>From 8bd74d5ced949f276e51d770092bff576d42fa79 Mon Sep 17 00:00:00 2001 From: Jan Kara Date: Wed, 2 Dec 2009 20:05:23 +0100 Subject: [PATCH 2/3] ext4: Fix data / filesystem corruption when write fails to copy data When ext4_write_begin fails after allocating some blocks or generic_perform_write fails to copy data to write, we truncate blocks already instantiated beyond i_size. Although these blocks were never inside i_size, we have to truncate pagecache of these blocks so that corresponding buffers get unmapped. Otherwise subsequent __block_prepare_write (called because we are retrying the write) will find the buffers mapped, not call ->get_block, and thus the page will be backed by already freed blocks leading to filesystem and data corruption. Signed-off-by: Jan Kara --- fs/ext4/inode.c | 20 +++++++++++++++----- 1 files changed, 15 insertions(+), 5 deletions(-) diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index 2c8caa5..e802988 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -1534,6 +1534,16 @@ static int do_journal_get_write_access(handle_t *handle, return ext4_journal_get_write_access(handle, bh); } +/* + * Truncate blocks that were not used by write. We have to truncate the + * pagecache as well so that corresponding buffers get properly unmapped. + */ +static void ext4_truncate_failed_write(struct inode *inode) +{ + truncate_inode_pages(inode->i_mapping, inode->i_size); + ext4_truncate(inode); +} + static int ext4_write_begin(struct file *file, struct address_space *mapping, loff_t pos, unsigned len, unsigned flags, struct page **pagep, void **fsdata) @@ -1599,7 +1609,7 @@ retry: ext4_journal_stop(handle); if (pos + len > inode->i_size) { - ext4_truncate(inode); + ext4_truncate_failed_write(inode); /* * If truncate failed early the inode might * still be on the orphan list; we need to @@ -1709,7 +1719,7 @@ static int ext4_ordered_write_end(struct file *file, ret = ret2; if (pos + len > inode->i_size) { - ext4_truncate(inode); + ext4_truncate_failed_write(inode); /* * If truncate failed early the inode might still be * on the orphan list; we need to make sure the inode @@ -1751,7 +1761,7 @@ static int ext4_writeback_write_end(struct file *file, ret = ret2; if (pos + len > inode->i_size) { - ext4_truncate(inode); + ext4_truncate_failed_write(inode); /* * If truncate failed early the inode might still be * on the orphan list; we need to make sure the inode @@ -1814,7 +1824,7 @@ static int ext4_journalled_write_end(struct file *file, if (!ret) ret = ret2; if (pos + len > inode->i_size) { - ext4_truncate(inode); + ext4_truncate_failed_write(inode); /* * If truncate failed early the inode might still be * on the orphan list; we need to make sure the inode @@ -3091,7 +3101,7 @@ retry: * i_size_read because we hold i_mutex. */ if (pos + len > inode->i_size) - ext4_truncate(inode); + ext4_truncate_failed_write(inode); } if (ret == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries)) -- 1.6.4.2