1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * linux/fs/ext4/truncate.h
4 *
5 * Common inline functions needed for truncate support
6 */
7
8 /*
9 * Truncate blocks that were not used by write. We have to truncate the
10 * pagecache as well so that corresponding buffers get properly unmapped.
11 */
12 static inline void ext4_truncate_failed_write(struct inode *inode)
13 {
14 struct address_space *mapping = inode->i_mapping;
15
16 /*
17 * We don't need to call ext4_break_layouts() because the blocks we
18 * are truncating were never visible to userspace.
19 */
20 filemap_invalidate_lock(mapping);
21 truncate_inode_pages(mapping, inode->i_size);
22 ext4_truncate(inode);
23 filemap_invalidate_unlock(mapping);
24 }
25
26 /*
27 * Work out how many blocks we need to proceed with the next chunk of a
28 * truncate transaction.
29 */
30 static inline unsigned long ext4_blocks_for_truncate(struct inode *inode)
31 {
32 ext4_lblk_t needed;
33
34 needed = inode->i_blocks >> (inode->i_sb->s_blocksize_bits - 9);
35
36 /* Give ourselves just enough room to cope with inodes in which
37 * i_blocks is corrupt: we've seen disk corruptions in the past
38 * which resulted in random data in an inode which looked enough
39 * like a regular file for ext4 to try to delete it. Things
40 * will go a bit crazy if that happens, but at least we should
41 * try not to panic the whole kernel. */
42 if (needed < 2)
43 needed = 2;
44
45 /* But we need to bound the transaction so we don't overflow the
46 * journal. */
47 if (needed > EXT4_MAX_TRANS_DATA)
48 needed = EXT4_MAX_TRANS_DATA;
49
50 return EXT4_DATA_TRANS_BLOCKS(inode->i_sb) + needed;
51 }
52
53
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