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Pull namespace fixes from Eric Biederman:
"This is a set of 3 regression fixes.
This fixes /proc/mounts when using "ip netns add <netns>" to display
the actual mount point.
This fixes a regression in clone that broke lxc-attach.
This fixes a regression in the permission checks for mounting /proc
that made proc unmountable if binfmt_misc was in use. Oops.
My apologies for sending this pull request so late. Al Viro gave
interesting review comments about the d_path fix that I wanted to
address in detail before I sent this pull request. Unfortunately a
bad round of colds kept from addressing that in detail until today.
The executive summary of the review was:
Al: Is patching d_path really sufficient?
The prepend_path, d_path, d_absolute_path, and __d_path family of
functions is a really mess.
Me: Yes, patching d_path is really sufficient. Yes, the code is mess.
No it is not appropriate to rewrite all of d_path for a regression
that has existed for entirely too long already, when a two line
change will do"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace:
vfs: Fix a regression in mounting proc
fork: Allow CLONE_PARENT after setns(CLONE_NEWPID)
vfs: In d_path don't call d_dname on a mount point
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We should always make sure the cached page is up-to-date when we're
determining whether we can extend a write to cover the full page -- even
if we've received a write delegation from the server.
Commit c7559663 added logic to skip this check if we have a write
delegation, which can lead to data corruption such as the following
scenario if client B receives a write delegation from the NFS server:
Client A:
# echo 123456789 > /mnt/file
Client B:
# echo abcdefghi >> /mnt/file
# cat /mnt/file
0�D0�abcdefghi
Just because we hold a write delegation doesn't mean that we've read in
the entire page contents.
Cc: <stable@vger.kernel.org> # v3.11+
Signed-off-by: Scott Mayhew <smayhew@redhat.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
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Once created, a kernfs_node is always destroyed by kernfs_put().
Since ba7443bc656e ("sysfs, kernfs: implement
kernfs_create/destroy_root()"), kernfs_put() depends on kernfs_root()
to locate the ino_ida. kernfs_root() in turn depends on
kernfs_node->parent being set for !dir nodes. This means that
kernfs_put() of a !dir node requires its ->parent to be initialized.
This leads to oops when a newly created !dir node is destroyed without
going through kernfs_add_one() or after failing kernfs_add_one()
before ->parent is set. kernfs_root() invoked from kernfs_put() will
try to dereference NULL parent.
Fix it by moving parent association to kernfs_new_node() from
kernfs_add_one(). kernfs_new_node() now takes @parent instead of
@root and determines the root from the parent and also sets the new
node's parent properly. @parent parameter is removed from
kernfs_add_one(). As there's no parent when creating the root node,
__kernfs_new_node() which takes @root as before and doesn't set the
parent is used in that case.
This ensures that a kernfs_node in any stage in its life has its
parent associated and thus can be put.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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"disconnected" is too easily confused with "DCACHE_DISCONNECTED". I
think "unhashed" is the more precise term here.
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Reviewed-by: Sage Weil <sage@inktank.com>
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This is a small cleanup to function gfs2_rgrp_go_lock so that it
uses rgd instead of its more complicated twin.
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
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Al Viro has tactfully pointed out that we are using the incorrect
error code in some cases. This patch fixes that, and also removes
the (unused) return value for glock dumping.
> * gfs2_iget() - ENOBUFS instead of ENOMEM. ENOBUFS is
> "No buffer space available (POSIX.1 (XSI STREAMS option))" and since
> we don't support STREAMS it's probably fair game, but... what the hell?
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
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Doing sync_meta_pages with META_FLUSH when checkpoint, we overide rw
using WRITE_FLUSH_FUA. At this time, we also should set
REQ_META|REQ_PRIO.
Signed-off-by: Changman Lee <cm224.lee@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
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This patch should resolve the following bug.
