Use new syncing helpers in .write and .aio_write functions. Also
remove superfluous syncing in ntfs_file_buffered_write() and update
comments about generic_osync_inode().
CC: Anton Altaparmakov <aia21@cantab.net>
CC: linux-ntfs-dev@lists.sourceforge.net
Signed-off-by: Jan Kara <jack@suse.cz>
The syncing is now properly handled by generic_file_aio_write() so
no special ext4 code is needed.
CC: linux-ext4@vger.kernel.org
CC: tytso@mit.edu
Signed-off-by: Jan Kara <jack@suse.cz>
Syncing is now properly done by generic_file_aio_write() so no special logic is
needed in ext3.
CC: linux-ext4@vger.kernel.org
Signed-off-by: Jan Kara <jack@suse.cz>
Introduce new function for generic inode syncing (vfs_fsync_range) and use
it from fsync() path. Introduce also new helper for syncing after a sync
write (generic_write_sync) using the generic function.
Use these new helpers for syncing from generic VFS functions. This makes
O_SYNC writes to block devices acquire i_mutex for syncing. If we really
care about this, we can make block_fsync() drop the i_mutex and reacquire
it before it returns.
CC: Evgeniy Polyakov <zbr@ioremap.net>
CC: ocfs2-devel@oss.oracle.com
CC: Joel Becker <joel.becker@oracle.com>
CC: Felix Blyakher <felixb@sgi.com>
CC: xfs@oss.sgi.com
CC: Anton Altaparmakov <aia21@cantab.net>
CC: linux-ntfs-dev@lists.sourceforge.net
CC: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
CC: linux-ext4@vger.kernel.org
CC: tytso@mit.edu
Acked-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jan Kara <jack@suse.cz>
generic_file_aio_write_nolock() is now used only by block devices and raw
character device. Filesystems should use __generic_file_aio_write() in case
generic_file_aio_write() doesn't suit them. So rename the function to
blkdev_aio_write() and move it to fs/blockdev.c.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jan Kara <jack@suse.cz>
Use the new helper. We have to submit data pages ourselves in case of O_SYNC
write because __generic_file_aio_write does not do it for us. OCFS2 developpers
might think about moving the sync out of i_mutex which seems to be easily
possible but that's out of scope of this patch.
CC: ocfs2-devel@oss.oracle.com
Acked-by: Joel Becker <joel.becker@oracle.com>
Signed-off-by: Jan Kara <jack@suse.cz>
* git://git.linux-nfs.org/projects/trondmy/nfs-2.6: (87 commits)
NFSv4: Disallow 'mount -t nfs4 -overs=2' and 'mount -t nfs4 -overs=3'
NFS: Allow the "nfs" file system type to support NFSv4
NFS: Move details of nfs4_get_sb() to a helper
NFS: Refactor NFSv4 text-based mount option validation
NFS: Mount option parser should detect missing "port="
NFS: out of date comment regarding O_EXCL above nfs3_proc_create()
NFS: Handle a zero-length auth flavor list
SUNRPC: Ensure that sunrpc gets initialised before nfs, lockd, etc...
nfs: fix compile error in rpc_pipefs.h
nfs: Remove reference to generic_osync_inode from a comment
SUNRPC: cache must take a reference to the cache detail's module on open()
NFS: Use the DNS resolver in the mount code.
NFS: Add a dns resolver for use with NFSv4 referrals and migration
SUNRPC: Fix a typo in cache_pipefs_files
nfs: nfs4xdr: optimize low level decoding
nfs: nfs4xdr: get rid of READ_BUF
nfs: nfs4xdr: simplify decode_exchange_id by reusing decode_opaque_inline
nfs: nfs4xdr: get rid of COPYMEM
nfs: nfs4xdr: introduce decode_sessionid helper
nfs: nfs4xdr: introduce decode_verifier helper
...
* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (64 commits)
sched: Fix sched::sched_stat_wait tracepoint field
sched: Disable NEW_FAIR_SLEEPERS for now
sched: Keep kthreads at default priority
sched: Re-tune the scheduler latency defaults to decrease worst-case latencies
sched: Turn off child_runs_first
sched: Ensure that a child can't gain time over it's parent after fork()
sched: enable SD_WAKE_IDLE
sched: Deal with low-load in wake_affine()
sched: Remove short cut from select_task_rq_fair()
sched: Turn on SD_BALANCE_NEWIDLE
sched: Clean up topology.h
sched: Fix dynamic power-balancing crash
sched: Remove reciprocal for cpu_power
sched: Try to deal with low capacity, fix update_sd_power_savings_stats()
sched: Try to deal with low capacity
sched: Scale down cpu_power due to RT tasks
sched: Implement dynamic cpu_power
sched: Add smt_gain
sched: Update the cpu_power sum during load-balance
sched: Add SD_PREFER_SIBLING
...
