From dd05add7b2b6004c5fa3a1f276f56d8668f86b65 Mon Sep 17 00:00:00 2001 From: Paulo Alcantara Date: Sat, 26 Sep 2026 19:20:30 -0300 Subject: netfs: zero the tail of a short DIO/unbuffered read The buffered read collector zero-fills the tail of a short read that stops below the inode's i_size (netfs_clear_unread()), so a read that races an extending write still returns the expected number of bytes. The non-buffered collector path does no such thing: it just records how much was transferred. Add the same zero-fill for the non-buffered case, gated on NETFS_SREQ_CLEAR_TAIL: a subreq's source sets that flag when a short result from it is known to be safe to treat as a hole, as opposed to NETFS_SREQ_HIT_EOF, which means the read genuinely ran off the end of the file and should be reported short as-is. Only CLEAR_TAIL should zero-fill here; a real EOF must stay a real short read. No source currently sets CLEAR_TAIL on an unbuffered/DIO subrequest, so this is inert on its own -- a following change teaches cifs to set it in the one case that needs it. Fixes: e2d46f2ec332 ("netfs: Change the read result collector to only use one work item") Reviewed-by: David Howells Reviewed-by: Namjae Jeon Signed-off-by: Paulo Alcantara Cc: Christian Brauner Cc: Matthew Wilcox Cc: Ronnie Sahlberg Cc: Shyam Prasad N Cc: Tom Talpey Cc: Bharath SM Cc: stable@vger.kernel.org --- include/net/dst_ops.h | 73 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 73 insertions(+) create mode 100644 include/net/dst_ops.h (limited to 'include/net/dst_ops.h') diff --git a/include/net/dst_ops.h b/include/net/dst_ops.h new file mode 100644 index 000000000..3a9001a04 --- /dev/null +++ b/include/net/dst_ops.h @@ -0,0 +1,73 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _NET_DST_OPS_H +#define _NET_DST_OPS_H +#include +#include +#include + +struct dst_entry; +struct kmem_cachep; +struct net_device; +struct sk_buff; +struct sock; +struct net; + +struct dst_ops { + unsigned short family; + unsigned int gc_thresh; + + void (*gc)(struct dst_ops *ops); + struct dst_entry * (*check)(struct dst_entry *, __u32 cookie); + unsigned int (*default_advmss)(const struct dst_entry *); + unsigned int (*mtu)(const struct dst_entry *); + u32 * (*cow_metrics)(struct dst_entry *, unsigned long); + void (*destroy)(struct dst_entry *); + void (*ifdown)(struct dst_entry *, + struct net_device *dev); + void (*negative_advice)(struct sock *sk, struct dst_entry *); + void (*link_failure)(struct sk_buff *); + void (*update_pmtu)(struct dst_entry *dst, struct sock *sk, + struct sk_buff *skb, u32 mtu, + bool confirm_neigh); + void (*redirect)(struct dst_entry *dst, struct sock *sk, + struct sk_buff *skb); + int (*local_out)(struct net *net, struct sock *sk, struct sk_buff *skb); + struct neighbour * (*neigh_lookup)(const struct dst_entry *dst, + struct sk_buff *skb, + const void *daddr); + void (*confirm_neigh)(const struct dst_entry *dst, + const void *daddr); + + struct kmem_cache *kmem_cachep; + + struct percpu_counter pcpuc_entries ____cacheline_aligned_in_smp; +}; + +static inline int dst_entries_get_fast(struct dst_ops *dst) +{ + return percpu_counter_read_positive(&dst->pcpuc_entries); +} + +static inline int dst_entries_get_slow(struct dst_ops *dst) +{ + return percpu_counter_sum_positive(&dst->pcpuc_entries); +} + +#define DST_PERCPU_COUNTER_BATCH 32 +static inline void dst_entries_add(struct dst_ops *dst, int val) +{ + percpu_counter_add_batch(&dst->pcpuc_entries, val, + DST_PERCPU_COUNTER_BATCH); +} + +static inline int dst_entries_init(struct dst_ops *dst) +{ + return percpu_counter_init(&dst->pcpuc_entries, 0, GFP_KERNEL); +} + +static inline void dst_entries_destroy(struct dst_ops *dst) +{ + percpu_counter_destroy(&dst->pcpuc_entries); +} + +#endif -- cgit v1.3.1