LXR linux/fs/ext4/truncate.h

   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 */
  12static inline void ext4_truncate_failed_write(struct inode *inode)
  13{
  14        down_write(&EXT4_I(inode)->i_mmap_sem);
  15        truncate_inode_pages(inode->i_mapping, inode->i_size);
  16        ext4_truncate(inode);
  17        up_write(&EXT4_I(inode)->i_mmap_sem);
  18}
  19
  20/*
  21 * Work out how many blocks we need to proceed with the next chunk of a
  22 * truncate transaction.
  23 */
  24static inline unsigned long ext4_blocks_for_truncate(struct inode *inode)
  25{
  26        ext4_lblk_t needed;
  27
  28        needed = inode->i_blocks >> (inode->i_sb->s_blocksize_bits - 9);
  29
  30        /* Give ourselves just enough room to cope with inodes in which
  31         * i_blocks is corrupt: we've seen disk corruptions in the past
  32         * which resulted in random data in an inode which looked enough
  33         * like a regular file for ext4 to try to delete it.  Things
  34         * will go a bit crazy if that happens, but at least we should
  35         * try not to panic the whole kernel. */
  36        if (needed < 2)
  37                needed = 2;
  38
  39        /* But we need to bound the transaction so we don't overflow the
  40         * journal. */
  41        if (needed > EXT4_MAX_TRANS_DATA)
  42                needed = EXT4_MAX_TRANS_DATA;
  43
  44        return EXT4_DATA_TRANS_BLOCKS(inode->i_sb) + needed;
  45}
  46
  47