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path: root/fs/gfs2/glops.h
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2014-11-17GFS2: update freeze code to use freeze/thaw_super on all nodesBenjamin Marzinski
The current gfs2 freezing code is considerably more complicated than it should be because it doesn't use the vfs freezing code on any node except the one that begins the freeze. This is because it needs to acquire a cluster glock before calling the vfs code to prevent a deadlock, and without the new freeze_super and thaw_super hooks, that was impossible. To deal with the issue, gfs2 had to do some hacky locking tricks to make sure that a frozen node couldn't be holding on a lock it needed to do the unfreeze ioctl. This patch makes use of the new hooks to simply the gfs2 locking code. Now, all the nodes in the cluster freeze and thaw in exactly the same way. Every node in the cluster caches the freeze glock in the shared state. The new freeze_super hook allows the freezing node to grab this freeze glock in the exclusive state without first calling the vfs freeze_super function. All the nodes in the cluster see this lock change, and call the vfs freeze_super function. The vfs locking code guarantees that the nodes can't get stuck holding the glocks necessary to unfreeze the system. To unfreeze, the freezing node uses the new thaw_super hook to drop the freeze glock. Again, all the nodes notice this, reacquire the glock in shared mode and call the vfs thaw_super function. Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com> Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
2014-05-14GFS2: remove transaction glockBenjamin Marzinski
GFS2 has a transaction glock, which must be grabbed for every transaction, whose purpose is to deal with freezing the filesystem. Aside from this involving a large amount of locking, it is very easy to make the current fsfreeze code hang on unfreezing. This patch rewrites how gfs2 handles freezing the filesystem. The transaction glock is removed. In it's place is a freeze glock, which is cached (but not held) in a shared state by every node in the cluster when the filesystem is mounted. This lock only needs to be grabbed on freezing, and actions which need to be safe from freezing, like recovery. When a node wants to freeze the filesystem, it grabs this glock exclusively. When the freeze glock state changes on the nodes (either from shared to unlocked, or shared to exclusive), the filesystem does a special log flush. gfs2_log_flush() does all the work for flushing out the and shutting down the incore log, and then it tries to grab the freeze glock in a shared state again. Since the filesystem is stuck in gfs2_log_flush, no new transaction can start, and nothing can be written to disk. Unfreezing the filesytem simply involes dropping the freeze glock, allowing gfs2_log_flush() to grab and then release the shared lock, so it is cached for next time. However, in order for the unfreezing ioctl to occur, gfs2 needs to get a shared lock on the filesystem root directory inode to check permissions. If that glock has already been grabbed exclusively, fsfreeze will be unable to get the shared lock and unfreeze the filesystem. In order to allow the unfreeze, this patch makes gfs2 grab a shared lock on the filesystem root directory during the freeze, and hold it until it unfreezes the filesystem. The functions which need to grab a shared lock in order to allow the unfreeze ioctl to be issued now use the lock grabbed by the freeze code instead. The freeze and unfreeze code take care to make sure that this shared lock will not be dropped while another process is using it. Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com> Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
2011-10-21GFS2: Fix AIL flush issue during fsyncSteven Whitehouse
Unfortunately, it is not enough to just ignore locked buffers during the AIL flush from fsync. We need to be able to ignore all buffers which are locked, dirty or pinned at this stage as they might have been added subsequent to the log flush earlier in the fsync function. In addition, this means that we no longer need to rely on i_mutex to keep out writes during fsync, so we can, as a side-effect, remove that protection too. Signed-off-by: Steven Whitehouse <swhiteho@redhat.com> Tested-By: Abhijith Das <adas@redhat.com>
2011-04-20GFS2: Clean up fsync()Steven Whitehouse
This patch is designed to clean up GFS2's fsync implementation and ensure that it really does get everything on disk. Since ->write_inode() has been updated, we can call that via the vfs library function sync_inode_metadata() and the only remaining thing that has to be done is to ensure that we get any revoke records in the log after the inode has been written back. Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
2009-03-24GFS2: Add a "demote a glock" interface to sysfsSteven Whitehouse
This adds a sysfs file called demote_rq to GFS2's per filesystem directory. Its possible to use this file to demote arbitrary glocks in exactly the same way as if a request had come in from a remote node. This is intended for testing issues relating to caching of data under glocks. Despite that, the interface is generic enough to send requests to any type of glock, but be careful as its not always safe to send an arbitrary message to an arbitrary glock. For that reason and to prevent DoS, this interface is restricted to root only. The messages look like this: <type>:<glocknumber> <mode> Example: echo -n "2:13324 EX" >/sys/fs/gfs2/unity:myfs/demote_rq Which means "please demote inode glock (type 2) number 13324 so that I can get an EX (exclusive) lock". The lock modes are those which would normally be sent by a remote node in its callback so if you want to unlock a glock, you use EX, to demote to shared, use SH or PR (depending on whether you like GFS2 or DLM lock modes better!). If the glock doesn't exist, you'll get -ENOENT returned. If the arguments don't make sense, you'll get -EINVAL returned. The plan is that this interface will be used in combination with the blktrace patch which I recently posted for comments although it is, of course, still useful in its own right. Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
2006-09-05[GFS2] Make headers compile on their ownSteven Whitehouse
As per Jan Engelhardt's comments, this should make all the headers compile on their own by including and/or declaring structures early. Cc: Jan Engelhardt <jengelh@linux01.gwdg.de> Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
2006-09-01[GFS2] Update copyright, tidy up incore.hSteven Whitehouse
As per comments from Jan Engelhardt <jengelh@linux01.gwdg.de> this updates the copyright message to say "version" in full rather than "v.2". Also incore.h has been updated to remove forward structure declarations which are not required. The gfs2_quota_lvb structure has now had endianess annotations added to it. Also quota.c has been updated so that we now store the lvb data locally in endian independant format to avoid needing a structure in host endianess too. As a result the endianess conversions are done as required at various points and thus the conversion routines in lvb.[ch] are no longer required. I've moved the one remaining constant in lvb.h thats used into lm.h and removed the unused lvb.[ch]. I have not changed the HIF_ constants. That is left to a later patch which I hope will unify the gh_flags and gh_iflags fields of the struct gfs2_holder. Cc: Jan Engelhardt <jengelh@linux01.gwdg.de> Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
2006-08-30[GFS2] Make glock operations constSteven Whitehouse
For all the usual reasons of enforcing correctness and potentially reducing code size, this patch makes the glock operations const. Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
2006-05-18[GFS2] Update copyright date to 2006Steven Whitehouse
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
2006-01-16[GFS2] The core of GFS2David Teigland
This patch contains all the core files for GFS2. Signed-off-by: David Teigland <teigland@redhat.com> Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>