Pull cifs fixes from Jeff Layton.
* 'for-linus' of git://git.samba.org/sfrench/cifs-2.6:
cifs: Do not lookup hashed negative dentry in cifs_atomic_open
cifs: fix potential buffer overrun in cifs.idmap handling code
Merge misc fixes from Andrew Morton:
"Five fixes"
* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (5 patches)
h8300: add missing L1_CACHE_SHIFT
mm: bugfix: set current->reclaim_state to NULL while returning from kswapd()
fanotify: fix missing break
revert "epoll: support for disabling items, and a self-test app"
checkpatch: improve network block comment style checking
Pull xfs bugfixes from Ben Myers:
- fix for large transactions spanning multiple iclog buffers
- zero the allocation_args structure on the stack before using it to
determine whether to use a worker for allocation
- move allocation stack switch to xfs_bmapi_allocate in order to
prevent deadlock on AGF buffers
- growfs no longer reads in garbage for new secondary superblocks
- silence a build warning
- ensure that invalid buffers never get written to disk while on free
list
- don't vmap inode cluster buffers during free
- fix buffer shutdown reference count mismatch
- fix reading of wrapped log data
* tag 'for-linus-v3.7-rc5' of git://oss.sgi.com/xfs/xfs:
xfs: fix reading of wrapped log data
xfs: fix buffer shudown reference count mismatch
xfs: don't vmap inode cluster buffers during free
xfs: invalidate allocbt blocks moved to the free list
xfs: silence uninitialised f.file warning.
xfs: growfs: don't read garbage for new secondary superblocks
xfs: move allocation stack switch up to xfs_bmapi_allocate
xfs: introduce XFS_BMAPI_STACK_SWITCH
xfs: zero allocation_args on the kernel stack
xfs: only update the last_sync_lsn when a transaction completes
Revert commit 03a7beb55b ("epoll: support for disabling items, and a
self-test app") pending resolution of the issues identified by Michael
Kerrisk, copied below.
We'll revisit this for 3.8.
: I've taken a look at this patch as it currently stands in 3.7-rc1, and
: done a bit of testing. (By the way, the test program
: tools/testing/selftests/epoll/test_epoll.c does not compile...)
:
: There are one or two places where the behavior seems a little strange,
: so I have a question or two at the end of this mail. But other than
: that, I want to check my understanding so that the interface can be
: correctly documented.
:
: Just to go though my understanding, the problem is the following
: scenario in a multithreaded application:
:
: 1. Multiple threads are performing epoll_wait() operations,
: and maintaining a user-space cache that contains information
: corresponding to each file descriptor being monitored by
: epoll_wait().
:
: 2. At some point, a thread wants to delete (EPOLL_CTL_DEL)
: a file descriptor from the epoll interest list, and
: delete the corresponding record from the user-space cache.
:
: 3. The problem with (2) is that some other thread may have
: previously done an epoll_wait() that retrieved information
: about the fd in question, and may be in the middle of using
: information in the cache that relates to that fd. Thus,
: there is a potential race.
:
: 4. The race can't solved purely in user space, because doing
: so would require applying a mutex across the epoll_wait()
: call, which would of course blow thread concurrency.
:
: Right?
:
: Your solution is the EPOLL_CTL_DISABLE operation. I want to
: confirm my understanding about how to use this flag, since
: the description that has accompanied the patches so far
: has been a bit sparse
:
: 0. In the scenario you're concerned about, deleting a file
: descriptor means (safely) doing the following:
: (a) Deleting the file descriptor from the epoll interest list
: using EPOLL_CTL_DEL
: (b) Deleting the corresponding record in the user-space cache
:
: 1. It's only meaningful to use this EPOLL_CTL_DISABLE in
: conjunction with EPOLLONESHOT.
:
: 2. Using EPOLL_CTL_DISABLE without using EPOLLONESHOT in
: conjunction is a logical error.
:
: 3. The correct way to code multithreaded applications using
: EPOLL_CTL_DISABLE and EPOLLONESHOT is as follows:
:
: a. All EPOLL_CTL_ADD and EPOLL_CTL_MOD operations should
: should EPOLLONESHOT.
:
: b. When a thread wants to delete a file descriptor, it
: should do the following:
:
: [1] Call epoll_ctl(EPOLL_CTL_DISABLE)
: [2] If the return status from epoll_ctl(EPOLL_CTL_DISABLE)
: was zero, then the file descriptor can be safely
: deleted by the thread that made this call.
: [3] If the epoll_ctl(EPOLL_CTL_DISABLE) fails with EBUSY,
: then the descriptor is in use. In this case, the calling
: thread should set a flag in the user-space cache to
: indicate that the thread that is using the descriptor
: should perform the deletion operation.
