Currently seq_read assumes that the offset passed to it is always the
offset it passed to user space. In the case pread this assumption is
broken and we do the wrong thing when presented with pread.
To solve this I introduce an offset cache inside of struct seq_file so we
know where our logical file position is. Then in seq_read if we try to
read from another offset we reset our data structures and attempt to go to
the offset user space wanted.
[akpm@linux-foundation.org: restore FMODE_PWRITE]
[pjt@google.com: seq_open needs its fmode opened up to take advantage of this]
Signed-off-by: Eric Biederman <ebiederm@xmission.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Paul Turner <pjt@google.com>
Cc: <stable@kernel.org> [2.6.25.x, 2.6.26.x, 2.6.27.x, 2.6.28.x]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* git://git.kernel.org/pub/scm/linux/kernel/git/mason/btrfs-unstable:
Btrfs: hold trans_mutex when using btrfs_record_root_in_trans
Btrfs: make a lockdep class for the extent buffer locks
Btrfs: fs/btrfs/volumes.c: remove useless kzalloc
Btrfs: remove unused code in split_state()
Btrfs: remove btrfs_init_path
Btrfs: balance_level checks !child after access
Btrfs: Avoid using __GFP_HIGHMEM with slab allocator
Btrfs: don't clean old snapshots on sync(1)
Btrfs: use larger metadata clusters in ssd mode
Btrfs: process mount options on mount -o remount,
Btrfs: make sure all pending extent operations are complete
* 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4:
ext4: Fix NULL dereference in ext4_ext_migrate()'s error handling
ext4: Implement range_cyclic in ext4_da_writepages instead of write_cache_pages
ext4: Initialize preallocation list_head's properly
ext4: Fix lockdep warning
ext4: Fix to read empty directory blocks correctly in 64k
jbd2: Avoid possible NULL dereference in jbd2_journal_begin_ordered_truncate()
Revert "ext4: wait on all pending commits in ext4_sync_fs()"
jbd2: Fix return value of jbd2_journal_start_commit()
Getting this wrong caused
WARNING: at fs/namespace.c:636 mntput_no_expire+0xac/0xf2()
due to optimistically checking cpu_writer->mnt outside the spinlock.
Here's what we really want:
* we know that nobody will set cpu_writer->mnt to mnt from now on
* all changes to that sucker are done under cpu_writer->lock
* we want the laziest equivalent of
spin_lock(&cpu_writer->lock);
if (likely(cpu_writer->mnt != mnt)) {
spin_unlock(&cpu_writer->lock);
continue;
}
/* do stuff */
that would make sure we won't miss earlier setting of ->mnt done by
another CPU.
Anyway, for now we just move the spin_lock() earlier and move the test
into the properly locked region.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Reported-and-tested-by: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This was found through a code checker (http://repo.or.cz/w/smatch.git/).
It looks like you might be able to trigger the error by trying to migrate
a readonly file system.
Signed-off-by: Dan Carpenter <error27@gmail.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
With delayed allocation we lock the page in write_cache_pages() and
try to build an in memory extent of contiguous blocks. This is needed
so that we can get large contiguous blocks request. If range_cyclic
mode is enabled, write_cache_pages() will loop back to the 0 index if
no I/O has been done yet, and try to start writing from the beginning
of the range. That causes an attempt to take the page lock of lower
index page while holding the page lock of higher index page, which can
cause a dead lock with another writeback thread.
The solution is to implement the range_cyclic behavior in
ext4_da_writepages() instead.
http://bugzilla.kernel.org/show_bug.cgi?id=12579
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
When creating a new ext4_prealloc_space structure, we have to
initialize its list_head pointers before we add them to any prealloc
lists. Otherwise, with list debug enabled, we will get list
corruption warnings.
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
btrfs_record_root_in_trans needs the trans_mutex held to make sure two
callers don't race to setup the root in a given transaction. This adds
it to all the places that were missing it.
Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
Btrfs is currently using spin_lock_nested with a nested value based
on the tree depth of the block. But, this doesn't quite work because
the max tree depth is bigger than what spin_lock_nested can deal with,
and because locks are sometimes taken before the level field is filled in.
The solution here is to use lockdep_set_class_and_name instead, and to
set the class before unlocking the pages when the block is read from the
disk and just after init of a freshly allocated tree block.
btrfs_clear_path_blocking is also changed to take the locks in the proper
order, and it also makes sure all the locks currently held are properly
set to blocking before it tries to retake the spinlocks. Otherwise, lockdep
gets upset about bad lock orderin.
The lockdep magic cam from Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
The call to kzalloc is followed by a kmalloc whose result is stored in the
same variable.
