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When overcommit is disabled, the core VM accounts for pages used by anonymous
shared, private mappings and special mappings. It keeps track of VMAs that
should be accounted for with VM_ACCOUNT and VMAs that never had a reserve
with VM_NORESERVE.
Overcommit for hugetlbfs is much riskier than overcommit for base pages
due to contiguity requirements. It avoids overcommiting on both shared and
private mappings using reservation counters that are checked and updated
during mmap(). This ensures (within limits) that hugepages exist in the
future when faults occurs or it is too easy to applications to be SIGKILLed.
As hugetlbfs makes its own reservations of a different unit to the base page
size, VM_ACCOUNT should never be set. Even if the units were correct, we would
double account for the usage in the core VM and hugetlbfs. VM_NORESERVE may
be set because an application can request no reserves be made for hugetlbfs
at the risk of getting killed later.
With commit fc8744adc870a8d4366908221508bb113d8b72ee, VM_NORESERVE and
VM_ACCOUNT are getting unconditionally set for hugetlbfs-backed mappings. This
breaks the accounting for both the core VM and hugetlbfs, can trigger an
OOM storm when hugepage pools are too small lockups and corrupted counters
otherwise are used. This patch brings hugetlbfs more in line with how the
core VM treats VM_NORESERVE but prevents VM_ACCOUNT being set.
Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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* git://git.kernel.org/pub/scm/linux/kernel/git/mason/btrfs-unstable:
Btrfs: don't use spin_is_contended
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Btrfs was using spin_is_contended to see if it should drop locks before
doing extent allocations during btrfs_search_slot. The idea was to avoid
expensive searches in the tree unless the lock was actually contended.
But, spin_is_contended is specific to the ticket spinlocks on x86, so this
is causing compile errors everywhere else.
In practice, the contention could easily appear some time after we started
doing the extent allocation, and it makes more sense to always drop the lock
instead.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
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* 'for-2.6.29' of git://linux-nfs.org/~bfields/linux:
lockd: fix regression in lockd's handling of blocked locks
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If a client requests a blocking lock, is denied, then requests it again,
then here in nlmsvc_lock() we will call vfs_lock_file() without FL_SLEEP
set, because we've already queued a block and don't need the locks code
to do it again.
But that means vfs_lock_file() will return -EAGAIN instead of
FILE_LOCK_DENIED. So we still need to translate that -EAGAIN return
into a nlm_lck_blocked error in this case, and put ourselves back on
lockd's block list.
The bug was introduced by bde74e4bc64415b1 "locks: add special return
value for asynchronous locks".
Thanks to Frank van Maarseveen for the report; his original test
case was essentially
for i in `seq 30`; do flock /nfsmount/foo sleep 10 & done
Tested-by: Frank van Maarseveen <frankvm@frankvm.com>
Reported-by: Frank van Maarseveen <frankvm@frankvm.com>
Cc: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
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Rename the async_*_special() functions to async_*_domain(), which
describes the purpose of these functions much better.
[Broke up long lines to silence checkpatch]
Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/security-testing-2.6
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/security-testing-2.6:
CRED: Fix SUID exec regression
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* git://git.kernel.org/pub/scm/linux/kernel/git/mason/btrfs-unstable: (37 commits)
Btrfs: Make sure dir is non-null before doing S_ISGID checks
Btrfs: Fix memory leak in cache_drop_leaf_ref
Btrfs: don't return congestion in write_cache_pages as often
Btrfs: Only prep for btree deletion balances when nodes are mostly empty
Btrfs: fix btrfs_unlock_up_safe to walk the entire path
Btrfs: change btrfs_del_leaf to drop locks earlier
Btrfs: Change btrfs_truncate_inode_items to stop when it hits the inode
Btrfs: Don't try to compress pages past i_size
Btrfs: join the transaction in __btrfs_setxattr
Btrfs: Handle SGID bit when creating inodes
Btrfs: Make btrfs_drop_snapshot work in larger and more efficient chunks
Btrfs: Change btree locking to use explicit blocking points
Btrfs: hash_lock is no longer needed
Btrfs: disable leak debugging checks in extent_io.c
Btrfs: sort references by byte number during btrfs_inc_ref
Btrfs: async threads should try harder to find work
Btrfs: selinux support
Btrfs: make btrfs acls selectable
Btrfs: Catch missed bios in the async bio submission thread
Btrfs: fix readdir on 32 bit machines
...
