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 --- tools/testing/radix-tree/xarray.c | 30 ++++++++++++++++++++++++++++++ 1 file changed, 30 insertions(+) create mode 100644 tools/testing/radix-tree/xarray.c (limited to 'tools/testing/radix-tree/xarray.c') diff --git a/tools/testing/radix-tree/xarray.c b/tools/testing/radix-tree/xarray.c new file mode 100644 index 000000000..253208a85 --- /dev/null +++ b/tools/testing/radix-tree/xarray.c @@ -0,0 +1,30 @@ +// SPDX-License-Identifier: GPL-2.0+ +/* + * xarray.c: Userspace shim for XArray test-suite + * Copyright (c) 2018 Matthew Wilcox + */ + +#include "xarray-shared.h" +#include "test.h" + +#undef XA_DEBUG +#include "../../../lib/test_xarray.c" + +void xarray_tests(void) +{ + xarray_checks(); + xarray_exit(); +} + +int __weak main(void) +{ + rcu_register_thread(); + radix_tree_init(); + xarray_tests(); + radix_tree_cpu_dead(1); + rcu_barrier(); + if (nr_allocated) + printf("nr_allocated = %d\n", nr_allocated); + rcu_unregister_thread(); + return 0; +} -- cgit v1.3.1