snapshots on UFS filesystems running with journaled soft updates.
This is the first of several bugs that need to be fixed before
removing the restriction added in -r230250 to prevent the use
of snapshots on filesystems running with journaled soft updates.
The deadlock occurs when holding the snapshot lock (snaplk)
and then trying to flush an inode via ffs_update(). We become
blocked by another process trying to flush a different inode
contained in the same inode block that we need. It holds the
inode block for which we are waiting locked. When it tries to
write the inode block, it gets blocked waiting for the our
snaplk when it calls ffs_copyonwrite() to see if the inode
block needs to be copied in our snapshot.
The most obvious place that this deadlock arises is in the
ffs_copyonwrite() routine when it updates critical metadata
in a snapshot and tries to write it out before proceeding.
The fix here is to write the data and indirect block pointer
for the snapshot, but to skip the call to ffs_update() to
write the snapshot inode. To ensure that we will never have
to update a pointer in the inode itself, the ffs_snapshot()
routine that creates the snapshot has to ensure that all the
direct blocks are allocated as part of the creation of the
snapshot.
A less obvious place that this deadlock occurs is when we hold
the snaplk because we are deleting a snapshot. In the course of
doing the deletion, we need to allocate various soft update
dependency structures and allocate some journal space. If we
hit a resource limit while doing this we decrease the resources
in use by flushing out an existing dirty file to get it to give
up the soft dependency resources that it holds. The flush can
cause an ffs_update() to be done on the inode for the file that
we have selected to flush resulting in the same deadlock as
described above when the inode that we have chosen to flush
resides in the same inode block as the snapshot inode that we hold.
The fix is to defer cleaning up any time that the inode on which
we are operating is a snapshot.
Help and review by: Jeff Roberson
Tested by: Peter Holm
MFC (to 9 only) after: 2 weeks
installs clang as /usr/bin/cc, /usr/bin/c++ and /usr/bin/cpp.
Note this does *not* disable building and installing gcc, which will
still be available as /usr/bin/gcc, /usr/bin/g++ and /usr/bin/gcpp. If
you want to disable gcc completely, you must use WITHOUT_GCC.
MFC after: 2 weeks
This is harmless because srandom() is called somewhere else, with time(NULL)
as a seed, but this is more correct.
Obtained from: https://bitbucket.org/mux/csup
Pointyhat to: not mux, somebody else
MFC after: 1 week
operations for setting and accessing vnode's v_socket field.
The operations are necessary to implement proper unix socket handling
on layered file systems like nullfs(5).
This change fixes the long standing issue with nullfs(5) being in that
unix sockets did not work between lower and upper layers: if we bound
to a socket on the lower layer we could connect only to the lower
path; if we bound to the upper layer we could connect only to the
upper path. The new behavior is one can connect to both the lower and
the upper paths regardless what layer path one binds to.
PR: kern/51583, kern/159663
Suggested by: kib
Reviewed by: arch
MFC after: 2 weeks
sys/xen/interface/io/blkif.h:
o Insert space in "Red Hat".
o Fix typo "discard-aligment" -> "discard-alignment"
o Fix typo "unamp" -> "unmap"
o Fix typo "formated" -> "formatted"
o Clarify the text for "params".
o Clarify the text for "sector-size".
o Clarify the text for "max-requests" in the backend section.
instead of accepting half-constructed vnode. Previous code cannot decide
what to do with such vnode anyway, and although processing it for hash
removal, paniced later when getting rid of nullfs reference on lowervp.
While there, remove initializations from the declaration block.
Tested by: pho
MFC after: 1 week
function null_destroy_proto() from null_insmntque_dtr(). Also
apply null_destroy_proto() in null_nodeget() when we raced and a vnode
is found in the hash, so the currently allocated protonode shall be
destroyed.
Lock the vnode interlock around reassigning the v_vnlock.
In fact, this path will not be exercised after several later commits,
since null_nodeget() cannot take shared-locked lowervp at all due to
insmntque() requirements.
Reported by: rea
Tested by: pho
MFC after: 1 week
- Reserver respective number of addresses for managment port
- octm uses base address directly
- other drivers get MACs on "first come first served" basis
Reviewed by: juli
external pagers in Mach. FreeBSD doesn't implement external pagers.
Moreover, it don't pageout the kernel object. So, the reasons for
having code don't hold.
Reviewed by: kib
MFC after: 6 weeks
following clang warning:
sys/kern/sys_pipe.c:1556:10: error: promoted type 'int' of K&R function parameter is not compatible with the parameter type 'mode_t'
(aka 'unsigned short') declared in a previous prototype [-Werror]
mode_t mode;
^
sys/kern/sys_pipe.c:155:19: note: previous declaration is here
static fo_chmod_t pipe_chmod;
^