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The addition of filename encryption caused a regression in unencrypted
filename symlink support. ecryptfs_copy_filename() is used when dealing
with unencrypted filenames and it reported that the new, copied filename
was a character longer than it should have been.
This caused the return value of readlink() to count the NULL byte of the
symlink target. Most applications don't care about the extra NULL byte,
but a version control system (bzr) helped in discovering the bug.
Signed-off-by: Tyler Hicks <tyhicks@linux.vnet.ibm.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/frob/linux-2.6-roland
* 'to-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/frob/linux-2.6-roland:
elf core dump: fix get_user use
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The elf_core_dump() code does its work with set_fs(KERNEL_DS) in force,
so vma_dump_size() needs to switch back with set_fs(USER_DS) to safely
use get_user() for a normal user-space address.
Checking for VM_READ optimizes out the case where get_user() would fail
anyway. The vm_file check here was already superfluous given the control
flow earlier in the function, so that is a cleanup/optimization unrelated
to other changes but an obvious and trivial one.
Reported-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Signed-off-by: Roland McGrath <roland@redhat.com>
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The patch:
commit a6f76f23d297f70e2a6b3ec607f7aeeea9e37e8d
CRED: Make execve() take advantage of copy-on-write credentials
moved the place in which the 'safeness' of a SUID/SGID exec was performed to
before de_thread() was called. This means that LSM_UNSAFE_SHARE is now
calculated incorrectly. This flag is set if any of the usage counts for
fs_struct, files_struct and sighand_struct are greater than 1 at the time the
determination is made. All of which are true for threads created by the
pthread library.
However, since we wish to make the security calculation before irrevocably
damaging the process so that we can return it an error code in the case where
we decide we want to reject the exec request on this basis, we have to make the
determination before calling de_thread().
So, instead, we count up the number of threads (CLONE_THREAD) that are sharing
our fs_struct (CLONE_FS), files_struct (CLONE_FILES) and sighand_structs
(CLONE_SIGHAND/CLONE_THREAD) with us. These will be killed by de_thread() and
so can be discounted by check_unsafe_exec().
We do have to be careful because CLONE_THREAD does not imply FS or FILES.
We _assume_ that there will be no extra references to these structs held by the
threads we're going to kill.
This can be tested with the attached pair of programs. Build the two programs
using the Makefile supplied, and run ./test1 as a non-root user. If
successful, you should see something like:
[dhowells@andromeda tmp]$ ./test1
--TEST1--
uid=4043, euid=4043 suid=4043
exec ./test2
--TEST2--
uid=4043, euid=0 suid=0
SUCCESS - Correct effective user ID
and if unsuccessful, something like:
[dhowells@andromeda tmp]$ ./test1
--TEST1--
uid=4043, euid=4043 suid=4043
exec ./test2
--TEST2--
uid=4043, euid=4043 suid=4043
ERROR - Incorrect effective user ID!
The non-root user ID you see will depend on the user you run as.
[test1.c]
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <pthread.h>
static void *thread_func(void *arg)
{
while (1) {}
}
int main(int argc, char **argv)
{
pthread_t tid;
uid_t uid, euid, suid;
printf("--TEST1--\n");
getresuid(&uid, &euid, &suid);
printf("uid=%d, euid=%d suid=%d\n", uid, euid, suid);
if (pthread_create(&tid, NULL, thread_func, NULL) < 0) {
perror("pthread_create");
exit(1);
}
printf("exec ./test2\n");
execlp("./test2", "test2", NULL);
perror("./test2");
_exit(1);
}
[test2.c]
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
int main(int argc, char **argv)
{
uid_t uid, euid, suid;
getresuid(&uid, &euid, &suid);
printf("--TEST2--\n");
printf("uid=%d, euid=%d suid=%d\n", uid, euid, suid);
if (euid != 0) {
fprintf(stderr, "ERROR - Incorrect effective user ID!\n");
exit(1);
}
printf("SUCCESS - Correct effective user ID\n");
exit(0);
}
[Makefile]
CFLAGS = -D_GNU_SOURCE -Wall -Werror -Wunused
all: test1 test2
test1: test1.c
gcc $(CFLAGS) -o test1 test1.c -lpthread
test2: test2.c
gcc $(CFLAGS) -o test2 test2.c
sudo chown root.root test2
sudo chmod +s test2
Reported-by: David Smith <dsmith@redhat.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: David Smith <dsmith@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>
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This is a modification of a patch by Bill Pemberton <wfp5p@virginia.edu>
nobh_write_end() could call attach_nobh_buffers() with head == NULL.
