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 /*
15 * We don't need to call ext4_break_layouts() because the blocks we
16 * are truncating were never visible to userspace.
17 */
18 down_write(&EXT4_I(inode)->i_mmap_sem);
19 truncate_inode_pages(inode->i_mapping, inode->i_size);
20 ext4_truncate(inode);
21 up_write(&EXT4_I(inode)->i_mmap_sem);
22 }
23
24 /*
25 * Work out how many blocks we need to proceed with the next chunk of a
26 * truncate transaction.
27 */
28 static inline unsigned long ext4_blocks_for_truncate(struct inode *inode)
29 {
30 ext4_lblk_t needed;
31
32 needed = inode->i_blocks >> (inode->i_sb->s_blocksize_bits - 9);
33
34 /* Give ourselves just enough room to cope with inodes in which
35 * i_blocks is corrupt: we've seen disk corruptions in the past
36 * which resulted in random data in an inode which looked enough
37 * like a regular file for ext4 to try to delete it. Things
38 * will go a bit crazy if that happens, but at least we should
39 * try not to panic the whole kernel. */
40 if (needed < 2)
41 needed = 2;
42
43 /* But we need to bound the transaction so we don't overflow the
44 * journal. */
45 if (needed > EXT4_MAX_TRANS_DATA)
46 needed = EXT4_MAX_TRANS_DATA;
47
48 return EXT4_DATA_TRANS_BLOCKS(inode->i_sb) + needed;
49 }
50