:
: Is all of the above correct?
:
: The implementation depends on checking on whether
: (events & ~EP_PRIVATE_BITS) == 0
: This replies on the fact that EPOLL_CTL_AD and EPOLL_CTL_MOD always
: set EPOLLHUP and EPOLLERR in the 'events' mask, and EPOLLONESHOT
: causes those flags (as well as all others in ~EP_PRIVATE_BITS) to be
: cleared.
:
: A corollary to the previous paragraph is that using EPOLL_CTL_DISABLE
: is only useful in conjunction with EPOLLONESHOT. However, as things
: stand, one can use EPOLL_CTL_DISABLE on a file descriptor that does
: not have EPOLLONESHOT set in 'events' This results in the following
: (slightly surprising) behavior:
:
: (a) The first call to epoll_ctl(EPOLL_CTL_DISABLE) returns 0
: (the indicator that the file descriptor can be safely deleted).
: (b) The next call to epoll_ctl(EPOLL_CTL_DISABLE) fails with EBUSY.
:
: This doesn't seem particularly useful, and in fact is probably an
: indication that the user made a logic error: they should only be using
: epoll_ctl(EPOLL_CTL_DISABLE) on a file descriptor for which
: EPOLLONESHOT was set in 'events'. If that is correct, then would it
: not make sense to return an error to user space for this case?
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: "Paton J. Lewis" <palewis@adobe.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit 4439647 ("xfs: reset buffer pointers before freeing them") in
3.0-rc1 introduced a regression when recovering log buffers that
wrapped around the end of log. The second part of the log buffer at
the start of the physical log was being read into the header buffer
rather than the data buffer, and hence recovery was seeing garbage
in the data buffer when it got to the region of the log buffer that
was incorrectly read.
Cc: <stable@vger.kernel.org> # 3.0.x, 3.2.x, 3.4.x 3.6.x
Reported-by: Torsten Kaiser <just.for.lkml@googlemail.com>
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
When we shut down the filesystem, we have to unpin and free all the
buffers currently active in the CIL. To do this we unpin and remove
them in one operation as a result of a failed iclogbuf write. For
buffers, we do this removal via a simultated IO completion of after
marking the buffer stale.
At the time we do this, we have two references to the buffer - the
active LRU reference and the buf log item. The LRU reference is
removed by marking the buffer stale, and the active CIL reference is
by the xfs_buf_iodone() callback that is run by
xfs_buf_do_callbacks() during ioend processing (via the bp->b_iodone
callback).
However, ioend processing requires one more reference - that of the
IO that it is completing. We don't have this reference, so we free
the buffer prematurely and use it after it is freed. For buffers
marked with XBF_ASYNC, this leads to assert failures in
xfs_buf_rele() on debug kernels because the b_hold count is zero.
Fix this by making sure we take the necessary IO reference before
starting IO completion processing on the stale buffer, and set the
XBF_ASYNC flag to ensure that IO completion processing removes all
the active references from the buffer to ensure it is fully torn
down.
Cc: <stable@vger.kernel.org>
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
Inode buffers do not need to be mapped as inodes are read or written
directly from/to the pages underlying the buffer. This fixes a
regression introduced by commit 611c994 ("xfs: make XBF_MAPPED the
default behaviour").
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
When we free a block from the alloc btree tree, we move it to the
freelist held in the AGFL and mark it busy in the busy extent tree.
This typically happens when we merge btree blocks.
Once the transaction is committed and checkpointed, the block can
remain on the free list for an indefinite amount of time. Now, this
isn't the end of the world at this point - if the free list is
shortened, the buffer is invalidated in the transaction that moves
it back to free space. If the buffer is allocated as metadata from
the free list, then all the modifications getted logged, and we have
no issues, either. And if it gets allocated as userdata direct from
the freelist, it gets invalidated and so will never get written.
However, during the time it sits on the free list, pressure on the
log can cause the AIL to be pushed and the buffer that covers the
block gets pushed for write. IOWs, we end up writing a freed
metadata block to disk. Again, this isn't the end of the world
because we know from the above we are only writing to free space.
The problem, however, is for validation callbacks. If the block was
on old btree root block, then the level of the block is going to be
higher than the current tree root, and so will fail validation.
There may be other inconsistencies in the block as well, and
currently we don't care because the block is in free space. Shutting
down the filesystem because a freed block doesn't pass write
validation, OTOH, is rather unfriendly.