This would result in a trap when attach_nobh_buffers() attempted to
access bh->b_this_page.
This can be illustrated by running the writev01 testcase from LTP on jfs.
This error was introduced by commit 5b41e74a "vfs: fix data leak in
nobh_write_end()". That patch did not take into account that if
PageMappedToDisk() is true upon entry to nobh_write_begin(), then no
buffers will be allocated for the page. In that case, we won't have to
worry about a failed write leaving unitialized data in the page.
Of course, head != NULL implies !page_has_buffers(page), so no need to
test both.
Signed-off-by: Dave Kleikamp <shaggy@linux.vnet.ibm.com>
Cc: Bill Pemberton <wfp5p@virginia.edu>
Cc: Dmitri Monakhov <dmonakhov@openvz.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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The S_ISGID check in btrfs_new_inode caused an oops during subvol creation
because sometimes the dir is null.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
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... and yes, gcc is insane enough to eat that without complaint.
We probably want sparse to scream on those...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/mfasheh/ocfs2
* 'upstream-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mfasheh/ocfs2:
Revert "configfs: Silence lockdep on mkdir(), rmdir() and configfs_depend_item()"
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lseek() further than length of the file will leave stale ->index
(second-to-last during iteration). Next seq_read() will not notice
that ->f_pos is big enough to return 0, but will print last item
as if ->f_pos is pointing to it.
Introduced in commit cb510b8172602a66467f3551b4be1911f5a7c8c2
aka "seq_file: more atomicity in traverse()".
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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In 2.6.25 some /proc files were converted to use the seq_file
infrastructure. But seq_files do not correctly support pread(), which
broke some usersapce applications.
To handle pread correctly we can't assume that f_pos is where we left it
in seq_read. So move traverse() so that we can eventually use it in
seq_read and do thus some day support pread().
Signed-off-by: Eric Biederman <ebiederm@xmission.com>
Cc: Paul Turner <pjt@google.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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The code wasn't doing a kfree on the sorted array
Signed-off-by: Chris Mason <chris.mason@oracle.com>
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configfs_depend_item()"
This reverts commit 0e0333429a6280e6eb3c98845e4eed90d5f8078a.
I committed this by accident - Joel and Louis are working with the lockdep
maintainer to provide a better solution than just turning lockdep off.
Signed-off-by: Mark Fasheh <mfasheh@suse.com>
Acked-by: <Joel Becker <joel.becker@oracle.com>
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On fast devices that go from congested to uncongested very quickly, pdflush
is waiting too often in congestion_wait, and the FS is backing off to
easily in write_cache_pages.
For now, fix this on the btrfs side by only checking congestion after
some bios have already gone down. Longer term a real fix is needed
for pdflush, but that is a larger project.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
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Whenever an item deletion is done, we need to balance all the nodes
in the tree to make sure we don't end up with an empty node if a pointer
is deleted. This balance prep happens from the root of the tree down
so we can drop our locks as we go.
reada_for_balance was triggering read-ahead on neighboring nodes even
when no balancing was required. This adds an extra check to avoid
calling balance_level() and avoid reada_for_balance() when a balance
won't be required.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
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btrfs_unlock_up_safe would break out at the first NULL node entry or
unlocked node it found in the path.
Some of the callers have missing nodes at the lower levels of the path, so this
commit fixes things to check all the nodes in the path before returning.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
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btrfs_del_leaf does two things. First it removes the pointer in the
parent, and then it frees the block that has the leaf. It has the
parent node locked for both operations.
But, it only needs the parent locked while it is deleting the pointer.
After that it can safely free the block without the parent locked.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
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btrfs_truncate_inode_items is setup to stop doing btree searches when
it has finished removing the items for the inode. It used to detect the
end of the inode by looking for an objectid that didn't match the
one we were searching for.
But, this would result in an extra search through the btree, which
adds extra balancing and cow costs to the operation.
This commit adds a check to see if we found the inode item, which means
we can stop searching early.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
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The compression code had some checks to make sure we were only
compressing bytes inside of i_size, but it wasn't catching every
case. To make things worse, some incorrect math about the number
of bytes remaining would make it try to compress more pages than the
file really had.
