We hit something like the following function call flows:

|->run_delalloc_range()
 |->btrfs_join_transaction()
   |->cow_file_range()
     |->btrfs_join_transaction()
       |->find_free_extent()
         |->btrfs_join_transaction()

Trace infomation can be seen as:

[ 7411.127040] ------------[ cut here ]------------
[ 7411.127060] WARNING: CPU: 0 PID: 11557 at fs/btrfs/transaction.c:383 start_transaction+0x561/0x580 [btrfs]()
[ 7411.127079] CPU: 0 PID: 11557 Comm: kworker/u8:9 Tainted: G           O 3.13.0+ #4
[ 7411.127080] Hardware name: LENOVO QiTianM4350/ , BIOS F1KT52AUS 05/24/2013
[ 7411.127085] Workqueue: writeback bdi_writeback_workfn (flush-btrfs-5)
[ 7411.127092] Call Trace:
[ 7411.127097]  [<ffffffff815b87b0>] dump_stack+0x45/0x56
[ 7411.127101]  [<ffffffff81051ffd>] warn_slowpath_common+0x7d/0xa0
[ 7411.127102]  [<ffffffff810520da>] warn_slowpath_null+0x1a/0x20
[ 7411.127109]  [<ffffffffa0444fb1>] start_transaction+0x561/0x580 [btrfs]
[ 7411.127115]  [<ffffffffa0445027>] btrfs_join_transaction+0x17/0x20 [btrfs]
[ 7411.127120]  [<ffffffffa0431c91>] find_free_extent+0xa21/0xb50 [btrfs]
[ 7411.127126]  [<ffffffffa0431f68>] btrfs_reserve_extent+0xa8/0x1a0 [btrfs]
[ 7411.127131]  [<ffffffffa04322ce>] btrfs_alloc_free_block+0xee/0x440 [btrfs]
[ 7411.127137]  [<ffffffffa043bd6e>] ? btree_set_page_dirty+0xe/0x10 [btrfs]
[ 7411.127142]  [<ffffffffa041da51>] __btrfs_cow_block+0x121/0x530 [btrfs]
[ 7411.127146]  [<ffffffffa041dfff>] btrfs_cow_block+0x11f/0x1c0 [btrfs]
[ 7411.127151]  [<ffffffffa0421b74>] btrfs_search_slot+0x1d4/0x9c0 [btrfs]
[ 7411.127157]  [<ffffffffa0438567>] btrfs_lookup_file_extent+0x37/0x40 [btrfs]
[ 7411.127163]  [<ffffffffa0456bfc>] __btrfs_drop_extents+0x16c/0xd90 [btrfs]
[ 7411.127169]  [<ffffffffa0444ae3>] ? start_transaction+0x93/0x580 [btrfs]
[ 7411.127171]  [<ffffffff811663e2>] ? kmem_cache_alloc+0x132/0x140
[ 7411.127176]  [<ffffffffa041cd9a>] ? btrfs_alloc_path+0x1a/0x20 [btrfs]
[ 7411.127182]  [<ffffffffa044aa61>] cow_file_range_inline+0x181/0x2e0 [btrfs]
[ 7411.127187]  [<ffffffffa044aead>] cow_file_range+0x2ed/0x440 [btrfs]
[ 7411.127194]  [<ffffffffa0464d7f>] ? free_extent_buffer+0x4f/0xb0 [btrfs]
[ 7411.127200]  [<ffffffffa044b38f>] run_delalloc_nocow+0x38f/0xa60 [btrfs]
[ 7411.127207]  [<ffffffffa0461600>] ? test_range_bit+0x30/0x180 [btrfs]
[ 7411.127212]  [<ffffffffa044bd48>] run_delalloc_range+0x2e8/0x350 [btrfs]
[ 7411.127219]  [<ffffffffa04618f9>] ? find_lock_delalloc_range+0x1a9/0x1e0 [btrfs]
[ 7411.127222]  [<ffffffff812a1e71>] ? blk_queue_bio+0x2c1/0x330
[ 7411.127228]  [<ffffffffa0462ad4>] __extent_writepage+0x2f4/0x760 [btrfs]

Here we fix it by avoiding joining transaction again if we have held
a transaction handle when allocating chunk in find_free_extent().
Signed-off-by: Wang Shilong <wangsl.fnst@cn.fujitsu.com>
Signed-off-by: Chris Mason <clm@fb.com>

Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Wang Shilong <wangsl.fnst@cn.fujitsu.com>
Signed-off-by: Chris Mason <clm@fb.com>

To ease finding bugs during development related to modifying btree leaves
in such a way that it makes its items not sorted by key anymore. Since this
is an expensive check, it's only enabled if CONFIG_BTRFS_FS_CHECK_INTEGRITY
is set, which isn't meant to be enabled for regular users.
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>

