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371 lines
7.8 KiB
371 lines
7.8 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* Generic part */ |
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typedef struct { |
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block_t *p; |
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block_t key; |
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struct buffer_head *bh; |
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} Indirect; |
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static DEFINE_RWLOCK(pointers_lock); |
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static inline void add_chain(Indirect *p, struct buffer_head *bh, block_t *v) |
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{ |
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p->key = *(p->p = v); |
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p->bh = bh; |
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} |
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static inline int verify_chain(Indirect *from, Indirect *to) |
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{ |
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while (from <= to && from->key == *from->p) |
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from++; |
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return (from > to); |
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} |
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static inline block_t *block_end(struct buffer_head *bh) |
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{ |
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return (block_t *)((char*)bh->b_data + bh->b_size); |
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} |
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static inline Indirect *get_branch(struct inode *inode, |
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int depth, |
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int *offsets, |
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Indirect chain[DEPTH], |
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int *err) |
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{ |
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struct super_block *sb = inode->i_sb; |
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Indirect *p = chain; |
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struct buffer_head *bh; |
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*err = 0; |
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/* i_data is not going away, no lock needed */ |
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add_chain (chain, NULL, i_data(inode) + *offsets); |
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if (!p->key) |
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goto no_block; |
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while (--depth) { |
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bh = sb_bread(sb, block_to_cpu(p->key)); |
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if (!bh) |
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goto failure; |
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read_lock(&pointers_lock); |
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if (!verify_chain(chain, p)) |
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goto changed; |
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add_chain(++p, bh, (block_t *)bh->b_data + *++offsets); |
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read_unlock(&pointers_lock); |
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if (!p->key) |
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goto no_block; |
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} |
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return NULL; |
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changed: |
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read_unlock(&pointers_lock); |
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brelse(bh); |
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*err = -EAGAIN; |
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goto no_block; |
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failure: |
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*err = -EIO; |
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no_block: |
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return p; |
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} |
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static int alloc_branch(struct inode *inode, |
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int num, |
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int *offsets, |
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Indirect *branch) |
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{ |
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int n = 0; |
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int i; |
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int parent = minix_new_block(inode); |
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int err = -ENOSPC; |
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branch[0].key = cpu_to_block(parent); |
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if (parent) for (n = 1; n < num; n++) { |
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struct buffer_head *bh; |
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/* Allocate the next block */ |
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int nr = minix_new_block(inode); |
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if (!nr) |
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break; |
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branch[n].key = cpu_to_block(nr); |
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bh = sb_getblk(inode->i_sb, parent); |
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if (!bh) { |
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minix_free_block(inode, nr); |
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err = -ENOMEM; |
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break; |
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} |
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lock_buffer(bh); |
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memset(bh->b_data, 0, bh->b_size); |
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branch[n].bh = bh; |
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branch[n].p = (block_t*) bh->b_data + offsets[n]; |
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*branch[n].p = branch[n].key; |
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set_buffer_uptodate(bh); |
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unlock_buffer(bh); |
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mark_buffer_dirty_inode(bh, inode); |
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parent = nr; |
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} |
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if (n == num) |
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return 0; |
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/* Allocation failed, free what we already allocated */ |
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for (i = 1; i < n; i++) |
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bforget(branch[i].bh); |
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for (i = 0; i < n; i++) |
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minix_free_block(inode, block_to_cpu(branch[i].key)); |
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return err; |
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} |
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static inline int splice_branch(struct inode *inode, |
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Indirect chain[DEPTH], |
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Indirect *where, |
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int num) |
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{ |
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int i; |
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write_lock(&pointers_lock); |
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/* Verify that place we are splicing to is still there and vacant */ |
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if (!verify_chain(chain, where-1) || *where->p) |
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goto changed; |
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*where->p = where->key; |
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write_unlock(&pointers_lock); |
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/* We are done with atomic stuff, now do the rest of housekeeping */ |
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inode->i_ctime = current_time(inode); |
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/* had we spliced it onto indirect block? */ |
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if (where->bh) |
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mark_buffer_dirty_inode(where->bh, inode); |
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mark_inode_dirty(inode); |
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return 0; |
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changed: |
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write_unlock(&pointers_lock); |
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for (i = 1; i < num; i++) |
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bforget(where[i].bh); |
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for (i = 0; i < num; i++) |
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minix_free_block(inode, block_to_cpu(where[i].key)); |
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return -EAGAIN; |
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} |
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static int get_block(struct inode * inode, sector_t block, |
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struct buffer_head *bh, int create) |
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{ |
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int err = -EIO; |
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int offsets[DEPTH]; |
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Indirect chain[DEPTH]; |
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Indirect *partial; |
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int left; |
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int depth = block_to_path(inode, block, offsets); |
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if (depth == 0) |
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goto out; |
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reread: |
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partial = get_branch(inode, depth, offsets, chain, &err); |
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/* Simplest case - block found, no allocation needed */ |
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if (!partial) { |
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got_it: |
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map_bh(bh, inode->i_sb, block_to_cpu(chain[depth-1].key)); |
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/* Clean up and exit */ |
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partial = chain+depth-1; /* the whole chain */ |
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goto cleanup; |
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} |
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/* Next simple case - plain lookup or failed read of indirect block */ |
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if (!create || err == -EIO) { |
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cleanup: |
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while (partial > chain) { |
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brelse(partial->bh); |
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partial--; |
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} |
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out: |
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return err; |
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} |
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/* |
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* Indirect block might be removed by truncate while we were |
