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 <[email protected]>
---
Hi!
(and sorry for the delay in my reply!)
So, from the discussion thread and some IRC chat with Jeff, I'm sending
v2. What changed? Everything! :-)
- Use i_count instead of __ceph_is_file_opened to check for open files
- Add call to ceph_do_getattr to make sure we have LINK caps before
accessing i_nlink
Cheers,
--
Luis
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);
}