When the csum tree is empty, our leaf (path->nodes[0]) has a number
of items equal to 0 and since btrfs_header_nritems() returns an
unsigned integer (and so is our local nritems variable) the following
comparison always evaluates to false:

     if (path->slots[0] >= nritems - 1) {

As the casting rules lead to:

     if ((u32)0 >= (u32)4294967295) {

This makes us access key at slot paths->slots[0] + 1 (1) of the empty leaf
some lines below:

    btrfs_item_key_to_cpu(path->nodes[0], &found_key, slot);
    if (found_key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
        found_key.type != BTRFS_EXTENT_CSUM_KEY) {
		found_next = 1;
		goto insert;
    }

So just don't access such non-existent slot and don't set found_next to 1
when the tree is empty. It's very unlikely we'll get a random key with the
objectid and type values above, which is where we could go into trouble.

If nritems is 0, just set found_next to 1 anyway as it will make us insert
a csum item covering our whole extent (or the whole leaf) when the tree is
empty.
Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com>
Signed-off-by: Chris Mason <clm@fb.com>

In close_ctree(), after we have stopped all workers,there maybe still
some read requests(for example readahead) to submit and this *maybe* trigger
an oops that user reported before:

kernel BUG at fs/btrfs/async-thread.c:619!

By hacking codes, i can reproduce this problem with one cpu available.
We fix this potential problem by invalidating all btree inode pages before
stopping all workers.

Thanks to Miao for pointing out this problem.
Signed-off-by: Wang Shilong <wangsl.fnst@cn.fujitsu.com>
Reviewed-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Chris Mason <clm@fb.com>

In btrfs_create_tree(), if btrfs_insert_root() fails, we should
free root->commit_root.
Reported-by: Alex Lyakas <alex@zadarastorage.com>
Signed-off-by: Tsutomu Itoh <t-itoh@jp.fujitsu.com>
Signed-off-by: Chris Mason <clm@fb.com>

posix_acl_xattr_set() already does the check, and it's the only
way to feed in an ACL from userspace.
So the check here is useless, remove it.
Signed-off-by: zhang zhen <zhenzhang.zhang@huawei.com>
Signed-off-by: Chris Mason <clm@fb.com>

This fix will ensure all SB copies on the disk is zeroed
when the disk is intentionally removed. This helps to
better manage disks in the user land.

This version of patch also merges the Zach patch as below.

 btrfs: don't double brelse on device rm
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Zach Brown <zab@redhat.com>
Signed-off-by: Chris Mason <clm@fb.com>

Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Wang Shilong <wangsl.fnst@cn.fujitsu.com>
Signed-off-by: Chris Mason <clm@fb.com>

This is a continuation of the previous changes titled:

   Btrfs: fix incremental send's decision to delay a dir move/rename
   Btrfs: part 2, fix incremental send's decision to delay a dir move/rename

There's a few more cases where a directory rename/move must be delayed which was
previously overlooked. If our immediate ancestor has a lower inode number than
ours and it doesn't have a delayed rename/move operation associated to it, it
doesn't mean there isn't any non-direct ancestor of our current inode that needs
to be renamed/moved before our current inode (i.e. with a higher inode number
than ours).

So we can't stop the search if our immediate ancestor has a lower inode number than
ours, we need to navigate the directory hierarchy upwards until we hit the root or:

1) find an ancestor with an higher inode number that was renamed/moved in the send
   root too (or already has a pending rename/move registered);
2) find an ancestor that is a new directory (higher inode number than ours and
   exists only in the send root).

Reproducer for case 1)

    $ mkfs.btrfs -f /dev/sdd
    $ mount /dev/sdd /mnt

    $ mkdir -p /mnt/a/b
    $ mkdir -p /mnt/a/c/d
    $ mkdir /mnt/a/b/e
    $ mkdir /mnt/a/c/d/f
    $ mv /mnt/a/b /mnt/a/c/d/2b
    $ mkdir /mnt/a/x
    $ mkdir /mnt/a/y

    $ btrfs subvolume snapshot -r /mnt /mnt/snap1
    $ btrfs send /mnt/snap1 -f /tmp/base.send

    $ mv /mnt/a/x /mnt/a/y
    $ mv /mnt/a/c/d/2b/e /mnt/a/c/d/2b/2e
    $ mv /mnt/a/c/d /mnt/a/h/2d
    $ mv /mnt/a/c /mnt/a/h/2d/2b/2c

    $ btrfs subvolume snapshot -r /mnt /mnt/snap2
    $ btrfs send -p /mnt/snap1 /mnt/snap2 -f /tmp/incremental.send

Simple reproducer for case 2)

