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Theodore Ts'o9f125d62011-06-27 19:16:04 -04001/*
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 */
11static 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 */
21static 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