Currently any time we try to update the block groups on disk we will walk _all_
block groups and check for the ->dirty flag to see if it is set. This function
can get called several times during a commit. So if you have several terabytes
of data you will be a very sad panda as we will loop through _all_ of the block
groups several times, which makes the commit take a while which slows down the
rest of the file system operations.
This patch introduces a dirty list for the block groups that we get added to
when we dirty the block group for the first time. Then we simply update any
block groups that have been dirtied since the last time we called
btrfs_write_dirty_block_groups. This allows us to clean up how we write the
free space cache out so it is much cleaner. Thanks,
Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Chris Mason <clm@fb.com>
I've been overloading root->dirty_list to keep track of dirty roots and which
roots need to have their commit roots switched at transaction commit time. This
could cause us to lose an update to the root which could corrupt the file
system. To fix this use a state bit to know if the root is dirty, and if it
isn't set we go ahead and move the root to the dirty list. This way if we
re-dirty the root after adding it to the switch_commit list we make sure to
update it. This also makes it so that the extent root is always the last root
on the dirty list to try and keep the amount of churn down at this point in the
commit. Thanks,
Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Chris Mason <clm@fb.com>
xfs_compat_attrmulti_by_handle() calls memdup_user() which returns a
negative error code. The error code is negated by the caller and thus
incorrectly converted to a positive error code.
Remove the error negation such that the negative error is passed
correctly back up to userspace.
Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
When the superblock is modified in a transaction, the commonly
modified fields are not actually copied to the superblock buffer to
avoid the buffer lock becoming a serialisation point. However, there
are some other operations that modify the superblock fields within
the transaction that don't directly log to the superblock but rely
on the changes to be applied during the transaction commit (to
minimise the buffer lock hold time).
When we do this, we fail to mark the buffer log item as being a
superblock buffer and that can lead to the buffer not being marked
with the corect type in the log and hence causing recovery issues.
Fix it by setting the type correctly, similar to xfs_mod_sb()...
cc: <stable@vger.kernel.org> # 3.10 to current
Tested-by: Jan Kara <jack@suse.cz>
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
Conversion from local to extent format does not set the buffer type
correctly on the new extent buffer when a symlink data is moved out
of line.
Fix the symlink code and leave a comment in the generic bmap code
reminding us that the format-specific data copy needs to set the
destination buffer type appropriately.
cc: <stable@vger.kernel.org> # 3.10 to current
Tested-by: Jan Kara <jack@suse.cz>
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
This leads to log recovery throwing errors like:
XFS (md0): Mounting V5 Filesystem
XFS (md0): Starting recovery (logdev: internal)
XFS (md0): Unknown buffer type 0!
XFS (md0): _xfs_buf_ioapply: no ops on block 0xaea8802/0x1
ffff8800ffc53800: 58 41 47 49 .....
Which is the AGI buffer magic number.
Ensure that we set the type appropriately in both unlink list
addition and removal.
cc: <stable@vger.kernel.org> # 3.10 to current
Tested-by: Jan Kara <jack@suse.cz>
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
Jan Kara reported that log recovery was finding buffers with invalid
types in them. This should not happen, and indicates a bug in the
logging of buffers. To catch this, add asserts to the buffer
formatting code to ensure that the buffer type is in range when the
transaction is committed.
We don't set a type on buffers being marked stale - they are not
going to get replayed, the format item exists only for recovery to
be able to prevent replay of the buffer, so the type does not
matter. Hence that needs special casing here.
cc: <stable@vger.kernel.org> # 3.10 to current
Reported-by: Jan Kara <jack@suse.cz>
Tested-by: Jan Kara <jack@suse.cz>
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
This function call was being optimized out during nfs_fhget(), leading
to situations where we have a valid fileid but still want to use the
mounted_on_fileid. For example, imagine we have our server configured
like this:
server % df
Filesystem Size Used Avail Use% Mounted on
/dev/vda1 9.1G 6.5G 1.9G 78% /
/dev/vdb1 487M 2.3M 456M 1% /exports
/dev/vdc1 487M 2.3M 456M 1% /exports/vol1
/dev/vdd1 487M 2.3M 456M 1% /exports/vol2
If our client mounts /exports and tries to do a "chown -R" across the
entire mountpoint, we will get a nasty message warning us about a circular
directory structure. Running chown with strace tells me that each directory
has the same device and inode number:
newfstatat(AT_FDCWD, "/nfs/", {st_dev=makedev(0, 38), st_ino=2, ...}) = 0
newfstatat(4, "vol1", {st_dev=makedev(0, 38), st_ino=2, ...}) = 0
newfstatat(4, "vol2", {st_dev=makedev(0, 38), st_ino=2, ...}) = 0
With this patch the mounted_on_fileid values are used for st_ino, so the
directory loop warning isn't reported.
