shmem: move the shmem_mapping assert into shmem_get_folio_gfp

Move the check that the inode really is a shmemfs one from
shmem_read_folio_gfp to shmem_get_folio_gfp given that shmem_get_folio
can also be called from outside of shmem.c.  Also turn it into a
WARN_ON_ONCE and error return instead of BUG_ON to be less severe.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>

diff --git a/mm/shmem.c b/mm/shmem.c
index 1900916aa84d13f722d36eba3d8006106e788f63..ad533b2f0721a7ef5f28a894db31679044d2e167 100644 (file)
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1972,6 +1972,9 @@ static int shmem_get_folio_gfp(struct inode *inode, pgoff_t index,
        int error;
        bool alloced;
 
+       if (WARN_ON_ONCE(!shmem_mapping(inode->i_mapping)))
+               return -EINVAL;
+
        if (index > (MAX_LFS_FILESIZE >> PAGE_SHIFT))
                return -EFBIG;
 repeat:
@@ -4915,7 +4918,6 @@ struct folio *shmem_read_folio_gfp(struct address_space *mapping,
        struct folio *folio;
        int error;
 
-       BUG_ON(!shmem_mapping(mapping));
        error = shmem_get_folio_gfp(inode, index, &folio, SGP_CACHE,
                                    gfp, NULL, NULL);
        if (error)