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2008-01-25[GFS2] Remove "reclaim limit"Steven Whitehouse
This call to reclaim glocks is not needed, and in particular we don't want it in the fast path for locking glocks. The limit was entirely arbitrary anyway and we can't expect users to adjust things like this, the remaining code will do the right thing on its own. Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
2008-01-25[GFS2] Remove unused variablesSteven Whitehouse
These haven't been used for some time, remove them. Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
2008-01-25[GFS2] Use correct include file in ops_address.cSteven Whitehouse
Something changed in the upstream kernel, and it needs this one-liner to allow ops_address.c to build. Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
2008-01-25[GFS2] Don't hold page lock when starting transactionSteven Whitehouse
This is an addendum to the new AOPs work which moves the point at which we take the page lock so that we don't get it until the last possible moment. This resolves a conflict between starting transactions and the page lock. Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
2008-01-25[GFS2] Add writepages for GFS2 jdataSteven Whitehouse
This patch resolves a lock ordering issue where we had been getting a transaction lock in the wrong order with respect to the page lock. By using writepages rather than just writepage, it is then possible to start a transaction before locking the page, and thus matching the locking order elsewhere in the code. Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
2008-01-25[GFS2] Split gfs2_writepage into three casesSteven Whitehouse
This patch splits gfs2_writepage into separate functions for each of the three cases: writeback, ordered and journalled. As a result it becomes a lot easier to see what each one is doing. The common code is moved into gfs2_writepage_common. This fixes a performance bug where we were doing more work than strictly required in the ordered write case. Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
2008-01-25[GFS2] Introduce gfs2_set_aops()Steven Whitehouse
Just like ext3 we now have three sets of address space operations to cover the cases of writeback, ordered and journalled data writes. This means that the individual operations can now become less complicated as we are able to remove some of the tests for file data mode from the code. Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
2008-01-25[GFS2] Add gfs2_is_writeback()Steven Whitehouse
This adds a function "gfs2_is_writeback()" along the lines of the existing "gfs2_is_jdata()" in order to clean up the code and make the various tests for the inode mode more obvious. It also fixes the PageChecked() logic where we were resetting the flag too early in the case of an error path. Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
2008-01-25[GFS2] Remove unused field in struct gfs2_inodeSteven Whitehouse
Removes a field that is not used. Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
2008-01-25[GFS2] Remove useless i_cache from inodesSteven Whitehouse
The i_cache was designed to keep references to the indirect blocks used during block mapping so that they didn't have to be looked up continually. The idea failed because there are too many places where the i_cache needs to be freed, and this has in the past been the cause of many bugs. In addition there was no performance benefit being gained since the disk blocks in question were cached anyway. So this patch removes it in order to simplify the code to prepare for other changes which would otherwise have had to add further support for this feature. Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
2008-01-25[GFS2] Use ->page_mkwrite() for mmap()Steven Whitehouse
This cleans up the mmap() code path for GFS2 by implementing the page_mkwrite function for GFS2. We are thus able to use the generic filemap_fault function for our ->fault() implementation. This now means that shared writable mappings will be much more efficiently shared across the cluster if there is a reasonable proportion of read activity (the greater proportion, the better). As a side effect, it also reduces the size of the code, removes special cases from readpage and readpages, and makes the code path easier to follow. Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
2008-01-25[GFS2] Clean up internal read functionSteven Whitehouse
As requested by Christoph, this patch cleans up GFS2's internal read function so that it no longer uses the do_generic_mapping_read function. This function is obsolete and GFS2 is the last user of it. As a side effect the internal read code gets smaller and easier to read and gfs2_readpage is split into two. One function has the locking and the other function has the rest of the logic. Signed-off-by: Steven Whitehouse <swhiteho@redhat.com> Cc: Christoph Hellwig <hch@infradead.org>
