ext4: Fix hole punching for files with indirect blocks (a93cd4cf) · Commits · 戴 / test

Hole punching code for files with indirect blocks wrongly computed number of blocks which need to be cleared when traversing the indirect block tree. That could result in punching more blocks than actually requested and thus effectively cause a data loss. For example: fallocate -n -p 10240000 4096 will punch the range 10240000 - 12632064 instead of the range 1024000 - 10244096. Fix the calculation. CC: stable@vger.kernel.org Fixes: Signed-off-by:

Jan Kara <jack@suse.cz> Signed-off-by:

Theodore Ts'o <tytso@mit.edu>

fs/ext4/indirect.c

+10 −2

Original line number	Diff line number	Diff line
		@@ -1316,16 +1316,24 @@ static int free_hole_blocks(handle_t handle, struct inode inode,
		blk = *i_data;
		if (level > 0) {
		ext4_lblk_t first2;
		ext4_lblk_t count2;

		bh = sb_bread(inode->i_sb, le32_to_cpu(blk));
		if (!bh) {
		EXT4_ERROR_INODE_BLOCK(inode, le32_to_cpu(blk),
		"Read failure");
		return -EIO;
		}
		first2 = (first > offset) ? first - offset : 0;
		if (first > offset) {
		first2 = first - offset;
		count2 = count;
		} else {
		first2 = 0;
		count2 = count - (offset - first);
		}
		ret = free_hole_blocks(handle, inode, bh,
		(__le32 *)bh->b_data, level - 1,
		first2, count - offset,
		first2, count2,
		inode->i_sb->s_blocksize >> 2);
		if (ret) {
		brelse(bh);

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