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This makes the binary trace understandable by trace-cmd.
CC: Dave Chinner <david@fromorbit.com>
CC: Curt Wohlgemuth <curtw@google.com>
CC: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
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There is no reason to drop qi_dqlist_lock around calls to xfs_qm_dqrele
because the free list lock now nests inside qi_dqlist_lock and the
dquot lock.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
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Commit fa8b18ed didn't prevent the integer overflow and possible
memory corruption. "count" can go negative and bypass the check.
Signed-off-by: Xi Wang <xi.wang@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ben Myers <bpm@sgi.com>
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XBT_FORCE_SLEEP is no longer ever tested; it is only set
and cleared. Remove it.
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs:
Btrfs: unplug every once and a while
Btrfs: deal with NULL srv_rsv in the delalloc inode reservation code
Btrfs: only set cache_generation if we setup the block group
Btrfs: don't panic if orphan item already exists
Btrfs: fix leaked space in truncate
Btrfs: fix how we do delalloc reservations and how we free reservations on error
Btrfs: deal with enospc from dirtying inodes properly
Btrfs: fix num_workers_starting bug and other bugs in async thread
BTRFS: Establish i_ops before calling d_instantiate
Btrfs: add a cond_resched() into the worker loop
Btrfs: fix ctime update of on-disk inode
btrfs: keep orphans for subvolume deletion
Btrfs: fix inaccurate available space on raid0 profile
Btrfs: fix wrong disk space information of the files
Btrfs: fix wrong i_size when truncating a file to a larger size
Btrfs: fix btrfs_end_bio to deal with write errors to a single mirror
* 'for-linus-3.2' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs:
btrfs: lower the dirty balance poll interval
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Tests show that the original large intervals can easily make the dirty
limit exceeded on 100 concurrent dd's. So adapt to as large as the
next check point selected by the dirty throttling algorithm.
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
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After commit 06222e491e663dac939f04b125c9dc52126a75c4 (fs: handle
SEEK_HOLE/SEEK_DATA properly in all fs's that define their own llseek)
the behaviour of llseek() was changed so that it always revalidates
the file size. The bug appears to be due to a logic error in the
afore-mentioned commit, which always evaluates to 'true'.
Reported-by: Roel Kluin <roel.kluin@gmail.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: stable@vger.kernel.org [>=3.1]
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The btrfs io submission threads can build up massive plug lists. This
keeps things more reasonable so we don't hand over huge dumps of IO at
once.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
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Just read the id 0 dquot from disk directly in xfs_qm_init_quotainfo instead
of going through dqget and requiring a special flag to not add the dquot to
any lists.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
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This function doesn't help the code flow, so merge the dquot allocation and
transaction handling into xfs_qm_dqread.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
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Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
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Factor the common pattern of:
xfs_dqlock(dqp);
XFS_DQHOLD(dqp);
xfs_dqunlock(dqp);
into a new helper, and remove XFS_DQHOLD now that only one other caller
is left.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
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http://git.kernel.org/pub/scm/linux/kernel/git/josef/btrfs-work into integration
Conflicts:
fs/btrfs/inode.c
Signed-off-by: Chris Mason <chris.mason@oracle.com>
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btrfs_update_inode is sometimes called with a null reservation.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
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No need to play games with the qlock now that the freelist lock nests inside
it. Also clean up various outdated comments.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
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A user reported a problem booting into a new kernel with the old format inodes.
