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ceph: fix deadlock or deadcode of misusing dget()

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[ Upstream commit b493ad718b ]

The lock order is incorrect between denty and its parent, we should
always make sure that the parent get the lock first.

But since this deadcode is never used and the parent dir will always
be set from the callers, let's just remove it.

Link: https://lore.kernel.org/r/20231116081919.GZ1957730@ZenIV
Reported-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Xiubo Li <xiubli@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Xiubo Li 2023-11-17 13:26:18 +08:00 committed by Greg Kroah-Hartman
parent 692ead237d
commit 7f2649c942
1 changed files with 3 additions and 6 deletions
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9
fs/ceph/caps.c
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@ -4597,12 +4597,14 @@ int ceph_encode_dentry_release(void **p, struct dentry *dentry,
struct inode *dir,
int mds, int drop, int unless)
{
struct dentry *parent = NULL;
struct ceph_mds_request_release *rel = *p;
struct ceph_dentry_info *di = ceph_dentry(dentry);
int force = 0;
int ret;
/* This shouldn't happen */
BUG_ON(!dir);
/*
* force an record for the directory caps if we have a dentry lease.
* this is racy (can't take i_ceph_lock and d_lock together), but it
@ -4612,14 +4614,9 @@ int ceph_encode_dentry_release(void **p, struct dentry *dentry,
spin_lock(&dentry->d_lock);
if (di->lease_session && di->lease_session->s_mds == mds)
force = 1;
if (!dir) {
parent = dget(dentry->d_parent);
dir = d_inode(parent);
}
spin_unlock(&dentry->d_lock);
ret = ceph_encode_inode_release(p, dir, mds, drop, unless, force);
dput(parent);
spin_lock(&dentry->d_lock);
if (ret && di->lease_session && di->lease_session->s_mds == mds) {