The fix used here is to fall back to the non-compression code in this
case, which does all the proper cleanup of delalloc and other accounting.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
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With selinux on we end up calling __btrfs_setxattr when we create an inode,
which calls btrfs_start_transaction(). The problem is we've already called
that in btrfs_new_inode, and in btrfs_start_transaction we end up doing a
wait_current_trans(). If btrfs-transaction has started committing it will wait
for all handles to finish, while the other process is waiting for the
transaction to commit. This is fixed by using btrfs_join_transaction, which
won't wait for the transaction to commit. Thanks,
Signed-off-by: Josef Bacik <jbacik@redhat.com>
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Before this patch, new files/dirs would ignore the SGID bit on their
parent directory and always be owned by the creating user's uid/gid.
Signed-off-by: Chris Ball <cjb@laptop.org>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
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Every transaction in btrfs creates a new snapshot, and then schedules the
snapshot from the last transaction for deletion. Snapshot deletion
works by walking down the btree and dropping the reference counts
on each btree block during the walk.
If if a given leaf or node has a reference count greater than one,
the reference count is decremented and the subtree pointed to by that
node is ignored.
If the reference count is one, walking continues down into that node
or leaf, and the references of everything it points to are decremented.
The old code would try to work in small pieces, walking down the tree
until it found the lowest leaf or node to free and then returning. This
was very friendly to the rest of the FS because it didn't have a huge
impact on other operations.
But it wouldn't always keep up with the rate that new commits added new
snapshots for deletion, and it wasn't very optimal for the extent
allocation tree because it wasn't finding leaves that were close together
on disk and processing them at the same time.
This changes things to walk down to a level 1 node and then process it
in bulk. All the leaf pointers are sorted and the leaves are dropped
in order based on their extent number.
The extent allocation tree and commit code are now fast enough for
this kind of bulk processing to work without slowing the rest of the FS
down. Overall it does less IO and is better able to keep up with
snapshot deletions under high load.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
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Most of the btrfs metadata operations can be protected by a spinlock,
but some operations still need to schedule.
So far, btrfs has been using a mutex along with a trylock loop,
most of the time it is able to avoid going for the full mutex, so
the trylock loop is a big performance gain.
This commit is step one for getting rid of the blocking locks entirely.
btrfs_tree_lock takes a spinlock, and the code explicitly switches
to a blocking lock when it starts an operation that can schedule.
We'll be able get rid of the blocking locks in smaller pieces over time.
Tracing allows us to find the most common cause of blocking, so we
can start with the hot spots first.
The basic idea is:
btrfs_tree_lock() returns with the spin lock held
btrfs_set_lock_blocking() sets the EXTENT_BUFFER_BLOCKING bit in
the extent buffer flags, and then drops the spin lock. The buffer is
still considered locked by all of the btrfs code.
If btrfs_tree_lock gets the spinlock but finds the blocking bit set, it drops
the spin lock and waits on a wait queue for the blocking bit to go away.
Much of the code that needs to set the blocking bit finishes without actually
blocking a good percentage of the time. So, an adaptive spin is still
used against the blocking bit to avoid very high context switch rates.
btrfs_clear_lock_blocking() clears the blocking bit and returns
with the spinlock held again.
btrfs_tree_unlock() can be called on either blocking or spinning locks,
it does the right thing based on the blocking bit.
ctree.c has a helper function to set/clear all the locked buffers in a
path as blocking.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
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Before metadata is written to disk, it is updated to reflect that writeout
has begun. Once this update is done, the block must be cow'd before it
can be modified again.
This update was originally synchronized by using a per-fs spinlock. Today
the buffers for the metadata blocks are locked before writeout begins,
and everyone that tests the flag has the buffer locked as well.
So, the per-fs spinlock (called hash_lock for no good reason) is no
longer required.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
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extent_io.c has debugging code to report and free leaked extent_state
and extent_buffer objects at rmmod time. This helps track down
leaks and it saves you from rebooting just to properly remove the
kmem_cache object.
But, the code runs under a fairly expensive spinlock and the checks to
see if it is currently enabled are not entirely consistent. Some use
#ifdef and some #if.
This changes everything to #if and disables the leak checking.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
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When a block goes through cow, we update the reference counts of
everything that block points to. The internal pointers of the block
can be in just about any order, and it is likely to have clusters of
things that are close together and clusters of things that are not.