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
We currently have to ensure that every time we update sb_features2
that we update sb_bad_features2. Now that we log and format the
superblock in it's entirety we actually don't have to care because
we can simply update the sb_bad_features2 when we format it into the
buffer. This removes the need for anything but the mount and
superblock formatting code to care about sb_bad_features2, and
hence removes the possibility that we forget to update bad_features2
when necessary in the future.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
We now have several superblock loggin functions that are identical
except for the transaction reservation and whether it shoul dbe a
synchronous transaction or not. Consolidate these all into a single
function, a single reserveration and a sync flag and call it
xfs_sync_sb().
Also, xfs_mod_sb() is not really a modification function - it's the
operation of logging the superblock buffer. hence change the name of
it to reflect this.
Note that we have to change the mp->m_update_flags that are passed
around at mount time to a boolean simply to indicate a superblock
update is needed.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
When we log changes to the superblock, we first have to write them
to the on-disk buffer, and then log that. Right now we have a
complex bitfield based arrangement to only write the modified field
to the buffer before we log it.
This used to be necessary as a performance optimisation because we
logged the superblock buffer in every extent or inode allocation or
freeing, and so performance was extremely important. We haven't done
this for years, however, ever since the lazy superblock counters
pulled the superblock logging out of the transaction commit
fast path.
Hence we have a bunch of complexity that is not necessary that makes
writing the in-core superblock to disk much more complex than it
needs to be. We only need to log the superblock now during
management operations (e.g. during mount, unmount or quota control
operations) so it is not a performance critical path anymore.
As such, remove the complex field based logging mechanism and
replace it with a simple conversion function similar to what we use
for all other on-disk structures.
This means we always log the entirity of the superblock, but again
because we rarely modify the superblock this is not an issue for log
bandwidth or CPU time. Indeed, if we do log the superblock
frequently, delayed logging will minimise the impact of this
overhead.
[Fixed gquota/pquota inode sharing regression noticed by bfoster.]
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
We only support swap file calling nfs_direct_IO. However, application
might be able to get to nfs_direct_IO if it toggles O_DIRECT flag
during IO and it can deadlock because we grab inode->i_mutex in
nfs_file_direct_write(). So return 0 for such case. Then the generic
layer will fall back to buffer IO.
Signed-off-by: Peng Tao <tao.peng@primarydata.com>
Cc: stable@vger.kernel.org
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
xfs_fs_get_xstate() and xfs_fs_get_xstatev() check whether there's quota
running before calling xfs_qm_scall_getqstat() or
xfs_qm_scall_getqstatv(). Thus we are certain that superblock supports
quota and xfs_sb_version_hasquota() check is pointless. Similarly we
know that when quota is running, mp->m_quotainfo will be allocated.
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Jan Kara <jack@suse.cz>
'flags' have XFS_ALL_QUOTA_ACCT cleared immediately on function entry.
There's no point in checking these bits later in the function. Also
because we check something is going to change, we know some enforcement
bits are being added and thus there's no point in testing that later.
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Q_XQUOTARM is never passed to xfs_fs_set_xstate() so remove the test.
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Currently flags passed via Q_SETINFO were just stored. This makes it
hard to add new flags since in theory userspace could be just setting /
clearing random flags. Since currently there is only one userspace
settable flag and that is somewhat obscure flags only for ancient v1
quota format, I'm reasonably sure noone operates these flags and
hopefully we are fine just adding the check that passed flags are sane.
If we indeed find some userspace program that gets broken by the strict
check, we can always remove it again.
Signed-off-by: Jan Kara <jack@suse.cz>
Currently all quota flags were defined just in kernel-private headers.
Export flags readable / writeable from userspace to userspace via
include/uapi/linux/quota.h.
Signed-off-by: Jan Kara <jack@suse.cz>
OLQF_CLEAN flag is used by OCFS2 on disk to recognize whether quota
recovery is needed or not. We also somewhat abuse mem_dqinfo->dqi_flags
to pass this flag around. Use private flags for this to avoid clashes
with other quota flags / not pollute generic quota flag namespace.
Signed-off-by: Jan Kara <jack@suse.cz>
Currently, v2 quota format blindly stored flags from in-memory dqinfo on
disk, although there are no flags supported. Since it is stupid to store
flags which have no effect, just store 0 unconditionally and don't
bother loading it from disk.
