My recent truncate patch uncovered this bug, but I can reproduce it without the
truncate patch. If you mount with -o compress-force, do a direct write to some
area, do a buffered write to some other area, and then do a direct read you will
get the wrong data for where you did the buffered write. This is because the
generic direct io helpers only call filemap_write_and_wait once, and for
compression we need it twice. So to be safe add the btrfs_wait_ordered_range to
the start of the direct io function to make sure any compressed writes have
truly been written. This patch makes xfstests 130 pass when you mount with -o
compress-force=lzo. Thanks,
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
We always just try and reserve data space when we write, but if we are out of
space but have prealloc'ed extents we should still successfully write. This
patch will try and see if we can write to prealloc'ed space and if we can go
ahead and allow the write to continue. With this patch we now pass xfstests
generic/274. Thanks,
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
We have an optimization that will go ahead and cache no acls on an inode if
there are no xattrs on the inode. This saves us a lookup later to check the
acls for writes or any other access. The problem is I use selinux so I always
have an xattr on inodes, so make this test a little smarter and check for the
actual acl hash on the key and if it isn't there then we still get to cache no
acl which makes everybody who uses selinux a little happier. Thanks,
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
This has plagued us forever and I'm so over working around it. When we truncate
down to a non-page aligned offset we will call btrfs_truncate_page to zero out
the end of the page and write it back to disk, this will keep us from exposing
stale data if we truncate back up from that point. The problem with this is it
requires data space to do this, and people don't really expect to get ENOSPC
from truncate() for these sort of things. This also tends to bite the orphan
cleanup stuff too which keeps people from mounting. To get around this we can
just move this into btrfs_cont_expand() to make sure if we are truncating up
from a non-page size aligned i_size we will zero out the rest of this page so
that we don't expose stale data. This will give ENOSPC if you try to truncate()
up or if you try to write past the end of isize, which is much more reasonable.
This fixes xfstests generic/083 failing to mount because of the orphan cleanup
failing. Thanks,
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
A user reported a deadlock where the async submit thread was blocked on the
lock_extent() lock, and then everybody behind him was locked on the page lock
for the page he was holding. Looking at the code I noticed we do not unlock the
extent range when we get ENOSPC and goto retry. This is bad because we
immediately try to lock that range again to do the cow, which will cause a
deadlock. Fix this by unlocking the range. Thanks,
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
When we cross into a different subvol when doing a lookup we will run the orhpan
cleanup. If this fails however we do not drop the ref to the inode we were
looking up before we return an error, which leads to busy inodes on umount.
Thanks,
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Dave pointed out a problem where if you filled up a file system as much as
possible you couldn't remove any files. The whole unlink reservation thing is
convoluted because it tries to guess if it's going to add space to unlink
something or not, and has all these odd uncommented cases where it simply does
not try. So to fix this I've added a way to conditionally steal from the global
reserve if we can't make our normal reservation. If we have more than half the
space in the global reserve free we will go ahead and steal from the global
reserve. With this patch Dave's reproducer now works and I can rm all the files
on the file system. Thanks,
Reported-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
The reason we introduce per-subvolume ordered extent list is the same
as the per-subvolume delalloc inode list.
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
When we create a snapshot, we need flush all delalloc inodes in the
fs, just flushing the inodes in the source tree is OK. So we introduce
per-subvolume delalloc inode list.
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
btrfs_read_fs_root_no_name() already checks if btrfs_root_refs()
is zero and returns ENOENT in this case. There is no need to do
it again in six places.
Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
There is a path where btrfs_drop_inode() is called with its inode's root
is NULL: In btrfs_new_inode(), when btrfs_set_inode_index() fails,
iput() is called. We should handle this case before taking look at the
root->root_item.
Signed-off-by: Naohiro Aota <naota@elisp.net>
Reviewed-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
Currently there is no way to truncate partial page where the end
truncate point is not at the end of the page. This is because it was not
needed and the functionality was enough for file system truncate
operation to work properly. However more file systems now support punch
hole feature and it can benefit from mm supporting truncating page just
up to the certain point.
Specifically, with this functionality truncate_inode_pages_range() can
be changed so it supports truncating partial page at the end of the
range (currently it will BUG_ON() if 'end' is not at the end of the
page).
This commit changes the invalidatepage() address space operation
prototype to accept range to be invalidated and update all the instances
for it.
We also change the block_invalidatepage() in the same way and actually
make a use of the new length argument implementing range invalidation.
Actual file system implementations will follow except the file systems
where the changes are really simple and should not change the behaviour
in any way .Implementation for truncate_page_range() which will be able
to accept page unaligned ranges will follow as well.
