Btrfs: use the inode own lock to protect its delalloc_bytes

We need not use a global lock to protect the delalloc_bytes of the
inode, just use its own lock. In this way, we can reduce the lock
contention and ->delalloc_lock will just protect delalloc inode
list.

Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>

1 files changed, 34 insertions, 13 deletions

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 24c0b7805fe1..82c7c66f8523 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -1514,15 +1514,22 @@ static void btrfs_set_bit_hook(struct inode *inode,
                         spin_unlock(&BTRFS_I(inode)->lock);
                 }
 
-                spin_lock(&root->fs_info->delalloc_lock);
-                BTRFS_I(inode)->delalloc_bytes += len;
                 __percpu_counter_add(&root->fs_info->delalloc_bytes, len,
                                      root->fs_info->delalloc_batch);
-                if (do_list && list_empty(&BTRFS_I(inode)->delalloc_inodes)) {
-                        list_add_tail(&BTRFS_I(inode)->delalloc_inodes,
-                                      &root->fs_info->delalloc_inodes);
+                spin_lock(&BTRFS_I(inode)->lock);
+                BTRFS_I(inode)->delalloc_bytes += len;
+                if (do_list && !test_bit(BTRFS_INODE_IN_DELALLOC_LIST,
+                                         &BTRFS_I(inode)->runtime_flags)) {
+                        spin_lock(&root->fs_info->delalloc_lock);
+                        if (list_empty(&BTRFS_I(inode)->delalloc_inodes)) {
+                                list_add_tail(&BTRFS_I(inode)->delalloc_inodes,
+                                              &root->fs_info->delalloc_inodes);
+                                set_bit(BTRFS_INODE_IN_DELALLOC_LIST,
+                                        &BTRFS_I(inode)->runtime_flags);
+                        }
+                        spin_unlock(&root->fs_info->delalloc_lock);
                 }
-                spin_unlock(&root->fs_info->delalloc_lock);
+                spin_unlock(&BTRFS_I(inode)->lock);
         }
 }
 
@@ -1557,16 +1564,22 @@ static void btrfs_clear_bit_hook(struct inode *inode,
                     && do_list)
                         btrfs_free_reserved_data_space(inode, len);
 
-                spin_lock(&root->fs_info->delalloc_lock);
                 __percpu_counter_add(&root->fs_info->delalloc_bytes, -len,
                                      root->fs_info->delalloc_batch);
+                spin_lock(&BTRFS_I(inode)->lock);
                 BTRFS_I(inode)->delalloc_bytes -= len;
-
                 if (do_list && BTRFS_I(inode)->delalloc_bytes == 0 &&
-                    !list_empty(&BTRFS_I(inode)->delalloc_inodes)) {
-                        list_del_init(&BTRFS_I(inode)->delalloc_inodes);
+                    test_bit(BTRFS_INODE_IN_DELALLOC_LIST,
+                             &BTRFS_I(inode)->runtime_flags)) {
+                        spin_lock(&root->fs_info->delalloc_lock);
+                        if (!list_empty(&BTRFS_I(inode)->delalloc_inodes)) {
+                                list_del_init(&BTRFS_I(inode)->delalloc_inodes);
+                                clear_bit(BTRFS_INODE_IN_DELALLOC_LIST,
+                                          &BTRFS_I(inode)->runtime_flags);
+                        }
+                        spin_unlock(&root->fs_info->delalloc_lock);
                 }
-                spin_unlock(&root->fs_info->delalloc_lock);
+                spin_unlock(&BTRFS_I(inode)->lock);
         }
 }
 
@@ -7326,14 +7339,19 @@ fail:
 static int btrfs_getattr(struct vfsmount *mnt,
                          struct dentry *dentry, struct kstat *stat)
 {
+        u64 delalloc_bytes;
         struct inode *inode = dentry->d_inode;
         u32 blocksize = inode->i_sb->s_blocksize;
 
         generic_fillattr(inode, stat);
         stat->dev = BTRFS_I(inode)->root->anon_dev;
         stat->blksize = PAGE_CACHE_SIZE;
+
+        spin_lock(&BTRFS_I(inode)->lock);
+        delalloc_bytes = BTRFS_I(inode)->delalloc_bytes;
+        spin_unlock(&BTRFS_I(inode)->lock);
         stat->blocks = (ALIGN(inode_get_bytes(inode), blocksize) +
-                ALIGN(BTRFS_I(inode)->delalloc_bytes, blocksize)) >> 9;
+                        ALIGN(delalloc_bytes, blocksize)) >> 9;
         return 0;
 }
 
@@ -7620,8 +7638,11 @@ int btrfs_start_delalloc_inodes(struct btrfs_root *root, int delay_iput)
                 list_del_init(&binode->delalloc_inodes);
 
                 inode = igrab(&binode->vfs_inode);
-                if (!inode)
+                if (!inode) {
+                        clear_bit(BTRFS_INODE_IN_DELALLOC_LIST,
+                                  &binode->runtime_flags);
                         continue;
+                }
 
                 list_add_tail(&binode->delalloc_inodes,
                               &root->fs_info->delalloc_inodes);