[PATCH 11/11] nfs: use wait_var_event_spinlock() to wait for nfsi->layout to change.

NeilBrown
2024-12-06T02:20:14Z

The recently added interface wait_var_event_spinlock() is designed for
waiting for events that can only be checked under a spinlock.
This matches the requirements for waiting for nfsi->layout so we can
change to using wait_var_event_spinlock().

This avoids a use of plain wake_up_var() which always needs to be
checked for correct barrier usage.

Signed-off-by: NeilBrown <neilb@suse.de>
---
fs/nfs/pnfs.c | 27 +++++++++------------------
1 file changed, 9 insertions(+), 18 deletions(-)

diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
index 400f409f45fa..04be1165a1c5 100644
--- a/fs/nfs/pnfs.c
+++ b/fs/nfs/pnfs.c
@@ -306,7 +306,6 @@ void
pnfs_put_layout_hdr(struct pnfs_layout_hdr *lo)
{
struct inode *inode;
- unsigned long i_state;

if (!lo)
return;
@@ -317,12 +316,11 @@ pnfs_put_layout_hdr(struct pnfs_layout_hdr *lo)
if (!list_empty(&lo->plh_segs))
WARN_ONCE(1, "NFS: BUG unfreed layout segments.\n");
pnfs_detach_layout_hdr(lo);
- i_state = inode->i_state;
+ /* Notify pnfs_destroy_layout_final() that we're done */
+ if (inode->i_state & (I_FREEING | I_CLEAR))
+ wake_up_var_locked(lo, &inode->i_lock);
spin_unlock(&inode->i_lock);
pnfs_free_layout_hdr(lo);
- /* Notify pnfs_destroy_layout_final() that we're done */
- if (i_state & (I_FREEING | I_CLEAR))
- wake_up_var(lo);
}
}

@@ -795,23 +793,16 @@ void pnfs_destroy_layout(struct nfs_inode *nfsi)
}
EXPORT_SYMBOL_GPL(pnfs_destroy_layout);

-static bool pnfs_layout_removed(struct nfs_inode *nfsi,
- struct pnfs_layout_hdr *lo)
-{
- bool ret;
-
- spin_lock(&nfsi->vfs_inode.i_lock);
- ret = nfsi->layout != lo;
- spin_unlock(&nfsi->vfs_inode.i_lock);
- return ret;
-}
-
void pnfs_destroy_layout_final(struct nfs_inode *nfsi)
{
struct pnfs_layout_hdr *lo = __pnfs_destroy_layout(nfsi);

- if (lo)
- wait_var_event(lo, pnfs_layout_removed(nfsi, lo));
+ if (lo) {
+ spin_lock(&nfsi->vfs_inode.i_lock);
+ wait_var_event_spinlock(lo, nfsi->layout != lo,
+ &nfsi->vfs_inode.i_lock);
+ spin_unlock(&nfsi->vfs_inode.i_lock);
+ }
}

static bool
--
2.47.0