Signed-off-by: Lukas Czerner <lczerner@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Hugh Dickins <hughd@google.com>
Btrfs has been pointer tagging bi_private and using bi_bdev
to store the stripe index and mirror number of failed IOs.
As bios bubble back up through the call chain, we use these
to decide if and how to retry our IOs. They are also used
to count IO failures on a per device basis.
Recently a bio tracepoint was added lead to crashes because
we were abusing bi_bdev.
This commit adds a btrfs bioset, and creates explicit fields
for the mirror number and stripe index. The plan is to
extend this structure for all of the fields currently in
struct btrfs_bio, which will mean one less kmalloc in
our IO path.
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
Reported-by: Tejun Heo <tj@kernel.org>
The root node of the rb-tree may be changed, so we should get it under
the lock. Fix it.
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
inode_tree_del() will move the tree root into the dead root list, and
then the tree will be destroyed by the cleaner. So if we remove the
delayed node which is cached in the inode after inode_tree_del(),
we may access a freed tree root. Fix it.
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
We need to set return value explicitly, otherwise we'll lose the error
value.
Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Big patch, but all it does is add statics to functions which
are in fact static, then remove the associated dead-code fallout.
removed functions:
btrfs_iref_to_path()
__btrfs_lookup_delayed_deletion_item()
__btrfs_search_delayed_insertion_item()
__btrfs_search_delayed_deletion_item()
find_eb_for_page()
btrfs_find_block_group()
range_straddles_pages()
extent_range_uptodate()
btrfs_file_extent_length()
btrfs_scrub_cancel_devid()
btrfs_start_transaction_lflush()
btrfs_print_tree() is left because it is used for debugging.
btrfs_start_transaction_lflush() and btrfs_reada_detach() are
left for symmetry.
ulist.c functions are left, another patch will take care of those.
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Replace some BUG_ONs with proper handling and take allocated space back to
free space cache for later use.
We don't have to worry about extent maps since they'd be freed in releasepage
path.
Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
This is the same as the fix from commit
Btrfs: fix bad extent logging
but for O_DIRECT. I missed this when I fixed the problem originally, we were
still using the em for the orig_start and orig_block_len, which would be the
merged extent. We need to use the actual extent from the on disk file extent
item, which we have to lookup to make sure it's ok to nocow anyway so just pass
in some pointers to hold this info. Thanks,
Cc: stable@vger.kernel.org
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
If argument 'trans' is unnecessary in the function where
fixup_low_keys() is called, 'trans' is deleted.
Signed-off-by: Tsutomu Itoh <t-itoh@jp.fujitsu.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
__btrfs_unlink_inode() aborts its transaction when it sees errors after
it removes the directory item. But it missed the case where
btrfs_del_dir_entries_in_log() returns an error. If this happens then
the unlink appears to fail but the items have been removed without
updating the directory size. The directory then has leaked bytes in
i_size and can never be removed.
Adding the missing transaction abort at least makes this failure
consistent with the other failure cases.
I noticed this while reading the code after someone on irc reported
having a directory with i_size but no entries. I tested it by forcing
btrfs_del_dir_entries_in_log() to return -ENOMEM.
Signed-off-by: Zach Brown <zab@redhat.com>
Reviewed-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
A user sent me a btrfs-image of a file system that was panicing on mount during
the log recovery. I had originally thought these problems were from a bug in
the free space cache code, but that was just a symptom of the problem. The
problem is if your application does something like this
[prealloc][prealloc][prealloc]
the internal extent maps will merge those all together into one extent map, even
though on disk they are 3 separate extents. So if you go to write into one of
these ranges the extent map will be right since we use the physical extent when
doing the write, but when we log the extents they will use the wrong sizes for
the remainder prealloc space. If this doesn't happen to trip up the free space
cache (which it won't in a lot of cases) then you will get bogus entries in your
extent tree which will screw stuff up later. The data and such will still work,
but everything else is broken. This patch fixes this by not allowing extents
that are on the modified list to be merged. This has the side effect that we
are no longer adding everything to the modified list all the time, which means
we now have to call btrfs_drop_extents every time we log an extent into the
tree. So this allows me to drop all this speciality code I was using to get
around calling btrfs_drop_extents. With this patch the testcase I've created no
longer creates a bogus file system after replaying the log. Thanks,
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
When logging changed extents I was logging ram_bytes as the current length,
which isn't correct, it's supposed to be the ram bytes of the original extent.