=========================================================
[ INFO: possible irq lock inversion dependency detected ]
3.13.0-rc5.f2fs+ #6 Not tainted
---------------------------------------------------------
kswapd0/41 just changed the state of lock:
(&sbi->gc_mutex){+.+.-.}, at: [<ffffffffa030503e>] f2fs_balance_fs+0xae/0xd0 [f2fs]
but this lock took another, RECLAIM_FS-READ-unsafe lock in the past:
(&sbi->cp_rwsem){++++.?}
and interrupts could create inverse lock ordering between them.
other info that might help us debug this:
Chain exists of:
&sbi->gc_mutex --> &sbi->cp_mutex --> &sbi->cp_rwsem
Possible interrupt unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&sbi->cp_rwsem);
local_irq_disable();
lock(&sbi->gc_mutex);
lock(&sbi->cp_mutex);
<Interrupt>
lock(&sbi->gc_mutex);
*** DEADLOCK ***
This bug is due to the f2fs_balance_fs call in f2fs_write_data_page.
If f2fs_write_data_page is triggered by wbc->for_reclaim via kswapd, it should
not call f2fs_balance_fs which tries to get a mutex grabbed by original syscall
flow.
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
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Pull writeback fix from Wu Fengguang:
"Fix data corruption on NFS writeback.
It has been in linux-next for one month"
* tag 'writeback-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/wfg/linux:
writeback: Fix data corruption on NFS
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Well I don't get the same warning locally as the kbuild
robot, but I guess this should fix the problem, anyway.
Here is the warning:
head: 2d9e72303d538024627fb1fe2cbde48aec12acc0
commit: ee2411a8db49a21bc55dc124e1b434ba194c8903 [19/20] GFS2: Clean up quota slot allocation
config: make ARCH=powerpc allmodconfig
All error/warnings:
fs/gfs2/quota.c: In function 'gfs2_quota_init':
>> fs/gfs2/quota.c:1246:3: error: implicit declaration of function '__vmalloc' [-Werror=implicit-function-declaration]
sdp->sd_quota_bitmap = __vmalloc(bm_size, GFP_NOFS, PAGE_KERNEL);
^
>> fs/gfs2/quota.c:1246:24: warning: assignment makes pointer from integer without a cast [enabled by default]
sdp->sd_quota_bitmap = __vmalloc(bm_size, GFP_NOFS, PAGE_KERNEL);
^
fs/gfs2/quota.c: In function 'gfs2_quota_cleanup':
>> fs/gfs2/quota.c:1361:4: error: implicit declaration of function 'vfree' [-Werror=implicit-function-declaration]
vfree(sdp->sd_quota_bitmap);
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
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There is a bug in the function nilfs_segctor_collect, which results in
active data being written to a segment, that is marked as clean. It is
possible, that this segment is selected for a later segment
construction, whereby the old data is overwritten.
The problem shows itself with the following kernel log message:
nilfs_sufile_do_cancel_free: segment 6533 must be clean
Usually a few hours later the file system gets corrupted:
NILFS: bad btree node (blocknr=8748107): level = 0, flags = 0x0, nchildren = 0
NILFS error (device sdc1): nilfs_bmap_last_key: broken bmap (inode number=114660)
The issue can be reproduced with a file system that is nearly full and
with the cleaner running, while some IO intensive task is running.
Although it is quite hard to reproduce.
This is what happens:
1. The cleaner starts the segment construction
2. nilfs_segctor_collect is called
3. sc_stage is on NILFS_ST_SUFILE and segments are freed
4. sc_stage is on NILFS_ST_DAT current segment is full
5. nilfs_segctor_extend_segments is called, which
allocates a new segment
6. The new segment is one of the segments freed in step 3
7. nilfs_sufile_cancel_freev is called and produces an error message
8. Loop around and the collection starts again
9. sc_stage is on NILFS_ST_SUFILE and segments are freed
including the newly allocated segment, which will contain active
data and can be allocated at a later time
10. A few hours later another segment construction allocates the
segment and causes file system corruption
This can be prevented by simply reordering the statements. If
nilfs_sufile_cancel_freev is called before nilfs_segctor_extend_segments
the freed segments are marked as dirty and cannot be allocated any more.
Signed-off-by: Andreas Rohner <andreas.rohner@gmx.net>
Reviewed-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Tested-by: Andreas Rohner <andreas.rohner@gmx.net>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Gradually, the global qd_lock is being used for less and less.