2008-01-25[GFS2] Handle multiple glock demote requestsWendy Cheng
Fix a race condition where multiple glock demote requests are sent to a node back-to-back. This patch does a check inside handle_callback() to see whether a demote request is in progress. If true, it sets a flag to make sure run_queue() will loop again to handle the new request, instead of erronously setting gl_demote_state to a different state. Signed-off-by: S. Wendy Cheng <wcheng@redhat.com> Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
2008-01-24Kobject: convert fs/* from kobject_unregister() to kobject_put()Greg Kroah-Hartman
There is no need for kobject_unregister() anymore, thanks to Kay's kobject cleanup changes, so replace all instances of it with kobject_put(). Cc: Kay Sievers <kay.sievers@vrfy.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2008-01-24Kobject: change GFS2 to use kobject_init_and_addGreg Kroah-Hartman
Stop using kobject_register, as this way we can control the sending of the uevent properly, after everything is properly initialized. Cc: Steven Whitehouse <swhiteho@redhat.com> Cc: Kay Sievers <kay.sievers@vrfy.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2008-01-24kobject: convert kernel_kset to be a kobjectGreg Kroah-Hartman
kernel_kset does not need to be a kset, but a much simpler kobject now that we have kobj_attributes. We also rename kernel_kset to kernel_kobj to catch all users of this symbol with a build error instead of an easy-to-ignore build warning. Cc: Kay Sievers <kay.sievers@vrfy.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2008-01-24kset: convert kernel_subsys to use kset_createGreg Kroah-Hartman
Dynamically create the kset instead of declaring it statically. We also rename kernel_subsys to kernel_kset to catch all users of this symbol with a build error instead of an easy-to-ignore build warning. Cc: Kay Sievers <kay.sievers@vrfy.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2008-01-24kset: convert gfs2 dlm to use kset_createGreg Kroah-Hartman
Dynamically create the kset instead of declaring it statically. Cc: Kay Sievers <kay.sievers@vrfy.org> Cc: Steven Whitehouse <swhiteho@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2008-01-24kset: convert gfs2 to use kset_createGreg Kroah-Hartman
Dynamically create the kset instead of declaring it statically. Cc: Kay Sievers <kay.sievers@vrfy.org> Cc: Steven Whitehouse <swhiteho@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2008-01-24kobject: convert main fs kobject to use kobject_createGreg Kroah-Hartman
This also renames fs_subsys to fs_kobj to catch all current users with a build error instead of a build warning which can easily be missed. Cc: Kay Sievers <kay.sievers@vrfy.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2008-01-24kobject: remove struct kobj_type from struct ksetGreg Kroah-Hartman
We don't need a "default" ktype for a kset. We should set this explicitly every time for each kset. This change is needed so that we can make ksets dynamic, and cleans up one of the odd, undocumented assumption that the kset/kobject/ktype model has. This patch is based on a lot of help from Kay Sievers. Nasty bug in the block code was found by Dave Young <hidave.darkstar@gmail.com> Cc: Kay Sievers <kay.sievers@vrfy.org> Cc: Dave Young <hidave.darkstar@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-10-22exportfs: make struct export_operations constChristoph Hellwig
Now that nfsd has stopped writing to the find_exported_dentry member we an mark the export_operations const Signed-off-by: Christoph Hellwig <hch@lst.de> Cc: Neil Brown <neilb@suse.de> Cc: "J. Bruce Fields" <bfields@fieldses.org> Cc: <linux-ext4@vger.kernel.org> Cc: Dave Kleikamp <shaggy@austin.ibm.com> Cc: Anton Altaparmakov <aia21@cantab.net> Cc: David Chinner <dgc@sgi.com> Cc: Timothy Shimmin <tes@sgi.com> Cc: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> Cc: Hugh Dickins <hugh@veritas.com> Cc: Chris Mason <mason@suse.com> Cc: Jeff Mahoney <jeffm@suse.com> Cc: "Vladimir V. Saveliev" <vs@namesys.com> Cc: Steven Whitehouse <swhiteho@redhat.com> Cc: Mark Fasheh <mark.fasheh@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-22gfs2: new export opsChristoph Hellwig
Convert gfs2 to the new ops. Uses a similar structure to the generic helpers, but gfs2 has it's own file handle formats. Signed-off-by: Christoph Hellwig <hch@lst.de> Cc: Neil Brown <neilb@suse.de> Cc: "J. Bruce Fields" <bfields@fieldses.org> Cc: Steven Whitehouse <swhiteho@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-17fs: correct SuS compliance for open of large file without optionsAlan Cox
