Pull btrfs fixes from Chris Mason:
"This fixes some lockups in btrfs reported with rc1. It probably has
some performance impact because it is backing off our spinning locks
more often and switching to a blocking lock. I'll be able to nail
that down next week, but for now I want to get the lockups taken care
of.
Otherwise some more stack reduction and assorted fixes"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs:
Btrfs: fix wrong error handle when the device is missing or is not writeable
Btrfs: fix deadlock when mounting a degraded fs
Btrfs: use bio_endio_nodec instead of open code
Btrfs: fix NULL pointer crash when running balance and scrub concurrently
btrfs: Skip scrubbing removed chunks to avoid -ENOENT.
Btrfs: fix broken free space cache after the system crashed
Btrfs: make free space cache write out functions more readable
Btrfs: remove unused wait queue in struct extent_buffer
Btrfs: fix deadlocks with trylock on tree nodes
The original bio might be submitted, so we shoud increase bi_remaining to
account for it when we deal with the error that the device is missing or
is not writeable, or we would skip the endio handle.
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Chris Mason <clm@fb.com>
The deadlock happened when we mount degraded filesystem, the reproduced
steps are following:
# mkfs.btrfs -f -m raid1 -d raid1 <dev0> <dev1>
# echo 1 > /sys/block/`basename <dev0>`/device/delete
# mount -o degraded <dev1> <mnt>
The reason was that the counter -- bi_remaining was wrong. If the missing
or unwriteable device was the last device in the mapping array, we would
not submit the original bio, so we shouldn't increase bi_remaining of it
in btrfs_end_bio(), or we would skip the final endio handle.
Fix this problem by adding a flag into btrfs bio structure. If we submit
the original bio, we will set the flag, and we increase bi_remaining counter,
or we don't.
Though there is another way to fix it -- decrease bi_remaining counter of the
original bio when we make sure the original bio is not submitted, this method
need add more check and is easy to make mistake.
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Reviewed-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: Chris Mason <clm@fb.com>
While running balance, scrub, fsstress concurrently we hit the
following kernel crash:
[56561.448845] BTRFS info (device sde): relocating block group 11005853696 flags 132
[56561.524077] BUG: unable to handle kernel NULL pointer dereference at 0000000000000078
[56561.524237] IP: [<ffffffffa038956d>] scrub_chunk.isra.12+0xdd/0x130 [btrfs]
[56561.524297] PGD 9be28067 PUD 7f3dd067 PMD 0
[56561.524325] Oops: 0000 [#1] SMP
[....]
[56561.527237] Call Trace:
[56561.527309] [<ffffffffa038980e>] scrub_enumerate_chunks+0x24e/0x490 [btrfs]
[56561.527392] [<ffffffff810abe00>] ? abort_exclusive_wait+0x50/0xb0
[56561.527476] [<ffffffffa038add4>] btrfs_scrub_dev+0x1a4/0x530 [btrfs]
[56561.527561] [<ffffffffa0368107>] btrfs_ioctl+0x13f7/0x2a90 [btrfs]
[56561.527639] [<ffffffff811c82f0>] do_vfs_ioctl+0x2e0/0x4c0
[56561.527712] [<ffffffff8109c384>] ? vtime_account_user+0x54/0x60
[56561.527788] [<ffffffff810f768c>] ? __audit_syscall_entry+0x9c/0xf0
[56561.527870] [<ffffffff811c8551>] SyS_ioctl+0x81/0xa0
[56561.527941] [<ffffffff815707f7>] tracesys+0xdd/0xe2
[...]
[56561.528304] RIP [<ffffffffa038956d>] scrub_chunk.isra.12+0xdd/0x130 [btrfs]
[56561.528395] RSP <ffff88004c0f5be8>
[56561.528454] CR2: 0000000000000078
This is because in btrfs_relocate_chunk(), we will free @bdev directly while
scrub may still hold extent mapping, and may access freed memory.