After this patch it will only be used for the per super block
list whose purpose is to allow syncing of changes back to the
master quota file from the local quota changes file. Fixing
up that process to make it more efficient will be the subject
of a later patch, however this patch removes another barrier
to doing that.
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
Cc: Abhijith Das <adas@redhat.com>
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Quota slot allocation has historically used a vector of pages
and a set of homegrown find/test/set/clear bit functions. Since
the size of the bitmap is likely to be based on the default
qc file size, thats a couple of pages at most. So we ought
to be able to allocate that as a single chunk, with a vmalloc
fallback, just in case of memory fragmentation.
We are then able to use the kernel's own find/test/set/clear
bit functions, rather than rolling our own.
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
Cc: Abhijith Das <adas@redhat.com>
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While investigating a rather strange bit of code in the quota
clean up function, I spotted that the reason for its existence
was that when remounting read only, we were not stopping the
quotad thread, and thus it was possible for it to still have
a reference to some of the quotas in that case.
This patch moves the logd and quota thread start and stop into
the make_fs_rw/ro functions, so that we now stop those threads
when mounted read only.
This means that quotad will always be stopped before we call
the quota clean up function, and we can thus dispose of the
(rather hackish) code that waits for it to give up its
reference on the quotas.
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
Cc: Abhijith Das <adas@redhat.com>
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Prior to this patch, GFS2 kept all the quotas for each
super block in a single linked list. This is rather slow
when there are large numbers of quotas.
This patch introduces a hlist_bl based hash table, similar
to the one used for glocks. The initial look up of the quota
is now lockless in the case where it is already cached,
although we still have to take the per quota spinlock in
order to bump the ref count. Either way though, this is a
big improvement on what was there before.
The qd_lock and the per super block list is preserved, for
the time being. However it is intended that since this is no
longer used for its original role, it should be possible to
shrink the number of items on that list in due course and
remove the requirement to take qd_lock in qd_get.
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
Cc: Abhijith Das <adas@redhat.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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We recently fixed the writeback of pages prior to performing
direct i/o, however the initial fix was perhaps a bit heavy
handed. There is no need to invalidate pages if the direct i/o
is only a read, since they will be identical to what has been
flushed to disk anyway.
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
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When kernfs_seq_start() fails to obtain an active reference, it
returns ERR_PTR(-ENODEV). kernfs_seq_stop() is then invoked with the
error pointer value; however, it still proceeds to invoke
kernfs_put_active() on the node leading to unbalanced put.
If kernfs_seq_stop() is called even after active ref failure, it
should skip invocation of @ops->seq_stop() and put_active.
Unfortunately, this is a bit complicated because active ref failure
isn't the only thing which may fail with ERR_PTR(-ENODEV).
@ops->seq_start/next() may also fail with the error value and
kernfs_seq_stop() doesn't have a way to tell apart those failures.
Work it around by factoring out the active part of kernfs_seq_stop()
into kernfs_seq_stop_active() and invoking it directly if
@ops->seq_start/next() fail with ERR_PTR(-ENODEV) and updating
kernfs_seq_stop() to skip kernfs_seq_stop_active() on
ERR_PTR(-ENODEV). This is a bit nasty but ensures that the active put
is skipped iff get_active failed in kernfs_seq_start().
tj: This was originally committed as d92d2e6bd72b but got reverted by
683bb2761fbf along with other kernfs self removal patches.
However, this one is an independent fix and shouldn't have been
reverted together. Reinstate the change. Sorry about the mess.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Support for f2fs-tools/tools/f2stat to monitor
/sys/kernel/debug/f2fs/status
Signed-off-by: Changman Lee <cm224.lee@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
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With the 2 previous changes, all the long time operations are moved out
of the protection region, so here we can use spinlock rather than mutex
(orphan_inode_mutex) for lower overhead.
Signed-off-by: Gu Zheng <guz.fnst@cn.fujitsu.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
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Move alloc new orphan node out of lock protection region.
Signed-off-by: Gu Zheng <guz.fnst@cn.fujitsu.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
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Move grabing orphan block page out of protection region, and grab all
the orphan block pages ahead.