Note that userspace could have stored some flags there via Q_SETINFO
quotactl and then later read them (although flags have no effect) but
I'm pretty sure noone does that (most definitely quota-tools don't and
quota interface doesn't have too much other users).
Signed-off-by: Jan Kara <jack@suse.cz>
Pull RCU updates from Paul E. McKenney:
- Documentation updates.
- Miscellaneous fixes.
- Preemptible-RCU fixes, including fixing an old bug in the
interaction of RCU priority boosting and CPU hotplug.
- SRCU updates.
- RCU CPU stall-warning updates.
- RCU torture-test updates.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Commit 6b5fe46dfa (btrfs: do commit in sync_fs if there are pending
changes) will call btrfs_start_transaction() in sync_fs(), to handle
some operations needed to be done in next transaction.
However this can cause deadlock if the filesystem is frozen, with the
following sys_r+w output:
[ 143.255932] Call Trace:
[ 143.255936] [<ffffffff816c0e09>] schedule+0x29/0x70
[ 143.255939] [<ffffffff811cb7f3>] __sb_start_write+0xb3/0x100
[ 143.255971] [<ffffffffa040ec06>] start_transaction+0x2e6/0x5a0
[btrfs]
[ 143.255992] [<ffffffffa040f1eb>] btrfs_start_transaction+0x1b/0x20
[btrfs]
[ 143.256003] [<ffffffffa03dc0ba>] btrfs_sync_fs+0xca/0xd0 [btrfs]
[ 143.256007] [<ffffffff811f7be0>] sync_fs_one_sb+0x20/0x30
[ 143.256011] [<ffffffff811cbd01>] iterate_supers+0xe1/0xf0
[ 143.256014] [<ffffffff811f7d75>] sys_sync+0x55/0x90
[ 143.256017] [<ffffffff816c49d2>] system_call_fastpath+0x12/0x17
[ 143.256111] Call Trace:
[ 143.256114] [<ffffffff816c0e09>] schedule+0x29/0x70
[ 143.256119] [<ffffffff816c3405>] rwsem_down_write_failed+0x1c5/0x2d0
[ 143.256123] [<ffffffff8133f013>] call_rwsem_down_write_failed+0x13/0x20
[ 143.256131] [<ffffffff811caae8>] thaw_super+0x28/0xc0
[ 143.256135] [<ffffffff811db3e5>] do_vfs_ioctl+0x3f5/0x540
[ 143.256187] [<ffffffff811db5c1>] SyS_ioctl+0x91/0xb0
[ 143.256213] [<ffffffff816c49d2>] system_call_fastpath+0x12/0x17
The reason is like the following:
(Holding s_umount)
VFS sync_fs staff:
|- btrfs_sync_fs()
|- btrfs_start_transaction()
|- sb_start_intwrite()
(Waiting thaw_fs to unfreeze)
VFS thaw_fs staff:
thaw_fs()
(Waiting sync_fs to release
s_umount)
So deadlock happens.
This can be easily triggered by fstest/generic/068 with inode_cache
mount option.
The fix is to check if the fs is frozen, if the fs is frozen, just
return and waiting for the next transaction.
Cc: David Sterba <dsterba@suse.cz>
Reported-by: Gui Hecheng <guihc.fnst@cn.fujitsu.com>
Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
[enhanced comment, changed to SB_FREEZE_WRITE]
Signed-off-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Chris Mason <clm@fb.com>
Fs_info->pending_changes is never cleared since the original code uses
cmpxchg(&fs_info->pending_changes, 0, 0), which will only clear it if
pending_changes is already 0.
This will cause a lot of problem when mount it with inode_cache mount
option.
If the btrfs is mounted as inode_cache, pending_changes will always be
1, even when the fs is frozen.
Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Reviewed-by: David Sterba <dsterba@suse.cz>
Signed-off-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Chris Mason <clm@fb.com>
Now that default_backing_dev_info is not used for writeback purposes we can
git rid of it easily:
- instead of using it's name for tracing unregistered bdi we just use
"unknown"
- btrfs and ceph can just assign the default read ahead window themselves
like several other filesystems already do.
- we can assign noop_backing_dev_info as the default one in alloc_super.
All filesystems already either assigned their own or
noop_backing_dev_info.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@fb.com>
bdi_destroy already does all the work, and if we delay freeing the
anon bdev we can get away with just that single call.
