debugfs.c

  1// SPDX-License-Identifier: GPL-2.0
  2
  3#include <linux/debugfs.h>
  4
  5#include "nfsd.h"
  6
  7static struct dentry *nfsd_top_dir __read_mostly;
  8
  9/*
 10 * /sys/kernel/debug/nfsd/disable-splice-read
 11 *
 12 * Contents:
 13 *   %0: NFS READ is allowed to use page splicing
 14 *   %1: NFS READ uses only iov iter read
 15 *
 16 * The default value of this setting is zero (page splicing is
 17 * allowed). This setting takes immediate effect for all NFS
 18 * versions, all exports, and in all NFSD net namespaces.
 19 */
 20
 21static int nfsd_dsr_get(void *data, u64 *val)
 22{
 23	*val = nfsd_disable_splice_read ? 1 : 0;
 24	return 0;
 25}
 26
 27static int nfsd_dsr_set(void *data, u64 val)
 28{
 29	nfsd_disable_splice_read = (val > 0);
 30	if (!nfsd_disable_splice_read) {
 31		/*
 32		 * Must use buffered I/O if splice_read is enabled.
 33		 */
 34		nfsd_io_cache_read = NFSD_IO_BUFFERED;
 35	}
 36	return 0;
 37}
 38
 39DEFINE_DEBUGFS_ATTRIBUTE(nfsd_dsr_fops, nfsd_dsr_get, nfsd_dsr_set, "%llu\n");
 40
 41/*
 42 * /sys/kernel/debug/nfsd/io_cache_read
 43 *
 44 * Contents:
 45 *   %0: NFS READ will use buffered IO
 46 *   %1: NFS READ will use dontcache (buffered IO w/ dropbehind)
 47 *   %2: NFS READ will use direct IO
 48 *
 49 * This setting takes immediate effect for all NFS versions,
 50 * all exports, and in all NFSD net namespaces.
 51 */
 52
 53static int nfsd_io_cache_read_get(void *data, u64 *val)
 54{
 55	*val = nfsd_io_cache_read;
 56	return 0;
 57}
 58
 59static int nfsd_io_cache_read_set(void *data, u64 val)
 60{
 61	int ret = 0;
 62
 63	switch (val) {
 64	case NFSD_IO_BUFFERED:
 65		nfsd_io_cache_read = NFSD_IO_BUFFERED;
 66		break;
 67	case NFSD_IO_DONTCACHE:
 68	case NFSD_IO_DIRECT:
 69		/*
 70		 * Must disable splice_read when enabling
 71		 * NFSD_IO_DONTCACHE.
 72		 */
 73		nfsd_disable_splice_read = true;
 74		nfsd_io_cache_read = val;
 75		break;
 76	default:
 77		ret = -EINVAL;
 78		break;
 79	}
 80
 81	return ret;
 82}
 83
 84DEFINE_DEBUGFS_ATTRIBUTE(nfsd_io_cache_read_fops, nfsd_io_cache_read_get,
 85			 nfsd_io_cache_read_set, "%llu\n");
 86
 87/*
 88 * /sys/kernel/debug/nfsd/io_cache_write
 89 *
 90 * Contents:
 91 *   %0: NFS WRITE will use buffered IO
 92 *   %1: NFS WRITE will use dontcache (buffered IO w/ dropbehind)
 93 *
 94 * This setting takes immediate effect for all NFS versions,
 95 * all exports, and in all NFSD net namespaces.
 96 */
 97
 98static int nfsd_io_cache_write_get(void *data, u64 *val)
 99{
100	*val = nfsd_io_cache_write;
101	return 0;
102}
103
104static int nfsd_io_cache_write_set(void *data, u64 val)
105{
106	int ret = 0;
107
108	switch (val) {
109	case NFSD_IO_BUFFERED:
110	case NFSD_IO_DONTCACHE:
111	case NFSD_IO_DIRECT:
112		nfsd_io_cache_write = val;
113		break;
114	default:
115		ret = -EINVAL;
116		break;
117	}
118
119	return ret;
120}
121
122DEFINE_DEBUGFS_ATTRIBUTE(nfsd_io_cache_write_fops, nfsd_io_cache_write_get,
123			 nfsd_io_cache_write_set, "%llu\n");
124
125void nfsd_debugfs_exit(void)
126{
127	debugfs_remove_recursive(nfsd_top_dir);
128	nfsd_top_dir = NULL;
129}
130
131void nfsd_debugfs_init(void)
132{
133	nfsd_top_dir = debugfs_create_dir("nfsd", NULL);
134
135	debugfs_create_file("disable-splice-read", S_IWUSR | S_IRUGO,
136			    nfsd_top_dir, NULL, &nfsd_dsr_fops);
137
138	debugfs_create_file("io_cache_read", 0644, nfsd_top_dir, NULL,
139			    &nfsd_io_cache_read_fops);
140
141	debugfs_create_file("io_cache_write", 0644, nfsd_top_dir, NULL,
142			    &nfsd_io_cache_write_fops);
143}