nilfs2: add helper functions to delete blocks from dat file

This adds delete functions for data blocks of metadata files using bitmap
based allocator.  nilfs_palloc_delete_entry_block() deletes an entry block
(e.g.  block storing dat entries), and nilfs_palloc_delete_bitmap_block()
deletes a bitmap block, respectively.

These helpers are intended to be used in the successive change on
deallocator of block addresses ("nilfs2: free unused dat file blocks
during garbage collection").

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/nilfs2/alloc.c b/fs/nilfs2/alloc.c
index 5b7ee36f84c7f0b168557fbb0c81e34432a46f19..225b797688654d5c1b802a9472d800f2a8e48e7f 100644 (file)
--- a/fs/nilfs2/alloc.c
+++ b/fs/nilfs2/alloc.c
@@ -235,6 +235,26 @@ static int nilfs_palloc_get_block(struct inode *inode, unsigned long blkoff,
        return ret;
 }
 
+/**
+ * nilfs_palloc_delete_block - delete a block on the persistent allocator file
+ * @inode: inode of metadata file using this allocator
+ * @blkoff: block offset
+ * @prev: nilfs_bh_assoc struct of the last used buffer
+ * @lock: spin lock protecting @prev
+ */
+static int nilfs_palloc_delete_block(struct inode *inode, unsigned long blkoff,
+                                    struct nilfs_bh_assoc *prev,
+                                    spinlock_t *lock)
+{
+       spin_lock(lock);
+       if (prev->bh && blkoff == prev->blkoff) {
+               brelse(prev->bh);
+               prev->bh = NULL;
+       }
+       spin_unlock(lock);
+       return nilfs_mdt_delete_block(inode, blkoff);
+}
+
 /**
  * nilfs_palloc_get_desc_block - get buffer head of a group descriptor block
  * @inode: inode of metadata file using this allocator
@@ -273,6 +293,22 @@ static int nilfs_palloc_get_bitmap_block(struct inode *inode,
                                      &cache->prev_bitmap, &cache->lock);
 }
 
+/**
+ * nilfs_palloc_delete_bitmap_block - delete a bitmap block
+ * @inode: inode of metadata file using this allocator
+ * @group: group number
+ */
+static int nilfs_palloc_delete_bitmap_block(struct inode *inode,
+                                           unsigned long group)
+{
+       struct nilfs_palloc_cache *cache = NILFS_MDT(inode)->mi_palloc_cache;
+
+       return nilfs_palloc_delete_block(inode,
+                                        nilfs_palloc_bitmap_blkoff(inode,
+                                                                   group),
+                                        &cache->prev_bitmap, &cache->lock);
+}
+
 /**
  * nilfs_palloc_get_entry_block - get buffer head of an entry block
  * @inode: inode of metadata file using this allocator
@@ -291,6 +327,20 @@ int nilfs_palloc_get_entry_block(struct inode *inode, __u64 nr,
                                      &cache->prev_entry, &cache->lock);
 }
 
+/**
+ * nilfs_palloc_delete_entry_block - delete an entry block
+ * @inode: inode of metadata file using this allocator
+ * @nr: serial number of the entry
+ */
+static int nilfs_palloc_delete_entry_block(struct inode *inode, __u64 nr)
+{
+       struct nilfs_palloc_cache *cache = NILFS_MDT(inode)->mi_palloc_cache;
+
+       return nilfs_palloc_delete_block(inode,
+                                        nilfs_palloc_entry_blkoff(inode, nr),
+                                        &cache->prev_entry, &cache->lock);
+}
+
 /**
  * nilfs_palloc_block_get_group_desc - get kernel address of a group descriptor
  * @inode: inode of metadata file using this allocator