Signed-off-by: Gu Zheng <guz.fnst@cn.fujitsu.com>
Reviewed-by: Chao Yu <chao2.yu@samsung.com>
[Jaegeuk Kim: remove unnecessary code pointed by Chao Yu]
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
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"boo sync" parameter is never referenced in f2fs_wait_on_page_writeback.
We should remove this parameter.
Signed-off-by: Yuan Zhong <yuan.mark.zhong@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
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This reverts commit d92d2e6bd72b653f9811e0c9c46307c743b3fc58.
Tejun writes:
I'm sorry but can you please revert the whole series?
get_active() waiting while a node is deactivated has potential
to lead to deadlock and that deactivate/reactivate interface is
something fundamentally flawed and that cgroup will have to work
with the remove_self() like everybody else. IOW, I think the
first posting was correct.
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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This reverts commit ea1c472dfeada211a0100daa7976e8e8e779b858.
Tejun writes:
I'm sorry but can you please revert the whole series?
get_active() waiting while a node is deactivated has potential
to lead to deadlock and that deactivate/reactivate interface is
something fundamentally flawed and that cgroup will have to work
with the remove_self() like everybody else. IOW, I think the
first posting was correct.
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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This reverts commit a69d001cfc712b96ec9d7ba44d6285702a38dabf.
Tejun writes:
I'm sorry but can you please revert the whole series?
get_active() waiting while a node is deactivated has potential
to lead to deadlock and that deactivate/reactivate interface is
something fundamentally flawed and that cgroup will have to work
with the remove_self() like everybody else. IOW, I think the
first posting was correct.
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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This reverts commit ae34372eb8408b3d07e870f1939f99007a730d28.
Tejun writes:
I'm sorry but can you please revert the whole series?
get_active() waiting while a node is deactivated has potential
to lead to deadlock and that deactivate/reactivate interface is
something fundamentally flawed and that cgroup will have to work
with the remove_self() like everybody else. IOW, I think the
first posting was correct.
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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This reverts commit 45a140e587f3d32d8d424ed940dffb61e1739047.
Tejun writes:
I'm sorry but can you please revert the whole series?
get_active() waiting while a node is deactivated has potential
to lead to deadlock and that deactivate/reactivate interface is
something fundamentally flawed and that cgroup will have to work
with the remove_self() like everybody else. IOW, I think the
first posting was correct.
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Make sure to properly invalidate the pagecache before performing direct I/O,
so that no stale pages are left around. This matches what the generic
direct I/O code does. Also take the i_mutex over the direct write submission
to avoid the lifelock vs truncate waiting for i_dio_count to decrease, and
to avoid having the pagecache easily repopulated while direct I/O is in
progrss. Again matching the generic direct I/O code.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
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We'll need the i_mutex to prevent i_dio_count from incrementing while
truncate is waiting for it to reach zero, and protects against having
the pagecache repopulated after we flushed it.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
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Simple code cleanup to prepare for later fixes.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
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Simple code cleanup to prepare for later fixes.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
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i_dio_count is used to protect dio access against truncate. We want
to make sure there are no dio reads pending either when doing a
truncate. I suspect on plain NFS things might work even without
this, but once we use a pnfs layout driver that access backing devices
directly things will go bad without the proper synchronization.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
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We need to have the I/O fully finished before telling the truncate code
that we are done.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
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nfs_file_direct_write only updates the inode size if it succeeded and
returned the number of bytes written. But in the AIO case nfs_direct_wait
turns the return value into -EIOCBQUEUED and we skip the size update.
Instead the aio completion path should updated it, which this patch
does. The implementation is a little hacky because there is no obvious
way to find out we are called for a write in nfs_direct_complete.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
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Don't check for -NFS4ERR_NOTSUPP, it's already been mapped to -ENOTSUPP
by nfs4_stat_to_errno.
This allows the client to mount v4.1 servers that don't support
SECINFO_NO_NAME by falling back to the "guess and check" method of
nfs4_find_root_sec.
Signed-off-by: Weston Andros Adamson <dros@primarydata.com>
Cc: stable@vger.kernel.org # 3.1+
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
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This reverts commit f601f9a2bf7dc1f7ee18feece4c4e2fc6845d6c4.