Fix this problem by wrapping freeing @bdev work into free_extent_map() which
is based on reference count.
Reported-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Signed-off-by: Wang Shilong <wangsl.fnst@cn.fujitsu.com>
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Chris Mason <clm@fb.com>
When run scrub with balance, sometimes -ENOENT will be returned, since
in scrub_enumerate_chunks() will search dev_extent in *COMMIT_ROOT*, but
btrfs_lookup_block_group() will search block group in *MEMORY*, so if a
chunk is removed but not committed, -ENOENT will be returned.
However, there is no need to stop scrubbing since other chunks may be
scrubbed without problem.
So this patch changes the behavior to skip removed chunks and continue
to scrub the rest.
Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Chris Mason <clm@fb.com>
When we mounted the filesystem after the crash, we got the following
message:
BTRFS error (device xxx): block group xxxx has wrong amount of free space
BTRFS error (device xxx): failed to load free space cache for block group xxx
It is because we didn't update the metadata of the allocated space (in extent
tree) until the file data was written into the disk. During this time, there was
no information about the allocated spaces in either the extent tree nor the
free space cache. when we wrote out the free space cache at this time (commit
transaction), those spaces were lost. In fact, only the free space that is
used to store the file data had this problem, the others didn't because
the metadata of them is updated in the same transaction context.
There are many methods which can fix the above problem
- track the allocated space, and write it out when we write out the free
space cache
- account the size of the allocated space that is used to store the file
data, if the size is not zero, don't write out the free space cache.
The first one is complex and may make the performance drop down.
This patch chose the second method, we use a per-block-group variant to
account the size of that allocated space. Besides that, we also introduce
a per-block-group read-write semaphore to avoid the race between
the allocation and the free space cache write out.
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Chris Mason <clm@fb.com>
This patch makes the free space cache write out functions more readable,
and beisdes that, it also reduces the stack space that the function --
__btrfs_write_out_cache uses from 194bytes to 144bytes.
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Chris Mason <clm@fb.com>
The lock_wq wait queue is not used anywhere, therefore just remove it.
On a x86_64 system, this reduced sizeof(struct extent_buffer) from 320
bytes down to 296 bytes, which means a 4Kb page can now be used for
13 extent buffers instead of 12.
Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com>
Signed-off-by: Chris Mason <clm@fb.com>
The Btrfs tree trylock function is poorly named. It always takes
the spinlock and backs off if the blocking lock is held. This
can lead to surprising lockups because people expect it to really be a
trylock.
This commit makes it a pure trylock, both for the spinlock and the
blocking lock. It also reworks the nested lock handling slightly to
avoid taking the read lock while a spinning write lock might be held.
Signed-off-by: Chris Mason <clm@fb.com>
Pull more btrfs updates from Chris Mason:
"This has a few fixes since our last pull and a new ioctl for doing
btree searches from userland. It's very similar to the existing
ioctl, but lets us return larger items back down to the app"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs:
btrfs: fix error handling in create_pending_snapshot
btrfs: fix use of uninit "ret" in end_extent_writepage()
btrfs: free ulist in qgroup_shared_accounting() error path
Btrfs: fix qgroups sanity test crash or hang
btrfs: prevent RCU warning when dereferencing radix tree slot
Btrfs: fix unfinished readahead thread for raid5/6 degraded mounting
btrfs: new ioctl TREE_SEARCH_V2
btrfs: tree_search, search_ioctl: direct copy to userspace
btrfs: new function read_extent_buffer_to_user
btrfs: tree_search, copy_to_sk: return needed size on EOVERFLOW
btrfs: tree_search, copy_to_sk: return EOVERFLOW for too small buffer
btrfs: tree_search, search_ioctl: accept varying buffer
btrfs: tree_search: eliminate redundant nr_items check
fcebe456 cut and pasted some code to a later point
in create_pending_snapshot(), but didn't switch
to the appropriate error handling for this stage
of the function.
