From: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
This (bcc) patch modifies bcc so that we can override some function
return values. We then create a new python script containing custom
logic to decide where a file's data goes (rtdev or datadev) and inject
the compiled eBPF code into the kernel.
Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
---
src/cc/compat/linux/bpf.h | 7 ++
src/cc/compat/linux/virtual_bpf.h | 3 +
src/cc/export/helpers.h | 2 +
tools/xfs_rt.py | 130 +++++++++++++++++++++++++++++++++++++
4 files changed, 140 insertions(+), 2 deletions(-)
create mode 100755 tools/xfs_rt.py
diff --git a/src/cc/compat/linux/bpf.h b/src/cc/compat/linux/bpf.h
index f896897..5a3ec0b 100644
--- a/src/cc/compat/linux/bpf.h
+++ b/src/cc/compat/linux/bpf.h
@@ -677,6 +677,10 @@ union bpf_attr {
* @buf: buf to fill
* @buf_size: size of the buf
* Return : 0 on success or negative error code
+ *
+ * int bpf_override_return(pt_regs, rc)
+ * @pt_regs: pointer to struct pt_regs
+ * @rc: the return value to set
*/
#define __BPF_FUNC_MAPPER(FN) \
FN(unspec), \
@@ -736,7 +740,8 @@ union bpf_attr {
FN(xdp_adjust_meta), \
FN(perf_event_read_value), \
FN(perf_prog_read_value), \
- FN(getsockopt),
+ FN(getsockopt), \
+ FN(override_return),
/* integer value in 'imm' field of BPF_CALL instruction selects which helper
* function eBPF program intends to call
diff --git a/src/cc/compat/linux/virtual_bpf.h b/src/cc/compat/linux/virtual_bpf.h
index a2bcf07..7fbc365 100644
--- a/src/cc/compat/linux/virtual_bpf.h
+++ b/src/cc/compat/linux/virtual_bpf.h
@@ -735,7 +735,8 @@ union bpf_attr {
FN(xdp_adjust_meta), \
FN(perf_event_read_value), \
FN(perf_prog_read_value), \
- FN(getsockopt),
+ FN(getsockopt), \
+ FN(override_return),
/* integer value in 'imm' field of BPF_CALL instruction selects which helper
* function eBPF program intends to call
diff --git a/src/cc/export/helpers.h b/src/cc/export/helpers.h
index 2b64ee8..571191e 100644
--- a/src/cc/export/helpers.h
+++ b/src/cc/export/helpers.h
@@ -204,6 +204,8 @@ static int (*bpf_probe_read)(void *dst, u64 size, const void *unsafe_ptr) =
(void *) BPF_FUNC_probe_read;
static u64 (*bpf_ktime_get_ns)(void) =
(void *) BPF_FUNC_ktime_get_ns;
+static void (*bpf_override_return)(void *ctx, unsigned long rc) =
+ (void *) BPF_FUNC_override_return;
static u32 (*bpf_get_prandom_u32)(void) =
(void *) BPF_FUNC_get_prandom_u32;
static int (*bpf_trace_printk_)(const char *fmt, u64 fmt_size, ...) =
diff --git a/tools/xfs_rt.py b/tools/xfs_rt.py
new file mode 100755
index 0000000..b44fa14
--- /dev/null
+++ b/tools/xfs_rt.py
@@ -0,0 +1,130 @@
+#!/usr/bin/python
+# @lint-avoid-python-3-compatibility-imports
+#
+# xfs_rt Decide on file data block device placement via custom algorithm.
+# Uses XFS hacks to inject... stuff.
+#
+# Copyright 2017 Oracle, Inc.
