6.1-stable review patch. If anyone has any objections, please let me know.
------------------
From: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
commit f63955721a8020e979b99cc417dcb6da3106aa24 upstream.
We are not allowed to call pnfs_mark_matching_lsegs_return() without
also holding a reference to the layout header, since doing so could lead
to the reference count going to zero when we call
pnfs_layout_remove_lseg(). This again can lead to a hang when we get to
nfs4_evict_inode() and are unable to clear the layout pointer.
pnfs_layout_return_unused_byserver() is guilty of this behaviour, and
has been seen to trigger the refcount warning prior to a hang.
Fixes: b6d49ecd1081 ("NFSv4: Fix a pNFS layout related use-after-free race when freeing the inode")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
Signed-off-by: Anna Schumaker <Anna.Schumaker@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/nfs/pnfs.c | 33 +++++++++++++++++++++++----------
1 file changed, 23 insertions(+), 10 deletions(-)
--- a/fs/nfs/pnfs.c
+++ b/fs/nfs/pnfs.c
@@ -2634,31 +2634,44 @@ pnfs_should_return_unused_layout(struct
return mode == 0;
}
-static int
-pnfs_layout_return_unused_byserver(struct nfs_server *server, void *data)
+static int pnfs_layout_return_unused_byserver(struct nfs_server *server,
+ void *data)
{
const struct pnfs_layout_range *range = data;
+ const struct cred *cred;
struct pnfs_layout_hdr *lo;
struct inode *inode;
+ nfs4_stateid stateid;
+ enum pnfs_iomode iomode;
+
restart:
rcu_read_lock();
list_for_each_entry_rcu(lo, &server->layouts, plh_layouts) {
- if (!pnfs_layout_can_be_returned(lo) ||
+ inode = lo->plh_inode;
+ if (!inode || !pnfs_layout_can_be_returned(lo) ||
test_bit(NFS_LAYOUT_RETURN_REQUESTED, &lo->plh_flags))
continue;
- inode = lo->plh_inode;
spin_lock(&inode->i_lock);
- if (!pnfs_should_return_unused_layout(lo, range)) {
+ if (!lo->plh_inode ||
+ !pnfs_should_return_unused_layout(lo, range)) {
spin_unlock(&inode->i_lock);
continue;
}
+ pnfs_get_layout_hdr(lo);
+ pnfs_set_plh_return_info(lo, range->iomode, 0);
+ if (pnfs_mark_matching_lsegs_return(lo, &lo->plh_return_segs,
+ range, 0) != 0 ||
+ !pnfs_prepare_layoutreturn(lo, &stateid, &cred, &iomode)) {
+ spin_unlock(&inode->i_lock);
+ rcu_read_unlock();
+ pnfs_put_layout_hdr(lo);
+ cond_resched();
+ goto restart;
+ }
spin_unlock(&inode->i_lock);
- inode = pnfs_grab_inode_layout_hdr(lo);
- if (!inode)
- continue;
rcu_read_unlock();
- pnfs_mark_layout_for_return(inode, range);
- iput(inode);
+ pnfs_send_layoutreturn(lo, &stateid, &cred, iomode, false);
+ pnfs_put_layout_hdr(lo);
cond_resched();
goto restart;
}
