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AFAICT chunk 0 is no longer special, and so it should be restriped just
like every other chunk. One reason for this change is us refusing the
relocation can lead to filesystems that can only be mounted ro, and
never rw -- see the bugzilla [1] for details. The other reason is that
device removal code is already doing this: it will happily relocate
chunk 0 is part of shrinking the device.
[1] https://bugzilla.kernel.org/show_bug.cgi?id=60594
Reported-by: Xavier Bassery <xavier@bartica.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
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Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
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To get name of the file from a pathname let's use kbasename() helper. It allows
to simplify code a bit.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
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now threads can return BTRFS_ERROR_DEV_EXCL_RUN_IN_PROGRESS
as defined in btrfs.h for the dev excl operation error in
the FS, which means with this kernel would stop logging
(almost an user error) into the /var/log/messages
v2: accepts Josef' comment
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
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We currently have this problem where you can truncate pages that have not yet
been written for an ordered extent. We do this because the truncate will be
coming behind to clean us up anyway so what's the harm right? Well if truncate
fails for whatever reason we leave an orphan item around for the file to be
cleaned up later. But if the user goes and truncates up the file and tries to
read from the area that had been discarded previously they will get a csum error
because we never actually wrote that data out.
This patch fixes this by allowing us to either discard the ordered extent
completely, by which I mean we just free up the space we had allocated and not
add the file extent, or adjust the length of the file extent we write. We do
this by setting the length we truncated down to in the ordered extent, and then
we set the file extent length and ram bytes to this length. The total disk
space stays unchanged since we may be compressed and we can't just chop off the
disk space, but at least this way the file extent only points to the valid data.
Then when the file extent is free'd the extent and csums will be freed normally.
This patch is needed for the next series which will give us more graceful
recovery of failed truncates. Thanks,
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
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All of these are logic checks to make sure we're not breaking anything, so
convert them over to ASSERT(). Thanks,
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
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One of the complaints we get a lot is how many BUG_ON()'s we have. So to help
with this I'm introducing a kconfig option to enable/disable a new ASSERT()
mechanism much like what XFS does. This will allow us developers to still get
our nice panics but allow users/distros to compile them out. With this we can
go through and convert any BUG_ON()'s that we have to catch actual programming
mistakes to the new ASSERT() and then fix everybody else to return errors. This
will also allow developers to leave sanity checks in their new code to make sure
we don't trip over problems while testing stuff and vetting new features.
Thanks,
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
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I noticed that if I tried to mount a file system with -o degraded after having
done it once already we would fail to mount. This is because the
fs_devices->missing count was getting bumped everytime we mounted, but not
getting reset whenever we unmounted. To fix this we just drop the missing count
as we're closing devices to make sure this doesn't happen. Thanks,
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
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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 three more places.
Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
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Mitch Harder noticed that the patch 3c64a1a mentioned in the subject
line was causing a kernel BUG() on snapshot deletion.
The patch was wrong. It did not handle cached roots correctly. The
check for root_refs == 0 was removed everywhere where
btrfs_read_fs_root_no_name() had been used to retrieve the root,
because this check was already dealt with in
btrfs_read_fs_root_no_name(). But in the case when the root was
found in the cache, there was no such check.
This patch adds the missing check in the case where the root is
found in the cache.
Reported-by: Mitch Harder <mitch.harder@sabayonlinux.org>
Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de>
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>
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The second round uses btrfs_error() and return -EIO, the first round
can handle write errors the same way.
Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
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struct __prelim_ref is allocated and freed frequently when
walking backref tree, using slab allocater can not only
speed up allocating but also detect memory leaks.
Signed-off-by: Wang Shilong <wangsl.fnst@cn.fujitsu.com>
Reviewed-by: Miao Xie <miaox@cn.fujitsu.com>
Reviewed-by: Jan Schmidt <list.btrfs@jan-o-sch.net>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
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Currently, only add_delayed_refs have to allocate with GFP_ATOMIC,
So just pass arg 'gfp_t' to decide which allocation mode.
