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         /*
  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  */
  28 static 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