ext4: use prandom_u32() instead of get_random_bytes()
Many of the uses of get_random_bytes() do not actually need
cryptographically secure random numbers. Replace those uses with a
call to prandom_u32(), which is faster and which doesn't consume
entropy from the /dev/random driver.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c
index 137193f..0ee59a6 100644
--- a/fs/ext4/ialloc.c
+++ b/fs/ext4/ialloc.c
@@ -432,7 +432,7 @@
ext4fs_dirhash(qstr->name, qstr->len, &hinfo);
grp = hinfo.hash;
} else
- get_random_bytes(&grp, sizeof(grp));
+ grp = prandom_u32();
parent_group = (unsigned)grp % ngroups;
for (i = 0; i < ngroups; i++) {
g = (parent_group + i) % ngroups;
diff --git a/fs/ext4/mmp.c b/fs/ext4/mmp.c
index 214461e..04434ad 100644
--- a/fs/ext4/mmp.c
+++ b/fs/ext4/mmp.c
@@ -259,7 +259,7 @@
u32 new_seq;
do {
- get_random_bytes(&new_seq, sizeof(u32));
+ new_seq = prandom_u32();
} while (new_seq > EXT4_MMP_SEQ_MAX);
return new_seq;
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index d3a857bf..c977f4e 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -3068,7 +3068,6 @@
{
struct ext4_sb_info *sbi = EXT4_SB(sb);
struct ext4_li_request *elr;
- unsigned long rnd;
elr = kzalloc(sizeof(*elr), GFP_KERNEL);
if (!elr)
@@ -3083,10 +3082,8 @@
* spread the inode table initialization requests
* better.
*/
- get_random_bytes(&rnd, sizeof(rnd));
- elr->lr_next_sched = jiffies + (unsigned long)rnd %
- (EXT4_DEF_LI_MAX_START_DELAY * HZ);
-
+ elr->lr_next_sched = jiffies + (prandom_u32() %
+ (EXT4_DEF_LI_MAX_START_DELAY * HZ));
return elr;
}
