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>

diff --git a/fs/btrfs/btrfs_inode.h b/fs/btrfs/btrfs_inode.h
index 2a8c242..c935a77 100644 (file)
--- a/fs/btrfs/btrfs_inode.h
+++ b/fs/btrfs/btrfs_inode.h
@@ -40,6 +40,7 @@
 #define BTRFS_INODE_HAS_ASYNC_EXTENT           6
 #define BTRFS_INODE_NEEDS_FULL_SYNC            7
 #define BTRFS_INODE_COPY_EVERYTHING            8
+#define BTRFS_INODE_IN_DELALLOC_LIST           9
 
 /* in memory btrfs inode */
 struct btrfs_inode {

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 2c9498a..11f6dbc 100644 (file)
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -3690,6 +3690,8 @@ static void btrfs_destroy_delalloc_inodes(struct btrfs_root *root)
                                    delalloc_inodes);
 
                list_del_init(&btrfs_inode->delalloc_inodes);
+               clear_bit(BTRFS_INODE_IN_DELALLOC_LIST,
+                         &btrfs_inode->runtime_flags);
 
                btrfs_invalidate_inodes(btrfs_inode->root);
        }

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 24c0b78..82c7c66 100644 (file)
--- 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);