1 /*
2  * linux/fs/ext4/truncate.h
3  *
4  * Common inline functions needed for truncate support
5  */
6 
7 /*
8  * Truncate blocks that were not used by write. We have to truncate the
9  * pagecache as well so that corresponding buffers get properly unmapped.
10  */
ext4_truncate_failed_write(struct inode * inode)11 static inline void ext4_truncate_failed_write(struct inode *inode)
12 {
13 	truncate_inode_pages(inode->i_mapping, inode->i_size);
14 	ext4_truncate(inode);
15 }
16 
17 /*
18  * Work out how many blocks we need to proceed with the next chunk of a
19  * truncate transaction.
20  */
ext4_blocks_for_truncate(struct inode * inode)21 static inline unsigned long ext4_blocks_for_truncate(struct inode *inode)
22 {
23 	ext4_lblk_t needed;
24 
25 	needed = inode->i_blocks >> (inode->i_sb->s_blocksize_bits - 9);
26 
27 	/* Give ourselves just enough room to cope with inodes in which
28 	 * i_blocks is corrupt: we've seen disk corruptions in the past
29 	 * which resulted in random data in an inode which looked enough
30 	 * like a regular file for ext4 to try to delete it.  Things
31 	 * will go a bit crazy if that happens, but at least we should
32 	 * try not to panic the whole kernel. */
33 	if (needed < 2)
34 		needed = 2;
35 
36 	/* But we need to bound the transaction so we don't overflow the
37 	 * journal. */
38 	if (needed > EXT4_MAX_TRANS_DATA)
39 		needed = EXT4_MAX_TRANS_DATA;
40 
41 	return EXT4_DATA_TRANS_BLOCKS(inode->i_sb) + needed;
42 }
43 
44