From: Darrick J. Wong Filesystems should never provide a delayed allocation mapping to writeback; they're supposed to allocate the space before replying. This can lead to weird IO errors and crashes in the block layer if the filesystem is being malicious, or if it hadn't set iomap->dev because it's a delalloc mapping. Fix this by failing writeback on delalloc mappings. Currently no filesystems actually misbehave in this manner, but we ought to be stricter about things like that. Cc: # v5.5 Fixes: 598ecfbaa742ac ("iomap: lift the xfs writeback code to iomap") Signed-off-by: "Darrick J. Wong" --- v2: futureproof new iomap types --- fs/iomap/ioend.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) diff --git a/fs/iomap/ioend.c b/fs/iomap/ioend.c index 4d1ef8a2cee90b..60546fa14dfe4d 100644 --- a/fs/iomap/ioend.c +++ b/fs/iomap/ioend.c @@ -215,17 +215,18 @@ ssize_t iomap_add_to_ioend(struct iomap_writepage_ctx *wpc, struct folio *folio, WARN_ON_ONCE(!folio->private && map_len < dirty_len); switch (wpc->iomap.type) { - case IOMAP_INLINE: - WARN_ON_ONCE(1); - return -EIO; + case IOMAP_UNWRITTEN: + ioend_flags |= IOMAP_IOEND_UNWRITTEN; + break; + case IOMAP_MAPPED: + break; case IOMAP_HOLE: return map_len; default: - break; + WARN_ON_ONCE(1); + return -EIO; } - if (wpc->iomap.type == IOMAP_UNWRITTEN) - ioend_flags |= IOMAP_IOEND_UNWRITTEN; if (wpc->iomap.flags & IOMAP_F_SHARED) ioend_flags |= IOMAP_IOEND_SHARED; if (folio_test_dropbehind(folio))