fixes for ITER_XARRAY > > Fix four things[1] in the patch that adds ITER_XARRAY[2]: > > (1) Remove the address_space struct predeclaration. This is a holdover > from when it was ITER_MAPPING. > > (2) Fix _copy_mc_to_iter() so that the xarray segment updates count and > iov_offset in the iterator before returning. > > (3) Fix iov_iter_alignment() to not loop in the xarray case. Because the > middle pages are all whole pages, only the end pages need be > considered - and this can be reduced to just looking at the start > position in the xarray and the iteration size. > > (4) Fix iov_iter_advance() to limit the size of the advance to no more > than the remaining iteration size. > > Reported-by: Al Viro <viro@zeniv.linux.org.uk> > Signed-off-by: David Howells <dhowells@redhat.com> > Link: https://lore.kernel.org/r/YIVrJT8GwLI0Wlgx@zeniv-ca.linux.org.uk [1] > Link: https://lore.kernel.org/r/161918448151.3145707.11541538916600921083.stgit@warthog.procyon.org.uk [2] > --- > include/linux/uio.h | 1 - > lib/iov_iter.c | 5 +++++ > 2 files changed, 5 insertions(+), 1 deletion(-) > > diff --git a/include/linux/uio.h b/include/linux/uio.h > index 5f5ffc45d4aa..d3ec87706d75 100644 > --- a/include/linux/uio.h > +++ b/include/linux/uio.h > @@ -10,7 +10,6 @@ > #include <uapi/linux/uio.h> > > > > > struct page; > -struct address_space; > struct pipe_inode_info; > > > > > struct kvec { > diff --git a/lib/iov_iter.c b/lib/iov_iter.c > index 44fa726a8323..61228a6c69f8 100644 > --- a/lib/iov_iter.c > +++ b/lib/iov_iter.c > @@ -791,6 +791,8 @@ size_t _copy_mc_to_iter(const void *addr, size_t bytes, struct iov_iter *i) > curr_addr = (unsigned long) from; > bytes = curr_addr - s_addr - rem; > rcu_read_unlock(); > + i->iov_offset += bytes; > + i->count -= bytes; > return bytes; > } > }) > @@ -1147,6 +1149,7 @@ void iov_iter_advance(struct iov_iter *i, size_t size) > return; > } > if (unlikely(iov_iter_is_xarray(i))) { > + size = min(size, i->count); > i->iov_offset += size; > i->count -= size; > return; > @@ -1346,6 +1349,8 @@ unsigned long iov_iter_alignment(const struct iov_iter *i) > return size | i->iov_offset; > return size; > } > + if (unlikely(iov_iter_is_xarray(i))) > + return (i->xarray_start + i->iov_offset) | i->count; > iterate_all_kinds(i, size, v, > (res |= (unsigned long)v.iov_base | v.iov_len, 0), > res |= v.bv_offset | v.bv_len, > I did a test run with your v7 pile, this patch, and my ceph fscache rework patches and it did fine. You can add: Tested-by: Jeff Layton <jlayton@redhat.com>
On Sun, Apr 25, 2021 at 7:15 PM David Howells <dhowells@redhat.com> wrote: > > Hi Al, > > I think this patch should include all the fixes necessary. I could merge > it in, but I think it might be better to tag it on the end as an additional > patch. > > David > --- > iov_iter: Four fixes for ITER_XARRAY > > Fix four things[1] in the patch that adds ITER_XARRAY[2]: > > (1) Remove the address_space struct predeclaration. This is a holdover > from when it was ITER_MAPPING. > > (2) Fix _copy_mc_to_iter() so that the xarray segment updates count and > iov_offset in the iterator before returning. > > (3) Fix iov_iter_alignment() to not loop in the xarray case. Because the > middle pages are all whole pages, only the end pages need be > considered - and this can be reduced to just looking at the start > position in the xarray and the iteration size. > > (4) Fix iov_iter_advance() to limit the size of the advance to no more > than the remaining iteration size. > > Reported-by: Al Viro <viro@zeniv.linux.org.uk> > Signed-off-by: David Howells <dhowells@redhat.com> > Link: https://lore.kernel.org/r/YIVrJT8GwLI0Wlgx@zeniv-ca.linux.org.uk [1] > Link: https://lore.kernel.org/r/161918448151.3145707.11541538916600921083.stgit@warthog.procyon.org.uk [2] > --- > include/linux/uio.h | 1 - > lib/iov_iter.c | 5 +++++ > 2 files changed, 5 insertions(+), 1 deletion(-) > > diff --git a/include/linux/uio.h