From 3af870aedbff10bfed220e280b57a405e972229f Mon Sep 17 00:00:00 2001 From: Mike Snitzer Date: Wed, 26 Nov 2025 01:01:25 -0500 Subject: [PATCH] nfs/localio: fix regression due to out-of-order __put_cred Commit f2060bdc21d7 ("nfs/localio: add refcounting for each iocb IO associated with NFS pgio header") inadvertantly reintroduced the same potential for __put_cred() triggering BUG_ON(cred == current->cred) that commit 992203a1fba5 ("nfs/localio: restore creds before releasing pageio data") fixed. Fix this by saving and restoring the cred around each {read,write}_iter call within the respective for loop of nfs_local_call_{read,write} using scoped_with_creds(). NOTE: this fix started by first reverting the following commits: 94afb627dfc2 ("nfs: use credential guards in nfs_local_call_read()") bff3c841f7bd ("nfs: use credential guards in nfs_local_call_write()") 1d18101a644e ("Merge tag 'kernel-6.19-rc1.cred' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs") followed by narrowly fixing the cred lifetime issue by using scoped_with_creds(). In doing so, this commit's changes appear more extensive than they really are (as evidenced by comparing to v6.18's fs/nfs/localio.c). Reported-by: Zorro Lang Signed-off-by: Mike Snitzer Acked-by: Trond Myklebust Reviewed-by: Christian Brauner Link: https://lore.kernel.org/linux-next/20251205111942.4150b06f@canb.auug.org.au/ Signed-off-by: Linus Torvalds --- fs/nfs/localio.c | 48 +++++++++++++++++------------------------------- 1 file changed, 17 insertions(+), 31 deletions(-) diff --git a/fs/nfs/localio.c b/fs/nfs/localio.c index 49ed90c6b9f2..f33bfa7b58e6 100644 --- a/fs/nfs/localio.c +++ b/fs/nfs/localio.c @@ -615,8 +615,11 @@ static void nfs_local_read_aio_complete(struct kiocb *kiocb, long ret) nfs_local_pgio_aio_complete(iocb); /* Calls nfs_local_read_aio_complete_work */ } -static void do_nfs_local_call_read(struct nfs_local_kiocb *iocb, struct file *filp) +static void nfs_local_call_read(struct work_struct *work) { + struct nfs_local_kiocb *iocb = + container_of(work, struct nfs_local_kiocb, work); + struct file *filp = iocb->kiocb.ki_filp; bool force_done = false; ssize_t status; int n_iters; @@ -633,7 +636,9 @@ static void do_nfs_local_call_read(struct nfs_local_kiocb *iocb, struct file *fi } else iocb->kiocb.ki_flags &= ~IOCB_DIRECT; - status = filp->f_op->read_iter(&iocb->kiocb, &iocb->iters[i]); + scoped_with_creds(filp->f_cred) + status = filp->f_op->read_iter(&iocb->kiocb, &iocb->iters[i]); + if (status != -EIOCBQUEUED) { if (unlikely(status >= 0 && status < iocb->iters[i].count)) force_done = true; /* Partial read */ @@ -645,16 +650,6 @@ static void do_nfs_local_call_read(struct nfs_local_kiocb *iocb, struct file *fi } } -static void nfs_local_call_read(struct work_struct *work) -{ - struct nfs_local_kiocb *iocb = - container_of(work, struct nfs_local_kiocb, work); - struct file *filp = iocb->kiocb.ki_filp; - - scoped_with_creds(filp->f_cred) - do_nfs_local_call_read(iocb, filp); -} - static int nfs_local_do_read(struct nfs_local_kiocb *iocb, const struct rpc_call_ops *call_ops) @@ -822,13 +817,18 @@ static void nfs_local_write_aio_complete(struct kiocb *kiocb, long ret) nfs_local_pgio_aio_complete(iocb); /* Calls nfs_local_write_aio_complete_work */ } -static ssize_t do_nfs_local_call_write(struct nfs_local_kiocb *iocb, - struct file *filp) +static void nfs_local_call_write(struct work_struct *work) { + struct nfs_local_kiocb *iocb = + container_of(work, struct nfs_local_kiocb, work); + struct file *filp = iocb->kiocb.ki_filp; + unsigned long old_flags = current->flags; bool force_done = false; ssize_t status; int n_iters; + current->flags |= PF_LOCAL_THROTTLE | PF_MEMALLOC_NOIO; + file_start_write(filp); n_iters = atomic_read(&iocb->n_iters); for (int i = 0; i < n_iters ; i++) { @@ -842,7 +842,9 @@ static ssize_t do_nfs_local_call_write(struct nfs_local_kiocb *iocb, } else iocb->kiocb.ki_flags &= ~IOCB_DIRECT; - status = filp->f_op->write_iter(&iocb->kiocb, &iocb->iters[i]); + scoped_with_creds(filp->f_cred) + status = filp->f_op->write_iter(&iocb->kiocb, &iocb->iters[i]); + if (status != -EIOCBQUEUED) { if (unlikely(status >= 0 && status < iocb->iters[i].count)) force_done = true; /* Partial write */ @@ -854,22 +856,6 @@ static ssize_t do_nfs_local_call_write(struct nfs_local_kiocb *iocb, } file_end_write(filp); - return status; -} - -static void nfs_local_call_write(struct work_struct *work) -{ - struct nfs_local_kiocb *iocb = - container_of(work, struct nfs_local_kiocb, work); - struct file *filp = iocb->kiocb.ki_filp; - unsigned long old_flags = current->flags; - ssize_t status; - - current->flags |= PF_LOCAL_THROTTLE | PF_MEMALLOC_NOIO; - - scoped_with_creds(filp->f_cred) - status = do_nfs_local_call_write(iocb, filp); - current->flags = old_flags; }