From: David Howells dhowells@redhat.com
[ Upstream commit 3ad216ee73abc554ed8f13f4f8b70845a7bef6da ]
When afs_write_end() is called with copied == 0, it tries to set the dirty region, but there's no way to actually encode a 0-length region in the encoding in page->private.
"0,0", for example, indicates a 1-byte region at offset 0. The maths miscalculates this and sets it incorrectly.
Fix it to just do nothing but unlock and put the page in this case. We don't actually need to mark the page dirty as nothing presumably changed.
Fixes: 65dd2d6072d3 ("afs: Alter dirty range encoding in page->private") Signed-off-by: David Howells dhowells@redhat.com Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Sasha Levin sashal@kernel.org --- fs/afs/write.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/fs/afs/write.c b/fs/afs/write.c index 50371207f3273..c9195fc67fd8f 100644 --- a/fs/afs/write.c +++ b/fs/afs/write.c @@ -169,11 +169,14 @@ int afs_write_end(struct file *file, struct address_space *mapping, unsigned int f, from = pos & (PAGE_SIZE - 1); unsigned int t, to = from + copied; loff_t i_size, maybe_i_size; - int ret; + int ret = 0;
_enter("{%llx:%llu},{%lx}", vnode->fid.vid, vnode->fid.vnode, page->index);
+ if (copied == 0) + goto out; + maybe_i_size = pos + copied;
i_size = i_size_read(&vnode->vfs_inode);