* 'writeback' of git://git.kernel.dk/linux-2.6-block:
writeback: check for registered bdi in flusher add and inode dirty
writeback: add name to backing_dev_info
writeback: add some debug inode list counters to bdi stats
writeback: get rid of pdflush completely
writeback: switch to per-bdi threads for flushing data
writeback: move dirty inodes from super_block to backing_dev_info
writeback: get rid of generic_sync_sb_inodes() export
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/security-testing-2.6: (57 commits)
binfmt_elf: fix PT_INTERP bss handling
TPM: Fixup boot probe timeout for tpm_tis driver
sysfs: Add labeling support for sysfs
LSM/SELinux: inode_{get,set,notify}secctx hooks to access LSM security context information.
VFS: Factor out part of vfs_setxattr so it can be called from the SELinux hook for inode_setsecctx.
KEYS: Add missing linux/tracehook.h #inclusions
KEYS: Fix default security_session_to_parent()
Security/SELinux: includecheck fix kernel/sysctl.c
KEYS: security_cred_alloc_blank() should return int under all circumstances
IMA: open new file for read
KEYS: Add a keyctl to install a process's session keyring on its parent [try #6]
KEYS: Extend TIF_NOTIFY_RESUME to (almost) all architectures [try #6]
KEYS: Do some whitespace cleanups [try #6]
KEYS: Make /proc/keys use keyid not numread as file position [try #6]
KEYS: Add garbage collection for dead, revoked and expired keys. [try #6]
KEYS: Flag dead keys to induce EKEYREVOKED [try #6]
KEYS: Allow keyctl_revoke() on keys that have SETATTR but not WRITE perm [try #6]
KEYS: Deal with dead-type keys appropriately [try #6]
CRED: Add some configurable debugging [try #6]
selinux: Support for the new TUN LSM hooks
...
Also a debugging aid. We want to catch dirty inodes being added to
backing devices that don't do writeback.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
This enables us to track who does what and print info. Its main use
is catching dirty inodes on the default_backing_dev_info, so we can
fix that up.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
This gets rid of pdflush for bdi writeout and kupdated style cleaning.
pdflush writeout suffers from lack of locality and also requires more
threads to handle the same workload, since it has to work in a
non-blocking fashion against each queue. This also introduces lumpy
behaviour and potential request starvation, since pdflush can be starved
for queue access if others are accessing it. A sample ffsb workload that
does random writes to files is about 8% faster here on a simple SATA drive
during the benchmark phase. File layout also seems a LOT more smooth in
vmstat:
r b swpd free buff cache si so bi bo in cs us sy id wa
0 1 0 608848 2652 375372 0 0 0 71024 604 24 1 10 48 42
0 1 0 549644 2712 433736 0 0 0 60692 505 27 1 8 48 44
1 0 0 476928 2784 505192 0 0 4 29540 553 24 0 9 53 37
0 1 0 457972 2808 524008 0 0 0 54876 331 16 0 4 38 58
0 1 0 366128 2928 614284 0 0 4 92168 710 58 0 13 53 34
0 1 0 295092 3000 684140 0 0 0 62924 572 23 0 9 53 37
0 1 0 236592 3064 741704 0 0 4 58256 523 17 0 8 48 44
0 1 0 165608 3132 811464 0 0 0 57460 560 21 0 8 54 38
0 1 0 102952 3200 873164 0 0 4 74748 540 29 1 10 48 41
0 1 0 48604 3252 926472 0 0 0 53248 469 29 0 7 47 45
where vanilla tends to fluctuate a lot in the creation phase:
r b swpd free buff cache si so bi bo in cs us sy id wa
1 1 0 678716 5792 303380 0 0 0 74064 565 50 1 11 52 36
1 0 0 662488 5864 319396 0 0 4 352 302 329 0 2 47 51
0 1 0 599312 5924 381468 0 0 0 78164 516 55 0 9 51 40
0 1 0 519952 6008 459516 0 0 4 78156 622 56 1 11 52 37
1 1 0 436640 6092 541632 0 0 0 82244 622 54 0 11 48 41
0 1 0 436640 6092 541660 0 0 0 8 152 39 0 0 51 49
0 1 0 332224 6200 644252 0 0 4 102800 728 46 1 13 49 36
1 0 0 274492 6260 701056 0 0 4 12328 459 49 0 7 50 43
0 1 0 211220 6324 763356 0 0 0 106940 515 37 1 10 51 39
1 0 0 160412 6376 813468 0 0 0 8224 415 43 0 6 49 45
1 1 0 85980 6452 886556 0 0 4 113516 575 39 1 11 54 34
0 2 0 85968 6452 886620 0 0 0 1640 158 211 0 0 46 54
A 10 disk test with btrfs performs 26% faster with per-bdi flushing. A
SSD based writeback test on XFS performs over 20% better as well, with
the throughput being very stable around 1GB/sec, where pdflush only
manages 750MB/sec and fluctuates wildly while doing so. Random buffered
writes to many files behave a lot better as well, as does random mmap'ed
writes.
