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ext3: Fix data / filesystem corruption when write fails to copy data 

When ext3_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.

Reported-by: James Y Knight <foom@fuhm.net>
Signed-off-by: Jan Kara <jack@suse.cz>
This commit is contained in:
Jan Kara 2009-12-01 16:53:06 +01:00
parent 5a20bdfcdc
commit 68eb3db083
1 changed files with 14 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

18
fs/ext3/inode.c
View File

@ -1151,6 +1151,16 @@ static int do_journal_get_write_access(handle_t *handle,
return ext3_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 ext3_truncate_failed_write(struct inode *inode)
{
truncate_inode_pages(inode->i_mapping, inode->i_size);
ext3_truncate(inode);
}
static int ext3_write_begin(struct file *file, struct address_space *mapping,
loff_t pos, unsigned len, unsigned flags,
struct page **pagep, void **fsdata)
@ -1209,7 +1219,7 @@ write_begin_failed:
unlock_page(page);
page_cache_release(page);
if (pos + len > inode->i_size)
ext3_truncate(inode);
ext3_truncate_failed_write(inode);
}
if (ret == -ENOSPC && ext3_should_retry_alloc(inode->i_sb, &retries))
goto retry;
@ -1304,7 +1314,7 @@ static int ext3_ordered_write_end(struct file *file,
page_cache_release(page);
if (pos + len > inode->i_size)
ext3_truncate(inode);
ext3_truncate_failed_write(inode);
return ret ? ret : copied;
}
@ -1330,7 +1340,7 @@ static int ext3_writeback_write_end(struct file *file,
page_cache_release(page);
if (pos + len > inode->i_size)
ext3_truncate(inode);
ext3_truncate_failed_write(inode);
return ret ? ret : copied;
}
@ -1383,7 +1393,7 @@ static int ext3_journalled_write_end(struct file *file,
page_cache_release(page);
if (pos + len > inode->i_size)
ext3_truncate(inode);
ext3_truncate_failed_write(inode);
return ret ? ret : copied;
}