b/include/linux/uio.h > index 5f5ffc45d4aa..d3ec87706d75 100644 > --- a/include/linux/uio.h > +++ b/include/linux/uio.h > @@ -10,7 +10,6 @@ > #include <uapi/linux/uio.h> > > struct page; > -struct address_space; > struct pipe_inode_info; > > struct kvec { > diff --git a/lib/iov_iter.c b/lib/iov_iter.c > index 44fa726a8323..61228a6c69f8 100644 > --- a/lib/iov_iter.c > +++ b/lib/iov_iter.c > @@ -791,6 +791,8 @@ size_t _copy_mc_to_iter(const void *addr, size_t bytes, struct iov_iter *i) > curr_addr = (unsigned long) from; > bytes = curr_addr - s_addr - rem; > rcu_read_unlock(); > + i->iov_offset += bytes; > + i->count -= bytes; > return bytes; > } > }) > @@ -1147,6 +1149,7 @@ void iov_iter_advance(struct iov_iter *i, size_t size) > return; > } > if (unlikely(iov_iter_is_xarray(i))) { > + size = min(size, i->count); > i->iov_offset += size; > i->count -= size; > return; > @@ -1346,6 +1349,8 @@ unsigned long iov_iter_alignment(const struct iov_iter *i) > return size | i->iov_offset; > return size; > } > + if (unlikely(iov_iter_is_xarray(i))) > + return (i->xarray_start + i->iov_offset) | i->count; > iterate_all_kinds(i, size, v, > (res |= (unsigned long)v.iov_base | v.iov_len, 0), > res |= v.bv_offset | v.bv_len, > You can add Tested-by: Dave Wysochanski <dwysocha@redhat.com> I added this patch on top of your v7 series then added my current NFS patches to use netfs lib. I ran xfstests with fscache enabled on NFS versions (3, 4.0, 4.1, 4.2), as well as connectathon and some unit tests.
diff --git a/include/linux/uio.h b/include/linux/uio.h index 5f5ffc45d4aa..d3ec87706d75 100644 --- a/include/linux/uio.h +++ b/include/linux/uio.h @@ -10,7 +10,6 @@ #include <uapi/linux/uio.h> struct page; -struct address_space; struct pipe_inode_info; struct kvec { diff --git a/lib/iov_iter.c b/lib/iov_iter.c index 44fa726a8323..61228a6c69f8 100644 --- a/lib/iov_iter.c +++ b/lib/iov_iter.c @@ -791,6 +791,8 @@ size_t _copy_mc_to_iter(const void *addr, size_t bytes, struct iov_iter *i) curr_addr = (unsigned long) from; bytes = curr_addr - s_addr - rem; rcu_read_unlock(); + i->iov_offset += bytes; + i->count -= bytes; return bytes; } }) @@ -1147,6 +1149,7 @@ void iov_iter_advance(struct iov_iter *i, size_t size) return; } if (unlikely(iov_iter_is_xarray(i))) { + size = min(size, i->count); i->iov_offset += size; i->count -= size; return; @@ -1346,6 +1349,8 @@ unsigned long iov_iter_alignment(const struct iov_iter *i) return size | i->iov_offset; return size; } + if (unlikely(iov_iter_is_xarray(i))) + return (i->xarray_start + i->iov_offset) | i->count; iterate_all_kinds(i, size, v, (res |= (unsigned long)v.iov_base | v.iov_len, 0), res |= v.bv_offset | v.bv_len,
Hi Al, I think this patch should include all the fixes necessary. I could merge it in, but I think it might be better to tag it on the end as an additional patch. David --- iov_iter: Four fixes for ITER_XARRAY Fix four things[1] in the patch that adds ITER_XARRAY[2]: (1) Remove the address_space struct predeclaration. This is a holdover from when it was ITER_MAPPING. (2) Fix _copy_mc_to_iter() so that the xarray segment updates count and iov_offset in the iterator before returning. (3) Fix iov_iter_alignment() to not loop in the xarray case. Because the middle pages are all whole pages, only the end pages need be considered - and this can be reduced to just looking at the start position in the xarray and the iteration size. (4) Fix iov_iter_advance() to limit the size of the advance to no more than the remaining iteration size. Reported-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: David Howells <dhowells@redhat.com> Link: https://lore.kernel.org/r/YIVrJT8GwLI0Wlgx@zeniv-ca.linux.org.uk [1] Link: https://lore.kernel.org/r/161918448151.3145707.11541538916600921083.stgit@warthog.procyon.org.uk [2] --- include/linux/uio.h | 1 - lib/iov_iter.c | 5 +++++ 2 files changed, 5 insertions(+), 1 deletion(-)