Tejun writes:
I'm sorry but can you please revert the whole series?
get_active() waiting while a node is deactivated has potential
to lead to deadlock and that deactivate/reactivate interface is
something fundamentally flawed and that cgroup will have to work
with the remove_self() like everybody else. IOW, I think the
first posting was correct.
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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This reverts commit 99177a34110889a8f2c36420c34e3bcc9bfd8a70.
Tejun writes:
I'm sorry but can you please revert the whole series?
get_active() waiting while a node is deactivated has potential
to lead to deadlock and that deactivate/reactivate interface is
something fundamentally flawed and that cgroup will have to work
with the remove_self() like everybody else. IOW, I think the
first posting was correct.
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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This reverts commit 895a068a524e134900b9d98b519309b7aae7bbb1.
Tejun writes:
I'm sorry but can you please revert the whole series?
get_active() waiting while a node is deactivated has potential
to lead to deadlock and that deactivate/reactivate interface is
something fundamentally flawed and that cgroup will have to work
with the remove_self() like everybody else. IOW, I think the
first posting was correct.
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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This reverts commit 9f010c2ad5194a4b682e747984477850fabd03be.
Tejun writes:
I'm sorry but can you please revert the whole series?
get_active() waiting while a node is deactivated has potential
to lead to deadlock and that deactivate/reactivate interface is
something fundamentally flawed and that cgroup will have to work
with the remove_self() like everybody else. IOW, I think the
first posting was correct.
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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This reverts commit 1ae06819c77cff1ea2833c94f8c093fe8a5c79db.
Tejun writes:
I'm sorry but can you please revert the whole series?
get_active() waiting while a node is deactivated has potential
to lead to deadlock and that deactivate/reactivate interface is
something fundamentally flawed and that cgroup will have to work
with the remove_self() like everybody else. IOW, I think the
first posting was correct.
Cc: Tejun Heo <tj@kernel.org>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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This reverts commit d1ba277e79889085a2faec3b68b91ce89c63f888.
Tejun writes:
I'm sorry but can you please revert the whole series?
get_active() waiting while a node is deactivated has potential
to lead to deadlock and that deactivate/reactivate interface is
something fundamentally flawed and that cgroup will have to work
with the remove_self() like everybody else. IOW, I think the
first posting was correct.
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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This reverts commit 88533f990c616cf50c2fe585ea03f75c806a293d.
Tejun writes:
I'm sorry but can you please revert the whole series?
get_active() waiting while a node is deactivated has potential
to lead to deadlock and that deactivate/reactivate interface is
something fundamentally flawed and that cgroup will have to work
with the remove_self() like everybody else. IOW, I think the
first posting was correct.
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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nfs4_write_inode() must not be allowed to exit until the layoutcommit
is done. That means that both NFS_INO_LAYOUTCOMMIT and
NFS_INO_LAYOUTCOMMITTING have to be cleared.
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
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If a LAYOUTCOMMIT is outstanding, then chances are that the metadata
server may still be returning incorrect values for the change attribute,
ctime, mtime and/or size.
Just ignore those attributes for now, and wait for the LAYOUTCOMMIT
rpc call to finish.
Reported-by: shaobingqing <shaobingqing@bwstor.com.cn>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
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895a068a524e ("kernfs: make kernfs_get_active() block if the node is
deactivated but not removed") added "struct kernfs_root *root =
kernfs_root(kn);" at the head of the function; however, the parameter
@kn is checked for later implying that the function may be called with
NULL. This means that we may end up invoking kernfs_root() with NULL
which will oops. None of the existing users invokes removal with NULL
@kn, so this bug doesn't actually trigger.
We can relocate kernfs_root() invocation after NULL check; however,
allowing NULL param tends to cause more confusion than actually
helping anything. As there's no existing user, let's remove the
spurious NULL check.
This bug was detected by smatch.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Signed-off-by: Jon Ernst <jonernst07@gmail.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Reviewed-by: Zheng Liu <wenqing.lz@taobao.com>
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All device_schedule_callback_owner() users are converted to use
device_remove_file_self(). Remove now unused
{sysfs|device}_schedule_callback_owner().
