From: Luis Henriques lhenriques@suse.com
[ Upstream commit 878dabb64117406abd40977b87544d05bb3031fc ]
Similarly to commit 03f219041fdb ("ceph: check i_nlink while converting a file handle to dentry"), this fixes another corner case with name_to_handle_at/open_by_handle_at. The issue has been detected by xfstest generic/467, when doing:
- name_to_handle_at("/cephfs/myfile") - open("/cephfs/myfile") - unlink("/cephfs/myfile") - sync; sync; - drop caches - open_by_handle_at()
The call to open_by_handle_at should not fail because the file hasn't been deleted yet (only unlinked) and we do have a valid handle to it. -ESTALE shall be returned only if i_nlink is 0 *and* i_count is 1.
This patch also makes sure we have LINK caps before checking i_nlink.
Signed-off-by: Luis Henriques lhenriques@suse.com Reviewed-by: Jeff Layton jlayton@kernel.org Acked-by: Amir Goldstein amir73il@gmail.com Signed-off-by: Ilya Dryomov idryomov@gmail.com Signed-off-by: Sasha Levin sashal@kernel.org --- fs/ceph/export.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/fs/ceph/export.c b/fs/ceph/export.c index 79dc06881e78..e088843a7734 100644 --- a/fs/ceph/export.c +++ b/fs/ceph/export.c @@ -172,9 +172,16 @@ struct inode *ceph_lookup_inode(struct super_block *sb, u64 ino) static struct dentry *__fh_to_dentry(struct super_block *sb, u64 ino) { struct inode *inode = __lookup_inode(sb, ino); + int err; + if (IS_ERR(inode)) return ERR_CAST(inode); - if (inode->i_nlink == 0) { + /* We need LINK caps to reliably check i_nlink */ + err = ceph_do_getattr(inode, CEPH_CAP_LINK_SHARED, false); + if (err) + return ERR_PTR(err); + /* -ESTALE if inode as been unlinked and no file is open */ + if ((inode->i_nlink == 0) && (atomic_read(&inode->i_count) == 1)) { iput(inode); return ERR_PTR(-ESTALE); }