mirror of
https://github.com/versity/scoutfs.git
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Add support for printing kernel traces
Add a 'trace' command which uses the debugfs file created by the scoutfs kernel module to read and print trace messages. Signed-off-by: Zach Brown <zab@versity.com>
This commit is contained in:
Zach Brown
30
utils/src/ioctl.h
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30
utils/src/ioctl.h
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@@ -0,0 +1,30 @@
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#ifndef _SCOUTFS_IOCTL_H_
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#define _SCOUTFS_IOCTL_H_
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/* XXX I have no idea how these are chosen. */
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#define SCOUTFS_IOCTL_MAGIC 's'
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struct scoutfs_ioctl_buf {
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__u64 ptr;
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__s32 len;
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} __packed;
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/*
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* Fills the buffer with a packed array of format strings. Trace records
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* refer to the format strings in the buffer by their byte offset.
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*/
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#define SCOUTFS_IOC_GET_TRACE_FORMATS _IOW(SCOUTFS_IOCTL_MAGIC, 1, \
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struct scoutfs_ioctl_buf)
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struct scoutfs_trace_record {
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__u16 format_off;
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__u8 nr;
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__u8 data[0];
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} __packed;
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/*
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* Fills the buffer with trace records.
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*/
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#define SCOUTFS_IOC_GET_TRACE_RECORDS _IOW(SCOUTFS_IOCTL_MAGIC, 2, \
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struct scoutfs_ioctl_buf)
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#endif
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@@ -24,12 +24,14 @@ extern unsigned int __builtin_ia32_crc32qi(unsigned int, unsigned char);
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typedef unsigned char u8;
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typedef unsigned short u16;
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typedef unsigned int u32;
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typedef int s32;
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typedef unsigned long long u64;
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typedef signed long long s64;
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typedef u8 __u8;
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typedef u16 __u16;
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typedef u32 __u32;
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typedef s32 __s32;
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typedef u64 __u64;
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typedef u16 __bitwise __le16;
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169
utils/src/trace.c
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169
utils/src/trace.c
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@@ -0,0 +1,169 @@
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#include <unistd.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <sys/ioctl.h>
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#include <fcntl.h>
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#include <errno.h>
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#include <string.h>
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#include "sparse.h"
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#include "util.h"
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#include "ioctl.h"
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#include "cmd.h"
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static int get_ibuf(int fd, int cmd, struct scoutfs_ioctl_buf *ibuf)
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{
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int ret;
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ibuf->ptr = 0;
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ret = 1024 * 1024;
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do {
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ibuf->len = ret;
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if (ibuf->ptr)
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free((void *)(intptr_t)ibuf->ptr);
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ibuf->ptr = (intptr_t)malloc(ibuf->len);
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if (!ibuf->ptr) {
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ret = -errno;
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fprintf(stderr, "allocate %d bytes failed: %s (%d)\n",
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ibuf->len, strerror(errno), errno);
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break;
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}
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ret = ioctl(fd, cmd, ibuf);
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if (ret < 0) {
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ret = -errno;
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fprintf(stderr, "ioctl cmd %u failed: %s (%d)\n",
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cmd, strerror(errno), errno);
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break;
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}
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} while (ret > ibuf->len);
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if (ret >= 0) {
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ibuf->len = ret;
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ret = 0;
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}
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return ret;
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}
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static int decode_u64_bytes(struct scoutfs_trace_record *rec, u64 *args)
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{
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u8 *data;
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int shift;
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u64 val;
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int i;
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data = rec->data;
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for (i = 0; i < rec->nr; i++) {
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val = 0;
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shift = 0;
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for (;;) {
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val |= (u64)(*data & 127) << shift;
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if (!((*(data++)) & 128))
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break;
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shift += 7;
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}
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args[i] = val;