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Chris Mason <clm@fb.com>
If this condition in end_extent_writepage() is false:
if (tree->ops && tree->ops->writepage_end_io_hook)
we will then test an uninitialized "ret" at:
ret = ret < 0 ? ret : -EIO;
The test for ret is for the case where ->writepage_end_io_hook
failed, and we'd choose that ret as the error; but if
there is no ->writepage_end_io_hook, nothing sets ret.
Initializing ret to 0 should be sufficient; if
writepage_end_io_hook wasn't set, (!uptodate) means
non-zero err was passed in, so we choose -EIO in that case.
Signed-of-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Chris Mason <clm@fb.com>
If tmp = ulist_alloc(GFP_NOFS) fails, we return without
freeing the previously allocated qgroups = ulist_alloc(GFP_NOFS)
and cause a memory leak.
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Chris Mason <clm@fb.com>
Mark the dereference as protected by lock. Not doing so triggers
an RCU warning since the radix tree assumed that RCU is in use.
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Chris Mason <clm@fb.com>
Steps to reproduce:
# mkfs.btrfs -f /dev/sd[b-f] -m raid5 -d raid5
# mkfs.ext4 /dev/sdc --->corrupt one of btrfs device
# mount /dev/sdb /mnt -o degraded
# btrfs scrub start -BRd /mnt
This is because readahead would skip missing device, this is not true
for RAID5/6, because REQ_GET_READ_MIRRORS return 1 for RAID5/6 block
mapping. If expected data locates in missing device, readahead thread
would not call __readahead_hook() which makes event @rc->elems=0
wait forever.
Fix this problem by checking return value of btrfs_map_block(),we
can only skip missing device safely if there are several mirrors.
Signed-off-by: Wang Shilong <wangsl.fnst@cn.fujitsu.com>
Signed-off-by: Chris Mason <clm@fb.com>
This new ioctl call allows the user to supply a buffer of varying size in which
a tree search can store its results. This is much more flexible if you want to
receive items which are larger than the current fixed buffer of 3992 bytes or
if you want to fetch more items at once. Items larger than this buffer are for
example some of the type EXTENT_CSUM.
Signed-off-by: Gerhard Heift <Gerhard@Heift.Name>
Signed-off-by: Chris Mason <clm@fb.com>
Acked-by: David Sterba <dsterba@suse.cz>
By copying each found item seperatly to userspace, we do not need extra
buffer in the kernel.
Signed-off-by: Gerhard Heift <Gerhard@Heift.Name>
Signed-off-by: Chris Mason <clm@fb.com>
Acked-by: David Sterba <dsterba@suse.cz>
This new function reads the content of an extent directly to user memory.
Signed-off-by: Gerhard Heift <Gerhard@Heift.Name>
Signed-off-by: Chris Mason <clm@fb.com>
Acked-by: David Sterba <dsterba@suse.cz>
If an item in tree_search is too large to be stored in the given buffer, return
the needed size (including the header).
Signed-off-by: Gerhard Heift <Gerhard@Heift.Name>
Signed-off-by: Chris Mason <clm@fb.com>
Acked-by: David Sterba <dsterba@suse.cz>
In copy_to_sk, if an item is too large for the given buffer, it now returns
-EOVERFLOW instead of copying a search_header with len = 0. For backward
compatibility for the first item it still copies such a header to the buffer,
but not any other following items, which could have fitted.
tree_search changes -EOVERFLOW back to 0 to behave similiar to the way it
behaved before this patch.
Signed-off-by: Gerhard Heift <Gerhard@Heift.Name>
Signed-off-by: Chris Mason <clm@fb.com>
Acked-by: David Sterba <dsterba@suse.cz>
rewrite search_ioctl to accept a buffer with varying size
Signed-off-by: Gerhard Heift <Gerhard@Heift.Name>
Signed-off-by: Chris Mason <clm@fb.com>
Acked-by: David Sterba <dsterba@suse.cz>
If the amount of items reached the given limit of nr_items, we can leave
copy_to_sk without updating the key. Also by returning 1 we leave the loop in
search_ioctl without rechecking if we reached the given limit.
