This is a proof of concept implementation of XFS's GOINGDOWN ioctl for ext4. I've tried to replicate XFS's semantics (as much as they can translate to ext4). This test series is currently *not* passing xfstests. Specifically, the following tests are failing: generic/042 generic/044 generic/045 generic/046 As near as I can tell, these tests are sensitive to how the file system implements and handles delayed allocation. In particular, generic/04[456] assumes that if you do a delayed allocation write of 64k, and then truncate the file to 64k or 32k, the file will either be zero length, or i_size is non-zero, it MUST NOT have no extents. It's not clear to me why this needs to be true. The test description says "test for NULL files problem". But since POSIX states that how truncate will handle truncates beyond i_size is unspecified, and what happens after a crash w/o an fsync() is similarly unspecified, it's not clear what is the best way to deal with this. One is to simply use a different ioctl code point, to avoid enabling the xfstests tests. Another to modify the tests to skip them for ext4. Or I can teach kvm-xfstests and gce-xfstests to ignore these test failures by skipping the tests in my test framework. Comments, thoughts? - Ted P.S. So I'm not implementing this just for increased xfstests coverage; I have an operational need for this functionality on production systems. The short version is if you are tearing down a container, and you don't care about its scratch space, being able to drop all of the writes from being sent to the storage device (which might be over the network, say using iSCSI), is a Good Thing. Theodore Ts'o (3): ext4: rename s_resize_flags to s_ext4_flags ext4: add shutdown bit and check for it ext4: add EXT4_IOC_GOINGDOWN ioctl fs/ext4/ext4.h | 26 +++++++++++++++++++++++--- fs/ext4/ext4_jbd2.c | 2 ++ fs/ext4/file.c | 12 ++++++++++++ fs/ext4/fsync.c | 3 +++ fs/ext4/ialloc.c | 3 +++ fs/ext4/inode.c | 25 +++++++++++++++++++++++++ fs/ext4/ioctl.c | 42 ++++++++++++++++++++++++++++++++++++++++++ fs/ext4/namei.c | 12 ++++++++++++ fs/ext4/resize.c | 5 +++-- fs/ext4/super.c | 2 +- fs/ext4/xattr.c | 3 +++ 11 files changed, 129 insertions(+), 6 deletions(-) -- 2.11.0.rc0.7.gbe5a750