    $ mkfs.btrfs -f /dev/sdd
    $ mount /dev/sdd /mnt

    $ mkdir -p /mnt/a/b
    $ mkdir /mnt/a/c
    $ mv /mnt/a/b /mnt/a/c/b2
    $ mkdir /mnt/a/e

    $ btrfs subvolume snapshot -r /mnt /mnt/snap1
    $ btrfs send /mnt/snap1 -f /tmp/base.send

    $ mv /mnt/a/c/b2 /mnt/a/e/b3
    $ mkdir /mnt/a/e/b3/f
    $ mkdir /mnt/a/h
    $ mv /mnt/a/c /mnt/a/e/b3/f/c2
    $ mv /mnt/a/e /mnt/a/h/e2

    $ btrfs subvolume snapshot -r /mnt /mnt/snap2
    $ btrfs send -p /mnt/snap1 /mnt/snap2 -f /tmp/incremental.send

Another simple reproducer for case 2)

    $ mkfs.btrfs -f /dev/sdd
    $ mount /dev/sdd /mnt

    $ mkdir -p /mnt/a/b
    $ mkdir /mnt/a/c
    $ mkdir /mnt/a/b/d
    $ mkdir /mnt/a/c/e

    $ btrfs subvolume snapshot -r /mnt /mnt/snap1
    $ btrfs send /mnt/snap1 -f /tmp/base.send

    $ mkdir /mnt/a/b/d/f
    $ mkdir /mnt/a/b/g
    $ mv /mnt/a/c/e /mnt/a/b/g/e2
    $ mv /mnt/a/c /mnt/a/b/d/f/c2
    $ mv /mnt/a/b/d/f /mnt/a/b/g/e2/f2

    $ btrfs subvolume snapshot -r /mnt /mnt/snap2
    $ btrfs send -p /mnt/snap1 /mnt/snap2 -f /tmp/incremental.send

More complex reproducer for case 2)

    $ mkfs.btrfs -f /dev/sdd
    $ mount /dev/sdd /mnt

    $ mkdir -p /mnt/a/b
    $ mkdir -p /mnt/a/c/d
    $ mkdir /mnt/a/b/e
    $ mkdir /mnt/a/c/d/f
    $ mv /mnt/a/b /mnt/a/c/d/2b
    $ mkdir /mnt/a/x
    $ mkdir /mnt/a/y

    $ btrfs subvolume snapshot -r /mnt /mnt/snap1
    $ btrfs send /mnt/snap1 -f /tmp/base.send

    $ mv /mnt/a/x /mnt/a/y
    $ mv /mnt/a/c/d/2b/e /mnt/a/c/d/2b/2e
    $ mv /mnt/a/c/d /mnt/a/h/2d
    $ mv /mnt/a/c /mnt/a/h/2d/2b/2c

    $ btrfs subvolume snapshot -r /mnt /mnt/snap2
    $ btrfs send -p /mnt/snap1 /mnt/snap2 -f /tmp/incremental.send

For both cases the incremental send would enter an infinite loop when building
path strings.

While solving these cases, this change also re-implements the code to detect
when directory moves/renames should be delayed. Instead of dealing with several
specific cases separately, it's now more generic handling all cases with a simple
detection algorithm and if when applying a delayed move/rename there's a path loop
detected, it further delays the move/rename registering a new ancestor inode as
the dependency inode (so our rename happens after that ancestor is renamed).

Tests for these cases is being added to xfstests too.
Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com>
Signed-off-by: Chris Mason <clm@fb.com>

Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com>
Signed-off-by: Chris Mason <clm@fb.com>

If we have directories with a pending move/rename operation, we must take into
account any orphan directories that got created before executing the pending
move/rename. Those orphan directories are directories with an inode number higher
then the current send progress and that don't exist in the parent snapshot, they
are created before current progress reaches their inode number, with a generated
name of the form oN-M-I and at the root of the filesystem tree, and later when
progress matches their inode number, moved/renamed to their final location.

Reproducer:

          $ mkfs.btrfs -f /dev/sdd
          $ mount /dev/sdd /mnt

          $ mkdir -p /mnt/a/b/c/d
          $ mkdir /mnt/a/b/e
          $ mv /mnt/a/b/c /mnt/a/b/e/CC
          $ mkdir /mnt/a/b/e/CC/d/f
	  $ mkdir /mnt/a/g

          $ btrfs subvolume snapshot -r /mnt /mnt/snap1
          $ btrfs send /mnt/snap1 -f /tmp/base.send

          $ mkdir /mnt/a/g/h
	  $ mv /mnt/a/b/e /mnt/a/g/h/EE
          $ mv /mnt/a/g/h/EE/CC/d /mnt/a/g/h/EE/DD

          $ btrfs subvolume snapshot -r /mnt /mnt/snap2
          $ btrfs send -p /mnt/snap1 /mnt/snap2 -f /tmp/incremental.send