The semantic match that finds the problem is as follows:
(http://www.emn.fr/x-info/coccinelle/)
// <smpl>
@r exists@
local idexpression x;
statement S;
expression E;
identifier f,l;
position p1,p2;
expression *ptr != NULL;
@@
(
if ((x@p1 = \(kmalloc\|kzalloc\|kcalloc\)(...)) == NULL) S
|
x@p1 = \(kmalloc\|kzalloc\|kcalloc\)(...);
...
if (x == NULL) S
)
<... when != x
when != if (...) { <+...x...+> }
x->f = E
...>
(
return \(0\|<+...x...+>\|ptr\);
|
return@p2 ...;
)
@script:python@
p1 << r.p1;
p2 << r.p2;
@@
print "* file: %s kmalloc %s return %s" % (p1[0].file,p1[0].line,p2[0].line)
// </smpl>
Signed-off-by: Julia Lawall <julia@diku.dk>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
btrfs_init_path was initially used when the path objects were on the
stack. Now all the work is done by btrfs_alloc_path and btrfs_init_path
isn't required.
This patch removes it, and just uses kmem_cache_zalloc to zero out the object.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
btrfs_releasepage may call kmem_cache_alloc indirectly,
and provide same GFP flags it gets to kmem_cache_alloc.
So it's possible to use __GFP_HIGHMEM with the slab
allocator.
Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
Cleaning old snapshots can make sync(1) somewhat slow, and some users
and applications still use it in a global fsync kind of workload.
This patch changes btrfs not to clean old snapshots during sync, which is
safe from a FS consistency point of view. The major downside is that it
makes it difficult to tell when old snapshots have been reaped and
the space they were using has been reclaimed. A new ioctl will be added
for this purpose instead.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
Larger metadata clusters can significantly improve writeback performance
on ssd drives with large erasure blocks. The larger clusters make it
more likely a given IO will completely overwrite the ssd block, so it
doesn't have to do an internal rwm cycle.
On spinning media, lager metadata clusters end up spreading out the
metadata more over time, which makes fsck slower, so we don't want this
to be the default.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
Btrfs wasn't parsing any new mount options during remount, making it
difficult to set mount options on a root drive.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
Theres a slight problem with finish_current_insert, if we set all to 1 and then
go through and don't actually skip any of the extents on the pending list, we
could exit right after we've added new extents.
This is a problem because by inserting the new extents we could have gotten new
COW's to happen and such, so we may have some pending updates to do or even
more inserts to do after that.
So this patch will only exit if we have never skipped any of the extents in the
pending list, and we have no extents to insert, this will make sure that all of
the pending work is truly done before we return. I've been running with this
patch for a few days with all of my other testing and have not seen issues.
Thanks,
Signed-off-by: Josef Bacik <jbacik@redhat.com>
For a reason that I was unable to understand in three months of debugging,
mount ext2 -o remount stopped working properly when remounting from
regular operation to xip, or the other way around. According to a git
bisect search, the problem was introduced with the VM_MIXEDMAP/PTE_SPECIAL
rework in the vm:
commit 70688e4dd1
Author: Nick Piggin <npiggin@suse.de>
Date: Mon Apr 28 02:13:02 2008 -0700
xip: support non-struct page backed memory
In the failing scenario, the filesystem is mounted read only via root=
kernel parameter on s390x. During remount (in rc.sysinit), the inodes of
the bash binary and its libraries are busy and cannot be invalidated (the
bash which is running rc.sysinit resides on subject filesystem).
Afterwards, another bash process (running ifup-eth) recurses into a
subshell, runs dup_mm (via fork). Some of the mappings in this bash
process were created from inodes that could not be invalidated during
remount.
Both parent and child process crash some time later due to inconsistencies
in their address spaces. The issue seems to be timing sensitive, various
attempts to recreate it have failed.
This patch refuses to change the xip flag during remount in case some
inodes cannot be invalidated. This patch keeps users from running into
that issue.
[akpm@linux-foundation.org: cleanup]
Signed-off-by: Carsten Otte <cotte@de.ibm.com>
Cc: Nick Piggin <npiggin@suse.de>
Cc: Jared Hulbert <jaredeh@gmail.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This reverts commit c87591b719.
Since journal_start_commit() is now fixed to return 1 when we started a
transaction commit, there's some transaction waiting to be committed or
there's a transaction already committing, we don't need to call
ext3_force_commit() in ext3_sync_fs(). Furthermore ext3_force_commit()
can unnecessarily create sync transaction which is expensive so it's
worthwhile to remove it when we can.
Cc: Eric Sandeen <sandeen@redhat.com>
Cc: <linux-ext4@vger.kernel.org>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
journal_start_commit() returns 1 if either a transaction is committing or
the function has queued a transaction commit. But it returns 0 if we
raced with somebody queueing the transaction commit as well. This
resulted in ext3_sync_fs() not functioning correctly (description from
Arthur Jones): In the case of a data=ordered umount with pending long
symlinks which are delayed due to a long list of other I/O on the backing
block device, this causes the buffer associated with the long symlinks to
not be moved to the inode dirty list in the second phase of fsync_super.
Then, before they can be dirtied again, kjournald exits, seeing the UMOUNT
flag and the dirty pages are never written to the backing block device,
causing long symlink corruption and exposing new or previously freed block
data to userspace.
