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  */
  12 static 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  */
  24 static 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