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         struct address_space *mapping = inode->i_mapping;
  15
  16         /*
  17          * We don't need to call ext4_break_layouts() because the blocks we
  18          * are truncating were never visible to userspace.
  19          */
  20         filemap_invalidate_lock(mapping);
  21         truncate_inode_pages(mapping, inode->i_size);
  22         ext4_truncate(inode);
  23         filemap_invalidate_unlock(mapping);
  24 }
  25
  26 /*
  27  * Work out how many blocks we need to proceed with the next chunk of a
  28  * truncate transaction.
  29  */
  30 static inline unsigned long ext4_blocks_for_truncate(struct inode *inode)
  31 {
  32         ext4_lblk_t needed;
  33
  34         needed = inode->i_blocks >> (inode->i_sb->s_blocksize_bits - 9);
  35
  36         /* Give ourselves just enough room to cope with inodes in which
  37          * i_blocks is corrupt: we've seen disk corruptions in the past
  38          * which resulted in random data in an inode which looked enough
  39          * like a regular file for ext4 to try to delete it.  Things
  40          * will go a bit crazy if that happens, but at least we should
  41          * try not to panic the whole kernel. */
  42         if (needed < 2)
  43                 needed = 2;
  44
  45         /* But we need to bound the transaction so we don't overflow the
  46          * journal. */
  47         if (needed > EXT4_MAX_TRANS_DATA)
  48                 needed = EXT4_MAX_TRANS_DATA;
  49
  50         return EXT4_DATA_TRANS_BLOCKS(inode->i_sb) + needed;
  51 }
  52