A separate thread is added to sync the super blocks. In the long term,
adding sync_supers_bdi() functionality could get rid of this thread again.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
This is a first step at introducing per-bdi flusher threads. We should
have no change in behaviour, although sb_has_dirty_inodes() is now
ridiculously expensive, as there's no easy way to answer that question.
Not a huge problem, since it'll be deleted in subsequent patches.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
This adds two new exported functions:
- writeback_inodes_sb(), which only attempts to writeback dirty inodes on
this super_block, for WB_SYNC_NONE writeout.
- sync_inodes_sb(), which writes out all dirty inodes on this super_block
and also waits for the IO to complete.
Acked-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* topic/soundcore-preclaim:
sound: make OSS device number claiming optional and schedule its removal
sound: request char-major-* module aliases for missing OSS devices
chrdev: implement __[un]register_chrdev()
In fs/binfmt_elf.c, load_elf_interp() calls padzero() for .bss even if
the PT_LOAD has no PROT_WRITE and no .bss. This generates EFAULT.
Here is a small test case. (Yes, there are other, useful PT_INTERP
which have only .text and no .data/.bss.)
----- ptinterp.S
_start: .globl _start
nop
int3
-----
$ gcc -m32 -nostartfiles -nostdlib -o ptinterp ptinterp.S
$ gcc -m32 -Wl,--dynamic-linker=ptinterp -o hello hello.c
$ ./hello
Segmentation fault # during execve() itself
After applying the patch:
$ ./hello
Trace trap # user-mode execution after execve() finishes
If the ELF headers are actually self-inconsistent, then dying is fine.
But having no PROT_WRITE segment is perfectly normal and correct if
there is no segment with p_memsz > p_filesz (i.e. bss). John Reiser
suggested checking for PROT_WRITE in the bss logic. I think it makes
most sense to simply apply the bss logic only when there is bss.
This patch looks less trivial than it is due to some reindentation.
It just moves the "if (last_bss > elf_bss) {" test up to include the
partial-page bss logic as well as the more-pages bss logic.
Reported-by: John Reiser <jreiser@bitwagon.com>
Signed-off-by: Roland McGrath <roland@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>
* lookup-permissions-cleanup:
jffs2/jfs/xfs: switch over to 'check_acl' rather than 'permission()'
ext[234]: move over to 'check_acl' permission model
shmfs: use 'check_acl' instead of 'permission'
Make 'check_acl()' a first-class filesystem op
Simplify exec_permission_lite(), part 3
Simplify exec_permission_lite() further
Simplify exec_permission_lite() logic
Do not call 'ima_path_check()' for each path component
In fs/binfmt_elf.c, load_elf_interp() calls padzero() for .bss even if
the PT_LOAD has no PROT_WRITE and no .bss. This generates EFAULT.
Here is a small test case. (Yes, there are other, useful PT_INTERP
which have only .text and no .data/.bss.)
----- ptinterp.S
_start: .globl _start
nop
int3
-----
$ gcc -m32 -nostartfiles -nostdlib -o ptinterp ptinterp.S
$ gcc -m32 -Wl,--dynamic-linker=ptinterp -o hello hello.c
$ ./hello
Segmentation fault # during execve() itself
After applying the patch:
$ ./hello
Trace trap # user-mode execution after execve() finishes
If the ELF headers are actually self-inconsistent, then dying is fine.
But having no PROT_WRITE segment is perfectly normal and correct if
there is no segment with p_memsz > p_filesz (i.e. bss). John Reiser
suggested checking for PROT_WRITE in the bss logic. I think it makes
most sense to simply apply the bss logic only when there is bss.
This patch looks less trivial than it is due to some reindentation.
It just moves the "if (last_bss > elf_bss) {" test up to include the
partial-page bss logic as well as the more-pages bss logic.