Signed-off-by: Gerhard Heift <Gerhard@Heift.Name>
Signed-off-by: Chris Mason <clm@fb.com>
Acked-by: David Sterba <dsterba@suse.cz>
Pull vfs updates from Al Viro:
"This the bunch that sat in -next + lock_parent() fix. This is the
minimal set; there's more pending stuff.
In particular, I really hope to get acct.c fixes merged this cycle -
we need that to deal sanely with delayed-mntput stuff. In the next
pile, hopefully - that series is fairly short and localized
(kernel/acct.c, fs/super.c and fs/namespace.c). In this pile: more
iov_iter work. Most of prereqs for ->splice_write with sane locking
order are there and Kent's dio rewrite would also fit nicely on top of
this pile"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (70 commits)
lock_parent: don't step on stale ->d_parent of all-but-freed one
kill generic_file_splice_write()
ceph: switch to iter_file_splice_write()
shmem: switch to iter_file_splice_write()
nfs: switch to iter_splice_write_file()
fs/splice.c: remove unneeded exports
ocfs2: switch to iter_file_splice_write()
->splice_write() via ->write_iter()
bio_vec-backed iov_iter
optimize copy_page_{to,from}_iter()
bury generic_file_aio_{read,write}
lustre: get rid of messing with iovecs
ceph: switch to ->write_iter()
ceph_sync_direct_write: stop poking into iov_iter guts
ceph_sync_read: stop poking into iov_iter guts
new helper: copy_page_from_iter()
fuse: switch to ->write_iter()
btrfs: switch to ->write_iter()
ocfs2: switch to ->write_iter()
xfs: switch to ->write_iter()
...
Pull btrfs updates from Chris Mason:
"The biggest change here is Josef's rework of the btrfs quota
accounting, which improves the in-memory tracking of delayed extent
operations.
I had been working on Btrfs stack usage for a while, mostly because it
had become impossible to do long stress runs with slab, lockdep and
pagealloc debugging turned on without blowing the stack. Even though
you upgraded us to a nice king sized stack, I kept most of the
patches.
We also have some very hard to find corruption fixes, an awesome sysfs
use after free, and the usual assortment of optimizations, cleanups
and other fixes"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs: (80 commits)
Btrfs: convert smp_mb__{before,after}_clear_bit
Btrfs: fix scrub_print_warning to handle skinny metadata extents
Btrfs: make fsync work after cloning into a file
Btrfs: use right type to get real comparison
Btrfs: don't check nodes for extent items
Btrfs: don't release invalid page in btrfs_page_exists_in_range()
Btrfs: make sure we retry if page is a retriable exception
Btrfs: make sure we retry if we couldn't get the page
btrfs: replace EINVAL with EOPNOTSUPP for dev_replace raid56
trivial: fs/btrfs/ioctl.c: fix typo s/substract/subtract/
Btrfs: fix leaf corruption after __btrfs_drop_extents
Btrfs: ensure btrfs_prev_leaf doesn't miss 1 item
Btrfs: fix clone to deal with holes when NO_HOLES feature is enabled
btrfs: free delayed node outside of root->inode_lock
btrfs: replace EINVAL with ERANGE for resize when ULLONG_MAX
Btrfs: fix transaction leak during fsync call
btrfs: Avoid trucating page or punching hole in a already existed hole.
Btrfs: update commit root on snapshot creation after orphan cleanup
Btrfs: ioctl, don't re-lock extent range when not necessary
Btrfs: avoid visiting all extent items when cloning a range
...
