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       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                 :          0 : 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                 :          0 :         down_write(&EXT4_I(inode)->i_mmap_sem);
      19                 :          0 :         truncate_inode_pages(inode->i_mapping, inode->i_size);
      20                 :          0 :         ext4_truncate(inode);
      21                 :          0 :         up_write(&EXT4_I(inode)->i_mmap_sem);
      22                 :          0 : }
      23                 :            : 
      24                 :            : /*
      25                 :            :  * Work out how many blocks we need to proceed with the next chunk of a
      26                 :            :  * truncate transaction.
      27                 :            :  */
      28                 :          3 : static inline unsigned long ext4_blocks_for_truncate(struct inode *inode)
      29                 :            : {
      30                 :            :         ext4_lblk_t needed;
      31                 :            : 
      32                 :          3 :         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                 :          3 :         if (needed < 2)
      41                 :            :                 needed = 2;
      42                 :            : 
      43                 :            :         /* But we need to bound the transaction so we don't overflow the
      44                 :            :          * journal. */
      45                 :          3 :         if (needed > EXT4_MAX_TRANS_DATA)
      46                 :            :                 needed = EXT4_MAX_TRANS_DATA;
      47                 :            : 
      48                 :          3 :         return EXT4_DATA_TRANS_BLOCKS(inode->i_sb) + needed;
      49                 :            : }
      50                 :            :