[systemd-devel] [PATCH v3] readahead: use BTRFS_IOC_DEFRAG_RANGE

[Timofey Titovets]

Just completed TODO:
* readahead: use BTRFS_IOC_DEFRAG_RANGE instead of BTRFS_IOC_DEFRAG 
ioctl, with START_IO

commit d3fc81bd6a5a046b22600ac1204df220c93d2c15 refs/tags/v30
Author: Lennart Poettering <lennart at poettering.net>
Date:   Wed Jun 15 15:39:10 2011 +0200

     update TODO

i no add this todo in TODO list (recursively todo %), and as this my 
opinion may be not relevant with author.

As i understand start_io option force write data after defragment, 
without buffering it in memory.


v1 -> v2
Fixed spelling in TODO

v2 -> v3
Deleted todo from code
Fix compilation issues
Delete fallback code, because BTRFS_IOC_DEFRAG_RANGE supported as 2.6.29 
oldest longterm 2.6.32.63

----
  TODO                              |  1 -
  src/readahead/readahead-collect.c | 15 ++++++++++++---
  src/shared/missing.h              | 16 ++++++++++++++++
  3 files changed, 28 insertions(+), 4 deletions(-)

diff --git a/TODO b/TODO
index bfa06de..636d25f 100644
--- a/TODO
+++ b/TODO
@@ -570,7 +570,6 @@ Features:
  * readahead:
    - drop /.readahead on bigger upgrades with yum
    - move readahead files into /var (look for them with .path units?)
-  - readahead: use BTRFS_IOC_DEFRAG_RANGE instead of BTRFS_IOC_DEFRAG 
ioctl, with START_IO
    - readahead: when bumping /sys readahead variable save mtime and 
compare later to detect changes
    - readahead: make use of EXT4_IOC_MOVE_EXT, as used by 
http://e4rat.sourceforge.net/

diff --git a/src/readahead/readahead-collect.c 
b/src/readahead/readahead-collect.c
index c1afd0d..c641f9a 100644
--- a/src/readahead/readahead-collect.c
+++ b/src/readahead/readahead-collect.c
@@ -48,6 +48,10 @@
  #include <linux/btrfs.h>
  #endif

+#ifdef HAVE_BTRFS_IOCTL_H
+#include <btrfs/ioctl.h>
+#endif
+
  #ifdef HAVE_FANOTIFY_INIT
  #include <sys/fanotify.h>
  #endif
@@ -78,10 +82,15 @@ static usec_t starttime;
  #define SECTOR_TO_PTR(s) ULONG_TO_PTR((s)+1)
  #define PTR_TO_SECTOR(p) (PTR_TO_ULONG(p)-1)

-static int btrfs_defrag(int fd) {
-        struct btrfs_ioctl_vol_args data = { .fd = fd };
+static int btrfs_defrag(int fd){
+        static struct btrfs_ioctl_defrag_range_args range = {
+                .start = 0,
+                .len = (uint64_t)-1,
+                .flags = 2,
+                .extent_thresh = 1
+        };

-        return ioctl(fd, BTRFS_IOC_DEFRAG, &data);
+        return ioctl(fd, BTRFS_IOC_DEFRAG_RANGE, &range);
  }

  static int pack_file(FILE *pack, const char *fn, bool on_btrfs) {
diff --git a/src/shared/missing.h b/src/shared/missing.h
index 818d704..8f54dc8 100644
--- a/src/shared/missing.h
+++ b/src/shared/missing.h
@@ -186,6 +186,17 @@ static inline int fanotify_mark(int fanotify_fd, 
unsigned int flags, uint64_t ma
  #define BTRFS_UUID_SIZE 16
  #endif

+#ifndef HAVE_BTRFS_IOCTL_H
+struct btrfs_ioctl_defrag_range_args {
+        uint64_t start;         /* start byte = 0 */
+        uint64_t len;           /* whole file uint64_t-1 */
+        uint64_t flags;         /* start_io 2 */
+        uint32_t extent_thresh; /* rewrite extents 0 */
+        uint32_t compress_type; /* unspecified -> zlib */
+        uint32_t unused[4];     /* reserved */
+};
+#endif
+
  #ifndef HAVE_LINUX_BTRFS_H
  struct btrfs_ioctl_vol_args {
          int64_t fd;
@@ -213,6 +224,11 @@ struct btrfs_ioctl_fs_info_args {
  #define BTRFS_IOC_DEFRAG _IOW(BTRFS_IOCTL_MAGIC, 2, struct 
btrfs_ioctl_vol_args)
  #endif

+#ifndef BTRFS_IOC_DEFRAG_RANGE
+#define BTRFS_IOC_DEFRAG_RANGE _IOW(BTRFS_IOCTL_MAGIC, 16, \
+                                           struct 
btrfs_ioctl_defrag_range_args)
+#endif
+
  #ifndef BTRFS_IOC_DEV_INFO
  #define BTRFS_IOC_DEV_INFO _IOWR(BTRFS_IOCTL_MAGIC, 30, \
                                   struct btrfs_ioctl_dev_info_args)