Reported-by: John Reiser <jreiser@bitwagon.com>
Signed-off-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patch adds a setxattr handler to the file, directory, and symlink
inode_operations structures for sysfs. The patch uses hooks introduced in the
previous patch to handle the getting and setting of security information for
the sysfs inodes. As was suggested by Eric Biederman the struct iattr in the
sysfs_dirent structure has been replaced by a structure which contains the
iattr, secdata and secdata length to allow the changes to persist in the event
that the inode representing the sysfs_dirent is evicted. Because sysfs only
stores this information when a change is made all the optional data is moved
into one dynamically allocated field.
This patch addresses an issue where SELinux was denying virtd access to the PCI
configuration entries in sysfs. The lack of setxattr handlers for sysfs
required that a single label be assigned to all entries in sysfs. Granting virtd
access to every entry in sysfs is not an acceptable solution so fine grained
labeling of sysfs is required such that individual entries can be labeled
appropriately.
[sds: Fixed compile-time warnings, coding style, and setting of inode security init flags.]
Signed-off-by: David P. Quigley <dpquigl@tycho.nsa.gov>
Signed-off-by: Stephen D. Smalley <sds@tycho.nsa.gov>
Signed-off-by: James Morris <jmorris@namei.org>
This factors out the part of the vfs_setxattr function that performs the
setting of the xattr and its notification. This is needed so the SELinux
implementation of inode_setsecctx can handle the setting of the xattr while
maintaining the proper separation of layers.
Signed-off-by: David P. Quigley <dpquigl@tycho.nsa.gov>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>
When mounting an "nfs" type file system, recognize "v4," "vers=4," or
"nfsvers=4" mount options, and convert the file system to "nfs4" under
the covers.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
[trondmy: fixed up binary mount code so it sets the 'version' field too]
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Clean up: Refactor nfs4_get_sb() to allow its guts to be invoked by
nfs_get_sb().
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Clean up: Refactor the part of nfs4_validate_mount_options() that
handles text-based options, so we can call it from the NFSv2/v3
option validation function.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
The meaning of not specifying the "port=" mount option is different
for "-t nfs" and "-t nfs4" mounts. The default port value for
NFSv2/v3 mounts is 0, but the default for NFSv4 mounts is 2049.
To support "-t nfs -o vers=4", the mount option parser must detect
when "port=" is missing so that the correct default port value can be
set depending on which NFS version is requested.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Hi Trond,
Recently we were observing the behaviour difference between a 2.4.x and
2.6.x kernel with respect to O_EXCL. A comment from 2.4.x era, "For now,
we don't implement O_EXCL." seems inaccurate in TOT.
If so, here's a patch to remove the comment.
This patch is against:
git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6
Signed-off-by: Harshula Jayasuriya <harshula@redhat.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
This avoids an indirect call in the VFS for each path component lookup.
Well, at least as long as you own the directory in question, and the ACL
check is unnecessary.
Reviewed-by: James Morris <jmorris@namei.org>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Don't implement per-filesystem 'extX_permission()' functions that have
to be called for every path component operation, and instead just expose
the actual ACL checking so that the VFS layer can now do it for us.
Reviewed-by: James Morris <jmorris@namei.org>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This is stage one in flattening out the callchains for the common
permission testing. Rather than have most filesystem implement their
own inode->i_op->permission function that just calls back down to the
VFS layers 'generic_permission()' with the per-filesystem ACL checking
function, the filesystem can just expose its 'check_acl' function
directly, and let the VFS layer do everything for it.
This is all just preparatory - no filesystem actually enables this yet.
Reviewed-by: James Morris <jmorris@namei.org>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Don't call down to the generic inode_permission() function just to
call the inode-specific permission function - just do it directly.
The generic inode_permission() code does things like checking MAY_WRITE
and devcgroup_inode_permission(), neither of which are relevant for the
light pathname walk permission checks (we always do just MAY_EXEC, and
the inode is never a special device).
Reviewed-by: James Morris <jmorris@namei.org>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This function is only called for path components that are already known
to be directories (they have a '->lookup' method). So don't bother
doing that whole S_ISDIR() testing, the whole point of the 'lite()'
version is that we know that we are looking at a directory component,
and that we're only checking name lookup permission.
Reviewed-by: James Morris <jmorris@namei.org>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Instead of returning EAGAIN and having the caller do something
special for that case, just do the special case directly.
Reviewed-by: James Morris <jmorris@namei.org>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Not only is that a supremely timing-critical path, but it's hopefully
some day going to be lockless for the common case, and ima can't do
that.
