tmpfs: no need to use i_lock
2.6.36's 7e496299d4d2 ("tmpfs: make tmpfs scalable with percpu_counter for
used blocks") to make tmpfs scalable with percpu_counter used
inode->i_lock in place of sbinfo->stat_lock around i_blocks updates; but
that was adverse to scalability, and unnecessary, since info->lock is
already held there in the fast paths.
Remove those uses of i_lock, and add info->lock in the three error paths
where it's then needed across shmem_free_blocks(). It's not actually
needed across shmem_unacct_blocks(), but they're so often paired that it
looks wrong to split them apart.
Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/shmem.c b/mm/shmem.c
index fcedf54..c1db11c 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -241,9 +241,7 @@
struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
if (sbinfo->max_blocks) {
percpu_counter_add(&sbinfo->used_blocks, -pages);
- spin_lock(&inode->i_lock);
inode->i_blocks -= pages*BLOCKS_PER_PAGE;
- spin_unlock(&inode->i_lock);
}
}
@@ -432,9 +430,7 @@
sbinfo->max_blocks - 1) >= 0)
return ERR_PTR(-ENOSPC);
percpu_counter_inc(&sbinfo->used_blocks);
- spin_lock(&inode->i_lock);
inode->i_blocks += BLOCKS_PER_PAGE;
- spin_unlock(&inode->i_lock);
}
spin_unlock(&info->lock);
@@ -1421,9 +1417,7 @@
shmem_acct_block(info->flags))
goto nospace;
percpu_counter_inc(&sbinfo->used_blocks);
- spin_lock(&inode->i_lock);
inode->i_blocks += BLOCKS_PER_PAGE;
- spin_unlock(&inode->i_lock);
} else if (shmem_acct_block(info->flags))
goto nospace;
@@ -1434,8 +1428,10 @@
spin_unlock(&info->lock);
filepage = shmem_alloc_page(gfp, info, idx);
if (!filepage) {
+ spin_lock(&info->lock);
shmem_unacct_blocks(info->flags, 1);
shmem_free_blocks(inode, 1);
+ spin_unlock(&info->lock);
error = -ENOMEM;
goto failed;
}
@@ -1449,8 +1445,10 @@
current->mm, GFP_KERNEL);
if (error) {
page_cache_release(filepage);
+ spin_lock(&info->lock);
shmem_unacct_blocks(info->flags, 1);
shmem_free_blocks(inode, 1);
+ spin_unlock(&info->lock);
filepage = NULL;
goto failed;
}
@@ -1480,10 +1478,10 @@
* be done automatically.
*/
if (ret) {
- spin_unlock(&info->lock);
- page_cache_release(filepage);
shmem_unacct_blocks(info->flags, 1);
shmem_free_blocks(inode, 1);
+ spin_unlock(&info->lock);
+ page_cache_release(filepage);
filepage = NULL;
if (error)
goto failed;