Fix block bitmap utilisation (#637)

vinc · Jun 6, 2024 · 73ba882 · 73ba882
1 parent 0806ba6
commit 73ba882
Showing 1 changed file with 15 additions and 21 deletions.
diff --git a/src/sys/fs/bitmap_block.rs b/src/sys/fs/bitmap_block.rs
@@ -11,52 +11,46 @@ pub const BITMAP_SIZE: usize = 8 * super::BLOCK_SIZE;
 pub struct BitmapBlock {}
 
 impl BitmapBlock {
-    fn block_index(addr: u32) -> u32 {
+    fn indexes(addr: u32) -> (u32, usize) {
         let sb = SuperBlock::read();
-        let size = sb.block_size();
         let i = addr - sb.data_area();
-        sb.bitmap_area() + (i / size / 8)
-    }
-
-    fn buffer_index(addr: u32) -> usize {
-        let sb = SuperBlock::read();
-        let i = (addr - sb.data_area()) as usize;
-        i % sb.block_size() as usize
+        let n = sb.block_size();
+        (sb.bitmap_area() + (i / n / 8), (i % (n * 8)) as usize)
     }
 
     pub fn alloc(addr: u32) {
-        let mut block = Block::read(BitmapBlock::block_index(addr));
+        let (a, i) = Self::indexes(addr);
+        let mut block = Block::read(a);
         let bitmap = block.data_mut();
-        let i = BitmapBlock::buffer_index(addr);
         if !bitmap[i / 8].get_bit(i % 8) {
             bitmap[i / 8].set_bit(i % 8, true);
             block.write();
             super_block::inc_alloc_count();
+        } else {
+            // TODO: alloc failed
         }
     }
 
     pub fn free(addr: u32) {
-        let mut block = Block::read(BitmapBlock::block_index(addr));
+        let (a, i) = Self::indexes(addr);
+        let mut block = Block::read(a);
         let bitmap = block.data_mut();
-        let i = BitmapBlock::buffer_index(addr);
         bitmap[i / 8].set_bit(i % 8, false);
         block.write();
         super_block::dec_alloc_count();
     }
 
     pub fn next_free_addr() -> Option<u32> {
         let sb = SuperBlock::read();
-        let size = sb.block_size();
-        let n = sb.block_count() / size / 8;
-        for i in 0..n {
+        let n = sb.block_size();
+        let m = sb.block_count() / n / 8;
+        for i in 0..m {
             let block = Block::read(sb.bitmap_area() + i);
             let bitmap = block.data();
-            let m = size / 8;
-            for j in 0..m {
+            for j in 0..n {
                 for k in 0..8 {
-                    if !bitmap[j as usize].get_bit(k) {
-                        let bs = BITMAP_SIZE as u32;
-                        let addr = sb.data_area() + i * bs + j * 8 + k as u32;
+                    if !bitmap[j as usize].get_bit(k as usize) {
+                        let addr = sb.data_area() + (i * n * 8) + (j * 8) + k;
                         return Some(addr);
                     }
                 }