This is for compression where even if we split the extent we need to know the
ram bytes so when we uncompress the extent we know how big it will be. This was
still working out right with compression for some reason but I think we were
getting lucky. It was definitely off for prealloc which is why I noticed it,
btrfsck was complaining about it. With this patch btrfsck no longer complains
after a log replay. Thanks,
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
The messages
btrfs: unlinked 123 orphans
btrfs: truncated 456 orphans
are not useful to regular users and raise questions whether there are
problems with the filesystem.
Signed-off-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
With more than one btrfs volume mounted, it can be very difficult to find
out which volume is hitting an error. btrfs_error() will print this, but
it is currently rigged as more of a fatal error handler, while many of
the printk()s are currently for debugging and yet-unhandled cases.
This patch just changes the functions where the device information is
already available. Some cases remain where the root or fs_info is not
passed to the function emitting the error.
This may introduce some confusion with volumes backed by multiple devices
emitting errors referring to the primary device in the set instead of the
one on which the error occurred.
Use btrfs_printk(fs_info, format, ...) rather than writing the device
string every time, and introduce macro wrappers ala XFS for brevity.
Since the function already cannot be used for continuations, print a
newline as part of the btrfs_printk() message rather than at each caller.
Signed-off-by: Simon Kirby <sim@hostway.ca>
Reviewed-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
We currently store the first key of the tree block inside the reference for the
tree block in the extent tree. This takes up quite a bit of space. Make a new
key type for metadata which holds the level as the offset and completely removes
storing the btrfs_tree_block_info inside the extent ref. This reduces the size
from 51 bytes to 33 bytes per extent reference for each tree block. In practice
this results in a 30-35% decrease in the size of our extent tree, which means we
COW less and can keep more of the extent tree in memory which makes our heavy
metadata operations go much faster. This is not an automatic format change, you
must enable it at mkfs time or with btrfstune. This patch deals with having
metadata stored as either the old format or the new format so it is easy to
convert. Thanks,
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
We reserve the space for csums only when we write data into a file, in
the other cases, such as tree log, log replay, we don't do reservation,
so we can use the reservation of the transaction handle just for the former.
And for the latter, we should use the tree's own reservation. But the
function - btrfs_csum_file_blocks() didn't differentiate between these
two types of the cases, fix it.
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
We are way over-reserving for unlink and rename. Rename is just some random
huge number and unlink accounts for tree log operations that don't actually
happen during unlink, not to mention the tree log doesn't take from the trans
block rsv anyway so it's completely useless. Thanks,
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Btrfs uses page_mkwrite to ensure stable pages during
crc calculations and mmap workloads. We call clear_page_dirty_for_io
before we do any crcs, and this forces any application with the file
mapped to wait for the crc to finish before it is allowed to change
the file.
With compression on, the clear_page_dirty_for_io step is happening after
we've compressed the pages. This means the applications might be
changing the pages while we are compressing them, and some of those
modifications might not hit the disk.
This commit adds the clear_page_dirty_for_io before compression starts
and makes sure to redirty the page if we have to fallback to
uncompressed IO as well.
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
Reported-by: Alexandre Oliva <oliva@gnu.org>
cc: stable@vger.kernel.org
Using spinning case instead of blocking will result in better concurrency
overall.
Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
Commit 24542bf7ea changed preallocation of
extents to cap the max size we try to allocate. It's a valid change,
but the extent reservation code is also used by balance, and that
can't tolerate a smaller extent being allocated.
__btrfs_prealloc_file_range already has a min_size parameter, which is
used by relocation to request a specific extent size. This commit
adds an extra check to enforce that minimum extent size.
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
Reported-by: Stefan Behrens <sbehrens@giantdisaster.de>
I noticed while looking into a tree logging bug that we aren't logging inline
extents properly. Since this requires copying and it shouldn't happen too often
just force us to copy everything for the inode into the tree log when we have an
inline extent. With this patch we have valid data after a crash when we write
an inline extent. Thanks,
Cc: stable@vger.kernel.org
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Though most of the btrfs codes are using ALIGN macro for page alignment,
there are still some codes using open-coded alignment like the
following:
------
u64 mask = ((u64)root->stripesize - 1);
u64 ret = (val + mask) & ~mask;
------
Or even hidden one:
------
num_bytes = (end - start + blocksize) & ~(blocksize - 1);
------
Sometimes these open-coded alignment is not so easy to understand for
newbie like me.
This commit changes the open-coded alignment to the ALIGN macro for a
better readability.