The skinny extents are intepreted incorrectly in scrub_print_warning(),
and end up hitting the BUG() in btrfs_extent_inline_ref_size.
Reported-by: Konstantinos Skarlatos <k.skarlatos@gmail.com>
Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: Chris Mason <clm@fb.com>
When cloning into a file, we were correctly replacing the extent
items in the target range and removing the extent maps. However
we weren't replacing the extent maps with new ones that point to
the new extents - as a consequence, an incremental fsync (when the
inode doesn't have the full sync flag) was a NOOP, since it relies
on the existence of extent maps in the modified list of the inode's
extent map tree, which was empty. Therefore add new extent maps to
reflect the target clone range.
A test case for xfstests follows.
Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com>
Signed-off-by: Chris Mason <clm@fb.com>
We want to make sure the point is still within the extent item, not to verify
the memory it's pointing to.
Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: Chris Mason <clm@fb.com>
The backref code was looking at nodes as well as leaves when we tried to
populate extent item entries. This is not good, and although we go away with it
for the most part because we'd skip where disk_bytenr != random_memory,
sometimes random_memory would match and suddenly boom. This fixes that problem.
Thanks,
Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Chris Mason <clm@fb.com>
In inode.c:btrfs_page_exists_in_range(), if the page we got from
the radix tree is an exception entry, which can't be retried, we
exit the loop with a non-NULL page and then call page_cache_release
against it, which is not ok since it's not a valid page. This could
also make us return true when we shouldn't.
Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com>
Signed-off-by: Chris Mason <clm@fb.com>
In inode.c:btrfs_page_exists_in_range(), if the page we get from the
radix tree is an exception which should make us retry, set page to
NULL in order to really retry, because otherwise we don't get another
loop iteration executed (page != NULL makes the while loop exit).
This also was making us call page_cache_release after exiting the loop,
which isn't correct because page doesn't point to a valid page, and
possibly return true from the function when we shouldn't.
Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com>
Signed-off-by: Chris Mason <clm@fb.com>
In inode.c:btrfs_page_exists_in_range(), if we can't get the page
we need to retry. However we weren't retrying because we weren't
setting page to NULL, which makes the while loop exit immediately
and will make us call page_cache_release after exiting the loop
which is incorrect because our page get didn't succeed. This could
also make us return true when we shouldn't.
Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com>
Signed-off-by: Chris Mason <clm@fb.com>
To return EOPNOTSUPP is more user friendly than to return EINVAL,
and then user-space tool will show that the dev_replace operation
for raid56 is not currently supported rather than showing that
there is an invalid argument.
Signed-off-by: Gui Hecheng <guihc.fnst@cn.fujitsu.com>
Signed-off-by: Chris Mason <clm@fb.com>
Signed-off-by: Antonio Ospite <ao2@ao2.it>
Cc: Chris Mason <clm@fb.com>
Cc: Josef Bacik <jbacik@fb.com>
Cc: linux-btrfs@vger.kernel.org
Signed-off-by: Chris Mason <clm@fb.com>
Several reports about leaf corruption has been floating on the list, one of them
points to __btrfs_drop_extents(), and we find that the leaf becomes corrupted
after __btrfs_drop_extents(), it's really a rare case but it does exist.
The problem turns out to be btrfs_next_leaf() called in __btrfs_drop_extents().
So in btrfs_next_leaf(), we release the current path to re-search the last key of
the leaf for locating next leaf, and we've taken it into account that there might
be balance operations between leafs during this 'unlock and re-lock' dance, so
we check the path again and advance it if there are now more items available.
But things are a bit different if that last key happens to be removed and balance
gets a bigger key as the last one, and btrfs_search_slot will return it with
ret > 0, IOW, nothing change in this leaf except the new last key, then we think
we're okay because there is no more item balanced in, fine, we thinks we can
go to the next leaf.
