Unverified Commit 86ad1a58 authored by David Howells's avatar David Howells Committed by Christian Brauner
Browse files

nfs: Fix oops in nfs_netfs_init_request() when copying to cache 



When netfslib wants to copy some data that has just been read on behalf of
nfs, it creates a new write request and calls nfs_netfs_init_request() to
initialise it, but with a NULL file pointer.  This causes
nfs_file_open_context() to oops - however, we don't actually need the nfs
context as we're only going to write to the cache.

Fix this by just returning if we aren't given a file pointer and emit a
warning if the request was for something other than copy-to-cache.

Further, fix nfs_netfs_free_request() so that it doesn't try to free the
context if the pointer is NULL.

Fixes: ee4cdf7b ("netfs: Speed up buffered reading")
Reported-by: default avatarMax Kellermann <max.kellermann@ionos.com>
Closes: https://lore.kernel.org/r/CAKPOu+9DyMbKLhyJb7aMLDTb=Fh0T8Teb9sjuf_pze+XWT1VaQ@mail.gmail.com/


Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
Link: https://lore.kernel.org/r/20241213135013.2964079-5-dhowells@redhat.com


cc: Trond Myklebust <trondmy@kernel.org>
cc: Anna Schumaker <anna@kernel.org>
cc: Dave Wysochanski <dwysocha@redhat.com>
cc: Jeff Layton <jlayton@kernel.org>
cc: linux-nfs@vger.kernel.org
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: default avatarChristian Brauner <brauner@kernel.org>
parent 105549d0

fs/nfs/fscache.c

+8 −1
Original line number Diff line number Diff line
@@ -263,6 +263,12 @@ int nfs_netfs_readahead(struct readahead_control *ractl) 
static atomic_t nfs_netfs_debug_id;

static int nfs_netfs_init_request(struct netfs_io_request *rreq, struct file *file)

{

	if (!file) {

		if (WARN_ON_ONCE(rreq->origin != NETFS_PGPRIV2_COPY_TO_CACHE))

			return -EIO;

		return 0;

	}



	rreq->netfs_priv = get_nfs_open_context(nfs_file_open_context(file));

	rreq->debug_id = atomic_inc_return(&nfs_netfs_debug_id);

	/* [DEPRECATED] Use PG_private_2 to mark folio being written to the cache. */
@@ -274,6 +280,7 @@ static int nfs_netfs_init_request(struct netfs_io_request *rreq, struct file *fi 


static void nfs_netfs_free_request(struct netfs_io_request *rreq)

{

	if (rreq->netfs_priv)

		put_nfs_open_context(rreq->netfs_priv);

}