+# Licensed under the Apache License, Version 2.0 (the "License")
+
+from __future__ import print_function
+from bcc import BPF
+import argparse
+from time import sleep, strftime
+import ctypes as ct
+
+# arguments
+examples = """examples:
+ ./xfs_rt
+"""
+parser = argparse.ArgumentParser(
+ description="Custom placement of data file blocks on XFS",
+ formatter_class=argparse.RawDescriptionHelpFormatter,
+ epilog=examples)
+args = parser.parse_args()
+debug = 0
+
+# define BPF program
+bpf_text = """
+#include <uapi/linux/ptrace.h>
+#include <linux/fs.h>
+
+struct xfs_fsop_geom {
+ __u32 blocksize; /* filesystem (data) block size */
+ __u32 rtextsize; /* realtime extent size */
+ __u32 agblocks; /* fsblocks in an AG */
+ __u32 agcount; /* number of allocation groups */
+ __u32 logblocks; /* fsblocks in the log */
+ __u32 sectsize; /* (data) sector size, bytes */
+ __u32 inodesize; /* inode size in bytes */
+ __u32 imaxpct; /* max allowed inode space(%) */
+ __u64 datablocks; /* fsblocks in data subvolume */
+ __u64 rtblocks; /* fsblocks in realtime subvol */
+ __u64 rtextents; /* rt extents in realtime subvol*/
+ __u64 logstart; /* starting fsblock of the log */
+ unsigned char uuid[16]; /* unique id of the filesystem */
+ __u32 sunit; /* stripe unit, fsblocks */
+ __u32 swidth; /* stripe width, fsblocks */
+ __s32 version; /* structure version */
+ __u32 flags; /* superblock version flags */
+ __u32 logsectsize; /* log sector size, bytes */
+ __u32 rtsectsize; /* realtime sector size, bytes */
+ __u32 dirblocksize; /* directory block size, bytes */
+ __u32 logsunit; /* log stripe unit, bytes */
+};
+
+/* Output for XFS_FS_COUNTS */
+struct xfs_fsop_counts {
+ __u64 freedata; /* free data section blocks */
+ __u64 freertx; /* free rt extents */
+ __u64 freeino; /* free inodes */
+ __u64 allocino; /* total allocated inodes */
+};
+
+typedef unsigned long long xfs_ino_t;
+
+int
+xfs_hack_filter_iflags_begin(
+ struct pt_regs *ctx,
+ struct xfs_fsop_geom *geo,
+ struct xfs_fsop_counts *stats,
+ xfs_ino_t ino,
+ loff_t offset,
+ loff_t length,
+ uint xflags)
+{
+ bool use_rt = false;
+
+#if 0
+ bpf_trace_printk("B: off=%llu len=%llu xflags=0x%x\\n", offset, length, xflags);
+ bpf_trace_printk("B: dblocks=%llu rblocks=%llu\\n", geo->datablocks, geo->rtblocks);
+ bpf_trace_printk("B: dfree=%llu rfree=%llu\\n", stats->freedata, stats->freertx);
+#endif
+
+ /*
+ * If the first allocation request is for >64k then we assume this
+ * is a "large" file and push it to the rt device.
+ */
+ if (length >= 65536)
+ use_rt = true;
+
+ /*
+ * Redirect files to the 'other' device if the chosen one is more
+ * than 80% full.
+ */
+ if (use_rt && stats->freertx < geo->rtblocks / 5)
+ use_rt = false;
+ else if (!use_rt && stats->freedata < geo->datablocks / 5)
+ use_rt = true;
+
+ if (use_rt)
+ xflags |= FS_XFLAG_REALTIME;
+ else
+ xflags &= ~FS_XFLAG_REALTIME;
+
+ bpf_override_return(ctx, xflags);
+ return 0;
+}
+
+"""
+if debug:
+ print(bpf_text)
+
+# initialize BPF
+b = BPF(text=bpf_text)
+
+# common file functions
+b.attach_kprobe(event="xfs_hack_filter_iflags", fn_name="xfs_hack_filter_iflags_begin")
+
+print("BPF HACKING XFS... Hit Ctrl-C to end.")
+
+# output
+exiting = 0
+while (1):
+ try:
+ sleep(99999999)
+ except KeyboardInterrupt:
+ exiting = 1
+
+ if exiting:
+ exit()
--
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