However, we should return that bigger key, otherwise we deserve leaf corruption,
for example, in endio, skipping that key means that __btrfs_drop_extents() thinks
it has dropped all extent matched the required range and finish_ordered_io can
safely insert a new extent, but it actually doesn't and ends up a leaf
corruption.
One may be asking that why our locking on extent io tree doesn't work as
expected, ie. it should avoid this kind of race situation. But in
__btrfs_drop_extents(), we don't always find extents which are included within
our locking range, IOW, extents can start before our searching start, in this
case locking on extent io tree doesn't protect us from the race.
This takes the special case into account.
Reviewed-by: Filipe Manana <fdmanana@gmail.com>
Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: Chris Mason <clm@fb.com>
We might have had an item with the previous key in the tree right
before we released our path. And after we released our path, that
item might have been pushed to the first slot (0) of the leaf we
were holding due to a tree balance. Alternatively, an item with the
previous key can exist as the only element of a leaf (big fat item).
Therefore account for these 2 cases, so that our callers (like
btrfs_previous_item) don't miss an existing item with a key matching
the previous key we computed above.
Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com>
Signed-off-by: Chris Mason <clm@fb.com>
If the NO_HOLES feature is enabled holes don't have file extent items in
the btree that represent them anymore. This made the clone operation
ignore the gaps that exist between consecutive file extent items and
therefore not create the holes at the destination. When not using the
NO_HOLES feature, the holes were created at the destination.
A test case for xfstests follows.
Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com>
Reviewed-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: Chris Mason <clm@fb.com>
On heavy workloads, we're seeing soft lockup warnings on
root->inode_lock in __btrfs_release_delayed_node. The low hanging fruit
is to reduce the size of the critical section.
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Reviewed-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Chris Mason <clm@fb.com>
To be accurate about the error case,
if the new size is beyond ULLONG_MAX, return ERANGE instead of EINVAL.
Signed-off-by: Gui Hecheng <guihc.fnst@cn.fujitsu.com>
Signed-off-by: Chris Mason <clm@fb.com>
If btrfs_log_dentry_safe() returns an error, we set ret to 1 and
fall through with the goal of committing the transaction. However,
in the case where the inode doesn't need a full sync, we would call
btrfs_wait_ordered_range() against the target range for our inode,
and if it returned an error, we would return without commiting or
ending the transaction.
Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com>
Signed-off-by: Chris Mason <clm@fb.com>
btrfs_punch_hole() will truncate unaligned pages or punch hole on a
already existed hole.
This will cause unneeded zero page or holes splitting the original huge
hole.
This patch will skip already existed holes before any page truncating or
hole punching.
Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Signed-off-by: Chris Mason <clm@fb.com>
On snapshot creation (either writable or read-only), we do orphan cleanup
against the root of the snapshot. If the cleanup did remove any orphans,
then the current root node will be different from the commit root node
until the next transaction commit happens.
A send operation always uses the commit root of a snapshot - this means
it will see the orphans if it starts computing the send stream before the
next transaction commit happens (triggered by a timer or sync() for .e.g),
which is when the commit root gets assigned a reference to current root,
where the orphans are not visible anymore. The consequence of send seeing
the orphans is explained below.
For example:
mkfs.btrfs -f /dev/sdd
mount -o commit=999 /dev/sdd /mnt
# open a file with O_TMPFILE and leave it open
# write some data to the file
btrfs subvolume snapshot -r /mnt /mnt/snap1
btrfs send /mnt/snap1 -f /tmp/send.data
The send operation will fail with the following error:
ERROR: send ioctl failed with -116: Stale file handle
What happens here is that our snapshot has an orphan inode still visible
through the commit root, that corresponds to the tmpfile. However send
will attempt to call inode.c:btrfs_iget(), with the goal of reading the
file's data, which will return -ESTALE because it will use the current
root (and not the commit root) of the snapshot.
Of course, there are other cases where we can get orphans, but this
example using a tmpfile makes it much easier to reproduce the issue.
