ext4: Make the length of the mb_history file tunable
In memory-constrained systems with many partitions, the ~68K for each
partition for the mb_history buffer can be excessive.
This patch adds a new mount option, mb_history_length, as well as a
way of setting the default via a module parameter (or via a sysfs
parameter in /sys/module/ext4/parameter/default_mb_history_length).
If the mb_history_length is set to zero, the mb_history facility is
disabled entirely.
Signed-off-by: Curt Wohlgemuth <curtw@google.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index dbd47ea..df75855 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -2413,7 +2413,8 @@
if (sbi->s_proc != NULL) {
remove_proc_entry("mb_groups", sbi->s_proc);
- remove_proc_entry("mb_history", sbi->s_proc);
+ if (sbi->s_mb_history_max)
+ remove_proc_entry("mb_history", sbi->s_proc);
}
kfree(sbi->s_mb_history);
}
@@ -2424,17 +2425,17 @@
int i;
if (sbi->s_proc != NULL) {
- proc_create_data("mb_history", S_IRUGO, sbi->s_proc,
- &ext4_mb_seq_history_fops, sb);
+ if (sbi->s_mb_history_max)
+ proc_create_data("mb_history", S_IRUGO, sbi->s_proc,
+ &ext4_mb_seq_history_fops, sb);
proc_create_data("mb_groups", S_IRUGO, sbi->s_proc,
&ext4_mb_seq_groups_fops, sb);
}
- sbi->s_mb_history_max = 1000;
sbi->s_mb_history_cur = 0;
spin_lock_init(&sbi->s_mb_history_lock);
i = sbi->s_mb_history_max * sizeof(struct ext4_mb_history);
- sbi->s_mb_history = kzalloc(i, GFP_KERNEL);
+ sbi->s_mb_history = i ? kzalloc(i, GFP_KERNEL) : NULL;
/* if we can't allocate history, then we simple won't use it */
}
@@ -2444,7 +2445,7 @@
struct ext4_sb_info *sbi = EXT4_SB(ac->ac_sb);
struct ext4_mb_history h;
- if (unlikely(sbi->s_mb_history == NULL))
+ if (sbi->s_mb_history == NULL)
return;
if (!(ac->ac_op & sbi->s_mb_history_filter))