From a93cd4cf86466caa49cfe64607bea7f0bde3f916 Mon Sep 17 00:00:00 2001 From: Jan Kara Date: Thu, 26 Jun 2014 12:30:54 -0400 Subject: [PATCH] ext4: Fix hole punching for files with indirect blocks 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: 8bad6fc813a3a5300f51369c39d315679fd88c72 Signed-off-by: Jan Kara Signed-off-by: Theodore Ts'o --- fs/ext4/indirect.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/fs/ext4/indirect.c b/fs/ext4/indirect.c index 6f3bb55567b6..fd69da194826 100644 --- a/fs/ext4/indirect.c +++ b/fs/ext4/indirect.c @@ -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);