He was panicing in cow_file_range while writing out the inode cache. This is
because if the block group is not cached we'll just skip writing out the cache,
however if it gets dirtied again in the same transaction and it finished caching
we'd go ahead and write it out, but since we set cache_generation to the transid
we think we've already truncated it and will just carry on, running into
cow_file_range and blowing up. We need to make sure we only set
cache_generation if we've done the truncate. The user tested this patch and
verified that the panic no longer occured. Thanks,
Reported-and-Tested-by: Klaus Bitto <klaus.bitto@gmail.com>
Signed-off-by: Josef Bacik <josef@redhat.com>
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I've been hitting this BUG_ON() in btrfs_orphan_add when running xfstest 269 in
a loop. This is because we will add an orphan item, do the truncate, the
truncate will fail for whatever reason (*cough*ENOSPC*cough*) and then we're
left with an orphan item still in the fs. Then we come back later to do another
truncate and it blows up because we already have an orphan item. This is ok so
just fix the BUG_ON() to only BUG() if ret is not EEXIST. Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>
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We were occasionaly leaking space when running xfstest 269. This is because if
we failed to start the transaction in the truncate loop we'd just goto out, but
we need to break so that the inode is removed from the orphan list and the space
is properly freed. Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>
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Running xfstests 269 with some tracing my scripts kept spitting out errors about
releasing bytes that we didn't actually have reserved. This took me down a huge
rabbit hole and it turns out the way we deal with reserved_extents is wrong,
we need to only be setting it if the reservation succeeds, otherwise the free()
method will come in and unreserve space that isn't actually reserved yet, which
can lead to other warnings and such. The math was all working out right in the
end, but it caused all sorts of other issues in addition to making my scripts
yell and scream and generally make it impossible for me to track down the
original issue I was looking for. The other problem is with our error handling
in the reservation code. There are two cases that we need to deal with
1) We raced with free. In this case free won't free anything because csum_bytes
is modified before we dro the lock in our reservation path, so free rightly
doesn't release any space because the reservation code may be depending on that
reservation. However if we fail, we need the reservation side to do the free at
that point since that space is no longer in use. So as it stands the code was
doing this fine and it worked out, except in case #2
2) We don't race with free. Nobody comes in and changes anything, and our
reservation fails. In this case we didn't reserve anything anyway and we just
need to clean up csum_bytes but not free anything. So we keep track of
csum_bytes before we drop the lock and if it hasn't changed we know we can just
decrement csum_bytes and carry on.
Because of the case where we can race with free()'s since we have to drop our
spin_lock to do the reservation, I'm going to serialize all reservations with
the i_mutex. We already get this for free in the heavy use paths, truncate and
file write all hold the i_mutex, just needed to add it to page_mkwrite and
various ioctl/balance things. With this patch my space leak scripts no longer
scream bloody murder. Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>
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Now that we're properly keeping track of delayed inode space we've been getting
a lot of warnings out of btrfs_dirty_inode() when running xfstest 83. This is
because a bunch of people call mark_inode_dirty, which is void so we can't
return ENOSPC. This needs to be fixed in a few areas
1) file_update_time - this updates the mtime and such when writing to a file,
which will call mark_inode_dirty. So copy file_update_time into btrfs so we can
call btrfs_dirty_inode directly and return an error if we get one appropriately.
2) fix symlinks to use btrfs_setattr for ->setattr. For some reason we weren't
setting ->setattr for symlinks, even though we should have been. This catches
one of the cases where we were getting errors in mark_inode_dirty.
3) Fix btrfs_setattr and btrfs_setsize to call btrfs_dirty_inode directly
instead of mark_inode_dirty. This lets us return errors properly for truncate
and chown/anything related to setattr.
4) Add a new btrfs_fs_dirty_inode which will just call btrfs_dirty_inode and
print an error if we have one. The only remaining user we can't control for
this is touch_atime(), but we don't really want to keep people from walking
down the tree if we don't have space to save the atime update, so just complain
but don't worry about it.
With this patch xfstests 83 complains a handful of times instead of hundreds of
times. Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>
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Al pointed out we have some random problems with the way we account for
num_workers_starting in the async thread stuff. First of all we need to make
sure to decrement num_workers_starting if we fail to start the worker, so make
__btrfs_start_workers do this. Also fix __btrfs_start_workers so that it
doesn't call btrfs_stop_workers(), there is no point in stopping everybody if we
failed to create a worker. Also check_pending_worker_creates needs to call
__btrfs_start_work in it's work function since it already increments
num_workers_starting.
People only start one worker at a time, so get rid of the num_workers argument
everywhere, and make btrfs_queue_worker a void since it will always succeed.
Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>
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The Smack LSM hook for security_d_instantiate checks
the inode's i_op->getxattr value to determine if the
containing filesystem supports extended attributes.
The BTRFS filesystem sets the inode's i_op value only
after it has instantiated the inode. This results in
Smack incorrectly giving new BTRFS inodes attributes
from the filesystem defaults on the assumption that
values can't be stored on the filesystem. This patch
moves the assignment of inode operation vectors ahead
of the calls to d_instantiate, letting Smack know that
the filesystem supports extended attributes. There
should be no impact on the performance or behavior of
BTRFS.
Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
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If we have a constant stream of end_io completions or crc work,
we can hit softlockup messages from the async helper threads. This
adds a cond_resched() into the loop to avoid them.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
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To reproduce the bug:
# touch /mnt/tmp
# stat /mnt/tmp | grep Change
Change: 2011-12-09 09:32:23.412105981 +0800
# chattr +i /mnt/tmp
# stat /mnt/tmp | grep Change
Change: 2011-12-09 09:32:43.198105295 +0800
# umount /mnt
# mount /dev/loop1 /mnt
# stat /mnt/tmp | grep Change
Change: 2011-12-09 09:32:23.412105981 +0800
We should update ctime of in-memory inode before calling
btrfs_update_inode().
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
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Since we have the free space caches, btrfs_orphan_cleanup also runs for
the tree_root. Unfortunately this also cleans up the orphans used to mark
subvol deletions in progress.
Currently if a subvol deletion gets interrupted twice by umount/mount, the
deletion will not be continued and the space permanently lost, though it
would be possible to write a tool to recover those lost subvol deletions.
This patch checks if the orphan belongs to a subvol (dead root) and skips
the deletion.
Signed-off-by: Arne Jansen <sensille@gmx.net>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
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When we use raid0 as the data profile, df command may show us a very
inaccurate value of the available space, which may be much less than the
real one. It may make the users puzzled. Fix it by changing the calculation
of the available space, and making it be more similar to a fake chunk
allocation.
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
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Btrfsck report errors after the 83th case of xfstests was run, The error
number is 400, it means the used disk space of the file is wrong.
The reason of this bug is that:
The file truncation may fail when the space of the file system is not enough,
and leave some file extents, whose offset are beyond the end of the files.
When we want to expand those files, we will drop those file extents, and
put in dummy file extents, and then we should update the i-node. But btrfs
forgets to do it.
This patch adds the forgotten i-node update.
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
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Btrfsck report error 100 after the 83th case of xfstests was run, it means
the i_size of the file is wrong.
The reason of this bug is that:
Btrfs increased i_size of the file at the beginning, but it failed to expand
the file, and failed to update the i_size to the old size because there is no
enough space in the file system, so we found a wrong i_size.
This patch fixes this bug by updating the i_size just when we pass the file
expanding and get enough space to update i-node.
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
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The patch below removes an extra semicolon.
Signed-off-by: Justin P. Mattock <justinmattock@gmail.com>
CC: Chris Mason <chris.mason@oracle.com>
CC: linux-btrfs@vger.kernel.org
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
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Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
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For 32-bit architectures using standard jiffies the idletime calculation
in uptime_proc_show will quickly overflow. It takes (2^32 / HZ) seconds
of idle-time, or e.g. 12.45 days with no load on a quad-core with HZ=1000.
Switch to 64-bit calculations.
Cc: stable@vger.kernel.org
Cc: Michael Abbott <michael.abbott@diamond.ac.uk>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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Make cputime_t and cputime64_t nocast to enable sparse checking to
detect incorrect use of cputime. Drop the cputime macros for simple
scalar operations. The conversion macros are still needed.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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Merge reason: Pick up the latest fixes.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Allow xfs_qm_dqput to work without trylock loops by nesting the freelist lock
inside the dquot qlock. In turn that requires trylocks in the reclaim path
instead, but given it's a classic tradeoff between fast and slow path, and
we follow the model of the inode and dentry caches.
Document our new lock order now that it has settled.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4
* tag 'tytso-for-linus-20111214' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4:
ext4: handle EOF correctly in ext4_bio_write_page()
ext4: remove a wrong BUG_ON in ext4_ext_convert_to_initialized
ext4: correctly handle pages w/o buffers in ext4_discard_partial_buffers()
ext4: avoid potential hang in mpage_submit_io() when blocksize < pagesize
ext4: avoid hangs in ext4_da_should_update_i_disksize()
ext4: display the correct mount option in /proc/mounts for [no]init_itable
ext4: Fix crash due to getting bogus eh_depth value on big-endian systems
ext4: fix ext4_end_io_dio() racing against fsync()
.. using the new signed tag merge of git that now verifies the gpg
signature automatically. Yay. The branchname was just 'dev', which is
prettier. I'll tell Ted to use nicer tag names for future cases.
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git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse:
fuse: llseek fix race
fuse: fix llseek bug
fuse: fix fuse_retrieve
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git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
fs/ncpfs: fix error paths and goto statements in ncp_fill_super()
configfs: register_filesystem() called too early
fuse: register_filesystem() called too early
ubifs: too early register_filesystem()
... and the same kind of leak for mqueue
procfs: fix a vfsmount longterm reference leak
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Otherwise the for loop could try to use a file recently removed from the
file_hashtbl list and oops.