Signed-off-by: Wang Shilong <wangsl.fnst@cn.fujitsu.com>
Reviewed-by: Miao Xie <miaox@cn.fujitsu.com>
Reviewed-by: Jan Schmidt <list.btrfs@jan-o-sch.net>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
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The handler for the ioctl BTRFS_IOC_FS_INFO was reading the
number of devices before acquiring the device list mutex.
This could lead to inconsistent results because the update of
the device list and the number of devices counter (amongst other
counters related to the device list) are updated in volumes.c
while holding the device list mutex - except for 2 places, one
was volumes.c:btrfs_prepare_sprout() and the other was
volumes.c:device_list_add().
For example, if we have 2 devices, with IDs 1 and 2 and then add
a new device, with ID 3, and while adding the device is in progress
an BTRFS_IOC_FS_INFO ioctl arrives, it could return a number of
devices of 2 and a max dev id of 3. This would be incorrect.
Also, this ioctl handler was reading the fsid while it can be
updated concurrently. This can happen when while a new device is
being added and the current filesystem is in seeding mode.
Example:
$ mkfs.btrfs -f /dev/sdb1
$ mkfs.btrfs -f /dev/sdb2
$ btrfstune -S 1 /dev/sdb1
$ mount /dev/sdb1 /mnt/test
$ btrfs device add /dev/sdb2 /mnt/test
If during the last step a BTRFS_IOC_FS_INFO ioctl was requested, it
could read an fsid that was never valid (some bits part of the old
fsid and others part of the new fsid). Also, it could read a number
of devices that doesn't match the number of devices in the list and
the max device id, as explained before.
Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
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This change fixes an issue when removing a device and writing
all super blocks run simultaneously. Here's the steps necessary
for the issue to happen:
1) disk-io.c:write_all_supers() gets a number of N devices from the
super_copy, so it will not panic if it fails to write super blocks
for N - 1 devices;
2) Then it tries to acquire the device_list_mutex, but blocks because
volumes.c:btrfs_rm_device() got it first;
3) btrfs_rm_device() removes the device from the list, then unlocks the
mutex and after the unlock it updates the number of devices in
super_copy to N - 1.
4) write_all_supers() finally acquires the mutex, iterates over all the
devices in the list and gets N - 1 errors, that is, it failed to write
super blocks to all the devices;
5) Because write_all_supers() thinks there are a total of N devices, it
considers N - 1 errors to be ok, and therefore won't panic.
So this change just makes sure that write_all_supers() reads the number
of devices from super_copy after it acquires the device_list_mutex.
Conversely, it changes btrfs_rm_device() to update the number of devices
in super_copy before it releases the device list mutex.
The code path to add a new device (volumes.c:btrfs_init_new_device),
already has the right behaviour: it updates the number of devices in
super_copy while holding the device_list_mutex.
The only code path that doesn't lock the device list mutex
before updating the number of devices in the super copy is
disk-io.c:next_root_backup(), called by open_ctree() during
mount time where concurrency issues can't happen.
Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
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A user was reporting weird warnings from btrfs_put_delayed_ref() and I noticed
that we were doing this list_del_init() on our head ref outside of
delayed_refs->lock. This is a problem if we have people still on the list, we
could end up modifying old pointers and such. Fix this by removing us from the
list before we do our run_delayed_ref on our head ref. Thanks,
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
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We were unconditionally clearing our runtime flag on the inode on error when
trying to insert an orphan item. This is wrong in the case of -EEXIST since we
obviously have an orphan item. This was causing us to not do the correct
cleanup of our orphan items which caused issues on cleanup. This happens
because currently when truncate fails we just leave the orphan item on there so
it can be cleaned up, so if we go to remove the file later we will hit this
issue. What we do for truncate isn't right either, but we shouldn't screw this
sort of thing up on error either, so fix this and then I'll fix truncate in a
different patch. Thanks,
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
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Send was just sending everything it found, even if the extent was a hole. This
is unpleasant for users, so just skip holes when we are sending. This will also
skip sending prealloc extents since the send spec doesn't have a prealloc
command. Eventually we will add a prealloc command and rev the send version so
we can send down the prealloc info. Thanks,
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
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The name buffer is not terminated by a '\0' character,
therefore it needs to be printed with %.*s and use the
length of the buffer.
Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
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Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
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sector_t may be either "u64" (always 64 bit) or "unsigned long" (32 or 64
bit). Casting it to "unsigned long" will truncate it on 32-bit platforms
where CONFIG_LBDAF=y.
Cast to "unsigned long long" and format using "ll" instead.
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
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PAGE_CACHE_SIZE == PAGE_SIZE is "unsigned long" everywhere, so there's no
need to cast it to "unsigned long".
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
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Internally, btrfs_header_chunk_tree_uuid() calculates an unsigned long, but
casts it to a pointer, while all callers cast it to unsigned long again.
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
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Internally, btrfs_header_fsid() calculates an unsigned long, but casts
it to a pointer, while all callers cast it to unsigned long again.
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
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Internally, btrfs_dev_extent_chunk_tree_uuid() calculates an unsigned long,
but casts it to a pointer, while all callers cast it to unsigned long
again.
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
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All callers of btrfs_device_fsid() cast its return type to unsigned long.
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
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All callers of btrfs_device_uuid() cast its return type to unsigned long.
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
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mirror_num is always "int", hence don't cast it to "unsigned long long" and
format it as a 64-bit number.
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
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PAGE_SIZE is "unsigned long" everywhere, so there's no need to cast it to
"unsigned long long" and format it as a 64-bit number.
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
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The internal btrfs device id is a u64, hence make the constant
BTRFS_DEV_REPLACE_DEVID "unsigned long long" as well, so we no longer need
a cast to print it.
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
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u64 is "unsigned long long" on all architectures now, so there's no need to
cast it when formatting it using the "ll" length modifier.
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
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This issue is simple to reproduce and observe if kmemleak is enabled.
Two simple ways to reproduce it:
** 1
$ mkfs.btrfs -f /dev/loop0
$ mount /dev/loop0 /mnt/btrfs
$ btrfs balance start /mnt/btrfs
$ umount /mnt/btrfs
** 2
$ mkfs.btrfs -f /dev/loop0
$ mount /dev/loop0 /mnt/btrfs
$ touch /mnt/btrfs/foobar
$ rm -f /mnt/btrfs/foobar
$ umount /mnt/btrfs
After a while, kmemleak reports the leak:
$ cat /sys/kernel/debug/kmemleak
unreferenced object 0xffff880402b13e00 (size 128):
comm "btrfs", pid 19621, jiffies 4341648183 (age 70057.844s)
hex dump (first 32 bytes):
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
00 fc c6 b1 04 88 ff ff 04 00 04 00 ad 4e ad de .............N..
backtrace:
[<ffffffff817275a6>] kmemleak_alloc+0x26/0x50
[<ffffffff8117832b>] kmem_cache_alloc_trace+0xeb/0x1d0
[<ffffffffa04db499>] btrfs_alloc_block_rsv+0x39/0x70 [btrfs]
[<ffffffffa04f8bad>] btrfs_orphan_add+0x13d/0x1b0 [btrfs]
[<ffffffffa04e2b13>] btrfs_remove_block_group+0x143/0x500 [btrfs]
[<ffffffffa0518158>] btrfs_relocate_chunk.isra.63+0x618/0x790 [btrfs]
[<ffffffffa051bc27>] btrfs_balance+0x8f7/0xe90 [btrfs]
[<ffffffffa05240a0>] btrfs_ioctl_balance+0x250/0x550 [btrfs]
[<ffffffffa05269ca>] btrfs_ioctl+0xdfa/0x25f0 [btrfs]
[<ffffffff8119c936>] do_vfs_ioctl+0x96/0x570
[<ffffffff8119cea1>] SyS_ioctl+0x91/0xb0
[<ffffffff81750242>] system_call_fastpath+0x16/0x1b
[<ffffffffffffffff>] 0xffffffffffffffff
This affects btrfs-next, revision be8e3cd00d7293dd177e3f8a4a1645ce09ca3acb
(Btrfs: separate out tests into their own directory).
Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
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It turns out we don't properly rollback in-core btrfs_device state on
umount. We zero out ->bdev, ->in_fs_metadata and that's about it. In
particular, we don't zero out ->generation, and this can lead to us
refusing a mount -- a non-NULL fs_devices->latest_bdev is essential, but
btrfs_close_extra_devices will happily assign NULL to ->latest_bdev if
the first device on the dev_list happens to be missing and consequently
has no bdev attached. This happens because since commit a6b0d5c8
btrfs_close_extra_devices adjusts ->latest_bdev, and in doing that,
relies on the ->generation. Fix this, and possibly other problems, by
zeroing out everything except for what device_list_add sets, so that a
mount right after insmod and 'btrfs dev scan' is no different from any
later mount in this respect.
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
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In the spirit of btrfs_alloc_device, add a helper for allocating and
doing some common initialization of btrfs_fs_devices struct.
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
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Currently btrfs_device is allocated ad-hoc in a few different places,
and as a result not all fields are initialized properly. In particular,
readahead state is only initialized in device_list_add (at scan time),
and not in btrfs_init_new_device (when the new device is added with
'btrfs dev add'). Fix this by adding an allocation helper and switch
everybody but __btrfs_close_devices to it. (__btrfs_close_devices is
dealt with in a later commit.)
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
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find_next_devid() knows which root to search, so it should take an
fs_info instead of an arbitrary root.
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
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If you start the replace procedure on a read only filesystem, at
the end the procedure fails to write the updated dev_items to the
chunk tree. The problem is that this error is not indicated except
for a WARN_ON(). If the user now thinks that everything was done
as expected and destroys the source device (with mkfs or with a
hammer). The next mount fails with "failed to read chunk root" and
the filesystem is gone.
This commit adds code to fail the attempt to start the replace
procedure if the filesystem is mounted read-only.
Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de>
Cc: <stable@vger.kernel.org> # 3.10+
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
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After we set force_compress with a new value (which was not being done
while holding the inode mutex), if an error happens and we jump to
the label out_ra, the force_compress property of the inode is not set
to BTRFS_COMPRESS_NONE (unlike in the case where no errors happen).
Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
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This should never be needed, but since all functions are there
to check and rebuild the UUID tree, a mount option is added that
allows to force this check and rebuild procedure.
Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
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If the filesystem was mounted with an old kernel that was not
aware of the UUID tree, this is detected by looking at the
uuid_tree_generation field of the superblock (similar to how
the free space cache is doing it). If a mismatch is detected
at mount time, a thread is started that does two things:
1. Iterate through the UUID tree, check each entry, delete those
entries that are not valid anymore (i.e., the subvol does not
exist anymore or the value changed).
2. Iterate through the root tree, for each found subvolume, add
the UUID tree entries for the subvolume (if they are not
already there).
This mechanism is also used to handle and repair errors that
happened during the initial creation and filling of the tree.
The update of the uuid_tree_generation field (which indicates
that the state of the UUID tree is up to date) is blocked until
all create and repair operations are successfully completed.
Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
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In order to be able to detect the case that a filesystem is mounted
with an old kernel, add a uuid-tree-gen field like the free space
cache is doing it. It is part of the super block and written with
each commit. Old kernels do not know this field and don't update it.
Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
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When the UUID tree is initially created, a task is spawned that
walks through the root tree. For each found subvolume root_item,
the uuid and received_uuid entries in the UUID tree are added.
