nilfs2: insert cache operation in palloc get block routines

This implements cache operation in get block routines of palloc code:
nilfs_palloc_get_desc_block(), nilfs_palloc_get_bitmap_block(), and
nilfs_palloc_get_entry_block().

This will complete the palloc cache.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

1 files changed, 54 insertions, 8 deletions

diff --git a/fs/nilfs2/alloc.c b/fs/nilfs2/alloc.c
index c56300d8d177..3f959f1879d8 100644
--- a/fs/nilfs2/alloc.c
+++ b/fs/nilfs2/alloc.c
@@ -142,29 +142,75 @@ static void nilfs_palloc_desc_block_init(struct inode *inode,
         }
 }
 
+static int nilfs_palloc_get_block(struct inode *inode, unsigned long blkoff,
+                                  int create,
+                                  void (*init_block)(struct inode *,
+                                                     struct buffer_head *,
+                                                     void *),
+                                  struct buffer_head **bhp,
+                                  struct nilfs_bh_assoc *prev,
+                                  spinlock_t *lock)
+{
+        int ret;
+
+        spin_lock(lock);
+        if (prev->bh && blkoff == prev->blkoff) {
+                get_bh(prev->bh);
+                *bhp = prev->bh;
+                spin_unlock(lock);
+                return 0;
+        }
+        spin_unlock(lock);
+
+        ret = nilfs_mdt_get_block(inode, blkoff, create, init_block, bhp);
+        if (!ret) {
+                spin_lock(lock);
+                /*
+                 * The following code must be safe for change of the
+                 * cache contents during the get block call.
+                 */
+                brelse(prev->bh);
+                get_bh(*bhp);
+                prev->bh = *bhp;
+                prev->blkoff = blkoff;
+                spin_unlock(lock);
+        }
+        return ret;
+}
+
 static int nilfs_palloc_get_desc_block(struct inode *inode,
                                        unsigned long group,
                                        int create, struct buffer_head **bhp)
 {
-        return nilfs_mdt_get_block(inode,
-                                   nilfs_palloc_desc_blkoff(inode, group),
-                                   create, nilfs_palloc_desc_block_init, bhp);
+        struct nilfs_palloc_cache *cache = NILFS_MDT(inode)->mi_palloc_cache;
+
+        return nilfs_palloc_get_block(inode,
+                                      nilfs_palloc_desc_blkoff(inode, group),
+                                      create, nilfs_palloc_desc_block_init,
+                                      bhp, &cache->prev_desc, &cache->lock);
 }
 
 static int nilfs_palloc_get_bitmap_block(struct inode *inode,
                                          unsigned long group,
                                          int create, struct buffer_head **bhp)
 {
-        return nilfs_mdt_get_block(inode,
-                                   nilfs_palloc_bitmap_blkoff(inode, group),
-                                   create, NULL, bhp);
+        struct nilfs_palloc_cache *cache = NILFS_MDT(inode)->mi_palloc_cache;
+
+        return nilfs_palloc_get_block(inode,
+                                      nilfs_palloc_bitmap_blkoff(inode, group),
+                                      create, NULL, bhp,
+                                      &cache->prev_bitmap, &cache->lock);
 }
 
 int nilfs_palloc_get_entry_block(struct inode *inode, __u64 nr,
                                  int create, struct buffer_head **bhp)
 {
-        return nilfs_mdt_get_block(inode, nilfs_palloc_entry_blkoff(inode, nr),
-                                   create, NULL, bhp);
+        struct nilfs_palloc_cache *cache = NILFS_MDT(inode)->mi_palloc_cache;
+
+        return nilfs_palloc_get_block(inode,
+                                      nilfs_palloc_entry_blkoff(inode, nr),
+                                      create, NULL, bhp,
+                                      &cache->prev_entry, &cache->lock);
 }
 
 static struct nilfs_palloc_group_desc *