p71924506
/
linux_old1
1
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

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>
This commit is contained in:
Theodore Ts'o 2013-11-08 00:14:53 -05:00
parent f275411440
commit dd1f723bf5
3 changed files with 4 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
fs/ext4/ialloc.c
View File

@ -432,7 +432,7 @@ static int find_group_orlov(struct super_block *sb, struct inode *parent,
ext4fs_dirhash(qstr->name, qstr->len, &hinfo); ext4fs_dirhash(qstr->name, qstr->len, &hinfo);
grp = hinfo.hash; grp = hinfo.hash;
} else } else
get_random_bytes(&grp, sizeof(grp)); grp = prandom_u32();
parent_group = (unsigned)grp % ngroups; parent_group = (unsigned)grp % ngroups;
for (i = 0; i < ngroups; i++) { for (i = 0; i < ngroups; i++) {
g = (parent_group + i) % ngroups; g = (parent_group + i) % ngroups;

2
fs/ext4/mmp.c
View File

@ -259,7 +259,7 @@ static unsigned int mmp_new_seq(void)
u32 new_seq; u32 new_seq;
do { do {
get_random_bytes(&new_seq, sizeof(u32)); new_seq = prandom_u32();
} while (new_seq > EXT4_MMP_SEQ_MAX); } while (new_seq > EXT4_MMP_SEQ_MAX);
return new_seq; return new_seq;

7
fs/ext4/super.c
View File

@ -3068,7 +3068,6 @@ static struct ext4_li_request *ext4_li_request_new(struct super_block *sb,
{ {
struct ext4_sb_info *sbi = EXT4_SB(sb); struct ext4_sb_info *sbi = EXT4_SB(sb);
struct ext4_li_request *elr; struct ext4_li_request *elr;
unsigned long rnd;
elr = kzalloc(sizeof(*elr), GFP_KERNEL); elr = kzalloc(sizeof(*elr), GFP_KERNEL);
if (!elr) if (!elr)
@ -3083,10 +3082,8 @@ static struct ext4_li_request *ext4_li_request_new(struct super_block *sb,
* spread the inode table initialization requests * spread the inode table initialization requests
* better. * better.
*/ */
get_random_bytes(&rnd, sizeof(rnd)); elr->lr_next_sched = jiffies + (prandom_u32() %
elr->lr_next_sched = jiffies + (unsigned long)rnd % (EXT4_DEF_LI_MAX_START_DELAY * HZ));
(EXT4_DEF_LI_MAX_START_DELAY * HZ);
return elr; return elr;
} }