Signed-off-by: Bryan Schumaker <bjschuma@netapp.com>
Tested-by: Casey Bodley <cbodley@citi.umich.edu>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
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Introduce a new XFS_DQ_FREEING flag that tells lookup and mplist walks
to skip a dquot that is beeing freed, and use this avoid the trylock
on the hash and mplist locks in xfs_qm_dqreclaim_one. Also simplify
xfs_dqpurge by moving the inodes to a dispose list after marking them
XFS_DQ_FREEING and avoid the locker ordering constraints.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
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The label 'out_bdi' should be followed by bdi_destroy() instead of
fput() which should be after the 'out_fput' label.
If bdi_setup_and_register() fails then jump to the 'out_fput' label
instead of the 'out_bdi' one.
If fget(data.info_fd) fails then jump to the previously fixed 'out_bdi'
label to call bdi_destroy() otherwise the bdi object will not be
destroyed.
Compile tested only.
Signed-off-by: Djalal Harouni <tixxdz@opendz.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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We need to zero out part of a page which beyond EOF before setting uptodate,
otherwise, mapread or write will see non-zero data beyond EOF.
Signed-off-by: Yongqiang Yang <xiaoqiangnk@gmail.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: stable@kernel.org
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If a file is fallocated on a hole, map->m_lblk + map->m_len may be greater
than ee_block + ee_len.
Signed-off-by: Yongqiang Yang <xiaoqiangnk@gmail.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: stable@kernel.org
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If a page has been read into memory and never been written, it has no
buffers, but we should handle the page in truncate or punch hole.
VFS code of writing operations has handled holes correctly, so this
patch removes the code handling holes in writing operations.
Signed-off-by: Yongqiang Yang <xiaoqiangnk@gmail.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: stable@kernel.org
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If there is an unwritten but clean buffer in a page and there is a
dirty buffer after the buffer, then mpage_submit_io does not write the
dirty buffer out. As a result, da_writepages loops forever.
This patch fixes the problem by checking dirty flag.
Signed-off-by: Yongqiang Yang <xiaoqiangnk@gmail.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: stable@kernel.org
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If the pte mapping in generic_perform_write() is unmapped between
iov_iter_fault_in_readable() and iov_iter_copy_from_user_atomic(), the
"copied" parameter to ->end_write can be zero. ext4 couldn't cope with
it with delayed allocations enabled. This skips the i_disksize
enlargement logic if copied is zero and no new data was appeneded to
the inode.
gdb> bt
#0 0xffffffff811afe80 in ext4_da_should_update_i_disksize (file=0xffff88003f606a80, mapping=0xffff88001d3824e0, pos=0x1\
08000, len=0x1000, copied=0x0, page=0xffffea0000d792e8, fsdata=0x0) at fs/ext4/inode.c:2467
#1 ext4_da_write_end (file=0xffff88003f606a80, mapping=0xffff88001d3824e0, pos=0x108000, len=0x1000, copied=0x0, page=0\
xffffea0000d792e8, fsdata=0x0) at fs/ext4/inode.c:2512
#2 0xffffffff810d97f1 in generic_perform_write (iocb=<value optimized out>, iov=<value optimized out>, nr_segs=<value o\
ptimized out>, pos=0x108000, ppos=0xffff88001e26be40, count=<value optimized out>, written=0x0) at mm/filemap.c:2440
#3 generic_file_buffered_write (iocb=<value optimized out>, iov=<value optimized out>, nr_segs=<value optimized out>, p\
os=0x108000, ppos=0xffff88001e26be40, count=<value optimized out>, written=0x0) at mm/filemap.c:2482
#4 0xffffffff810db5d1 in __generic_file_aio_write (iocb=0xffff88001e26bde8, iov=0xffff88001e26bec8, nr_segs=0x1, ppos=0\
xffff88001e26be40) at mm/filemap.c:2600
#5 0xffffffff810db853 in generic_file_aio_write (iocb=0xffff88001e26bde8, iov=0xffff88001e26bec8, nr_segs=<value optimi\
zed out>, pos=<value optimized out>) at mm/filemap.c:2632
