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Add fs mount point identification in 'tools/opensnoop.py' #5153

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Add fs mount point identification in 'tools/opensnoop.py' #5153

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30 changes: 26 additions & 4 deletions tools/opensnoop.py
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Original file line number Diff line number Diff line change
Expand Up @@ -103,12 +103,15 @@
#ifdef FULLPATH
#include <linux/fs_struct.h>
#include <linux/dcache.h>
#include <linux/fs.h>
#include <linux/mount.h>

#define MAX_ENTRIES 32

enum event_type {
EVENT_ENTRY,
EVENT_END,
EVENT_MOUNTPOINT,
};
#endif

Expand All @@ -126,6 +129,7 @@
int ret;
char comm[TASK_COMM_LEN];
#ifdef FULLPATH
u32 mnt_dev; // actually of type 'dev_t', which is currently a redefinition of u32 in `linux/types.h`
enum event_type type;
#endif
char name[NAME_MAX];
Expand Down Expand Up @@ -358,14 +362,18 @@
dentry = task->fs->pwd.dentry;

for (i = 1; i < MAX_ENTRIES; i++) {
bpf_probe_read_kernel(&data.name, sizeof(data.name), (void *)dentry->d_name.name);
data.type = EVENT_ENTRY;
events.perf_submit(ctx, &data, sizeof(data));


if (dentry == dentry->d_parent) { // root directory
data.type = EVENT_MOUNTPOINT;
data.mnt_dev = task->fs->pwd.mnt->mnt_sb->s_dev;
events.perf_submit(ctx, &data, sizeof(data));
break;
}

bpf_probe_read_kernel(&data.name, sizeof(data.name), (void *)dentry->d_name.name);
data.type = EVENT_ENTRY;
events.perf_submit(ctx, &data, sizeof(data));

dentry = dentry->d_parent;
}
}
Expand Down Expand Up @@ -412,6 +420,7 @@
class EventType(object):
EVENT_ENTRY = 0
EVENT_END = 1
EVENT_MOUNTPOINT = 2

entries = defaultdict(list)

Expand Down Expand Up @@ -462,13 +471,26 @@ def print_event(cpu, data, size):
paths.reverse()
printb(b"%s" % os.path.join(*paths))


if args.full_path:
try:
del(entries[event.id])
except Exception:
pass
elif event.type == EventType.EVENT_ENTRY:
entries[event.id].append(event.name)
elif event.type == EventType.EVENT_MOUNTPOINT:
dev_t = event.mnt_dev;
# get mountpoint info from /proc/self/mountinfo
with open("/proc/self/mountinfo", "r") as mountinfo:
for line in mountinfo:
parts = line.strip().split()
major, minor = map(int, parts[2].split(":"))
mountpoint = parts[4]
line_dev_t = (major << 12) | minor # reconstruct an u32 from the major:minor components of the current line_dev_t.
# 12 bits according to linux/include/kdev_t.h "MAJOR"/"MINOR" macros
if line_dev_t == dev_t:
entries[event.id].append(mountpoint.encode())

# loop with callback to print_event
b["events"].open_perf_buffer(print_event, page_cnt=args.buffer_pages)
Expand Down