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}
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return data - rec->data;
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}
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/* MY EYES */
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static void printf_nr_args(char *fmt, int nr, u64 *args)
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{
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switch(nr) {
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case 0: printf(fmt); break;
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case 1: printf(fmt, args[0]); break;
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case 2: printf(fmt, args[0], args[1]); break;
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case 3: printf(fmt, args[0], args[1], args[2]); break;
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case 4: printf(fmt, args[0], args[1], args[2], args[3]); break;
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case 5: printf(fmt, args[0], args[1], args[2], args[3], args[4]); break;
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case 6: printf(fmt, args[0], args[1], args[2], args[3], args[4],
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args[5]); break;
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case 7: printf(fmt, args[0], args[1], args[2], args[3], args[4],
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args[5], args[6]); break;
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case 8: printf(fmt, args[0], args[1], args[2], args[3], args[4],
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args[5], args[6], args[7]); break;
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case 9: printf(fmt, args[0], args[1], args[2], args[3], args[4],
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args[5], args[6], args[7], args[8]); break;
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case 10: printf(fmt, args[0], args[1], args[2], args[3], args[4],
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args[5], args[6], args[7], args[8], args[9]); break;
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case 11: printf(fmt, args[0], args[1], args[2], args[3], args[4],
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args[5], args[6], args[7], args[8], args[9],
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args[10]); break;
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case 12: printf(fmt, args[0], args[1], args[2], args[3], args[4],
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args[5], args[6], args[7], args[8], args[9],
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args[10], args[11]); break;
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case 13: printf(fmt, args[0], args[1], args[2], args[3], args[4],
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args[5], args[6], args[7], args[8], args[9],
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args[10], args[11], args[12]); break;
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case 14: printf(fmt, args[0], args[1], args[2], args[3], args[4],
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args[5], args[6], args[7], args[8], args[9],
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args[10], args[11], args[12], args[13]); break;
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case 15: printf(fmt, args[0], args[1], args[2], args[3], args[4],
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args[5], args[6], args[7], args[8], args[9],
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args[10], args[11], args[12], args[13], args[14]); break;
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case 16: printf(fmt, args[0], args[1], args[2], args[3], args[4],
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args[5], args[6], args[7], args[8], args[9],
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args[10], args[11], args[12], args[13], args[14],
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args[15]); break;
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default:
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printf("(too many args: fmt '%s' nr %d)\n", fmt, nr);
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break;
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}
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}
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static int trace_cmd(int argc, char **argv)
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{
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char *path = "/sys/kernel/debug/scoutfs/trace";
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struct scoutfs_ioctl_buf fmts = {0,};
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struct scoutfs_ioctl_buf recs = {0,};
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struct scoutfs_trace_record *rec;
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u64 args[32]; /* absurdly huge */
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int off;
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int ret;
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int fd;
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fd = open(path, O_RDONLY);
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if (fd < 0) {
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ret = -errno;
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fprintf(stderr, "failed to open '%s': %s (%d)\n",
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path, strerror(errno), errno);
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return ret;
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}
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/*
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* Read the formats and records. Our fd on the debugfs file
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* should prevent the module from unloading which is the only
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* way the per-module formats could change.
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*/
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ret = get_ibuf(fd, SCOUTFS_IOC_GET_TRACE_FORMATS, &fmts) ?:
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get_ibuf(fd, SCOUTFS_IOC_GET_TRACE_RECORDS, &recs);
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if (ret)
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goto out;
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for (off = 0; off < recs.len; ) {
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rec = (void *)(intptr_t)(recs.ptr + off);
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off += sizeof(*rec) + decode_u64_bytes(rec, args);
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printf_nr_args((char *)fmts.ptr + rec->format_off,
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rec->nr, args);
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printf("\n");
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}
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out:
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close(fd);
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return ret;
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};
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static void __attribute__((constructor)) trace_ctor(void)
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{
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cmd_register("trace", "<device>", "print scoutfs kernel traces",
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trace_cmd);
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}
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