The second receive command failed with the following error:

    ERROR: rename a/b/e/CC/d -> o264-7-0/EE/DD failed. No such file or directory

A test case for xfstests follows soon.
Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com>
Signed-off-by: Chris Mason <clm@fb.com>

Regardless of whether the caller is interested or not in knowing the inode's
generation (dir_gen != NULL), get_first_ref always does a btree lookup to get
the inode item. Avoid this useless lookup if dir_gen parameter is NULL (which
is in some cases).
Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com>
Signed-off-by: Chris Mason <clm@fb.com>

For RAID0,5,6,10,
For system chunk, there shouldn't be too many stripes to
make a btrfs_chunk that exceeds BTRFS_SYSTEM_CHUNK_ARRAY_SIZE
For data/meta chunk, there shouldn't be too many stripes to
make a btrfs_chunk that exceeds a leaf.
Signed-off-by: Gui Hecheng <guihc.fnst@cn.fujitsu.com>
Signed-off-by: Chris Mason <clm@fb.com>

For system chunk array,
We copy a "disk_key" and an chunk item each time,
so there should be enough space to hold both of them,
not only the chunk item.
Signed-off-by: Gui Hecheng <guihc.fnst@cn.fujitsu.com>
Signed-off-by: Chris Mason <clm@fb.com>

Current btrfs_orphan_cleanup will also cleanup roots which is already in
fs_info->dead_roots without protection.
This will have conditional race with fs_info->cleaner_kthread.

This patch will use refs in root->root_item to detect roots in
dead_roots and avoid conflicts.
Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Signed-off-by: Chris Mason <clm@fb.com>

Before applying this patch, the task had to reclaim the metadata space
by itself if the metadata space was not enough. And When the task started
the space reclamation, all the other tasks which wanted to reserve the
metadata space were blocked. At some cases, they would be blocked for
a long time, it made the performance fluctuate wildly.

So we introduce the background metadata space reclamation, when the space
is about to be exhausted, we insert a reclaim work into the workqueue, the
worker of the workqueue helps us to reclaim the reserved space at the
background. By this way, the tasks needn't reclaim the space by themselves at
most cases, and even if the tasks have to reclaim the space or are blocked
for the space reclamation, they will get enough space more quickly.

Here is my test result(Tested by compilebench):
 Memory:	2GB
 CPU:		2Cores * 1CPU
 Partition:	40GB(SSD)

Test command:
 # compilebench -D <mnt> -m

Without this patch:
 intial create total runs 30 avg 54.36 MB/s (user 0.52s sys 2.44s)
 compile total runs 30 avg 123.72 MB/s (user 0.13s sys 1.17s)
 read compiled tree total runs 3 avg 81.15 MB/s (user 0.74s sys 4.89s)
 delete compiled tree total runs 30 avg 5.32 seconds (user 0.35s sys 4.37s)

With this patch:
 intial create total runs 30 avg 59.80 MB/s (user 0.52s sys 2.53s)
 compile total runs 30 avg 151.44 MB/s (user 0.13s sys 1.11s)
 read compiled tree total runs 3 avg 83.25 MB/s (user 0.76s sys 4.91s)
 delete compiled tree total runs 30 avg 5.29 seconds (user 0.34s sys 4.34s)
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Chris Mason <clm@fb.com>

If we fail to load a free space cache, we can rebuild it from the extent tree,
so it is not a serious error, we should not output a error message that
would make the users uncomfortable. This patch uses warning message instead
of it.
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Chris Mason <clm@fb.com>

Btrfs will send uevent to udev inform the device change,
but ctime/mtime for the block device inode is not udpated, which cause
libblkid used by btrfs-progs unable to detect device change and use old
cache, causing 'btrfs dev scan; btrfs dev rmove; btrfs dev scan' give an
error message.
Reported-by: Tsutomu Itoh <t-itoh@jp.fujitsu.com>
Cc: Karel Zak <kzak@redhat.com>
Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Signed-off-by: Chris Mason <clm@fb.com>

CC: Miao Xie <miaox@cn.fujitsu.com>
CC: Wang Shilong <wangsl.fnst@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Chris Mason <clm@fb.com>

The patch "Btrfs: fix protection between send and root deletion"
(18f687d5) does not actually prevent to delete the snapshot
and just takes care during background cleaning, but this seems rather
user unfriendly, this patch implements the idea presented in

http://www.spinics.net/lists/linux-btrfs/msg30813.html

- add an internal root_item flag to denote a dead root
- check if the send_in_progress is set and refuse to delete, otherwise
  set the flag and proceed
- check the flag in send similar to the btrfs_root_readonly checks, for
  all involved roots

The root lookup in send via btrfs_read_fs_root_no_name will check if the
root is really dead or not. If it is, ENOENT, aborted send. If it's
alive, it's protected by send_in_progress, send can continue.

