ext4: Use tracepoints for mb_history trace file

The /proc/fs/ext4/<dev>/mb_history was maintained manually, and had a
number of problems: it required a largish amount of memory to be
allocated for each ext4 filesystem, and the s_mb_history_lock
introduced a CPU contention problem.  

By ripping out the mb_history code and replacing it with ftrace
tracepoints, and we get more functionality: timestamps, event
filtering, the ability to correlate mballoc history with other ext4
tracepoints, etc.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

1 files changed, 0 insertions, 33 deletions

diff --git a/fs/ext4/mballoc.h b/fs/ext4/mballoc.h
index 14f25f253112..0ca811061bc7 100644
--- a/fs/ext4/mballoc.h
+++ b/fs/ext4/mballoc.h
@@ -52,18 +52,8 @@ extern u8 mb_enable_debug;
 #define mb_debug(n, fmt, a...)
 #endif
 
-/*
- * with EXT4_MB_HISTORY mballoc stores last N allocations in memory
- * and you can monitor it in /proc/fs/ext4/<dev>/mb_history
- */
-#define EXT4_MB_HISTORY
 #define EXT4_MB_HISTORY_ALLOC           1       /* allocation */
 #define EXT4_MB_HISTORY_PREALLOC        2       /* preallocated blocks used */
-#define EXT4_MB_HISTORY_DISCARD         4       /* preallocation discarded */
-#define EXT4_MB_HISTORY_FREE            8       /* free */
-
-#define EXT4_MB_HISTORY_DEFAULT         (EXT4_MB_HISTORY_ALLOC | \
-                                         EXT4_MB_HISTORY_PREALLOC)
 
 /*
  * How long mballoc can look for a best extent (in found extents)
@@ -217,22 +207,6 @@ struct ext4_allocation_context {
 #define AC_STATUS_FOUND         2
 #define AC_STATUS_BREAK         3
 
-struct ext4_mb_history {
-        struct ext4_free_extent orig;   /* orig allocation */
-        struct ext4_free_extent goal;   /* goal allocation */
-        struct ext4_free_extent result; /* result allocation */
-        unsigned pid;
-        unsigned ino;
-        __u16 found;    /* how many extents have been found */
-        __u16 groups;   /* how many groups have been scanned */
-        __u16 tail;     /* what tail broke some buddy */
-        __u16 buddy;    /* buddy the tail ^^^ broke */
-        __u16 flags;
-        __u8 cr:3;      /* which phase the result extent was found at */
-        __u8 op:4;
-        __u8 merged:1;
-};
-
 struct ext4_buddy {
         struct page *bd_buddy_page;
         void *bd_buddy;
@@ -247,13 +221,6 @@ struct ext4_buddy {
 #define EXT4_MB_BITMAP(e4b)     ((e4b)->bd_bitmap)
 #define EXT4_MB_BUDDY(e4b)      ((e4b)->bd_buddy)
 
-#ifndef EXT4_MB_HISTORY
-static inline void ext4_mb_store_history(struct ext4_allocation_context *ac)
-{
-        return;
-}
-#endif
-
 #define in_range(b, first, len) ((b) >= (first) && (b) <= (first) + (len) - 1)
 
 static inline ext4_fsblk_t ext4_grp_offs_to_block(struct super_block *sb,