[PATCH AUTOSEL 4.19 217/671] NFS/pnfs: Bulk destroy of layouts needs to be safe w.r.t. umount

Sasha Levin
2020-01-16T19:05:09Z

From: Trond Myklebust <trond.myklebust@hammerspace.com>

[ Upstream commit 5085607d209102b37b169bc94d0aa39566a9842a ]

If a bulk layout recall or a metadata server reboot coincides with a
umount, then holding a reference to an inode is unsafe unless we
also hold a reference to the super block.

Fixes: fd9a8d7160937 ("NFSv4.1: Fix bulk recall and destroy of layouts")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/nfs/pnfs.c | 33 +++++++++++++++++++++++----------
fs/nfs/pnfs.h | 1 +
2 files changed, 24 insertions(+), 10 deletions(-)

diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
index c818f9886f61..66f699e18755 100644
--- a/fs/nfs/pnfs.c
+++ b/fs/nfs/pnfs.c
@@ -758,22 +758,35 @@ static int
pnfs_layout_bulk_destroy_byserver_locked(struct nfs_client *clp,
struct nfs_server *server,
struct list_head *layout_list)
+ __must_hold(&clp->cl_lock)
+ __must_hold(RCU)
{
struct pnfs_layout_hdr *lo, *next;
struct inode *inode;

list_for_each_entry_safe(lo, next, &server->layouts, plh_layouts) {
- if (test_bit(NFS_LAYOUT_INVALID_STID, &lo->plh_flags))
+ if (test_bit(NFS_LAYOUT_INVALID_STID, &lo->plh_flags) ||
+ test_bit(NFS_LAYOUT_INODE_FREEING, &lo->plh_flags) ||
+ !list_empty(&lo->plh_bulk_destroy))
continue;
+ /* If the sb is being destroyed, just bail */
+ if (!nfs_sb_active(server->super))
+ break;
inode = igrab(lo->plh_inode);
- if (inode == NULL)
- continue;
- list_del_init(&lo->plh_layouts);
- if (pnfs_layout_add_bulk_destroy_list(inode, layout_list))
- continue;
- rcu_read_unlock();
- spin_unlock(&clp->cl_lock);
- iput(inode);
+ if (inode != NULL) {
+ list_del_init(&lo->plh_layouts);
+ if (pnfs_layout_add_bulk_destroy_list(inode,
+ layout_list))
+ continue;
+ rcu_read_unlock();
+ spin_unlock(&clp->cl_lock);
+ iput(inode);
+ } else {
+ rcu_read_unlock();
+ spin_unlock(&clp->cl_lock);
+ set_bit(NFS_LAYOUT_INODE_FREEING, &lo->plh_flags);
+ }
+ nfs_sb_deactive(server->super);
spin_lock(&clp->cl_lock);
rcu_read_lock();
return -EAGAIN;
@@ -811,7 +824,7 @@ pnfs_layout_free_bulk_destroy_list(struct list_head *layout_list,
/* Free all lsegs that are attached to commit buckets */
nfs_commit_inode(inode, 0);
pnfs_put_layout_hdr(lo);
- iput(inode);
+ nfs_iput_and_deactive(inode);
}
return ret;
}
diff --git a/fs/nfs/pnfs.h b/fs/nfs/pnfs.h
index ece367ebde69..3ba44819a88a 100644
--- a/fs/nfs/pnfs.h
+++ b/fs/nfs/pnfs.h
@@ -104,6 +104,7 @@ enum {
NFS_LAYOUT_RETURN_REQUESTED, /* Return this layout ASAP */
NFS_LAYOUT_INVALID_STID, /* layout stateid id is invalid */
NFS_LAYOUT_FIRST_LAYOUTGET, /* Serialize first layoutget */
+ NFS_LAYOUT_INODE_FREEING, /* The inode is being freed */
};

enum layoutdriver_policy_flags {
--
2.20.1