CC: Miao Xie <miaox@cn.fujitsu.com>
CC: Wang Shilong <wangsl.fnst@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Chris Mason <clm@fb.com>

It doesn't need to check NULL for kfree()
Signed-off-by: Daeseok Youn <daeseok.youn@gmail.com>
Signed-off-by: Chris Mason <clm@fb.com>

This implements the tmpfile callback of struct inode_operations, introduced
in the linux kernel 3.11, and implemented already by some filesystems. This
callback is invoked by the VFS when the flag O_TMPFILE is passed to the open
system call.
Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com>
Signed-off-by: Chris Mason <clm@fb.com>
Reviewed-by: David Sterba <dsterba@suse.cz>

This ioctl provides basic info about the filesystem that can be obtained
in other ways (eg. sysfs), there's no reason to restrict it to
CAP_SYSADMIN.
Signed-off-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Chris Mason <clm@fb.com>

This ioctl provides basic info about the devices that can be obtained in
other ways (eg. sysfs), there's no reason to restrict it to
CAP_SYSADMIN.
Signed-off-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Chris Mason <clm@fb.com>

Similar to the FS_INFO updates, export the basic filesystem info through
sysfs: node size, sector size and clone alignment.
Signed-off-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Chris Mason <clm@fb.com>

Provide the basic information about filesystem through the ioctl:
* b-tree node size (same as leaf size)
* sector size
* expected alignment of CLONE_RANGE and EXTENT_SAME ioctl arguments

Backward compatibility: if the values are 0, kernel does not provide
this information, the applications should ignore them.
Signed-off-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Chris Mason <clm@fb.com>

This started as debugging helper, to watch the effects of converting
between raid levels on multiple devices, but could be useful standalone.

In my case the usage filter was not finegrained enough and led to
converting too many chunks at once. Another example use is in connection
with drange+devid or vrange filters that allow to work with a specific
chunk or even with a chunk on a given device.

The limit filter applies last, the value of 0 means no limiting.

CC: Ilya Dryomov <idryomov@gmail.com>
CC: Hugo Mills <hugo@carfax.org.uk>
Signed-off-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Chris Mason <clm@fb.com>

While running a stress test with multiple threads writing to the same btrfs
file system, I ended up with a situation where a leaf was corrupted in that
it had 2 file extent item keys that had the same exact key. I was able to
detect this quickly thanks to the following patch which triggers an assertion
as soon as a leaf is marked dirty if there are duplicated keys or out of order
keys:

    Btrfs: check if items are ordered when a leaf is marked dirty
    (https://patchwork.kernel.org/patch/3955431/)

Basically while running the test, I got the following in dmesg:

    [28877.415877] WARNING: CPU: 2 PID: 10706 at fs/btrfs/file.c:553 btrfs_drop_extent_cache+0x435/0x440 [btrfs]()
    (...)
    [28877.415917] Call Trace:
    [28877.415922]  [<ffffffff816f1189>] dump_stack+0x4e/0x68
    [28877.415926]  [<ffffffff8104a32c>] warn_slowpath_common+0x8c/0xc0
    [28877.415929]  [<ffffffff8104a37a>] warn_slowpath_null+0x1a/0x20
    [28877.415944]  [<ffffffffa03775a5>] btrfs_drop_extent_cache+0x435/0x440 [btrfs]
    [28877.415949]  [<ffffffff8118e7be>] ? kmem_cache_alloc+0xfe/0x1c0
    [28877.415962]  [<ffffffffa03777d9>] fill_holes+0x229/0x3e0 [btrfs]
    [28877.415972]  [<ffffffffa0345865>] ? block_rsv_add_bytes+0x55/0x80 [btrfs]
    [28877.415984]  [<ffffffffa03792cb>] btrfs_fallocate+0xb6b/0xc20 [btrfs]
    (...)
    [29854.132560] BTRFS critical (device sdc): corrupt leaf, bad key order: block=955232256,root=1, slot=24
    [29854.132565] BTRFS info (device sdc): leaf 955232256 total ptrs 40 free space 778
    (...)
    [29854.132637] 	item 23 key (3486 108 667648) itemoff 2694 itemsize 53
    [29854.132638] 		extent data disk bytenr 14574411776 nr 286720
    [29854.132639] 		extent data offset 0 nr 286720 ram 286720
    [29854.132640] 	item 24 key (3486 108 954368) itemoff 2641 itemsize 53
    [29854.132641] 		extent data disk bytenr 0 nr 0
    [29854.132643] 		extent data offset 0 nr 0 ram 0
    [29854.132644] 	item 25 key (3486 108 954368) itemoff 2588 itemsize 53
    [29854.132645] 		extent data disk bytenr 8699670528 nr 77824
    [29854.132646] 		extent data offset 0 nr 77824 ram 77824
    [29854.132647] 	item 26 key (3486 108 1146880) itemoff 2535 itemsize 53
    [29854.132648] 		extent data disk bytenr 8699670528 nr 77824
    [29854.132649] 		extent data offset 0 nr 77824 ram 77824
    (...)
    [29854.132707] kernel BUG at fs/btrfs/ctree.h:3901!
    (...)
    [29854.132771] Call Trace:
    [29854.132779]  [<ffffffffa0342b5c>] setup_items_for_insert+0x2dc/0x400 [btrfs]
    [29854.132791]  [<ffffffffa0378537>] __btrfs_drop_extents+0xba7/0xdd0 [btrfs]
    [29854.132794]  [<ffffffff8109c0d6>] ? trace_hardirqs_on_caller+0x16/0x1d0
    [29854.132797]  [<ffffffff8109c29d>] ? trace_hardirqs_on+0xd/0x10
    [29854.132800]  [<ffffffff8118e7be>] ? kmem_cache_alloc+0xfe/0x1c0
    [29854.132810]  [<ffffffffa036783b>] insert_reserved_file_extent.constprop.66+0xab/0x310 [btrfs]
    [29854.132820]  [<ffffffffa036a6c6>] __btrfs_prealloc_file_range+0x116/0x340 [btrfs]
    [29854.132830]  [<ffffffffa0374d53>] btrfs_prealloc_file_range+0x23/0x30 [btrfs]
    (...)

