ext4: count hits/misses of extent cache and expose in sysfs
The number of hits and misses for each filesystem is exposed in
/sys/fs/ext4/<dev>/extent_cache_{hits, misses}.
Tested: fsstress, manual checks.
Signed-off-by: Vivek Haldar <haldar@google.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 9a3844a..4444317 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -2035,6 +2035,7 @@
struct ext4_extent *ex)
{
struct ext4_ext_cache *cex;
+ struct ext4_sb_info *sbi;
int ret = 0;
/*
@@ -2042,6 +2043,7 @@
*/
spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
cex = &EXT4_I(inode)->i_cached_extent;
+ sbi = EXT4_SB(inode->i_sb);
/* has cache valid data? */
if (cex->ec_len == 0)
@@ -2057,6 +2059,10 @@
ret = 1;
}
errout:
+ if (!ret)
+ sbi->extent_cache_misses++;
+ else
+ sbi->extent_cache_hits++;
spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
return ret;
}
@@ -3901,4 +3907,3 @@
return error;
}
-