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* reading it. Handling of that case (forget what we've got and |
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* reread) is taken out of the main path. |
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*/ |
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if (err == -EAGAIN) |
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goto changed; |
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left = (chain + depth) - partial; |
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err = alloc_branch(inode, left, offsets+(partial-chain), partial); |
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if (err) |
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goto cleanup; |
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if (splice_branch(inode, chain, partial, left) < 0) |
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goto changed; |
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set_buffer_new(bh); |
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goto got_it; |
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changed: |
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while (partial > chain) { |
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brelse(partial->bh); |
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partial--; |
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} |
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goto reread; |
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} |
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static inline int all_zeroes(block_t *p, block_t *q) |
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{ |
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while (p < q) |
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if (*p++) |
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return 0; |
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return 1; |
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} |
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static Indirect *find_shared(struct inode *inode, |
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int depth, |
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int offsets[DEPTH], |
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Indirect chain[DEPTH], |
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block_t *top) |
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{ |
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Indirect *partial, *p; |
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int k, err; |
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*top = 0; |
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for (k = depth; k > 1 && !offsets[k-1]; k--) |
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; |
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partial = get_branch(inode, k, offsets, chain, &err); |
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write_lock(&pointers_lock); |
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if (!partial) |
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partial = chain + k-1; |
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if (!partial->key && *partial->p) { |
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write_unlock(&pointers_lock); |
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goto no_top; |
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} |
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for (p=partial;p>chain && all_zeroes((block_t*)p->bh->b_data,p->p);p--) |
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; |
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if (p == chain + k - 1 && p > chain) { |
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p->p--; |
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} else { |
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*top = *p->p; |
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*p->p = 0; |
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} |
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write_unlock(&pointers_lock); |
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while(partial > p) |
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{ |
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brelse(partial->bh); |
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partial--; |
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} |
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no_top: |
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return partial; |
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} |
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static inline void free_data(struct inode *inode, block_t *p, block_t *q) |
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{ |
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unsigned long nr; |
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for ( ; p < q ; p++) { |
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nr = block_to_cpu(*p); |
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if (nr) { |
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*p = 0; |
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minix_free_block(inode, nr); |
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} |
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} |
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} |
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static void free_branches(struct inode *inode, block_t *p, block_t *q, int depth) |
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{ |
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struct buffer_head * bh; |
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unsigned long nr; |
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if (depth--) { |
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for ( ; p < q ; p++) { |
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nr = block_to_cpu(*p); |
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if (!nr) |
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continue; |
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*p = 0; |
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bh = sb_bread(inode->i_sb, nr); |
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if (!bh) |
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continue; |
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free_branches(inode, (block_t*)bh->b_data, |
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block_end(bh), depth); |
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bforget(bh); |
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minix_free_block(inode, nr); |
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mark_inode_dirty(inode); |
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} |
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} else |
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free_data(inode, p, q); |
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} |
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static inline void truncate (struct inode * inode) |
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{ |
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struct super_block *sb = inode->i_sb; |
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block_t *idata = i_data(inode); |
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int offsets[DEPTH]; |
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Indirect chain[DEPTH]; |
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Indirect *partial; |
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block_t nr = 0; |
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int n; |
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int first_whole; |
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long iblock; |
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iblock = (inode->i_size + sb->s_blocksize -1) >> sb->s_blocksize_bits; |
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block_truncate_page(inode->i_mapping, inode->i_size, get_block); |
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n = block_to_path(inode, iblock, offsets); |
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if (!n) |
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return; |
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if (n == 1) { |
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free_data(inode, idata+offsets[0], idata + DIRECT); |
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first_whole = 0; |
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goto do_indirects; |
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} |
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first_whole = offsets[0] + 1 - DIRECT; |
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partial = find_shared(inode, n, offsets, chain, &nr); |
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if (nr) { |
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if (partial == chain) |
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mark_inode_dirty(inode); |
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else |
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mark_buffer_dirty_inode(partial->bh, inode); |
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free_branches(inode, &nr, &nr+1, (chain+n-1) - partial); |
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} |
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/* Clear the ends of indirect blocks on the shared branch */ |
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while (partial > chain) { |
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free_branches(inode, partial->p + 1, block_end(partial->bh), |
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(chain+n-1) - partial); |
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mark_buffer_dirty_inode(partial->bh, inode); |
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brelse (partial->bh); |
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partial--; |
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} |
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do_indirects: |
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/* Kill the remaining (whole) subtrees */ |
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while (first_whole < DEPTH-1) { |
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nr = idata[DIRECT+first_whole]; |
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if (nr) { |
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idata[DIRECT+first_whole] = 0; |
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mark_inode_dirty(inode); |
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free_branches(inode, &nr, &nr+1, first_whole+1); |
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} |
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first_whole++; |
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} |
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inode->i_mtime = inode->i_ctime = current_time(inode); |
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mark_inode_dirty(inode); |
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} |
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static inline unsigned nblocks(loff_t size, struct super_block *sb) |
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{ |
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int k = sb->s_blocksize_bits - 10; |
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unsigned blocks, res, direct = DIRECT, i = DEPTH; |
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blocks = (size + sb->s_blocksize - 1) >> (BLOCK_SIZE_BITS + k); |
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res = blocks; |
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while (--i && blocks > direct) { |
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blocks -= direct; |
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blocks += sb->s_blocksize/sizeof(block_t) - 1; |
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blocks /= sb->s_blocksize/sizeof(block_t); |
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res += blocks; |
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direct = 1; |
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} |
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return res; |
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}
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