So this is caused by getting an -ENOSPC error while punching a file hole, more
specifically, we get -ENOSPC error from __btrfs_drop_extents in the while loop
of file.c:btrfs_punch_hole() when it's unable to modify the btree to delete one
or more file extent items due to lack of enough free space. When this happens,
in btrfs_punch_hole(), we attempt to reclaim free space by switching our transaction
block reservation object to root->fs_info->trans_block_rsv, end our transaction and
start a new transaction basically - and, we keep increasing our current offset
(cur_offset) as long as it's smaller than the end of the target range (lockend) -
this makes use leave the loop with cur_offset == drop_end which in turn makes us
call fill_holes() for inserting a file extent item that represents a 0 bytes range
hole (and this insertion succeeds, as in the meanwhile more space became available).

This 0 bytes file hole extent item is a problem because any subsequent caller of
__btrfs_drop_extents (regular file writes, or fallocate calls for e.g.), with a
start file offset that is equal to the offset of the hole, will not remove this
extent item due to the following conditional in the while loop of
__btrfs_drop_extents:

    if (extent_end <= search_start) {
            path->slots[0]++;
            goto next_slot;
    }

This later makes the call to setup_items_for_insert() (at the very end of
__btrfs_drop_extents), insert a new file extent item with the same offset as
the 0 bytes file hole extent item that follows it. Needless is to say that this
causes chaos, either when reading the leaf from disk (btree_readpage_end_io_hook),
where we perform leaf sanity checks or in subsequent operations that manipulate
file extent items, as in the fallocate call as shown by the dmesg trace above.

Without my other patch to perform the leaf sanity checks once a leaf is marked
as dirty (if the integrity checker is enabled), it would have been much harder
to debug this issue.

This change might fix a few similar issues reported by users in the mailing
list regarding assertion failures in btrfs_set_item_key_safe calls performed
by __btrfs_drop_extents, such as the following report:

    http://comments.gmane.org/gmane.comp.file-systems.btrfs/32938

Asking fill_holes() to create a 0 bytes wide file hole item also produced the
first warning in the trace above, as we passed a range to btrfs_drop_extent_cache
that has an end smaller (by -1) than its start.

On 3.14 kernels this issue manifests itself through leaf corruption, as we get
duplicated file extent item keys in a leaf when calling setup_items_for_insert(),
but on older kernels, setup_items_for_insert() isn't called by __btrfs_drop_extents(),
instead we have callers of __btrfs_drop_extents(), namely the functions
inode.c:insert_inline_extent() and inode.c:insert_reserved_file_extent(), calling
btrfs_insert_empty_item() to insert the new file extent item, which would fail with
error -EEXIST, instead of inserting a duplicated key - which is still a serious
issue as it would make all similar file extent item replace operations keep
failing if they target the same file range.

Cc: stable@vger.kernel.org
Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com>
Signed-off-by: Chris Mason <clm@fb.com>

'bio_index' is just a index, it's really not necessary to do increment
one by one.
Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Chris Mason <clm@fb.com>

In a previous change, commit 12870f1c,
I accidentally moved the roundup of inode->i_size to outside of the
critical section delimited by the inode mutex, which is not atomic and
not correct since the size can be changed by other task before we acquire
the mutex. Therefore fix it.
Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com>
Signed-off-by: Chris Mason <clm@fb.com>

iput() already checks for the inode being NULL, thus it's unnecessary to
check before calling.
Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
Signed-off-by: Chris Mason <clm@fb.com>

uncompress_inline() is dropping the error from btrfs_decompress() after
testing it and zeroing the page that was supposed to hold decompressed
data.  This can silently turn compressed inline data in to zeros if
decompression fails due to corrupt compressed data or memory allocation
failure.

