@@ -62,7 +62,7 @@ struct ext4_sb_info {
struct percpu_counter s_freeinodes_counter;
struct percpu_counter s_dirs_counter;
struct percpu_counter s_dirtyblocks_counter;
- struct blockgroup_lock s_blockgroup_lock;
+ struct blockgroup_lock *s_blockgroup_lock;
struct proc_dir_entry *s_proc;
/* root of the per fs reservation window tree */
@@ -150,7 +150,7 @@ struct ext4_sb_info {
static inline spinlock_t *
sb_bgl_lock(struct ext4_sb_info *sbi, unsigned int block_group)
{
- return bgl_lock_ptr(&sbi->s_blockgroup_lock, block_group);
+ return bgl_lock_ptr(sbi->s_blockgroup_lock, block_group);
}
#endif /* _EXT4_SB */
@@ -497,6 +497,7 @@ static void ext4_put_super(struct super_
ext4_blkdev_remove(sbi);
}
sb->s_fs_info = NULL;
+ kfree(sbi->s_blockgroup_lock);
kfree(sbi);
return;
}
@@ -1891,6 +1892,13 @@ static int ext4_fill_super(struct super_
sbi = kzalloc(sizeof(*sbi), GFP_KERNEL);
if (!sbi)
return -ENOMEM;
+
+ sbi->s_blockgroup_lock =
+ kzalloc(sizeof(struct blockgroup_lock), GFP_KERNEL);
+ if (!sbi->s_blockgroup_lock) {
+ kfree(sbi);
+ return -ENOMEM;
+ }
sb->s_fs_info = sbi;
sbi->s_mount_opt = 0;
sbi->s_resuid = EXT4_DEF_RESUID;
@@ -2199,7 +2207,7 @@ static int ext4_fill_super(struct super_
&sbi->s_inode_readahead_blks);
#endif
- bgl_lock_init(&sbi->s_blockgroup_lock);
+ bgl_lock_init(sbi->s_blockgroup_lock);
for (i = 0; i < db_count; i++) {
block = descriptor_loc(sb, logical_sb_block, i);
The patch titled ext4: allocate ->s_blockgroup_lock separately has been added to the -mm tree. Its filename is ext4-allocate-s_blockgroup_lock-separately.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find out what to do about this The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: ext4: allocate ->s_blockgroup_lock separately From: Pekka Enberg <penberg@cs.helsinki.fi> As spotted by kmemtrace, struct ext4_sb_info is 17664 bytes on 64-bit which makes it a very bad fit for SLAB allocators. The culprit of the wasted memory is ->s_blockgroup_lock which can be as big as 16 KB when NR_CPUS >= 32. To fix that, allocate ->s_blockgroup_lock, which fits nicely in a order 2 page in the worst case, separately. This shinks down struct ext4_sb_info enough to fit a 2 KB slab cache so now we allocate 16 KB + 2 KB instead of 32 KB saving 14 KB of memory. Cc: Andreas Dilger <adilger@sun.com> Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi> Cc: <linux-ext4@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> --- fs/ext4/ext4_sb.h | 4 ++-- fs/ext4/super.c | 10 +++++++++- 2 files changed, 11 insertions(+), 3 deletions(-)