cachefiles: perform test on s_blocksize when opening cache file.

cachefiles requires that s_blocksize in the cache is not greater than
PAGE_SIZE, and performs the check every time a block is accessed.

Move the test to the place where the file is "opened", where other
file-validity tests are performed.

Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 2 insertions, 0 deletions

diff --git a/fs/cachefiles/namei.c b/fs/cachefiles/namei.c
index fc1056f5c96a..c4b893453e0e 100644
--- a/fs/cachefiles/namei.c
+++ b/fs/cachefiles/namei.c
@@ -655,6 +655,8 @@ lookup_again:
                         aops = d_backing_inode(object->dentry)->i_mapping->a_ops;
                         if (!aops->bmap)
                                 goto check_error;
+                        if (object->dentry->d_sb->s_blocksize > PAGE_SIZE)
+                                goto check_error;
 
                         object->backer = object->dentry;
                 } else {