Therefore on snapshot creation, after calling btrfs_orphan_cleanup, if
the commit root is different from the current root, just commit the
transaction associated with the snapshot's root (if it exists), so that
a send will not see any orphans that don't exist anymore. This also
guarantees a send will always see the same content regardless of whether
a transaction commit happened already before the send was requested and
after the orphan cleanup (meaning the commit root and current roots are
the same) or it hasn't happened yet (commit and current roots are
different).
Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com>
Signed-off-by: Chris Mason <clm@fb.com>
In ioctl.c:lock_extent_range(), after locking our target range, the
ordered extent that btrfs_lookup_first_ordered_extent() returns us
may not overlap our target range at all. In this case we would just
unlock our target range, wait for any new ordered extents that overlap
the range to complete, lock again the range and repeat all these steps
until we don't get any ordered extent and the delalloc flag isn't set
in the io tree for our target range.
Therefore just stop if we get an ordered extent that doesn't overlap
our target range and the dealalloc flag isn't set for the range in
the inode's io tree.
Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com>
Signed-off-by: Chris Mason <clm@fb.com>
When cloning a range of a file, we were visiting all the extent items in
the btree that belong to our source inode. We don't need to visit those
extent items that don't overlap the range we are cloning, as doing so only
makes us waste time and do unnecessary btree navigations (btrfs_next_leaf)
for inodes that have a large number of file extent items in the btree.
Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com>
Signed-off-by: Chris Mason <clm@fb.com>
We were setting the BTRFS_ROOT_SUBVOL_DEAD flag on the root of the
parent of our target snapshot, instead of setting it in the target
snapshot's root.
This is easy to observe by running the following scenario:
mkfs.btrfs -f /dev/sdd
mount /dev/sdd /mnt
btrfs subvolume create /mnt/first_subvol
btrfs subvolume snapshot -r /mnt /mnt/mysnap1
btrfs subvolume delete /mnt/first_subvol
btrfs subvolume snapshot -r /mnt /mnt/mysnap2
btrfs send -p /mnt/mysnap1 /mnt/mysnap2 -f /tmp/send.data
The send command failed because the send ioctl returned -EPERM.
A test case for xfstests follows.
Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com>
Reviewed-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Chris Mason <clm@fb.com>
We were cleaning the clone target file range from the page cache before
we did replace the file extent items in the fs tree. This was racy,
as right after cleaning the relevant range from the page cache and before
replacing the file extent items, a read against that range could be
performed by another task and populate again the page cache with stale
data (stale after the cloning finishes). This would result in reads after
the clone operation successfully finishes to get old data (and potentially
for a very long time). Therefore evict the pages after replacing the file
extent items, so that subsequent reads will always get the new data.
Similarly, we were prone to races while cloning the file extent items
because we weren't locking the target range and wait for any existing
ordered extents against that range to complete. It was possible that
after cloning the extent items, a write operation that was performed
before the clone operation and overlaps the same range, would end up
undoing all or part of the work the clone operation did (a worker task
running inode.c:btrfs_finish_ordered_io). Therefore lock the target
range in the io tree, wait for all pending ordered extents against that
range to finish and then safely perform the cloning.
The issue of reading stale data after the clone operation is easy to
reproduce by running the following C program in a loop until it exits
with return value 1.