So, make sure we always invalidate buffers as they move from the
free space trees to the free list so that we guarantee they never
get written to disk while on the free list.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Phil White <pwhite@sgi.com>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
Uninitialised variable build warning introduced by 2903ff0 ("switch
simple cases of fget_light to fdget"), gcc is not smart enough to
work out that the variable is not used uninitialised, and the commit
removed the initialisation at declaration that the old variable had.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
When updating new secondary superblocks in a growfs operation, the
superblock buffer is read from the newly grown region of the
underlying device. This is not guaranteed to be zero, so violates
the underlying assumption that the unused parts of superblocks are
zero filled. Get a new buffer for these secondary superblocks to
ensure that the unused regions are zero filled correctly.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
Switching stacks are xfs_alloc_vextent can cause deadlocks when we
run out of worker threads on the allocation workqueue. This can
occur because xfs_bmap_btalloc can make multiple calls to
xfs_alloc_vextent() and even if xfs_alloc_vextent() fails it can
return with the AGF locked in the current allocation transaction.
If we then need to make another allocation, and all the allocation
worker contexts are exhausted because the are blocked waiting for
the AGF lock, holder of the AGF cannot get it's xfs-alloc_vextent
work completed to release the AGF. Hence allocation effectively
deadlocks.
To avoid this, move the stack switch one layer up to
xfs_bmapi_allocate() so that all of the allocation attempts in a
single switched stack transaction occur in a single worker context.
This avoids the problem of an allocation being blocked waiting for
a worker thread whilst holding the AGF.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
Certain allocation paths through xfs_bmapi_write() are in situations
where we have limited stack available. These are almost always in
the buffered IO writeback path when convertion delayed allocation
extents to real extents.
The current stack switch occurs for userdata allocations, which
means we also do stack switches for preallocation, direct IO and
unwritten extent conversion, even those these call chains have never
been implicated in a stack overrun.
Hence, let's target just the single stack overun offended for stack
switches. To do that, introduce a XFS_BMAPI_STACK_SWITCH flag that
the caller can pass xfs_bmapi_write() to indicate it should switch
stacks if it needs to do allocation.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
Zero the kernel stack space that makes up the xfs_alloc_arg structures.
Signed-off-by: Mark Tinguely <tinguely@sgi.com>
Reviewed-by: Ben Myers <bpm@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
The log write code stamps each iclog with the current tail LSN in
the iclog header so that recovery knows where to find the tail of
thelog once it has found the head. Normally this is taken from the
first item on the AIL - the log item that corresponds to the oldest
active item in the log.
The problem is that when the AIL is empty, the tail lsn is dervied
from the the l_last_sync_lsn, which is the LSN of the last iclog to
be written to the log. In most cases this doesn't happen, because
the AIL is rarely empty on an active filesystem. However, when it
does, it opens up an interesting case when the transaction being
committed to the iclog spans multiple iclogs.
That is, the first iclog is stamped with the l_last_sync_lsn, and IO
is issued. Then the next iclog is setup, the changes copied into the
iclog (takes some time), and then the l_last_sync_lsn is stamped
into the header and IO is issued. This is still the same
transaction, so the tail lsn of both iclogs must be the same for log
recovery to find the entire transaction to be able to replay it.
The problem arises in that the iclog buffer IO completion updates
the l_last_sync_lsn with it's own LSN. Therefore, If the first iclog
completes it's IO before the second iclog is filled and has the tail
lsn stamped in it, it will stamp the LSN of the first iclog into
it's tail lsn field. If the system fails at this point, log recovery
will not see a complete transaction, so the transaction will no be
replayed.
The fix is simple - the l_last_sync_lsn is updated when a iclog
buffer IO completes, and this is incorrect. The l_last_sync_lsn
shoul dbe updated when a transaction is completed by a iclog buffer
IO. That is, only iclog buffers that have transaction commit
callbacks attached to them should update the l_last_sync_lsn. This
means that the last_sync_lsn will only move forward when a commit
record it written, not in the middle of a large transaction that is
rolling through multiple iclog buffers.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ben Myers <bpm@sgi.com>
Pull gfs2 fixes from Steven Whitehouse:
"Here are a number of GFS2 bug fixes. There are three from Andy Price
which fix various issues spotted by automated code analysis. There
are two from Lukas Czerner fixing my mistaken assumptions as to how
FITRIM should work. Finally Ben Marzinski has fixed a bug relating to
mmap and atime and also a bug relating to a locking issue in the
transaction code."