This is such a quick operation so that in case somebody wants
to unmount the filesystem while the task is still running, the
unmount is delayed until the UUID tree building task is finished.
Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
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When a new subvolume or snapshot is created, a new UUID item is added
to the UUID tree. Such items are removed when the subvolume is deleted.
The ioctl to set the received subvolume UUID is also touched and will
now also add this received UUID into the UUID tree together with the
ID of the subvolume. The latter is also done when read-only snapshots
are created which inherit all the send/receive information from the
parent subvolume.
User mode programs use the BTRFS_IOC_TREE_SEARCH ioctl to search and
read in the UUID tree.
Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
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This tree is not created by mkfs.btrfs. Therefore when a filesystem
is mounted writable and the UUID tree does not exist, this tree is
created if required. The tree is also added to the fs_info structure
and initialized, but this commit does not yet read or write UUID tree
elements.
Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
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This commit adds support to print UUID tree elements to print-tree.c.
Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
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Mapping UUIDs to subvolume IDs is an operation with a high effort
today. Today, the algorithm even has quadratic effort (based on the
number of existing subvolumes), which means, that it takes minutes
to send/receive a single subvolume if 10,000 subvolumes exist. But
even linear effort would be too much since it is a waste. And these
data structures to allow mapping UUIDs to subvolume IDs are created
every time a btrfs send/receive instance is started.
It is much more efficient to maintain a searchable persistent data
structure in the filesystem, one that is updated whenever a
subvolume/snapshot is created and deleted, and when the received
subvolume UUID is set by the btrfs-receive tool.
Therefore kernel code is added with this commit that is able to
maintain data structures in the filesystem that allow to quickly
search for a given UUID and to retrieve data that is assigned to
this UUID, like which subvolume ID is related to this UUID.
This commit adds a new tree to hold UUID-to-data mapping items. The
key of the items is the full UUID plus the key type BTRFS_UUID_KEY.
Multiple data blocks can be stored for a given UUID, a type/length/
value scheme is used.
Now follows the lengthy justification, why a new tree was added
instead of using the existing root tree:
The first approach was to not create another tree that holds UUID
items. Instead, the items should just go into the top root tree.
Unfortunately this confused the algorithm to assign the objectid
of subvolumes and snapshots. The reason is that
btrfs_find_free_objectid() calls btrfs_find_highest_objectid() for
the first created subvol or snapshot after mounting a filesystem,
and this function simply searches for the largest used objectid in
the root tree keys to pick the next objectid to assign. Of course,
the UUID keys have always been the ones with the highest offset
value, and the next assigned subvol ID was wastefully huge.
To use any other existing tree did not look proper. To apply a
workaround such as setting the objectid to zero in the UUID item
key and to implement collision handling would either add
limitations (in case of a btrfs_extend_item() approach to handle
the collisions) or a lot of complexity and source code (in case a
key would be looked up that is free of collisions). Adding new code
that introduces limitations is not good, and adding code that is
complex and lengthy for no good reason is also not good. That's the
justification why a completely new tree was introduced.
Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
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Cc: Josef Bacik <jbacik@fusionio.com>
Cc: Chris Mason <chris.mason@fusionio.com>
Signed-off-by: Sergei Trofimovich <slyfox@gentoo.org>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
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make C=2 fs/btrfs/ CF=-D__CHECK_ENDIAN__
I tried to filter out the warnings for which patches have already
been sent to the mailing list, pending for inclusion in btrfs-next.
All these changes should be obviously safe.
Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
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If the inode ref key was not found and the current leaf slot
was 0 (first item in the leaf) the code would always return
-ENOENT. This was not correct because the desired inode ref
item might be the last item in the previous leaf.
Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
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If the path doesn't fit in the input buffer, return ENAMETOOLONG
instead of returning with a success code (0) and a partially
filled and right justified buffer.
Also removed useless buffer pointer check outside the while loop.
Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
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