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authorTheodore Ts'o <tytso@mit.edu>2017-11-09 06:23:20 +0300
committerTheodore Ts'o <tytso@mit.edu>2017-11-09 06:23:20 +0300
commit232530680290ba94ca37852ab10d9556ea28badf (patch)
treecf23ba2b6c563adc685f3b9fee830ac7d202546c /fs/ext4/ioctl.c
parentd77147ff443b255d82c907a632c825b2cc610b10 (diff)
downloadlinux-232530680290ba94ca37852ab10d9556ea28badf.tar.xz
ext4: improve smp scalability for inode generation
->s_next_generation is protected by s_next_gen_lock but its usage pattern is very primitive. We don't actually need sequentially increasing new generation numbers, so let's use prandom_u32() instead. Reported-by: Dmitry Monakhov <dmonakhov@openvz.org> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Diffstat (limited to 'fs/ext4/ioctl.c')
-rw-r--r--fs/ext4/ioctl.c8
1 files changed, 3 insertions, 5 deletions
diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c
index 144bbda2b808..23a4766f6678 100644
--- a/fs/ext4/ioctl.c
+++ b/fs/ext4/ioctl.c
@@ -14,6 +14,7 @@
#include <linux/mount.h>
#include <linux/file.h>
#include <linux/quotaops.h>
+#include <linux/random.h>
#include <linux/uuid.h>
#include <linux/uaccess.h>
#include <linux/delay.h>
@@ -98,7 +99,6 @@ static long swap_inode_boot_loader(struct super_block *sb,
int err;
struct inode *inode_bl;
struct ext4_inode_info *ei_bl;
- struct ext4_sb_info *sbi = EXT4_SB(sb);
if (inode->i_nlink != 1 || !S_ISREG(inode->i_mode))
return -EINVAL;
@@ -157,10 +157,8 @@ static long swap_inode_boot_loader(struct super_block *sb,
inode->i_ctime = inode_bl->i_ctime = current_time(inode);
- spin_lock(&sbi->s_next_gen_lock);
- inode->i_generation = sbi->s_next_generation++;
- inode_bl->i_generation = sbi->s_next_generation++;
- spin_unlock(&sbi->s_next_gen_lock);
+ inode->i_generation = prandom_u32();
+ inode_bl->i_generation = prandom_u32();
ext4_discard_preallocations(inode);