On Mon, Jul 12, 2021 at 1:28 PM David Howells <dhowells@xxxxxxxxxx> wrote:
>
> From: Tom Rix <trix@xxxxxxxxxx>
>
> Static analysis reports this problem
>
> write.c:773:29: warning: Assigned value is garbage or undefined
> mapping->writeback_index = next;
> ^ ~~~~
> The call to afs_writepages_region() can return without setting
> next. So check the function return before using next.
>
> Changes:
> ver #2:
> - Need to fix the range_cyclic case also[1].
>
> Fixes: e87b03f5830e ("afs: Prepare for use of THPs")
> Signed-off-by: Tom Rix <trix@xxxxxxxxxx>
> Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
> Link: https://lore.kernel.org/r/20210430155031.3287870-1-trix@xxxxxxxxxx
> Link: https://lore.kernel.org/r/162609464716.3133237.10354897554363093252.stgit@xxxxxxxxxxxxxxxxxxxxxx/ # v1
> Link: https://lore.kernel.org/r/CAB9dFdvHsLsw7CMnB+4cgciWDSqVjuij4mH3TaXnHQB8sz5rHw@xxxxxxxxxxxxxx/ [1]
> ---
>
> fs/afs/write.c | 16 +++++++++++-----
> 1 file changed, 11 insertions(+), 5 deletions(-)
>
> diff --git a/fs/afs/write.c b/fs/afs/write.c
> index 3104b62c2082..1ed62e0ccfe5 100644
> --- a/fs/afs/write.c
> +++ b/fs/afs/write.c
> @@ -771,13 +771,19 @@ int afs_writepages(struct address_space *mapping,
> if (wbc->range_cyclic) {
> start = mapping->writeback_index * PAGE_SIZE;
> ret = afs_writepages_region(mapping, wbc, start, LLONG_MAX, &next);
> - if (start > 0 && wbc->nr_to_write > 0 && ret == 0)
> - ret = afs_writepages_region(mapping, wbc, 0, start,
> - &next);
> - mapping->writeback_index = next / PAGE_SIZE;
> + if (ret == 0) {
> + mapping->writeback_index = next / PAGE_SIZE;
> + if (start > 0 && wbc->nr_to_write > 0) {
> + ret = afs_writepages_region(mapping, wbc, 0,
> + start, &next);
> + if (ret == 0)
> + mapping->writeback_index =
> + next / PAGE_SIZE;
> + }
> + }
> } else if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX) {
> ret = afs_writepages_region(mapping, wbc, 0, LLONG_MAX, &next);
> - if (wbc->nr_to_write > 0)
> + if (wbc->nr_to_write > 0 && ret == 0)
> mapping->writeback_index = next;
> } else {
> ret = afs_writepages_region(mapping, wbc,
>
>
Reviewed-by: Marc Dionne <marc.dionne@xxxxxxxxxxxx>
Marc
