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mufs: add mufs_shrink_tree() to shrink a file tree to a specific size in terms of VAS

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This commit is contained in:
S.J.R. van Schaik 2017-05-29 14:57:13 +02:00
parent 281c1abdfa
commit ba12823d8b
2 changed files with 45 additions and 0 deletions
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44
source/fs/mufs/tree.c
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@ -116,3 +116,47 @@ int mufs_extend_tree(struct mufs *fs, struct mufs_tree *tree, uint8_t depth)
return 0;
}
int mufs_shrink_tree(struct mufs *fs, struct mufs_tree *tree, uint32_t max_size)
{
char data[1 << fs->dev->log2_block_size];
uint32_t *table = (uint32_t *)data;
size_t index;
uint32_t base, size;
uint8_t log2_nentries = fs->dev->log2_block_size - ilog2(sizeof(uint32_t));
uint8_t depth;
base = tree->root;
for (depth = tree->depth; depth; --depth) {
size = 1 << (depth * log2_nentries + fs->dev->log2_block_size);
if (size < max_size)
return 0;
index = max_size >> ((depth - 1) * log2_nentries +
fs->dev->log2_block_size);
if (flash_read(fs->dev, base, data, sizeof data) == 0)
return -1;
if (index <= 1) {
tree->root = table[0];
--tree->depth;
mufs_free_block(fs, base);
continue;
}
for (; index < (UINT32_C(1) << log2_nentries); ++index) {
table[index] = 0;
}
if (flash_write(fs->dev, base << fs->dev->log2_block_size, data,
sizeof data) == 0)
return -1;
}
return 0;
}

1
source/fs/mufs/tree.h
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@ -6,3 +6,4 @@ int mufs_alloc_page(struct mufs *fs, struct mufs_tree *tree, uint32_t *page,
uint32_t va);
void mufs_free_page(struct mufs *fs, struct mufs_tree *tree, uint32_t va);
int mufs_extend_tree(struct mufs *fs, struct mufs_tree *tree, uint8_t depth);
int mufs_shrink_tree(struct mufs *fs, struct mufs_tree *tree, uint32_t max_size);