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  */
ext4_truncate_failed_write(struct inode * inode)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  */
ext4_blocks_for_truncate(struct inode * inode)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 
51