Addintionally remove the call during mount failure, as
deactivate_super_locked will already call ->kill_sb and clean up
the bdi for us.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@fb.com>
bdi_destroy already does all the work, and if we delay freeing the
anon bdev we can get away with just that single call.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@fb.com>
Now that we never use the backing_dev_info pointer in struct address_space
we can simply remove it and save 4 to 8 bytes in every inode.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Reviewed-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@fb.com>
Now that we got rid of the bdi abuse on character devices we can always use
sb->s_bdi to get at the backing_dev_info for a file, except for the block
device special case. Export inode_to_bdi and replace uses of
mapping->backing_dev_info with it to prepare for the removal of
mapping->backing_dev_info.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@fb.com>
mapping->backing_dev_info will go away, so don't rely on it.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Reviewed-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@fb.com>
Directly grab the backing_dev_info from the request_queue instead of
detouring through the address_space.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@fb.com>
Since 018a17bdc8 ("bdi: reimplement bdev_inode_switch_bdi()") the
block device code writes out all dirty data whenever switching the
backing_dev_info for a block device inode. But a block device inode can
only be dirtied when it is in use, which means we only have to write it
out on the final blkdev_put, but not when doing a blkdev_get.
Factoring out the write out from the bdi list switch prepares from
removing the list switch later in the series.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@fb.com>
Since "BDI: Provide backing device capability information [try #3]" the
backing_dev_info structure also provides flags for the kind of mmap
operation available in a nommu environment, which is entirely unrelated
to it's original purpose.
Introduce a new nommu-only file operation to provide this information to
the nommu mmap code instead. Splitting this from the backing_dev_info
structure allows to remove lots of backing_dev_info instance that aren't
otherwise needed, and entirely gets rid of the concept of providing a
backing_dev_info for a character device. It also removes the need for
the mtd_inodefs filesystem.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Tejun Heo <tj@kernel.org>
Acked-by: Brian Norris <computersforpeace@gmail.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
hugetlbfs, kernfs and dlmfs can simply use noop_backing_dev_info instead
of creating a local duplicate.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@fb.com>
Commit
c11f1df500
requires writers to wait for any pending oplock break handler to
complete before proceeding to write. This is done by waiting on bit
CIFS_INODE_PENDING_OPLOCK_BREAK in cifsFileInfo->flags. This bit is
cleared by the oplock break handler job queued on the workqueue once it
has completed handling the oplock break allowing writers to proceed with
writing to the file.
While testing, it was noticed that the filehandle could be closed while
there is a pending oplock break which results in the oplock break
handler on the cifsiod workqueue being cancelled before it has had a
chance to execute and clear the CIFS_INODE_PENDING_OPLOCK_BREAK bit.
Any subsequent attempt to write to this file hangs waiting for the
CIFS_INODE_PENDING_OPLOCK_BREAK bit to be cleared.
We fix this by ensuring that we also clear the bit
CIFS_INODE_PENDING_OPLOCK_BREAK when we remove the oplock break handler
from the workqueue.
The bug was found by Red Hat QA while testing using ltp's fsstress
command.
Signed-off-by: Sachin Prabhu <sprabhu@redhat.com>
Acked-by: Shirish Pargaonkar <shirishpargaonkar@gmail.com>
Signed-off-by: Jeff Layton <jlayton@samba.org>
Cc: stable@vger.kernel.org
Signed-off-by: Steve French <steve.french@primarydata.com>
When leaving a function use memzero_explicit instead of memset(0) to
clear stack allocated buffers. memset(0) may be optimized away.
This particular buffer is highly likely to contain sensitive data which
we shouldn't leak (it's named 'passwd' after all).
Signed-off-by: Giel van Schijndel <me@mortis.eu>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Reported-at: http://www.viva64.com/en/b/0299/
Reported-by: Andrey Karpov
Reported-by: Svyatoslav Razmyslov
Signed-off-by: Steve French <steve.french@primarydata.com>
Suppress the following warning displayed on building 32bit (i686) kernel.
===============================================================================
...
CC [M] fs/btrfs/extent_io.o
fs/btrfs/extent_io.c: In function ‘btrfs_free_io_failure_record’:
fs/btrfs/extent_io.c:2193:13: warning: cast to pointer from integer of
different size [-Wint-to-pointer-cast]
failrec = (struct io_failure_record *)state->private;
...
===============================================================================
Signed-off-by: Satoru Takeuchi <takeuchi_satoru@jp.fujitsu.com>
Reported-by: Chris Murphy <chris@colorremedies.com>
Signed-off-by: Chris Mason <clm@fb.com>
When removing a block group we were deleting it from its space_info's
ro_bgs list without the correct protection - the space info's spinlock.
