ext4: refactor duplicated block placement code

I found that ext4_ext_find_goal() and ext4_find_near()
share the same code for returning a coloured start block
based on i_block_group.

We can refactor this into a common function so that they
don't diverge in the future.

Thanks to adilger for suggesting the new function name.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

4 files changed, 51 insertions, 63 deletions

diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c
index 264f6949511e..f8224adf496e 100644
--- a/fs/ext4/balloc.c
+++ b/fs/ext4/balloc.c
@@ -620,3 +620,51 @@ unsigned long ext4_bg_num_gdb(struct super_block *sb, ext4_group_t group)
 
 }
 
+/**
+ *      ext4_inode_to_goal_block - return a hint for block allocation
+ *      @inode: inode for block allocation
+ *
+ *      Return the ideal location to start allocating blocks for a
+ *      newly created inode.
+ */
+ext4_fsblk_t ext4_inode_to_goal_block(struct inode *inode)
+{
+        struct ext4_inode_info *ei = EXT4_I(inode);
+        ext4_group_t block_group;
+        ext4_grpblk_t colour;
+        int flex_size = ext4_flex_bg_size(EXT4_SB(inode->i_sb));
+        ext4_fsblk_t bg_start;
+        ext4_fsblk_t last_block;
+
+        block_group = ei->i_block_group;
+        if (flex_size >= EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME) {
+                /*
+                 * If there are at least EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME
+                 * block groups per flexgroup, reserve the first block
+                 * group for directories and special files.  Regular
+                 * files will start at the second block group.  This
+                 * tends to speed up directory access and improves
+                 * fsck times.
+                 */
+                block_group &= ~(flex_size-1);
+                if (S_ISREG(inode->i_mode))
+                        block_group++;
+        }
+        bg_start = ext4_group_first_block_no(inode->i_sb, block_group);
+        last_block = ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es) - 1;
+
+        /*
+         * If we are doing delayed allocation, we don't need take
+         * colour into account.
+         */
+        if (test_opt(inode->i_sb, DELALLOC))
+                return bg_start;
+
+        if (bg_start + EXT4_BLOCKS_PER_GROUP(inode->i_sb) <= last_block)
+                colour = (current->pid % 16) *
+                        (EXT4_BLOCKS_PER_GROUP(inode->i_sb) / 16);
+        else
+                colour = (current->pid % 16) * ((last_block - bg_start) / 16);
+        return bg_start + colour;
+}
+
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index ddaf5043fb38..49d2cea47382 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1743,6 +1743,7 @@ extern unsigned ext4_init_block_bitmap(struct super_block *sb,
                                        struct ext4_group_desc *desc);
 #define ext4_free_blocks_after_init(sb, group, desc)                    \
                 ext4_init_block_bitmap(sb, NULL, group, desc)
+ext4_fsblk_t ext4_inode_to_goal_block(struct inode *);
 
 /* dir.c */
 extern int __ext4_check_dir_entry(const char *, unsigned int, struct inode *,
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index eb63c7b8dfd2..f331e5010f68 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -114,12 +114,6 @@ static ext4_fsblk_t ext4_ext_find_goal(struct inode *inode,
                               struct ext4_ext_path *path,
                               ext4_lblk_t block)
 {
-        struct ext4_inode_info *ei = EXT4_I(inode);
-        ext4_fsblk_t bg_start;
-        ext4_fsblk_t last_block;
-        ext4_grpblk_t colour;
-        ext4_group_t block_group;
-        int flex_size = ext4_flex_bg_size(EXT4_SB(inode->i_sb));
         int depth;
 
         if (path) {
@@ -161,36 +155,7 @@ static ext4_fsblk_t ext4_ext_find_goal(struct inode *inode,
         }
 
         /* OK. use inode's group */
-        block_group = ei->i_block_group;
-        if (flex_size >= EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME) {
-                /*
-                 * If there are at least EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME
-                 * block groups per flexgroup, reserve the first block
-                 * group for directories and special files.  Regular
-                 * files will start at the second block group.  This
-                 * tends to speed up directory access and improves
-                 * fsck times.
-                 */
-                block_group &= ~(flex_size-1);
-                if (S_ISREG(inode->i_mode))
-                        block_group++;
-        }
-        bg_start = ext4_group_first_block_no(inode->i_sb, block_group);
-        last_block = ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es) - 1;
-
-        /*
-         * If we are doing delayed allocation, we don't need take
-         * colour into account.
-         */
-        if (test_opt(inode->i_sb, DELALLOC))
-                return bg_start;
-
-        if (bg_start + EXT4_BLOCKS_PER_GROUP(inode->i_sb) <= last_block)
-                colour = (current->pid % 16) *
-                        (EXT4_BLOCKS_PER_GROUP(inode->i_sb) / 16);
-        else
-                colour = (current->pid % 16) * ((last_block - bg_start) / 16);
-        return bg_start + colour + block;
+        return ext4_inode_to_goal_block(inode);
 }
 
 /*
diff --git a/fs/ext4/indirect.c b/fs/ext4/indirect.c
index c3e85a86e821..6c271115dbb6 100644
--- a/fs/ext4/indirect.c
+++ b/fs/ext4/indirect.c
@@ -207,11 +207,6 @@ static ext4_fsblk_t ext4_find_near(struct inode *inode, Indirect *ind)
         struct ext4_inode_info *ei = EXT4_I(inode);
         __le32 *start = ind->bh ? (__le32 *) ind->bh->b_data : ei->i_data;
         __le32 *p;
-        ext4_fsblk_t bg_start;
-        ext4_fsblk_t last_block;
-        ext4_grpblk_t colour;
-        ext4_group_t block_group;
-        int flex_size = ext4_flex_bg_size(EXT4_SB(inode->i_sb));
 
         /* Try to find previous block */
         for (p = ind->p - 1; p >= start; p--) {
@@ -227,28 +222,7 @@ static ext4_fsblk_t ext4_find_near(struct inode *inode, Indirect *ind)
          * It is going to be referred to from the inode itself? OK, just put it
          * into the same cylinder group then.
          */
-        block_group = ei->i_block_group;
-        if (flex_size >= EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME) {
-                block_group &= ~(flex_size-1);
-                if (S_ISREG(inode->i_mode))
-                        block_group++;
-        }
-        bg_start = ext4_group_first_block_no(inode->i_sb, block_group);
-        last_block = ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es) - 1;
-
-        /*
-         * If we are doing delayed allocation, we don't need take
-         * colour into account.
-         */
-        if (test_opt(inode->i_sb, DELALLOC))
-                return bg_start;
-
-        if (bg_start + EXT4_BLOCKS_PER_GROUP(inode->i_sb) <= last_block)
-                colour = (current->pid % 16) *
-                        (EXT4_BLOCKS_PER_GROUP(inode->i_sb) / 16);
-        else
-                colour = (current->pid % 16) * ((last_block - bg_start) / 16);
-        return bg_start + colour;
+        return ext4_inode_to_goal_block(inode);
 }
 
 /**