The early LFS work that Linux uses favours EFBIG in various places. SuSv3 specifically uses EOVERFLOW for this as noted by Michael (Bug 7253) [EOVERFLOW] The named file is a regular file and the size of the file cannot be represented correctly in an object of type off_t. We should therefore transition to the proper error return code Signed-off-by: Alan Cox <alan@redhat.com> Cc: Theodore Tso <tytso@mit.edu> Cc: Jens Axboe <jens.axboe@oracle.com> Cc: Arjan van de Ven <arjan@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-17Slab API: remove useless ctor parameter and reorder parametersChristoph Lameter
Slab constructors currently have a flags parameter that is never used. And the order of the arguments is opposite to other slab functions. The object pointer is placed before the kmem_cache pointer. Convert ctor(void *object, struct kmem_cache *s, unsigned long flags) to ctor(struct kmem_cache *s, void *object) throughout the kernel [akpm@linux-foundation.org: coupla fixes] Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-16gfs2: convert to new aopsSteven Whitehouse
Cc: Nick Piggin <nickpiggin@yahoo.com.au> Cc: Steven Whitehouse <swhiteho@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-15Merge branch 'locks' of git://linux-nfs.org/~bfields/linuxLinus Torvalds
* 'locks' of git://linux-nfs.org/~bfields/linux: nfsd: remove IS_ISMNDLCK macro Rework /proc/locks via seq_files and seq_list helpers fs/locks.c: use list_for_each_entry() instead of list_for_each() NFS: clean up explicit check for mandatory locks AFS: clean up explicit check for mandatory locks 9PFS: clean up explicit check for mandatory locks GFS2: clean up explicit check for mandatory locks Cleanup macros for distinguishing mandatory locks Documentation: move locks.txt in filesystems/ locks: add warning about mandatory locking races Documentation: move mandatory locking documentation to filesystems/ locks: Fix potential OOPS in generic_setlease() Use list_first_entry in locks_wake_up_blocks locks: fix flock_lock_file() comment Memory shortage can result in inconsistent flocks state locks: kill redundant local variable locks: reverse order of posix_locks_conflict() arguments
2007-10-12Merge master.kernel.org:/pub/scm/linux/kernel/git/gregkh/driver-2.6Linus Torvalds
* master.kernel.org:/pub/scm/linux/kernel/git/gregkh/driver-2.6: (75 commits) PM: merge device power-management source files sysfs: add copyrights kobject: update the copyrights kset: add some kerneldoc to help describe what these strange things are Driver core: rename ktype_edd and ktype_efivar Driver core: rename ktype_driver Driver core: rename ktype_device Driver core: rename ktype_class driver core: remove subsystem_init() sysfs: move sysfs file poll implementation to sysfs_open_dirent sysfs: implement sysfs_open_dirent sysfs: move sysfs_dirent->s_children into sysfs_dirent->s_dir sysfs: make sysfs_root a regular directory dirent sysfs: open code sysfs_attach_dentry() sysfs: make s_elem an anonymous union sysfs: make bin attr open get active reference of parent too sysfs: kill unnecessary NULL pointer check in sysfs_release() sysfs: kill unnecessary sysfs_get() in open paths sysfs: reposition sysfs_dirent->s_mode. sysfs: kill sysfs_update_file() ...
2007-10-12Drivers: clean up direct setting of the name of a ksetGreg Kroah-Hartman
A kset should not have its name set directly, so dynamically set the name at runtime. This is needed to remove the static array in the kobject structure which will be changed in a future patch. Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-10-12Merge git://git.kernel.org/pub/scm/linux/kernel/git/steve/gfs2-2.6-nmwLinus Torvalds
* git://git.kernel.org/pub/scm/linux/kernel/git/steve/gfs2-2.6-nmw: (51 commits) [DLM] block dlm_recv in recovery transition [DLM] don't overwrite castparam if it's NULL [GFS2] Get superblock a different way [GFS2] Don't try to remove buffers that don't exist [GFS2] Alternate gfs2_iget to avoid looking up inodes being freed [GFS2] Data corruption fix [GFS2] Clean up journaled data writing [GFS2] GFS2: chmod hung - fix race in thread creation [DLM] Make dlm_sendd cond_resched more [GFS2] Move inode deletion out of blocking_cb [GFS2] flocks from same process trip kernel BUG at fs/gfs2/glock.c:1118! [GFS2] Clean up gfs2_trans_add_revoke() [GFS2] Use slab operations for all gfs2_bufdata allocations [GFS2] Replace revoke structure with bufdata structure [GFS2] Fix ordering of dirty/journal for ordered buffer unstuffing [GFS2] Clean up ordered write code [GFS2] Move pin/unpin into lops.c, clean up locking [GFS2] Don't mark jdata dirty in gfs2_unstuffer_page() [GFS2] Introduce gfs2_remove_from_ail [GFS2] Correct lock ordering in unlink ...