Fix this by doing the list delete while holding the spinlock of the
corresponding space info, which is the correct lock for any operation
on that list.
This issue was introduced in the 3.19 kernel by the following change:
Btrfs: move read only block groups onto their own list V2
commit 633c0aad4c
I ran into a kernel crash while a task was running statfs, which iterates
the space_info->ro_bgs list while holding the space info's spinlock,
and another task was deleting it from the same list, without holding that
spinlock, as part of the block group remove operation (while running the
function btrfs_remove_block_group). This happened often when running the
stress test xfstests/generic/038 I recently made.
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Chris Mason <clm@fb.com>
The address that should be freed is not 'ppath' but 'path'.
Signed-off-by: Tsutomu Itoh <t-itoh@jp.fujitsu.com>
Reviewed-by: Miao Xie <miaoxie@huawei.com>
Signed-off-by: Chris Mason <clm@fb.com>
The version merged to 3.19 did not handle errors from start_trancaction
and could pass an invalid pointer to commit_transaction.
Fixes: 6b5fe46dfa ("btrfs: do commit in sync_fs if there are pending changes")
Reported-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Chris Mason <clm@fb.com>
We should complain in dmesg when journal recovery fails on account of
the descriptor block being corrupt, so that the diagnostic data can
be recovered.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
It really needs to check that src is non-directory *and* use
{un,}lock_two_nodirectories(). As it is, it's trivial to cause
double-lock (ioctl(fd, CIFS_IOC_COPYCHUNK_FILE, fd)) and if the
last argument is an fd of directory, we are asking for trouble
by violating the locking order - all directories go before all
non-directories. If the last argument is an fd of parent
directory, it has 50% odds of locking child before parent,
which will cause AB-BA deadlock if we race with unlink().
Cc: stable@vger.kernel.org @ 3.13+
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Contrary to common expectations for an "int" return, these functions
return only a positive value -- if used correctly they cannot even
return 0 because the message header will necessarily be in the skb.
This makes the very common pattern of
if (genlmsg_end(...) < 0) { ... }
be a whole bunch of dead code. Many places also simply do
return nlmsg_end(...);
and the caller is expected to deal with it.
This also commonly (at least for me) causes errors, because it is very
common to write
if (my_function(...))
/* error condition */
and if my_function() does "return nlmsg_end()" this is of course wrong.
Additionally, there's not a single place in the kernel that actually
needs the message length returned, and if anyone needs it later then
it'll be very easy to just use skb->len there.
Remove this, and make the functions void. This removes a bunch of dead
code as described above. The patch adds lines because I did
- return nlmsg_end(...);
+ nlmsg_end(...);
+ return 0;
I could have preserved all the function's return values by returning
skb->len, but instead I've audited all the places calling the affected
functions and found that none cared. A few places actually compared
the return value with <= 0 in dump functionality, but that could just
be changed to < 0 with no change in behaviour, so I opted for the more
efficient version.
One instance of the error I've made numerous times now is also present
in net/phonet/pn_netlink.c in the route_dumpit() function - it didn't
check for <0 or <=0 and thus broke out of the loop every single time.
I've preserved this since it will (I think) have caused the messages to
userspace to be formatted differently with just a single message for
every SKB returned to userspace. It's possible that this isn't needed
for the tools that actually use this, but I don't even know what they
are so couldn't test that changing this behaviour would be acceptable.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
We should use sprintf format specifier "%u" instead of "%d" for
argument of type 'unsigned int' in pstore_dump().
Signed-off-by: Alex Chen <alex.chen@huawei.com>
Reviewed-by: Joseph Qi <joseph.qi@huawei.com>
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Tony Luck <tony.luck@intel.com>
A secured user-space accessible pstore object. Writes
to /dev/pmsg0 are appended to the buffer, on reboot
the persistent contents are available in
/sys/fs/pstore/pmsg-ramoops-[ID].
One possible use is syslogd, or other daemon, can
write messages, then on reboot provides a means to
triage user-space activities leading up to a panic
as a companion to the pstore dmesg or console logs.
Signed-off-by: Mark Salyzyn <salyzyn@android.com>
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Tony Luck <tony.luck@intel.com>
ramoops_pstore_read fails to return the next in a prz
series after first zero-sized entry, not venturing to
the next non-zero entry.
Signed-off-by: Mark Salyzyn <salyzyn@android.com>
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Tony Luck <tony.luck@intel.com>
