2 Commits

Author	SHA1	Message	Date
Jan Kara	ea3d7209ca	ext4: fix races between page faults and hole punching ... Currently, page faults and hole punching are completely unsynchronized. This can result in page fault faulting in a page into a range that we are punching after truncate_pagecache_range() has been called and thus we can end up with a page mapped to disk blocks that will be shortly freed. Filesystem corruption will shortly follow. Note that the same race is avoided for truncate by checking page fault offset against i_size but there isn't similar mechanism available for punching holes. Fix the problem by creating new rw semaphore i_mmap_sem in inode and grab it for writing over truncate, hole punching, and other functions removing blocks from extent tree and for read over page faults. We cannot easily use i_data_sem for this since that ranks below transaction start and we need something ranking above it so that it can be held over the whole truncate / hole punching operation. Also remove various workarounds we had in the code to reduce race window when page fault could have created pages with stale mapping information. Signed-off-by: Jan Kara <jack@suse.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu>	2015-12-07 14:28:03 -05:00
Theodore Ts'o	9f125d641b	ext4: move common truncate functions to header file ... Move two functions that will be needed by the indirect functions to be moved to indirect.c as well as inode.c to truncate.h as inline functions, so that we can avoid having duplicate copies of the function (which can be a maintenance problem) without having to expose them as globally functions. Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>	2011-06-27 19:16:04 -04:00