Also there is a previous patch from David Sterba with similar changes,
but the patch is for 3.2 kernel and seems not merged.
http://www.spinics.net/lists/linux-btrfs/msg12747.html
Cc: David Sterba <dave@jikos.cz>
Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Before we forced to change a file's NOCOW and COMPRESS flag due to
the parent directory's, but this ends up a bad idea, because it
confuses end users a lot about file's NOCOW status, eg. if someone
change a file to NOCOW via 'chattr' and then rename it in the current
directory which is without NOCOW attribute, the file will lose the
NOCOW flag silently.
This diables 'change flags in rename', so from now on we'll only
inherit flags from the parent directory on creation stage while in
other places we can use 'chattr' to set NOCOW or COMPRESS flags.
Reported-by: Marios Titas <redneb8888@gmail.com>
Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
A user reported hitting the BUG_ON() in btrfs_finished_ordered_io() where we had
csums on a NOCOW extent. This can happen if we have NODATACOW set but not
NODATASUM set, which can happen in two cases, either we mount with -o nodatacow
and then write into preallocated space, or chattr +C a directory and move a file
into that directory. Liu has fixed the move case in a different place, but this
fixes the mount -o nodatacow case. Thanks,
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
When running the 083th case of xfstests on the filesystem with
"compress-force=lzo", the following WARNINGs were triggered.
WARNING: at fs/btrfs/inode.c:7908
WARNING: at fs/btrfs/inode.c:7909
WARNING: at fs/btrfs/inode.c:7911
WARNING: at fs/btrfs/extent-tree.c:4510
WARNING: at fs/btrfs/extent-tree.c:4511
This problem was introduced by the patch "Btrfs: fix deadlock due
to unsubmitted". In this patch, there are two bugs which caused
the above problem.
The 1st one is a off-by-one bug, if the DIO write return 0, it is
also a short write, we need release the reserved space for it. But
we didn't do it in that patch. Fix it by change "ret > 0" to
"ret >= 0".
The 2nd one is ->outstanding_extents was increased twice when
a short write happened. As we know, ->outstanding_extents is
a counter to keep track of the number of extent items we may
use duo to delalloc, when we reserve the free space for a
delalloc write, we assume that the write will introduce just
one extent item, so we increase ->outstanding_extents by 1 at
that time. And then we will increase it every time we split the
write, it is done at the beginning of btrfs_get_blocks_direct().
So when a short write happens, we needn't increase
->outstanding_extents again. But this patch done.
In order to fix the 2nd problem, I re-write the logic for
->outstanding_extents operation. We don't increase it at the
beginning of btrfs_get_blocks_direct(), instead, we just
increase it when the split actually happens.
Reported-by: Mitch Harder <mitch.harder@sabayonlinux.org>
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
This comes from one of btrfs's project ideas,
As we defragment files, we break any sharing from other snapshots.
The balancing code will preserve the sharing, and defrag needs to grow this
as well.
Now we're able to fill the blank with this patch, in which we make full use of
backref walking stuff.
Here is the basic idea,
o set the writeback ranges started by defragment with flag EXTENT_DEFRAG
o at endio, after we finish updating fs tree, we use backref walking to find
all parents of the ranges and re-link them with the new COWed file layout by
adding corresponding backrefs.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
Very large fallocate requests are cpu bound and result in extents with a
repeating pattern of ever decreasing size:
$ time fallocate -l 1T file
real 0m13.039s
( an excerpt of the extents from btrfs-debug-tree: )
prealloc data disk byte 1536292564992 nr 397312
prealloc data disk byte 1536292962304 nr 196608
prealloc data disk byte 1536293158912 nr 98304
prealloc data disk byte 1536293257216 nr 49152
prealloc data disk byte 1536293306368 nr 24576
prealloc data disk byte 1536293330944 nr 12288
prealloc data disk byte 1536293343232 nr 8192
prealloc data disk byte 1536293351424 nr 4096
prealloc data disk byte 1536293355520 nr 4096
prealloc data disk byte 1536293359616 nr 4096
The excessive cpu use comes from __btrfs_prealloc_file_range() trying to
allocate the entire remaining size after each extent is allocated.
btrfs_reserve_extent() repeatedly cuts this requested size in half until
it gets down to the size that the allocators can return. We limit the
problem for now by capping each reservation at 256 meg.
The small extents come from a masking bug when decreasing the requested
reservation size. The high 32bits are cleared and the remaining low
bits might happen to reserve a small size. Fix this by using
round_down() which properly casts the mask.
After these fixes huge fallocate requests are fast and result in nice
large extents:
$ time fallocate -l 1T file
real 0m0.082s
prealloc data disk byte 1112425889792 nr 268435456
prealloc data disk byte 1112694325248 nr 268435456
prealloc data disk byte 1112962760704 nr 268435456
Reported-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Zach Brown <zab@redhat.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
Right now inode cache inode is treated as the same as space cache
inode, ie. keep inode in memory till putting super.
