From b9a4207d5e911b938f73079a83cc2ae10524ec7f Mon Sep 17 00:00:00 2001 From: Jan Kara Date: Tue, 8 Dec 2009 21:24:33 -0500 Subject: ext4: Avoid 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 the 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 Signed-off-by: "Theodore Ts'o" --- fs/ext4/inode.c | 20 +++++++++++++++----- 1 file changed, 15 insertions(+), 5 deletions(-) diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index d3f99e9..0e2ea57 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -1492,6 +1492,16 @@ 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) @@ -1557,7 +1567,7 @@ 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 @@ -1667,7 +1677,7 @@ 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 @@ -1709,7 +1719,7 @@ 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 @@ -1772,7 +1782,7 @@ 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 @@ -3048,7 +3058,7 @@ 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)) -- cgit v1.1