Plus the integrity code doesn't even care about non-regular files, so it
was always a total waste of time and effort.
Acked-by: Serge Hallyn <serue@us.ibm.com>
Acked-by: Mimi Zohar <zohar@us.ibm.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
- As ima_counts_put() may be called after the inode has been freed,
verify that the inode is not NULL, before dereferencing it.
- Maintain the IMA file counters in may_open() properly, decrementing
any counter increments on subsequent errors.
Reported-by: Ciprian Docan <docan@eden.rutgers.edu>
Reported-by: J.R. Okajima <hooanon05@yahoo.co.jp>
Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
Acked-by: Eric Paris <eparis@redhat.com
Signed-off-by: James Morris <jmorris@namei.org>
In ext2_rename(), dir_page is acquired through ext2_dotdot(). It is
then released through ext2_set_link() but only if old_dir != new_dir.
Failing that, the pkmap reference count is never decremented and the
page remains pinned forever. Repeat that a couple times with highmem
pages and all pkmap slots get exhausted, and every further kmap() calls
end up stalling on the pkmap_map_wait queue at which point the whole
system comes to a halt.
Signed-off-by: Nicolas Pitre <nico@marvell.com>
Acked-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* 'upstream-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jlbec/ocfs2:
ocfs2: ocfs2_write_begin_nolock() should handle len=0
ocfs2: invalidate dentry if its dentry_lock isn't initialized.
Tom Horsley reports that his debugger hangs when it tries to read
/proc/pid_of_tracee/maps, this happens since
"mm_for_maps: take ->cred_guard_mutex to fix the race with exec"
04b836cbf19e885f8366bccb2e4b0474346c02d
commit in 2.6.31.
But the root of the problem lies in the fact that do_execve() path calls
tracehook_report_exec() which can stop if the tracer sets PT_TRACE_EXEC.
The tracee must not sleep in TASK_TRACED holding this mutex. Even if we
remove ->cred_guard_mutex from mm_for_maps() and proc_pid_attr_write(),
another task doing PTRACE_ATTACH should not hang until it is killed or the
tracee resumes.
With this patch do_execve() does not use ->cred_guard_mutex directly and
we do not hold it throughout, instead:
- introduce prepare_bprm_creds() helper, it locks the mutex
and calls prepare_exec_creds() to initialize bprm->cred.
- install_exec_creds() drops the mutex after commit_creds(),
and thus before tracehook_report_exec()->ptrace_stop().
or, if exec fails,
free_bprm() drops this mutex when bprm->cred != NULL which
indicates install_exec_creds() was not called.
Reported-by: Tom Horsley <tom.horsley@att.net>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: David Howells <dhowells@redhat.com>
Cc: Roland McGrath <roland@redhat.com>
Cc: James Morris <jmorris@namei.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Bug introduced by mainline commit e7432675f8
The bug causes ocfs2_write_begin_nolock() to oops when len=0.
Signed-off-by: Sunil Mushran <sunil.mushran@oracle.com>
Cc: stable@kernel.org
Signed-off-by: Joel Becker <joel.becker@oracle.com>
The function jffs2_nor_wbuf_flash_setup() doesn't allocate the verify buffer
if CONFIG_JFFS2_FS_WBUF_VERIFY is defined, so causing a kernel panic when
that macro is enabled and the verify function is called. Similarly the
jffs2_nor_wbuf_flash_cleanup() must free the buffer if
CONFIG_JFFS2_FS_WBUF_VERIFY is enabled.
The following patch fixes the problem.
The following patch applies to 2.6.30 kernel.
Signed-off-by: Massimo Cirillo <maxcir@gmail.com>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Cc: stable@kernel.org
When creating a new file, ima_path_check() assumed the new file
was being opened for write. Call ima_path_check() with the
appropriate acc_mode so that the read/write counters are
incremented correctly.
Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>
Add a config option (CONFIG_DEBUG_CREDENTIALS) to turn on some debug checking
for credential management. The additional code keeps track of the number of
pointers from task_structs to any given cred struct, and checks to see that
this number never exceeds the usage count of the cred struct (which includes
all references, not just those from task_structs).
Furthermore, if SELinux is enabled, the code also checks that the security
pointer in the cred struct is never seen to be invalid.
This attempts to catch the bug whereby inode_has_perm() faults in an nfsd
kernel thread on seeing cred->security be a NULL pointer (it appears that the
credential struct has been previously released):
http://www.kerneloops.org/oops.php?number=252883
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>
