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