But this leads to an awkward situation.
If we're going to delete a snapshot/subvolume, btrfs will not
actually delete it and return free space, but will add it to dead
roots list until the last inode on this snap/subvol being destroyed.
Then we'll fetch deleted roots and cleanup them via cleaner thread.
So here is the problem, if we enable inode cache option, each
snap/subvol has a cached inode which is used to store inode allcation
information. And this cache inode will be kept in memory, as the above
said. So with inode cache, snap/subvol can only be added into
dead roots list during freeing roots stage in umount, so that we can
ONLY get space back after another remount(we cleanup dead roots on mount).
But the real thing is we'll no more use the snap/subvol if we mark it
deleted, so we can safely iput its cache inode when we delete snap/subvol.
Another thing is that we need to change the rules of droping inode, we
don't keep snap/subvol's cache inode in memory till end so that we can
add snap/subvol into dead roots list in time.
Reported-by: Mitch Harder <mitch.harder@sabayonlinux.org>
Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
This idea is from ext4. By this patch, we can make the dio write parallel,
and improve the performance. But because we can not update isize without
i_mutex, the unlocked dio write just can be done in front of the EOF.
We needn't worry about the race between dio write and truncate, because the
truncate need wait untill all the dio write end.
And we also needn't worry about the race between dio write and punch hole,
because we have extent lock to protect our operation.
I ran fio to test the performance of this feature.
== Hardware ==
CPU: Intel(R) Core(TM)2 Duo CPU E7500 @ 2.93GHz
Mem: 2GB
SSD: Intel X25-M 120GB (Test Partition: 60GB)
== config file ==
[global]
ioengine=psync
direct=1
bs=4k
size=32G
runtime=60
directory=/mnt/btrfs/
filename=testfile
group_reporting
thread
[file1]
numjobs=1 # 2 4
rw=randwrite
== result (KBps) ==
write 1 2 4
lock 24936 24738 24726
nolock 24962 30866 32101
== result (iops) ==
write 1 2 4
lock 6234 6184 6181
nolock 6240 7716 8025
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Currently, we can do unlocked dio reads, but the following race
is possible:
dio_read_task truncate_task
->btrfs_setattr()
->btrfs_direct_IO
->__blockdev_direct_IO
->btrfs_get_block
->btrfs_truncate()
#alloc truncated blocks
#to other inode
->submit_io()
#INFORMATION LEAK
In order to avoid this problem, we must serialize unlocked dio reads with
truncate. There are two approaches:
- use extent lock to protect the extent that we truncate
- use inode_dio_wait() to make sure the truncating task will wait for
the read DIO.
If we use the 1st one, we will meet the endless truncation problem due to
the nonlocked read DIO after we implement the nonlocked write DIO. It is
because we still need invoke inode_dio_wait() avoid the race between write
DIO and truncation. By that time, we have to introduce
btrfs_inode_{block, resume}_nolock_dio()
again. That is we have to implement this patch again, so I choose the 2nd
way to fix the problem.
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
The deadlock problem happened when running fsstress(a test program in LTP).
Steps to reproduce:
# mkfs.btrfs -b 100M <partition>
# mount <partition> <mnt>
# <Path>/fsstress -p 3 -n 10000000 -d <mnt>
The reason is:
btrfs_direct_IO()
|->do_direct_IO()
|->get_page()
|->get_blocks()
| |->btrfs_delalloc_resereve_space()
| |->btrfs_add_ordered_extent() ------- Add a new ordered extent
|->dio_send_cur_page(page0) -------------- We didn't submit bio here
|->get_page()
|->get_blocks()
|->btrfs_delalloc_resereve_space()
|->flush_space()
|->btrfs_start_ordered_extent()
|->wait_event() ---------- Wait the completion of
the ordered extent that is
mentioned above
But because we didn't submit the bio that is mentioned above, the ordered
extent can not complete, we would wait for its completion forever.
There are two methods which can fix this deadlock problem:
1. submit the bio before we invoke get_blocks()
2. reserve the space before we do dio
Though the 1st is the simplest way, we need modify the code of VFS, and it
is likely to break contiguous requests, and introduce performance regression
for the other filesystems.
So we have to choose the 2nd way.
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Cc: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
I noticed we were getting lots of warnings with xfstest 83 because we have
reservations outstanding. This is because we moved the orphan add outside
of the truncate, but we don't actually cleanup our reservation if something
fails. This fixes the problem and I no longer see warnings. Thanks,
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Josef Bacik