Re: [PATCH v2 18/18] NFS: Remove unnecessary check in nfs_read_folio()
From: Matthew Wilcox <willy@infradead.org>
Date: 2023-02-23 13:23:04
On Thu, Jan 19, 2023 at 04:33:51PM -0500, trondmy@kernel.org wrote:
From: Trond Myklebust <redacted> 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.
quoted hunk ↗ jump to hunk
Reported-by: kernel test robot <redacted> Reported-by: Dan Carpenter <redacted> Signed-off-by: Trond Myklebust <redacted> --- 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