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        /*
  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 */
  28static 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