[PATCH] EXT2: Remove superblock lock contention in ext2_statfs

Fix a performance degradation introduced in 2.6.17.  (30% degradation
running dbench with 16 threads)

Commit 21730eed11de42f22afcbd43f450a1872a0b5ea1, which claims to make
EXT2_DEBUG work again, moves the taking of the kernel lock out of
debug-only code in ext2_count_free_inodes and ext2_count_free_blocks and
into ext2_statfs.

The same problem was fixed in ext3 by removing the lock completely (commit
5b11687924e40790deb0d5f959247ade82196665)

Signed-off-by: Dave Kleikamp <shaggy@austin.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

3 files changed, 0 insertions, 4 deletions

diff --git a/fs/ext2/balloc.c b/fs/ext2/balloc.c
index d4870432ecfc..b1981d0e95ad 100644
--- a/fs/ext2/balloc.c
+++ b/fs/ext2/balloc.c
@@ -539,7 +539,6 @@ unsigned long ext2_count_free (struct buffer_head * map, unsigned int numchars)
 
 #endif  /*  EXT2FS_DEBUG  */
 
-/* Superblock must be locked */
 unsigned long ext2_count_free_blocks (struct super_block * sb)
 {
         struct ext2_group_desc * desc;
diff --git a/fs/ext2/ialloc.c b/fs/ext2/ialloc.c
index de85c61c58c5..695f69ccf908 100644
--- a/fs/ext2/ialloc.c
+++ b/fs/ext2/ialloc.c
@@ -637,7 +637,6 @@ fail:
         return ERR_PTR(err);
 }
 
-/* Superblock must be locked */
 unsigned long ext2_count_free_inodes (struct super_block * sb)
 {
         struct ext2_group_desc *desc;
diff --git a/fs/ext2/super.c b/fs/ext2/super.c
index ca5bfb6914d2..4286ff6330b6 100644
--- a/fs/ext2/super.c
+++ b/fs/ext2/super.c
@@ -1083,7 +1083,6 @@ static int ext2_statfs (struct dentry * dentry, struct kstatfs * buf)
         unsigned long overhead;
         int i;
 
-        lock_super(sb);
         if (test_opt (sb, MINIX_DF))
                 overhead = 0;
         else {
@@ -1124,7 +1123,6 @@ static int ext2_statfs (struct dentry * dentry, struct kstatfs * buf)
         buf->f_files = le32_to_cpu(sbi->s_es->s_inodes_count);
         buf->f_ffree = ext2_count_free_inodes (sb);
         buf->f_namelen = EXT2_NAME_LEN;
-        unlock_super(sb);
         return 0;
 }