I verified this by manually forcing the error from btrfs_decompress()
for a silly named copy of od:

	if (!strcmp(current->comm, "failod"))
		ret = -ENOMEM;

  # od -x /mnt/btrfs/dir/80 | head -1
  0000000 3031 3038 310a 2d30 6f70 6e69 0a74 3031
  # echo 3 > /proc/sys/vm/drop_caches
  # cp $(which od) /tmp/failod
  # /tmp/failod -x /mnt/btrfs/dir/80 | head -1
  0000000 0000 0000 0000 0000 0000 0000 0000 0000

The fix is to pass the error to its caller.  Which still has a BUG_ON().
So we fix that too.

There seems to be no reason for the zeroing of the page on the error
from btrfs_decompress() but not from the allocation error a few lines
above.  So the page zeroing is removed.
Signed-off-by: Zach Brown <zab@redhat.com>
Reviewed-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Chris Mason <clm@fb.com>

The btrfs compression wrappers translated errors from workspace
allocation to either -ENOMEM or -1.  The compression type workspace
allocators are already returning a ERR_PTR(-ENOMEM).  Just return that
and get rid of the magical -1.

This helps a future patch return errors from the compression wrappers.
Signed-off-by: Zach Brown <zab@redhat.com>
Reviewed-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Chris Mason <clm@fb.com>

The compression layer seems to have been built to return -1 and have
callers make up errors that make sense.  This isn't great because there
are different errors that originate down in the compression layer.

Let's return real negative errnos from the compression layer so that
callers can pass on the error without having to guess what happened.
ENOMEM for allocation failure, E2BIG when compression exceeds the
uncompressed input, and EIO for everything else.

This helps a future path return errors from btrfs_decompress().
Signed-off-by: Zach Brown <zab@redhat.com>
Signed-off-by: Chris Mason <clm@fb.com>

This issue was not causing any harm but IMO (and in the opinion of the
static code checker) it is better to propagate this error status upwards.
Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Chris Mason <clm@fb.com>

When running low on available disk space and having several processes
doing buffered file IO, I got the following trace in dmesg:

[ 4202.720152] INFO: task kworker/u8:1:5450 blocked for more than 120 seconds.
[ 4202.720401]       Not tainted 3.13.0-fdm-btrfs-next-26+ #1
[ 4202.720596] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[ 4202.720874] kworker/u8:1    D 0000000000000001     0  5450      2 0x00000000
[ 4202.720904] Workqueue: btrfs-flush_delalloc normal_work_helper [btrfs]
[ 4202.720908]  ffff8801f62ddc38 0000000000000082 ffff880203ac2490 00000000001d3f40
[ 4202.720913]  ffff8801f62ddfd8 00000000001d3f40 ffff8800c4f0c920 ffff880203ac2490
[ 4202.720918]  00000000001d4a40 ffff88020fe85a40 ffff88020fe85ab8 0000000000000001
[ 4202.720922] Call Trace:
[ 4202.720931]  [<ffffffff816a3cb9>] schedule+0x29/0x70
[ 4202.720950]  [<ffffffffa01ec48d>] btrfs_start_ordered_extent+0x6d/0x110 [btrfs]
[ 4202.720956]  [<ffffffff8108e620>] ? bit_waitqueue+0xc0/0xc0
[ 4202.720972]  [<ffffffffa01ec559>] btrfs_run_ordered_extent_work+0x29/0x40 [btrfs]
[ 4202.720988]  [<ffffffffa0201987>] normal_work_helper+0x137/0x2c0 [btrfs]
[ 4202.720994]  [<ffffffff810680e5>] process_one_work+0x1f5/0x530
(...)
[ 4202.721027] 2 locks held by kworker/u8:1/5450:
[ 4202.721028]  #0:  (%s-%s){++++..}, at: [<ffffffff81068083>] process_one_work+0x193/0x530
[ 4202.721037]  #1:  ((&work->normal_work)){+.+...}, at: [<ffffffff81068083>] process_one_work+0x193/0x530
[ 4202.721054] INFO: task btrfs:7891 blocked for more than 120 seconds.
[ 4202.721258]       Not tainted 3.13.0-fdm-btrfs-next-26+ #1
[ 4202.721444] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[ 4202.721699] btrfs           D 0000000000000001     0  7891   7890 0x00000001
[ 4202.721704]  ffff88018c2119e8 0000000000000086 ffff8800a33d2490 00000000001d3f40
[ 4202.721710]  ffff88018c211fd8 00000000001d3f40 ffff8802144b0000 ffff8800a33d2490
[ 4202.721714]  ffff8800d8576640 ffff88020fe85bc0 ffff88020fe85bc8 7fffffffffffffff
[ 4202.721718] Call Trace:
[ 4202.721723]  [<ffffffff816a3cb9>] schedule+0x29/0x70
[ 4202.721727]  [<ffffffff816a2ebc>] schedule_timeout+0x1dc/0x270
[ 4202.721732]  [<ffffffff8109bd79>] ? mark_held_locks+0xb9/0x140
[ 4202.721736]  [<ffffffff816a90c0>] ? _raw_spin_unlock_irq+0x30/0x40
[ 4202.721740]  [<ffffffff8109bf0d>] ? trace_hardirqs_on_caller+0x10d/0x1d0
[ 4202.721744]  [<ffffffff816a488f>] wait_for_completion+0xdf/0x120
[ 4202.721749]  [<ffffffff8107fa90>] ? try_to_wake_up+0x310/0x310
[ 4202.721765]  [<ffffffffa01ebee4>] btrfs_wait_ordered_extents+0x1f4/0x280 [btrfs]
[ 4202.721781]  [<ffffffffa020526e>] btrfs_mksubvol.isra.62+0x30e/0x5a0 [btrfs]
[ 4202.721786]  [<ffffffff8108e620>] ? bit_waitqueue+0xc0/0xc0
[ 4202.721799]  [<ffffffffa02056a9>] btrfs_ioctl_snap_create_transid+0x1a9/0x1b0 [btrfs]
[ 4202.721813]  [<ffffffffa020583a>] btrfs_ioctl_snap_create_v2+0x10a/0x170 [btrfs]
(...)

