On Thu, Jan 19, 2023 at 04:33:51PM -0500, trondmy@xxxxxxxxxx wrote:
> From: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
>
> All the callers are expected to supply a valid struct file argument, so
> there is no need for the NULL check.
Ummm. Not sure that's true. Look at this path:
mapping_read_folio_gfp(mapping, index, gfp)
do_read_cache_folio(mapping, index, NULL, NULL, gfp)
filemap_read_folio(NULL, mapping->a_ops->read_folio, folio)
It could well be that nobody does this to an NFS file! The places where
I see this called tend to be filesystems doing it to block devices,
or filesystems doing it to their own files (eg reading a journal file
or quota file)
But I'm suspicious of static match tools claiming it can't ever happen,
and I'd like more details please. I can't find the original report.
Also, it would have been nice to be cc'd on the folio conversion patches.
> Reported-by: kernel test robot <lkp@xxxxxxxxx>
> Reported-by: Dan Carpenter <error27@xxxxxxxxx>
> Signed-off-by: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
> ---
> fs/nfs/read.c | 8 +-------
> 1 file changed, 1 insertion(+), 7 deletions(-)
>
> diff --git a/fs/nfs/read.c b/fs/nfs/read.c
> index bf4154f9b48c..c380cff4108e 100644
> --- a/fs/nfs/read.c
> +++ b/fs/nfs/read.c
> @@ -355,13 +355,7 @@ int nfs_read_folio(struct file *file, struct folio *folio)
> if (NFS_STALE(inode))
> goto out_unlock;
>
> - if (file == NULL) {
> - ret = -EBADF;
> - desc.ctx = nfs_find_open_context(inode, NULL, FMODE_READ);
> - if (desc.ctx == NULL)
> - goto out_unlock;
> - } else
> - desc.ctx = get_nfs_open_context(nfs_file_open_context(file));
> + desc.ctx = get_nfs_open_context(nfs_file_open_context(file));
>
> xchg(&desc.ctx->error, 0);
> nfs_pageio_init_read(&desc.pgio, inode, false,
> --
> 2.39.0
>