* git://git.kernel.org/pub/scm/linux/kernel/git/steve/gfs2-3.0-fixes:
GFS2: Test bufdata with buffer locked and gfs2_log_lock held
GFS2: Don't call file_accessed() with a shared glock
GFS2: Fix FITRIM argument handling
GFS2: Require user to provide argument for FITRIM
GFS2: Clean up some unused assignments
GFS2: Fix possible null pointer deref in gfs2_rs_alloc
GFS2: Fix an unchecked error from gfs2_rs_alloc
In gfs2_trans_add_bh(), gfs2 was testing if a there was a bd attached to the
buffer without having the gfs2_log_lock held. It was then assuming it would
stay attached for the rest of the function. However, without either the log
lock being held of the buffer locked, __gfs2_ail_flush() could detach bd at any
time. This patch moves the locking before the test. If there isn't a bd
already attached, gfs2 can safely allocate one and attach it before locking.
There is no way that the newly allocated bd could be on the ail list,
and thus no way for __gfs2_ail_flush() to detach it.
Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
file_accessed() was being called by gfs2_mmap() with a shared glock. If it
needed to update the atime, it was crashing because it dirtied the inode in
gfs2_dirty_inode() without holding an exclusive lock. gfs2_dirty_inode()
checked if the caller was already holding a glock, but it didn't make sure that
the glock was in the exclusive state. Now, instead of calling file_accessed()
while holding the shared lock in gfs2_mmap(), file_accessed() is called after
grabbing and releasing the glock to update the inode. If file_accessed() needs
to update the atime, it will grab an exclusive lock in gfs2_dirty_inode().
gfs2_dirty_inode() now also checks to make sure that if the calling process has
already locked the glock, it has an exclusive lock.
Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
Currently implementation in gfs2 uses FITRIM arguments as it were in
file system blocks units which is wrong. The FITRIM arguments
(fstrim_range.start, fstrim_range.len and fstrim_range.minlen) are
actually in bytes.
Moreover, check for start argument beyond the end of file system, len
argument being smaller than file system block and minlen argument being
bigger than biggest resource group were missing.
This commit converts the code to convert FITRIM argument to file system
blocks and also adds appropriate checks mentioned above.
All the problems were recognised by xfstests 251 and 260.
Signed-off-by: Lukas Czerner <lczerner@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
When the fstrim_range argument is not provided by user in FITRIM ioctl
we should just return EFAULT and not promoting bad behaviour by filling
the structure in kernel. Let the user deal with it.
Signed-off-by: Lukas Czerner <lczerner@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
Cleans up two cases where variables were assigned values but then never
used again.
Signed-off-by: Andrew Price <anprice@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
Despite the return value from kmem_cache_zalloc() being checked, the
error wasn't being returned until after a possible null pointer
dereference. This patch returns the error immediately, allowing the
removal of the error variable.
Signed-off-by: Andrew Price <anprice@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
Check the return value of gfs2_rs_alloc(ip) and avoid a possible null
pointer dereference.
Signed-off-by: Andrew Price <anprice@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
We do not need to lookup a hashed negative directory since we have
already revalidated it before and have found it to be fine.
This also prevents a crash in cifs_lookup() when it attempts to rehash
the already hashed negative lookup dentry.
The patch has been tested using the reproducer at
https://bugzilla.redhat.com/show_bug.cgi?id=867344#c28
Cc: <stable@kernel.org> # 3.6.x
Reported-by: Vit Zahradka <vit.zahradka@tiscali.cz>
Signed-off-by: Sachin Prabhu <sprabhu@redhat.com>
The userspace cifs.idmap program generally works with the wbclient libs
to generate binary SIDs in userspace. That program defines the struct
that holds these values as having a max of 15 subauthorities. The kernel
idmapping code however limits that value to 5.
When the kernel copies those values around though, it doesn't sanity
check the num_subauths value handed back from userspace or from the
server. It's possible therefore for userspace to hand us back a bogus
num_subauths value (or one that's valid, but greater than 5) that could
cause the kernel to walk off the end of the cifs_sid->sub_auths array.
Fix this by defining a new routine for copying sids and using that in
all of the places that copy it. If we end up with a sid that's longer
than expected then this approach will just lop off the "extra" subauths,
but that's basically what the code does today already. Better approaches
might be to fix this code to reject SIDs with >5 subauths, or fix it
to handle the subauths array dynamically.
At the same time, change the kernel to check the length of the data
returned by userspace. If it's shorter than struct cifs_sid, reject it
and return -EIO. If that happens we'll end up with fields that are
basically uninitialized.
Long term, it might make sense to redefine cifs_sid using a flexarray at
the end, to allow for variable-length subauth lists, and teach the code
to handle the case where the subauths array being passed in from
userspace is shorter than 5 elements.
Note too, that I don't consider this a security issue since you'd need
a compromised cifs.idmap program. If you have that, you can do all sorts
of nefarious stuff. Still, this is probably reasonable for stable.
Cc: stable@kernel.org
Reviewed-by: Shirish Pargaonkar <shirishpargaonkar@gmail.com>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