It turns out that extent_io.c:__extent_writepage(), which ends up being called
through filemap_fdatawrite_range() in btrfs_start_ordered_extent(), was getting
-ENOSPC when calling the fill_delalloc callback. In this situation, it returned
without the writepage_end_io_hook callback (inode.c:btrfs_writepage_end_io_hook)
ever being called for the respective page, which prevents the ordered extent's
bytes_left count from ever reaching 0, and therefore a finish_ordered_fn work
is never queued into the endio_write_workers queue. This makes the task that
called btrfs_start_ordered_extent() hang forever on the wait queue of the ordered
extent.

This is fairly easy to reproduce using a small filesystem and fsstress on
a quad core vm:

    mkfs.btrfs -f -b `expr 2100 \* 1024 \* 1024` /dev/sdd
    mount /dev/sdd /mnt

    fsstress -p 6 -d /mnt -n 100000 -x \
        "btrfs subvolume snapshot -r /mnt /mnt/mysnap" \
	    -f allocsp=0 \
	    -f bulkstat=0 \
	    -f bulkstat1=0 \
	    -f chown=0 \
	    -f creat=1 \
	    -f dread=0 \
	    -f dwrite=0 \
	    -f fallocate=1 \
	    -f fdatasync=0 \
	    -f fiemap=0 \
	    -f freesp=0 \
	    -f fsync=0 \
	    -f getattr=0 \
	    -f getdents=0 \
	    -f link=0 \
	    -f mkdir=0 \
	    -f mknod=0 \
	    -f punch=1 \
	    -f read=0 \
	    -f readlink=0 \
	    -f rename=0 \
	    -f resvsp=0 \
	    -f rmdir=0 \
	    -f setxattr=0 \
	    -f stat=0 \
	    -f symlink=0 \
	    -f sync=0 \
	    -f truncate=1 \
	    -f unlink=0 \
	    -f unresvsp=0 \
	    -f write=4

So just ensure that if an error happens while writing the extent page
we call the writepage_end_io_hook callback. Also make it return the
error code and ensure the caller (extent_write_cache_pages) processes
all pages in the page vector even if an error happens only for some
of them, so that ordered extents end up released.
Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com>
Signed-off-by: Chris Mason <clm@fb.com>

This reverts commit 3e1a878b.

It came in very late, and already has one reported failure: Sitsofe
reports that the current tree fails to boot on his EeePC, and bisected
it down to this.  Rather than waste time trying to figure out what's
wrong, just revert it.
Reported-by: Sitsofe Wheeler <sitsofe@gmail.com>
Cc: Igor Mammedov <imammedo@redhat.com>
Cc: Toshi Kani <toshi.kani@hp.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Pull btrfs fix from Chris Mason:
 "I had this in my 3.16 merge window queue, but it is small and obvious
  enough for 3.15.  I cherry-picked and retested against current rc8"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs:
  Btrfs: send, fix corrupted path strings for long paths