#6 0xffffffff811a71aa in ext4_file_write (iocb=0xffff88001e26bde8, iov=0xffff88001e26bec8, nr_segs=0x1, pos=0x108000) a\
t fs/ext4/file.c:136
#7 0xffffffff811375aa in do_sync_write (filp=0xffff88003f606a80, buf=<value optimized out>, len=<value optimized out>, \
ppos=0xffff88001e26bf48) at fs/read_write.c:406
#8 0xffffffff81137e56 in vfs_write (file=0xffff88003f606a80, buf=0x1ec2960 <Address 0x1ec2960 out of bounds>, count=0x4\
000, pos=0xffff88001e26bf48) at fs/read_write.c:435
#9 0xffffffff8113816c in sys_write (fd=<value optimized out>, buf=0x1ec2960 <Address 0x1ec2960 out of bounds>, count=0x\
4000) at fs/read_write.c:487
#10 <signal handler called>
#11 0x00007f120077a390 in __brk_reservation_fn_dmi_alloc__ ()
#12 0x0000000000000000 in ?? ()
gdb> print offset
$22 = 0xffffffffffffffff
gdb> print idx
$23 = 0xffffffff
gdb> print inode->i_blkbits
$24 = 0xc
gdb> up
#1 ext4_da_write_end (file=0xffff88003f606a80, mapping=0xffff88001d3824e0, pos=0x108000, len=0x1000, copied=0x0, page=0\
xffffea0000d792e8, fsdata=0x0) at fs/ext4/inode.c:2512
2512 if (ext4_da_should_update_i_disksize(page, end)) {
gdb> print start
$25 = 0x0
gdb> print end
$26 = 0xffffffffffffffff
gdb> print pos
$27 = 0x108000
gdb> print new_i_size
$28 = 0x108000
gdb> print ((struct ext4_inode_info *)((char *)inode-((int)(&((struct ext4_inode_info *)0)->vfs_inode))))->i_disksize
$29 = 0xd9000
gdb> down
2467 for (i = 0; i < idx; i++)
gdb> print i
$30 = 0xd44acbee
This is 100% reproducible with some autonuma development code tuned in
a very aggressive manner (not normal way even for knumad) which does
"exotic" changes to the ptes. It wouldn't normally trigger but I don't
see why it can't happen normally if the page is added to swap cache in
between the two faults leading to "copied" being zero (which then
hangs in ext4). So it should be fixed. Especially possible with lumpy
reclaim (albeit disabled if compaction is enabled) as that would
ignore the young bits in the ptes.
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: stable@kernel.org
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cic is association between io_context and request_queue. A cic is
linked from both ioc and q and should be destroyed when either one
goes away. As ioc and q both have their own locks, locking becomes a
bit complex - both orders work for removal from one but not from the
other.
Currently, cfq tries to circumvent this locking order issue with RCU.
ioc->lock nests inside queue_lock but the radix tree and cic's are
also protected by RCU allowing either side to walk their lists without
grabbing lock.
This rather unconventional use of RCU quickly devolves into extremely
fragile convolution. e.g. The following is from cfqd going away too
soon after ioc and q exits raced.
general protection fault: 0000 [#1] PREEMPT SMP
CPU 2
Modules linked in:
[ 88.503444]
Pid: 599, comm: hexdump Not tainted 3.1.0-rc10-work+ #158 Bochs Bochs
RIP: 0010:[<ffffffff81397628>] [<ffffffff81397628>] cfq_exit_single_io_context+0x58/0xf0
...
Call Trace:
[<ffffffff81395a4a>] call_for_each_cic+0x5a/0x90
[<ffffffff81395ab5>] cfq_exit_io_context+0x15/0x20
[<ffffffff81389130>] exit_io_context+0x100/0x140
[<ffffffff81098a29>] do_exit+0x579/0x850
[<ffffffff81098d5b>] do_group_exit+0x5b/0xd0
[<ffffffff81098de7>] sys_exit_group+0x17/0x20
[<ffffffff81b02f2b>] system_call_fastpath+0x16/0x1b
The only real hot path here is cic lookup during request
initialization and avoiding extra locking requires very confined use
of RCU. This patch makes cic removal from both ioc and request_queue
perform double-locking and unlink immediately.
* From q side, the change is almost trivial as ioc->lock nests inside
queue_lock. It just needs to grab each ioc->lock as it walks
cic_list and unlink it.
* From ioc side, it's a bit more difficult because of inversed lock
order. ioc needs its lock to walk its cic_list but can't grab the
matching queue_lock and needs to perform unlock-relock dancing.
Unlinking is now wholly done from put_io_context() and fast path is
optimized by using the queue_lock the caller already holds, which is
by far the most common case. If the ioc accessed multiple devices,
it tries with trylock. In unlikely cases of fast path failure, it
falls back to full double-locking dance from workqueue.
