Rolling back a mounted filesystem with open file handles and
cached dentries+inodes never worked properly in ZoL. The
major issue was that Linux provides no easy mechanism for
modules to invalidate the inode cache for a file system.
Because of this it was possible that an inode from the previous
filesystem would not get properly dropped from the cache during
rolling back. Then a new inode with the same inode number would
be create and collide with the existing cached inode. Ideally
this would trigger an VERIFY() but in practice the error wasn't
handled and it would just NULL reference.
Luckily, this issue can be resolved by sprucing up the existing
Solaris zfs_rezget() functionality for the Linux VFS.
The way it works now is that when a file system is rolled back
all the cached inodes will be traversed and refetched from disk.
If a version of the cached inode exists on disk the in-core
copy will be updated accordingly. If there is no match for that
object on disk it will be unhashed from the inode cache and
marked as stale.
This will effectively make the inode unfindable for lookups
allowing the inode number to be immediately recycled. The inode
will then only be accessible from the cached dentries. Subsequent
dentry lookups which reference a stale inode will result in the
dentry being invalidated. Once invalidated the dentry will drop
its reference on the inode allowing it to be safely pruned from
the cache.
Special care is taken for negative dentries since they do not
reference any inode. These dentires will be invalidate based
on when they were added to the dentry cache. Entries added
before the last rollback will be invalidate to prevent them
from masking real files in the dataset.
Two nice side effects of this fix are:
* Removes the dependency on spl_invalidate_inodes(), it can now
be safely removed from the SPL when we choose to do so.
* zfs_znode_alloc() no longer requires a dentry to be passed.
This effectively reverts this portition of the code to its
upstream counterpart. The dentry is not instantiated more
correctly in the Linux ZPL layer.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ned Bass <bass6@llnl.gov>
Closes#795
A misplaced single quote caused the umount command to fail with a
syntax error when unmounting snapshots under the .zfs/snapshot
control directory.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#1210
As of Linux 3.4 the UMH_WAIT_* constants were renumbered. In
particular, the meaning of "1" changed from UMH_WAIT_PROC (wait for
process to complete), to UMH_WAIT_EXEC (wait for the exec, but not the
process). A number of call sites used the number 1 instead of the
constant name, so the behavior was not as expected on kernels with this
change.
One visible consequence of this change was that processes accessing
automounted snapshots received an ELOOP error because they failed to
wait for zfs.mount to complete.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#816
Linux kernel commit d8e794d accidentally broke the delayed work
APIs for non-GPL callers. While the APIs to schedule a delayed
work item are still available to all callers, it is no longer
possible to initialize the delayed work item.
I'm cautiously optimistic we could get the delayed_work_timer_fn
exported for all callers in the upstream kernel. But frankly
the compatibility code to use this kernel interface has always
been problematic.
Therefore, this patch abandons direct use the of the Linux
kernel interface in favor of the new delayed taskq interface.
It provides roughly the same functionality as delayed work queues
but it's a stable interface under our control.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#1053
When automounting a snapshot in the .zfs/snapshot directory
make sure to quote both the dataset name and the mount point.
This ensures that if either component contains spaces, which
are allowed, they get handled correctly.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#1027
Otherwise it will cause zpl_shares_lookup() to return a invalid
pointer when an error occurs.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Yuxuan Shui <yshuiv7@gmail.com>
Closes#626#885#947#977
As of Linux commit 9249e17fe094d853d1ef7475dd559a2cc7e23d42 the
mount flags are now passed to sget() so they can be used when
initializing a new superblock.
ZFS never uses sget() in this fashion so we can simply pass a
zero and add a zpl_sget() compatibility wrapper.
Signed-off-by: Yuxuan Shui <yshuiv7@gmail.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #873
The .zfs control directory implementation currently relies on
the fact that there is a direct 1:1 mapping from an object id
to its inode number. This works well as long as the system
uses a 64-bit value to store the inode number.
Unfortunately, the Linux kernel defines the inode number as
an 'unsigned long' type. This means that for 32-bit systems
will only have 32-bit inode numbers but we still have 64-bit
object ids.
This problem is particularly acute for the .zfs directories
which leverage those upper 32-bits. This is done to avoid
conflicting with object ids which are allocated monotonically
starting from 0. This is likely to also be a problem for
datasets on 32-bit systems with more than ~2 billion files.
The right long term fix must remove the simple 1:1 mapping.
Until that's done the only safe thing to do is to disable the
.zfs directory on 32-bit systems.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Because the .zfs ctldir inodes are not backed by physical storage
they use a different create path which was not properly accounting
for them as used. This could result in ->nr_cached_objects()
returning 0 and cause a divide by zero error in prune_super().
In my option there's a kernel bug here too which allows this to
happen. They should either be checking for 0 or adding +1 like
they correctly do earlier in the function.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#617
Add support for the .zfs control directory. This was accomplished
by leveraging as much of the existing ZFS infrastructure as posible
and updating it for Linux as required. The bulk of the core
functionality is now all there with the following limitations.
*) The .zfs/snapshot directory automount support requires a 2.6.37
or newer kernel. The exception is RHEL6.2 which has backported
the d_automount patches.
*) Creating/destroying/renaming snapshots with mkdir/rmdir/mv
in the .zfs/snapshot directory works as expected. However,
this functionality is only available to root until zfs
delegations are finished.
* mkdir - create a snapshot
* rmdir - destroy a snapshot
* mv - rename a snapshot
The following issues are known defeciences, but we expect them to
be addressed by future commits.
*) Add automount support for kernels older the 2.6.37. This should
be possible using follow_link() which is what Linux did before.
*) Accessing the .zfs/snapshot directory via NFS is not yet possible.
The majority of the ground work for this is complete. However,
finishing this work will require resolving some lingering
integration issues with the Linux NFS kernel server.
*) The .zfs/shares directory exists but no futher smb functionality
has yet been implemented.
Contributions-by: Rohan Puri <rohan.puri15@gmail.com>
Contributiobs-by: Andrew Barnes <barnes333@gmail.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#173
This code is used for snapshot and heavily leverages Solaris
functionality we do not want to reimplement. These files have
been removed, including references to them, and will be replaced
by a zfs_snap.c/zpl_snap.c implementation which handles snapshots.
The ZFS code is being restructured to act as a library and a stand
alone module. This allows us to leverage most of the existing code
with minimal modification. It also means we need to drop the Solaris
vfs/vnode functions they will be replaced by Linux equivilants and
updated to be Linux friendly.