2007-10-12Fix up more bio falloutAl Viro
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-10[GFS2] Get superblock a different waySteven Whitehouse
The mapping may be NULL by the time the I/O has completed, so we now get the superblock by a different route (via the bd and glock) to avoid this problem. Signed-off-by: Steven Whitehouse <swhiteho@redhat.com> Cc: Wendy Cheng <wcheng@redhat.com>
2007-10-10[GFS2] Don't try to remove buffers that don't existSteven Whitehouse
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
2007-10-10[GFS2] Alternate gfs2_iget to avoid looking up inodes being freedBenjamin Marzinski
There is a possible deadlock between two processes on the same node, where one process is deleting an inode, and another process is looking for allocated but unused inodes to delete in order to create more space. process A does an iput() on inode X, and it's i_count drops to 0. This causes iput_final() to be called, which puts an inode into state I_FREEING at generic_delete_inode(). There no point between when iput_final() is called, and when I_FREEING is set where GFS2 could acquire any glocks. Once I_FREEING is set, no other process on that node can successfully look up that inode until the delete finishes. process B locks the the resource group for the same inode in get_local_rgrp(), which is called by gfs2_inplace_reserve_i() process A tries to lock the resource group for the inode in gfs2_dinode_dealloc(), but it's already locked by process B process B waits in find_inode for the inode to have the I_FREEING state cleared. Deadlock. This patch solves the problem by adding an alternative to gfs2_iget(), gfs2_iget_skip(), that simply skips any inodes that are in the I_FREEING state.o The alternate test function is just like the original one, except that it fails if the inode is being freed, and sets a skipped flag. The alternate set function is just like the original, except that it fails if the skipped flag is set. Only try_rgrp_unlink() calls gfs2_iget_skip() instead of gfs2_iget(). Signed-off-by: Benjamin E. Marzinski <bmarzins@redhat.com> Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
2007-10-10[GFS2] Data corruption fixWendy Cheng
* GFS2 has been using i_cache array to store its indirect meta blocks. Its flush routine doesn't correctly clean up all the entries. The problem would show while multiple nodes do simultaneous writes to the same file. Upon glock exclusive lock transfer, if the file is a sparse file with large file size where the indirect meta blocks span multiple array entries with "zero" entries in between. The flush routine prematurely stops the flushing that leaves old (stale) entries around. This leads to several nasty issues, including data corruption. * Fix gfs2_get_block_noalloc checking to correctly return EIO upon unmapped buffer. Signed-off-by: Wendy Cheng <wcheng@redhat.com> Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
2007-10-10[GFS2] Clean up journaled data writingSteven Whitehouse
This patch cleans up the code for writing journaled data into the log. It also removes the need to allocate a small "tag" structure for each block written into the log. Instead we just keep count of the outstanding I/O so that we can be sure that its all been written at the correct time. Another result of this patch is that a number of ll_rw_block() calls have become submit_bh() calls, closing some races at the same time. Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
2007-10-10[GFS2] GFS2: chmod hung - fix race in thread creationBob Peterson
The problem boiled down to a race between the gdlm_init_threads() function initializing thread1 and its setting of blist = 1. Essentially, "if (current == ls->thread1)" was checked by the thread before the thread creator set ls->thread1. Since thread1 is the only thread who is allowed to work on the blocking queue, and since neither thread thought it was thread1, no one was working on the queue. So everything just sat. This patch reuses the ls->async_lock spin_lock to fix the race, and it fixes the problem. I've done more than 2000 iterations of the loop that was recreating the failure and it seems to work. Signed-off-by: Bob Peterson <rpeterso@redhat.com> Signed-off-by: Steven Whitehouse <swhiteho@redhat.com> --
2007-10-10[GFS2] Move inode deletion out of blocking_cbWendy Cheng
Move inode deletion code out of blocking_cb handle_callback route to avoid racy conditions that end up blocking lock_dlm1 thread. Fix bugzilla 286821. Signed-off-by: Wendy Cheng <wcheng@redhat.com> Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
2007-10-10[GFS2] flocks from same process trip kernel BUG at fs/gfs2/glock.c:1118!Abhijith Das
This patch adds a new flag to the gfs2_holder structure GL_FLOCK. It is set on holders of glocks representing flocks. This flag is checked in add_to_queue() and a process is permitted to queue more than one holder onto a glock if it is set. This solves the issue of a process not being able to do multiple flocks on the same file. Through a single descriptor, a process can now promote and demote flocks. Through multiple descriptors a process can now queue multiple flocks on the same file. There's still the problem of a process deadlocking itself (because gfs2 blocking locks are not interruptible) by queueing incompatible deadlock. Signed-off-by: Abhijith Das <adas@redhat.com> Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
2007-10-10[GFS2] Clean up gfs2_trans_add_revoke()Steven Whitehouse