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Pull xfs bugfixes from Ben Myers:
"Here we have a bugfix for an off-by-one in the remote attribute
verifier that results in a forced shutdown which you can hit with v5
superblock by creating a 64k xattr, and a fix for a missing
destroy_work_on_stack() in the allocation worker.
It's a bit late, but they are both fairly straightforward"
* tag 'xfs-for-linus-v3.13-rc8' of git://oss.sgi.com/xfs/xfs:
xfs: Calling destroy_work_on_stack() to pair with INIT_WORK_ONSTACK()
xfs: fix off-by-one error in xfs_attr3_rmt_verify
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Sometimes it's necessary to implement a node which wants to delete
nodes including itself. This isn't straightforward because of kernfs
active reference. While a file operation is in progress, an active
reference is held and kernfs_remove() waits for all such references to
drain before completing. For a self-deleting node, this is a deadlock
as kernfs_remove() ends up waiting for an active reference that itself
is sitting on top of.
This currently is worked around in the sysfs layer using
sysfs_schedule_callback() which makes such removals asynchronous.
While it works, it's rather cumbersome and inherently breaks
synchronicity of the operation - the file operation which triggered
the operation may complete before the removal is finished (or even
started) and the removal may fail asynchronously. If a removal
operation is immmediately followed by another operation which expects
the specific name to be available (e.g. removal followed by rename
onto the same name), there's no way to make the latter operation
reliable.
The thing is there's no inherent reason for this to be asynchrnous.
All that's necessary to do this synchronous is a dedicated operation
which drops its own active ref and deactivates self. This patch
implements kernfs_remove_self() and its wrappers in sysfs and driver
core. kernfs_remove_self() is to be called from one of the file
operations, drops the active ref and deactivates using
__kernfs_deactivate_self(), removes the self node, and restores active
ref to the dead node using __kernfs_reactivate_self() so that the ref
is balanced afterwards. __kernfs_remove() is updated so that it takes
an early exit if the target node is already fully removed so that the
active ref restored by kernfs_remove_self() after removal doesn't
confuse the deactivation path.
This makes implementing self-deleting nodes very easy. The normal
removal path doesn't even need to be changed to use
kernfs_remove_self() for the self-deleting node. The method can
invoke kernfs_remove_self() on itself before proceeding the normal
removal path. kernfs_remove() invoked on the node by the normal
deletion path will simply be ignored.
This will replace sysfs_schedule_callback(). A subtle feature of
sysfs_schedule_callback() is that it collapses multiple invocations -
even if multiple removals are triggered, the removal callback is run
only once. An equivalent effect can be achieved by testing the return
value of kernfs_remove_self() - only the one which gets %true return
value should proceed with actual deletion. All other instances of
kernfs_remove_self() will wait till the enclosing kernfs operation
which invoked the winning instance of kernfs_remove_self() finishes
and then return %false. This trivially makes all users of
kernfs_remove_self() automatically show correct synchronous behavior
even when there are multiple concurrent operations - all "echo 1 >
delete" instances will finish only after the whole operation is
completed by one of the instances.
v2: For !CONFIG_SYSFS, dummy version kernfs_remove_self() was missing
and sysfs_remove_file_self() had incorrect return type. Fix it.
Reported by kbuild test bot.
v3: Updated to use __kernfs_{de|re}activate_self().
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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This patch implements four functions to manipulate deactivation state
- deactivate, reactivate and the _self suffixed pair. A new fields
kernfs_node->deact_depth is added so that concurrent and nested
deactivations are handled properly. kernfs_node->hash is moved so
that it's paired with the new field so that it doesn't increase the
size of kernfs_node.
A kernfs user's lock would normally nest inside active ref but during
removal the user may want to perform kernfs_remove() while holding the
said lock, which would introduce a reverse locking dependency. This
function can be used to break such reverse dependency by allowing
deactivation step to performed separately outside user's critical
section.
This will also be used implement kernfs_remove_self().
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Linus Torvalds
Scott Mayhew
Tejun Heo
J. Bruce Fields
Bob Peterson
Steven Whitehouse
Changman Lee
Jaegeuk Kim
Andreas Rohner
Gu Zheng
Yuan Zhong
Greg Kroah-Hartman
Christoph Hellwig
Weston Andros Adamson
Trond Myklebust
jon ernst