To help reduce the seeks that come with updating all of these reference
counts, sort them by byte number before actual updates are done.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
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Tracing shows the delay between when an async thread goes to sleep
and when more work is added is often very short. This commit adds
a little bit of delay and extra checking to the code right before
we schedule out.
It allows more work to be added to the worker
without requiring notifications from other procs.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
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Add call to LSM security initialization and save
resulting security xattr for new inodes.
Add xattr support to symlink inode ops.
Set inode->i_op for existing special files.
Signed-off-by: jim owens <jowens@hp.com>
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This patch adds a menu entry to kconfig to enable acls for btrfs.
This allows you to enable FS_POSIX_ACL at kernel compile time.
(updated by Jeff Mahoney to make the changes in fs/btrfs/Kconfig instead)
Signed-off-by: Christian Hesse <mail@earthworm.de>
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
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The async bio submission thread was missing some bios that were
added after it had decided there was no work left to do.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
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* 'linux-next' of git://git.infradead.org/ubifs-2.6:
UBIFS: remove fast unmounting
UBIFS: return sensible error codes
UBIFS: remount ro fixes
UBIFS: spelling fix 'date' -> 'data'
UBIFS: sync wbufs after syncing inodes and pages
UBIFS: fix LPT out-of-space bug (again)
UBIFS: fix no_chk_data_crc
UBIFS: fix assertions
UBIFS: ensure orphan area head is initialized
UBIFS: always clean up GC LEB space
UBIFS: add re-mount debugging checks
UBIFS: fix LEB list freeing
UBIFS: simplify locking
UBIFS: document dark_wm and dead_wm better
UBIFS: do not treat all data as short term
UBIFS: constify operations
UBIFS: do not commit twice
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git://git.kernel.org/pub/scm/linux/kernel/git/mfasheh/ocfs2
* 'upstream-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mfasheh/ocfs2:
ocfs2: add quota call to ocfs2_remove_btree_range()
ocfs2: Wakeup the downconvert thread after a successful cancel convert
ocfs2: Access the xattr bucket only before modifying it.
configfs: Silence lockdep on mkdir(), rmdir() and configfs_depend_item()
ocfs2: Fix possible deadlock in ocfs2_write_dquot()
ocfs2: Push out dropping of dentry lock to ocfs2_wq
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Till VFS can correctly support read-only remount without racing,
use WARN_ON instead of BUG_ON on detecting transaction in flight
after quiescing filesystem.
Signed-off-by: Felix Blyakher <felixb@sgi.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
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Before trying to obtain, read or write a buffer,
check that the buffer length is actually valid. If
it is not valid, then something read in the recovery
process has been corrupted and we should abort
recovery.
Reported-by: Eric Sesterhenn <snakebyte@gmx.de>
Tested-by: Eric Sesterhenn <snakebyte@gmx.de>
Reviewed-by: Christoph Hellwig <hch@infradead.org>
Reviewed-by: Felix Blyakher <felixb@sgi.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
Signed-off-by: Felix Blyakher <felixb@sgi.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6 into for-linus
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We weren't reclaiming the clusters which get free'd from this function,
so any user punching holes in a file would still have those bytes accounted
against him/her. Add the call to vfs_dq_free_space_nodirty() to fix this.
Interestingly enough, the journal credits calculation already took this into
account.
Signed-off-by: Mark Fasheh <mfasheh@suse.com>
Acked-by: Jan Kara <jack@suse.cz>
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When two nodes holding PR locks on a resource concurrently attempt to
upconvert the locks to EX, the master sends a BAST to one of the nodes. This
message tells that node to first cancel convert the upconvert request,
followed by downconvert to a NL. Only when this lock is downconverted to NL,
can the master upconvert the first node's lock to EX.
While the fs was doing the cancel convert, it was forgetting to wake up the
dc thread after a successful cancel, leading to a deadlock.
Reported-and-Tested-by: David Teigland <teigland@redhat.com>
Signed-off-by: Sunil Mushran <sunil.mushran@oracle.com>
Signed-off-by: Mark Fasheh <mfasheh@suse.com>
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In ocfs2_xattr_value_truncate, we may call b-tree codes which will
extend the journal transaction. It has a potential problem that it
may let the already-accessed-but-not-dirtied buffers gone. So we'd
better access the bucket after we call ocfs2_xattr_value_truncate.
And as for the root buffer for the xattr value, b-tree code will
acess and dirty it, so we don't need to worry about it.