The following alters gfs2_trans_add_revoke() to take a struct gfs2_bufdata as an argument. This eliminates the memory allocation which was previously required by making use of the already existing struct gfs2_bufdata. It makes some sanity checks to ensure that the gfs2_bufdata has been removed from all the lists before its recycled as a revoke structure. This saves one memory allocation and one free per revoke structure. Also as a result, and to simplify the locking, since there is no longer any blocking code in gfs2_trans_add_revoke() we must hold the log lock whenever this function is called. This reduces the amount of times we take and unlock the log lock. Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
2007-10-10[GFS2] Use slab operations for all gfs2_bufdata allocationsSteven Whitehouse
The old revoke structure was allocated using kalloc/kfree but there is a slab cache for gfs2_bufdata, so we should use that now that the structures have been converted. This is part two of the patch series to merge the revoke and gfs2_bufdata structures. Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
2007-10-10[GFS2] Replace revoke structure with bufdata structureSteven Whitehouse
Both the revoke structure and the bufdata structure are quite similar. They are basically small tags which are put on lists. In addition to which the revoke structure is always allocated when there is a bufdata structure which is (or can be) freed. As such it should be possible to reduce the number of frees and allocations by using the same structure for both purposes. This patch is the first step along that path. It replaces existing uses of the revoke structure with the bufdata structure. Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
2007-10-10[GFS2] Fix ordering of dirty/journal for ordered buffer unstuffingBob Peterson
Signed-off-by: Bob Peterson <rpeterso@redhat.com> Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
2007-10-10[GFS2] Clean up ordered write codeSteven Whitehouse
The following patch removes the ordered write processing from databuf_lo_before_commit() and moves it to log.c. This has the effect of greatly simplyfying databuf_lo_before_commit() and well as potentially making the ordered write code more efficient. As a side effect of this, its now possible to remove ordered buffers from the ordered buffer list at any time, so we now make use of this in invalidatepage and releasepage to ensure timely release of these buffers. Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
2007-10-10[GFS2] Move pin/unpin into lops.c, clean up lockingSteven Whitehouse
gfs2_pin and gfs2_unpin are only used in lops.c, despite being defined in meta_io.c, so this patch moves them into lops.c and makes them static. At the same time, its possible to clean up the locking in the buf and databuf _lo_add() functions so that we only need to grab the spinlock once. Also we have to move lock_buffer() around the _lo_add() functions since we can't do that in gfs2_pin() any more since we hold the spinlock for the duration of that function. As a result, the code shrinks by 12 lines and we do far fewer operations when adding buffers to the log. It also makes the code somewhat easier to read & understand. Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
2007-10-10[GFS2] Don't mark jdata dirty in gfs2_unstuffer_page()Steven Whitehouse
Journaled data is marked dirty by gfs2_unpin and should not be marked dirty here. Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
2007-10-10[GFS2] Introduce gfs2_remove_from_ailSteven Whitehouse
This collects together the operations required to remove a gfs2_bufdata from the ail lists. Its only called from two places to start with, but expect to see more of this function in future. Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
2007-10-10[GFS2] Correct lock ordering in unlinkSteven Whitehouse
This patch corrects the lock ordering in unlink to be the same as that in the rest of GFS2, i.e. parent -> child -> rgrp. Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
2007-10-10[GFS2] fix inode meta data corruptionWendy Cheng
Fix a nasty inode meta data corruption issue by keeping the buffer head in icache array. This buffer needs to stay in memory until journal flush occurs Otherwise, gfs2_meta_inode_buffer could do a disk read before the inode hits disk. It ends up with meta data corruptions. The buffer will be released as part of the existing journal flush logic. Signed-off-by: S. Wendy Cheng <wcheng@redhat.com> Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
2007-10-10[GFS2] delay glock demote for a minimum hold timeBenjamin Marzinski
When a lot of IO, with some distributed mmap IO, is run on a GFS2 filesystem in a cluster, it will deadlock. The reason is that do_no_page() will repeatedly call gfs2_sharewrite_nopage(), because each node keeps giving up the glock too early, and is forced to call unmap_mapping_range(). This bumps the mapping->truncate_count sequence count, forcing do_no_page() to retry. This patch institutes a minimum glock hold time a tenth a second. This insures that even in heavy contention cases, the node has enough time to get some useful work done before it gives up the glock. A second issue is that when gfs2_glock_dq() is called from within a page fault to demote a lock, and the associated page needs to be written out, it will try to acqire a lock on it, but it has already been locked at a higher level. This patch puts makes gfs2_glock_dq() use the work queue as well, to avoid this issue. This is the same patch as Steve Whitehouse originally proposed to fix this issue, execpt that gfs2_glock_dq() now grabs a reference to the glock before it queues up the work on it. Signed-off-by: Benjamin E. Marzinski <bmarzins@redhat.com> Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>