Double-locking isn't the prettiest thing in the world but it's *far*
simpler and more understandable than RCU trick without adding any
meaningful overhead.
This still leaves a lot of now unnecessary RCU logics. Future patches
will trim them.
-v2: Vivek pointed out that cic->q was being dereferenced after
cic->release() was called. Updated to use local variable @this_q
instead.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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ioprio/cgroup change was handled by marking the changed state in ioc
and, on the following access to the ioc, performing RCU-protected
iteration through all cic's grabbing the matching queue_lock.
This patch moves the changed state to each cic. When ioprio or cgroup
changes, the respective bit is set on all cic's of the ioc and when
each of those cic (not ioc) is accessed, change is applied for that
specific ioc-queue pair.
This also fixes the following two race conditions between setting and
clearing of changed states.
* Missing barrier between assign/load of ioprio and ioprio_changed
allowed applying old ioprio.
* Change requests could happen between application of change and
clearing of changed variables.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Ignoring copy_io() during fork, io_context can be allocated from two
places - current_io_context() and set_task_ioprio(). The former is
always called from local task while the latter can be called from
different task. The synchornization between them are peculiar and
dubious.
* current_io_context() doesn't grab task_lock() and assumes that if it
saw %NULL ->io_context, it would stay that way until allocation and
assignment is complete. It has smp_wmb() between alloc/init and
assignment.
* set_task_ioprio() grabs task_lock() for assignment and does
smp_read_barrier_depends() between "ioc = task->io_context" and "if
(ioc)". Unfortunately, this doesn't achieve anything - the latter
is not a dependent load of the former. ie, if ioc itself were being
dereferenced "ioc->xxx", it would mean something (not sure what tho)
but as the code currently stands, the dependent read barrier is
noop.
As only one of the the two test-assignment sequences is task_lock()
protected, the task_lock() can't do much about race between the two.
Nothing prevents current_io_context() and set_task_ioprio() allocating
its own ioc for the same task and overwriting the other's.
Also, set_task_ioprio() can race with exiting task and create a new
ioc after exit_io_context() is finished.
ioc get/put doesn't have any reason to be complex. The only hot path
is accessing the existing ioc of %current, which is simple to achieve
given that ->io_context is never destroyed as long as the task is
alive. All other paths can happily go through task_lock() like all
other task sub structures without impacting anything.
This patch updates ioc get/put so that it becomes more conventional.
* alloc_io_context() is replaced with get_task_io_context(). This is
the only interface which can acquire access to ioc of another task.
On return, the caller has an explicit reference to the object which
should be put using put_io_context() afterwards.
* The functionality of current_io_context() remains the same but when
creating a new ioc, it shares the code path with
get_task_io_context() and always goes through task_lock().
* get_io_context() now means incrementing ref on an ioc which the
caller already has access to (be that an explicit refcnt or implicit
%current one).
* PF_EXITING inhibits creation of new io_context and once
exit_io_context() is finished, it's guaranteed that both ioc
acquisition functions return %NULL.
* All users are updated. Most are trivial but
smp_read_barrier_depends() removal from cfq_get_io_context() needs a
bit of explanation. I suppose the original intention was to ensure
ioc->ioprio is visible when set_task_ioprio() allocates new
io_context and installs it; however, this wouldn't have worked
because set_task_ioprio() doesn't have wmb between init and install.
There are other problems with this which will be fixed in another
patch.
* While at it, use NUMA_NO_NODE instead of -1 for wildcard node
specification.
-v2: Vivek spotted contamination from debug patch. Removed.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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git://git.kernel.org/pub/scm/linux/kernel/git/sage/ceph-client
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/sage/ceph-client:
ceph: add missing spin_unlock at ceph_mdsc_build_path()
ceph: fix SEEK_CUR, SEEK_SET regression
crush: fix mapping calculation when force argument doesn't exist
ceph: use i_ceph_lock instead of i_lock
rbd: remove buggy rollback functionality
rbd: return an error when an invalid header is read
ceph: fix rasize reporting by ceph_show_options
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git://git.kernel.org/pub/scm/linux/kernel/git/wfg/linux
* 'writeback-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/wfg/linux:
writeback: set max_pause to lowest value on zero bdi_dirty
writeback: permit through good bdi even when global dirty exceeded
writeback: comment on the bdi dirty threshold
fs: Make write(2) interruptible by a fatal signal
writeback: Fix issue on make htmldocs
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