Signed-off-by: Tao Ma <tao.ma@oracle.com>
Signed-off-by: Mark Fasheh <mfasheh@suse.com>
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When attaching default groups (subdirs) of a new group (in mkdir() or
in configfs_register()), configfs recursively takes inode's mutexes
along the path from the parent of the new group to the default
subdirs. This is needed to ensure that the VFS will not race with
operations on these sub-dirs. This is safe for the following reasons:
- the VFS allows one to lock first an inode and second one of its
children (The lock subclasses for this pattern are respectively
I_MUTEX_PARENT and I_MUTEX_CHILD);
- from this rule any inode path can be recursively locked in
descending order as long as it stays under a single mountpoint and
does not follow symlinks.
Unfortunately lockdep does not know (yet?) how to handle such
recursion.
I've tried to use Peter Zijlstra's lock_set_subclass() helper to
upgrade i_mutexes from I_MUTEX_CHILD to I_MUTEX_PARENT when we know
that we might recursively lock some of their descendant, but this
usage does not seem to fit the purpose of lock_set_subclass() because
it leads to several i_mutex locked with subclass I_MUTEX_PARENT by
the same task.
>From inside configfs it is not possible to serialize those recursive
locking with a top-level one, because mkdir() and rmdir() are already
called with inodes locked by the VFS. So using some
mutex_lock_nest_lock() is not an option.
I am proposing two solutions:
1) one that wraps recursive mutex_lock()s with
lockdep_off()/lockdep_on().
2) (as suggested earlier by Peter Zijlstra) one that puts the
i_mutexes recursively locked in different classes based on their
depth from the top-level config_group created. This
induces an arbitrary limit (MAX_LOCK_DEPTH - 2 == 46) on the
nesting of configfs default groups whenever lockdep is activated
but this limit looks reasonably high. Unfortunately, this alos
isolates VFS operations on configfs default groups from the others
and thus lowers the chances to detect locking issues.
This patch implements solution 1).
Solution 2) looks better from lockdep's point of view, but fails with
configfs_depend_item(). This needs to rework the locking
scheme of configfs_depend_item() by removing the variable lock recursion
depth, and I think that it's doable thanks to the configfs_dirent_lock.
For now, let's stick to solution 1).
Signed-off-by: Louis Rilling <louis.rilling@kerlabs.com>
Acked-by: Joel Becker <joel.becker@oracle.com>
Signed-off-by: Mark Fasheh <mfasheh@suse.com>
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It could happen that some limit has been set via quotactl() and in parallel
->mark_dirty() is called from another thread doing e.g. dquot_alloc_space(). In
such case ocfs2_write_dquot() must not try to sync the dquot because that needs
global quota lock but that ranks above transaction start.
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Mark Fasheh <mfasheh@suse.com>
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Dropping of last reference to dentry lock is a complicated operation involving
dropping of reference to inode. This can get complicated and quota code in
particular needs to obtain some quota locks which leads to potential deadlock.
Thus we defer dropping of inode reference to ocfs2_wq.
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Mark Fasheh <mfasheh@suse.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4
* 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4:
ext4: Remove bogus BUG() check in ext4_bmap()
ext4: Fix building with EXT4FS_DEBUG
ext4: Initialize the new group descriptor when resizing the filesystem
ext4: Fix ext4_free_blocks() w/o a journal when files have indirect blocks
jbd2: On a __journal_expect() assertion failure printk "JBD2", not "EXT3-fs"
ext3: Add sanity check to make_indexed_dir
ext4: Add sanity check to make_indexed_dir
ext4: only use i_size_high for regular files
ext4: fix wrong use of do_div
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* 'for-linus' of git://git.kernel.dk/linux-2.6-block:
cfq-iosched: Allow RT requests to pre-empt ongoing BE timeslice
block: add sysfs file for controlling io stats accounting
Mark mandatory elevator functions in the biodoc.txt
include/linux: Add bsg.h to the Kernel exported headers
block: silently error an unsupported barrier bio
block: Fix documentation for blkdev_issue_flush()
block: add bio_rw_flagged() for testing bio->bi_rw
block: seperate bio/request unplug and sync bits
block: export SSD/non-rotational queue flag through sysfs
Fix small typo in bio.h's documentation
block: get rid of the manual directory counting in blktrace
block: Allow empty integrity profile
block: Remove obsolete BUG_ON
block: Don't verify integrity metadata on read error
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