fs/ext4/truncate.h

   1 /*
   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  */
  11 static inline void ext4_truncate_failed_write(struct inode *inode)
  12 {
  13         down_write(&EXT4_I(inode)->i_mmap_sem);
  14         truncate_inode_pages(inode->i_mapping, inode->i_size);
  15         ext4_truncate(inode);
  16         up_write(&EXT4_I(inode)->i_mmap_sem);
  17 }
  18
  19 /*
  20  * Work out how many blocks we need to proceed with the next chunk of a
  21  * truncate transaction.
  22  */
  23 static inline unsigned long ext4_blocks_for_truncate(struct inode *inode)
  24 {
  25         ext4_lblk_t needed;
  26
  27         needed = inode->i_blocks >> (inode->i_sb->s_blocksize_bits - 9);
  28
  29         /* Give ourselves just enough room to cope with inodes in which
  30          * i_blocks is corrupt: we've seen disk corruptions in the past
  31          * which resulted in random data in an inode which looked enough
  32          * like a regular file for ext4 to try to delete it.  Things
  33          * will go a bit crazy if that happens, but at least we should
  34          * try not to panic the whole kernel. */
  35         if (needed < 2)
  36                 needed = 2;
  37
  38         /* But we need to bound the transaction so we don't overflow the
  39          * journal. */
  40         if (needed > EXT4_MAX_TRANS_DATA)
  41                 needed = EXT4_MAX_TRANS_DATA;
  42
  43         return EXT4_DATA_TRANS_BLOCKS(inode->i_sb) + needed;
  44 }
  45