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <pthread.h>
#include <fcntl.h>
#include <assert.h>
#include <asm/types.h>
#include <linux/ioctl.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/ioctl.h>
#define SRC_FILE "/mnt/sdd/foo"
#define DST_FILE "/mnt/sdd/bar"
#define FILE_SIZE (16 * 1024)
#define PATTERN_SRC 'X'
#define PATTERN_DST 'Y'
struct btrfs_ioctl_clone_range_args {
__s64 src_fd;
__u64 src_offset, src_length;
__u64 dest_offset;
};
#define BTRFS_IOCTL_MAGIC 0x94
#define BTRFS_IOC_CLONE_RANGE _IOW(BTRFS_IOCTL_MAGIC, 13, \
struct btrfs_ioctl_clone_range_args)
static pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
static int clone_done = 0;
static int reader_ready = 0;
static int stale_data = 0;
static void *reader_loop(void *arg)
{
char buf[4096], want_buf[4096];
memset(want_buf, PATTERN_SRC, 4096);
pthread_mutex_lock(&mutex);
reader_ready = 1;
pthread_mutex_unlock(&mutex);
while (1) {
int done, fd, ret;
fd = open(DST_FILE, O_RDONLY);
assert(fd != -1);
pthread_mutex_lock(&mutex);
done = clone_done;
pthread_mutex_unlock(&mutex);
ret = read(fd, buf, 4096);
assert(ret == 4096);
close(fd);
if (done) {
ret = memcmp(buf, want_buf, 4096);
if (ret == 0) {
printf("Found new content\n");
} else {
printf("Found old content\n");
pthread_mutex_lock(&mutex);
stale_data = 1;
pthread_mutex_unlock(&mutex);
}
break;
}
}
return NULL;
}
int main(int argc, char *argv[])
{
pthread_t reader;
int ret, i, fd;
struct btrfs_ioctl_clone_range_args clone_args;
int fd1, fd2;
ret = remove(SRC_FILE);
if (ret == -1 && errno != ENOENT) {
fprintf(stderr, "Error deleting src file: %s\n", strerror(errno));
return 1;
}
ret = remove(DST_FILE);
if (ret == -1 && errno != ENOENT) {
fprintf(stderr, "Error deleting dst file: %s\n", strerror(errno));
return 1;
}
fd = open(SRC_FILE, O_CREAT | O_WRONLY | O_TRUNC, S_IRWXU);
assert(fd != -1);
for (i = 0; i < FILE_SIZE; i++) {
char c = PATTERN_SRC;
ret = write(fd, &c, 1);
assert(ret == 1);
}
close(fd);
fd = open(DST_FILE, O_CREAT | O_WRONLY | O_TRUNC, S_IRWXU);
assert(fd != -1);
for (i = 0; i < FILE_SIZE; i++) {
char c = PATTERN_DST;
ret = write(fd, &c, 1);
assert(ret == 1);
}
close(fd);
sync();
ret = pthread_create(&reader, NULL, reader_loop, NULL);
assert(ret == 0);
while (1) {
int r;
pthread_mutex_lock(&mutex);
r = reader_ready;
pthread_mutex_unlock(&mutex);
if (r) break;
}
fd1 = open(SRC_FILE, O_RDONLY);
if (fd1 < 0) {
fprintf(stderr, "Error open src file: %s\n", strerror(errno));
return 1;
}
fd2 = open(DST_FILE, O_RDWR);
if (fd2 < 0) {
fprintf(stderr, "Error open dst file: %s\n", strerror(errno));
return 1;
}
clone_args.src_fd = fd1;
clone_args.src_offset = 0;
clone_args.src_length = 4096;
clone_args.dest_offset = 0;
ret = ioctl(fd2, BTRFS_IOC_CLONE_RANGE, &clone_args);
assert(ret == 0);
close(fd1);
close(fd2);
pthread_mutex_lock(&mutex);
clone_done = 1;
pthread_mutex_unlock(&mutex);
ret = pthread_join(reader, NULL);
assert(ret == 0);
pthread_mutex_lock(&mutex);
ret = stale_data ? 1 : 0;
pthread_mutex_unlock(&mutex);
return ret;
}
Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com>
Signed-off-by: Chris Mason <clm@fb.com>
There is otherwise a risk of a possible null pointer dereference.
Was largely found by using a static code analysis program called cppcheck.
Signed-off-by: Rickard Strandqvist <rickard_strandqvist@spectrumdigital.se>
Signed-off-by: Chris Mason <clm@fb.com>
