Changeset f8c60f5 in mainline

Timestamp:

2011-03-09T21:59:30Z (13 years ago)

Author:

Martin Sucha <sucha14@…>

Branches:

lfn, master, serial, ticket/834-toolchain-update, topic/msim-upgrade, topic/simplify-dev-export

Children:

c3f95d8

Parents:

66bea243

Message:

Basic sketch of code for allocating blocks

Location:

uspace/lib/ext2

Files:

• libext2_block_group.c (modified) (1 diff)
• libext2_block_group.h (modified) (1 diff)
• libext2_filesystem.c (modified) (1 diff)
• libext2_filesystem.h (modified) (1 diff)

uspace/lib/ext2/libext2_block_group.c

@@ -79 +79 @@
 
 /**
+ * Set amount of free blocks in this block group
+ * 
+ * @param bg pointer to block group descriptor
+ * @param val new value
+ */
+inline void ext2_block_group_set_free_block_count(ext2_block_group_t *bg,
+        uint16_t val)
+{
+        bg->free_block_count = host2uint16_t_le(val);
+}
+
+/**
  * Get amount of free inodes in this block group
  * 

uspace/lib/ext2/libext2_block_group.h

@@ -62 +62 @@
 inline uint16_t ext2_block_group_get_directory_inode_count(ext2_block_group_t *);
 
+inline void     ext2_block_group_set_free_block_count(ext2_block_group_t *, uint16_t);
+
 #endif
 

uspace/lib/ext2/libext2_filesystem.c

@@ -384 +384 @@
 
 /**
+ * Allocate a given number of blocks and store their ids in blocks
+ * 
+ * @param fs pointer to filesystem
+ * @param blocks array of count uint32_t values where store block ids
+ * @param count number of blocks to allocate and elements in blocks array
+ * @param preferred_bg preferred block group number
+ * 
+ * @return              EOK on success or negative error code on failure
+ */
+int ext2_filesystem_allocate_blocks(ext2_filesystem_t *fs, uint32_t *blocks,
+    size_t count, uint32_t preferred_bg)
+{
+        uint32_t bg_count = ext2_superblock_get_block_group_count(fs->superblock);
+        uint32_t bpg = ext2_superblock_get_blocks_per_group(fs->superblock);
+        uint32_t block_size = ext2_superblock_get_block_size(fs->superblock);
+        uint32_t block_group = preferred_bg;
+        uint32_t free_blocks_sb;
+        uint32_t block_groups_left;
+        size_t idx;
+        ext2_block_group_ref_t *bg;
+        int rc;
+        uint32_t bb_block;
+        block_t *block;
+        size_t bb_idx;
+        size_t bb_bit;
+        
+        free_blocks_sb = ext2_superblock_get_free_block_count(fs->superblock);
+        
+        if (count > free_blocks_sb) {
+                return EIO;
+        }
+        
+        block_groups_left = bg_count;
+        
+        idx = 0;
+        
+        // Read the block group descriptor
+        rc = ext2_filesystem_get_block_group_ref(fs, block_group, &bg);
+        if (rc != EOK) {
+                goto failed;
+        }
+        
+        while (idx < count && block_groups_left > 0) {
+                uint16_t fb = ext2_block_group_get_free_block_count(bg->block_group);
+                if (fb == 0) {
+                        block_group = (block_group + 1) % bg_count;
+                        block_groups_left -= 1;
+                        
+                        rc = ext2_filesystem_put_block_group_ref(bg);
+                        if (rc != EOK) {
+                                goto failed;
+                        }
+                        
+                        rc = ext2_filesystem_get_block_group_ref(fs, block_group, &bg);
+                        if (rc != EOK) {
+                                goto failed;
+                        }
+                        continue;
+                }
+                
+                // We found a block group with free block, let's look at the block bitmap
+                bb_block = ext2_block_group_get_block_bitmap_block(bg->block_group);
+                
+                rc = block_get(&block, fs->device, bb_block, BLOCK_FLAGS_NONE);
+                if (rc != EOK) {
+                        goto failed;
+                }
+                
+                // Use all blocks from this block group
+                for (bb_idx = 0; bb_idx < block_size && idx < count; bb_idx++) {
+                        uint8_t *data = (uint8_t *) block->data;
+                        if (data[bb_idx] == 0xff) {
+                                continue;
+                        }
+                        // find an empty bit
+                        uint8_t mask;
+                        for (mask = 1, bb_bit = 0;
+                                 bb_bit < 8 && idx < count; 
+                                 bb_bit++, mask = mask << 1) {
+                                if ((data[bb_idx] & mask) == 0) {
+                                        // free block found
+                                        blocks[idx] = block_group * bpg + bb_idx*8 + bb_bit;
+                                        data[bb_idx] |= mask;
+                                        idx += 1;
+                                        fb -= 1;
+                                        ext2_block_group_set_free_block_count(bg->block_group, fb);
+                                }
+                        }
+                }
+        }
+        
+        rc = ext2_filesystem_put_block_group_ref(bg);
+        if (rc != EOK) {
+                goto failed;
+        }
+        
+        // TODO update superblock
+        
+        return EOK;
+failed:
+        // TODO deallocate already allocated blocks, if possible
+        
+        return rc;
+}
+
+/**
  * Finalize an instance of filesystem
  * 

uspace/lib/ext2/libext2_filesystem.h

@@ -70 +70 @@
 extern int ext2_filesystem_get_inode_data_block_index(ext2_filesystem_t *, ext2_inode_t*,
     aoff64_t, uint32_t*);
+extern int ext2_filesystem_allocate_blocks(ext2_filesystem_t *, uint32_t *, size_t, uint32_t);
 extern void ext2_filesystem_fini(ext2_filesystem_t *);