This can be reproduced with a script created by Eric Sandeen
<sandeen@redhat.com>:
#!/bin/bash
umount /mnt/test2
mount /dev/sdb4 /mnt/test2
rm -f /mnt/test2/*
dd if=/dev/zero of=/mnt/test2/bigfile bs=1M count=512
touch /mnt/test2/thisisveryveryveryveryveryveryveryveryveryveryveryveryveryveryveryverylongfilename
ln -s /mnt/test2/thisisveryveryveryveryveryveryveryveryveryveryveryveryveryveryveryverylongfilename
/mnt/test2/link
umount /mnt/test2
mount /dev/sdb4 /mnt/test2
ls /mnt/test2/
This patch fixes journal_start_commit() to always return 1 when there's
a transaction committing or queued for commit.
Cc: Eric Sandeen <sandeen@redhat.com>
Cc: Mike Snitzer <snitzer@gmail.com>
Cc: <linux-ext4@vger.kernel.org>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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 fc8744adc8, 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>
The rec_len field in the directory entry is 16 bits, so there was a
problem representing rec_len for filesystems with a 64k block size in
the case where the directory entry takes the entire 64k block.
Unfortunately, there were two schemes that were proposed; one where
all zeros meant 65536 and one where all ones (65535) meant 65536.
E2fsprogs used 0, whereas the kernel used 65535. Oops. Fortunately
this case happens extremely rarely, with the most common case being
the lost+found directory, created by mke2fs.
So we will be liberal in what we accept, and accept both encodings,
but we will continue to encode 65536 as 65535. This will require a
change in e2fsprogs, but with fortunately ext4 filesystems normally
have the dir_index feature enabled, which precludes having a
completely empty directory block.
Signed-off-by: Wei Yongjun <yjwei@cn.fujitsu.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
If we race with commit code setting i_transaction to NULL, we could
possibly dereference it. Proper locking requires the journal pointer
(to access journal->j_list_lock), which we don't have. So we have to
change the prototype of the function so that filesystem passes us the
journal pointer. Also add a more detailed comment about why the
function jbd2_journal_begin_ordered_truncate() does what it does and
how it should be used.
Thanks to Dan Carpenter <error27@gmail.com> for pointing to the
suspitious code.
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Acked-by: Joel Becker <joel.becker@oracle.com>
CC: linux-ext4@vger.kernel.org
CC: ocfs2-devel@oss.oracle.com
CC: mfasheh@suse.de
CC: Dan Carpenter <error27@gmail.com>
This undoes commit 14ce0cb411.
Since jbd2_journal_start_commit() is now fixed to return 1 when we
started a transaction commit, there's some transaction waiting to be
committed or there's a transaction already committing, we don't
need to call ext4_force_commit() in ext4_sync_fs(). Furthermore
ext4_force_commit() can unnecessarily create sync transaction which is
expensive so it's worthwhile to remove it when we can.
http://bugzilla.kernel.org/show_bug.cgi?id=12224
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: Eric Sandeen <sandeen@redhat.com>
Cc: linux-ext4@vger.kernel.org
The function jbd2_journal_start_commit() returns 1 if either a
transaction is committing or the function has queued a transaction
commit. But it returns 0 if we raced with somebody queueing the
transaction commit as well. This resulted in ext4_sync_fs() not
functioning correctly (description from Arthur Jones):
In the case of a data=ordered umount with pending long symlinks
which are delayed due to a long list of other I/O on the backing
block device, this causes the buffer associated with the long
symlinks to not be moved to the inode dirty list in the second
phase of fsync_super. Then, before they can be dirtied again,
kjournald exits, seeing the UMOUNT flag and the dirty pages are
never written to the backing block device, causing long symlink
corruption and exposing new or previously freed block data to
userspace.
This can be reproduced with a script created by Eric Sandeen
<sandeen@redhat.com>:
#!/bin/bash
umount /mnt/test2
mount /dev/sdb4 /mnt/test2
rm -f /mnt/test2/*
dd if=/dev/zero of=/mnt/test2/bigfile bs=1M count=512
touch /mnt/test2/thisisveryveryveryveryveryveryveryveryveryveryveryveryveryveryveryverylongfilename
ln -s /mnt/test2/thisisveryveryveryveryveryveryveryveryveryveryveryveryveryveryveryverylongfilename
/mnt/test2/link
umount /mnt/test2
mount /dev/sdb4 /mnt/test2
ls /mnt/test2/
This patch fixes jbd2_journal_start_commit() to always return 1 when
there's a transaction committing or queued for commit.
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
CC: Eric Sandeen <sandeen@redhat.com>
CC: linux-ext4@vger.kernel.org
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>
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 bde74e4bc6 "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>
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>
* 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
...
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>
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>
The patch:
commit a6f76f23d2
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>
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>
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>
... 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>
* '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()"
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 cb510b8172
aka "seq_file: more atomicity in traverse()".
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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>
This reverts commit 0e0333429a.
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>
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>
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>
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>
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>
Eric Biederman