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commit 410f954cb1d1c79ae485dd83a175f21954fd87cd upstream.
Sometimes when fsync'ing a file we need to log that other inodes exist and
when we need to do that we acquire a reference on the inodes and then drop
that reference using iput() after logging them.
That generally is not a problem except if we end up doing the final iput()
(dropping the last reference) on the inode and that inode has a link count
of 0, which can happen in a very short time window if the logging path
gets a reference on the inode while it's being unlinked.
In that case we end up getting the eviction callback, btrfs_evict_inode(),
invoked through the iput() call chain which needs to drop all of the
inode's items from its subvolume btree, and in order to do that, it needs
to join a transaction at the helper function evict_refill_and_join().
However because the task previously started a transaction at the fsync
handler, btrfs_sync_file(), it has current->journal_info already pointing
to a transaction handle and therefore evict_refill_and_join() will get
that transaction handle from btrfs_join_transaction(). From this point on,
two different problems can happen:
1) evict_refill_and_join() will often change the transaction handle's
block reserve (->block_rsv) and set its ->bytes_reserved field to a
value greater than 0. If evict_refill_and_join() never commits the
transaction, the eviction handler ends up decreasing the reference
count (->use_count) of the transaction handle through the call to
btrfs_end_transaction(), and after that point we have a transaction
handle with a NULL ->block_rsv (which is the value prior to the
transaction join from evict_refill_and_join()) and a ->bytes_reserved
value greater than 0. If after the eviction/iput completes the inode
logging path hits an error or it decides that it must fallback to a
transaction commit, the btrfs fsync handle, btrfs_sync_file(), gets a
non-zero value from btrfs_log_dentry_safe(), and because of that
non-zero value it tries to commit the transaction using a handle with
a NULL ->block_rsv and a non-zero ->bytes_reserved value. This makes
the transaction commit hit an assertion failure at
btrfs_trans_release_metadata() because ->bytes_reserved is not zero but
the ->block_rsv is NULL. The produced stack trace for that is like the
following:
[192922.917158] assertion failed: !trans->bytes_reserved, file: fs/btrfs/transaction.c, line: 816
[192922.917553] ------------[ cut here ]------------
[192922.917922] kernel BUG at fs/btrfs/ctree.h:3532!
[192922.918310] invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC PTI
[192922.918666] CPU: 2 PID: 883 Comm: fsstress Tainted: G W 5.1.4-btrfs-next-47 #1
[192922.919035] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.11.2-0-gf9626ccb91-prebuilt.qemu-project.org 04/01/2014
[192922.919801] RIP: 0010:assfail.constprop.25+0x18/0x1a [btrfs]
(...)
[192922.920925] RSP: 0018:ffffaebdc8a27da8 EFLAGS: 00010286
[192922.921315] RAX: 0000000000000051 RBX: ffff95c9c16a41c0 RCX: 0000000000000000
[192922.921692] RDX: 0000000000000000 RSI: ffff95cab6b16838 RDI: ffff95cab6b16838
[192922.922066] RBP: ffff95c9c16a41c0 R08: 0000000000000000 R09: 0000000000000000
[192922.922442] R10: ffffaebdc8a27e70 R11: 0000000000000000 R12: ffff95ca731a0980
[192922.922820] R13: 0000000000000000 R14: ffff95ca84c73338 R15: ffff95ca731a0ea8
[192922.923200] FS: 00007f337eda4e80(0000) GS:ffff95cab6b00000(0000) knlGS:0000000000000000
[192922.923579] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[192922.923948] CR2: 00007f337edad000 CR3: 00000001e00f6002 CR4: 00000000003606e0
[192922.924329] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[192922.924711] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[192922.925105] Call Trace:
[192922.925505] btrfs_trans_release_metadata+0x10c/0x170 [btrfs]
[192922.925911] btrfs_commit_transaction+0x3e/0xaf0 [btrfs]
[192922.926324] btrfs_sync_file+0x44c/0x490 [btrfs]
[192922.926731] do_fsync+0x38/0x60
[192922.927138] __x64_sys_fdatasync+0x13/0x20
[192922.927543] do_syscall_64+0x60/0x1c0
[192922.927939] entry_SYSCALL_64_after_hwframe+0x49/0xbe
(...)
[192922.934077] ---[ end trace f00808b12068168f ]---
2) If evict_refill_and_join() decides to commit the transaction, it will
be able to do it, since the nested transaction join only increments the
transaction handle's ->use_count reference counter and it does not
prevent the transaction from getting committed. This means that after
eviction completes, the fsync logging path will be using a transaction
handle that refers to an already committed transaction. What happens
when using such a stale transaction can be unpredictable, we are at
least having a use-after-free on the transaction handle itself, since
the transaction commit will call kmem_cache_free() against the handle
regardless of its ->use_count value, or we can end up silently losing
all the updates to the log tree after that iput() in the logging path,
or using a transaction handle that in the meanwhile was allocated to
another task for a new transaction, etc, pretty much unpredictable
what can happen.
In order to fix both of them, instead of using iput() during logging, use
btrfs_add_delayed_iput(), so that the logging path of fsync never drops
the last reference on an inode, that step is offloaded to a safe context
(usually the cleaner kthread).
The assertion failure issue was sporadically triggered by the test case
generic/475 from fstests, which loads the dm error target while fsstress
is running, which lead to fsync failing while logging inodes with -EIO
errors and then trying later to commit the transaction, triggering the
assertion failure.
CC: stable@vger.kernel.org # 4.4+
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 06989c799f04810f6876900d4760c0edda369cf7 upstream.
When syncing the log, the final phase of a fsync operation, we need to
either create a log root's item or update the existing item in the log
tree of log roots, and that depends on the current value of the log
root's log_transid - if it's 1 we need to create the log root item,
otherwise it must exist already and we update it. Since there is no
synchronization between updating the log_transid and checking it for
deciding whether the log root's item needs to be created or updated, we
end up with a tiny race window that results in attempts to update the
item to fail because the item was not yet created:
CPU 1 CPU 2
btrfs_sync_log()
lock root->log_mutex
set log root's log_transid to 1
unlock root->log_mutex
btrfs_sync_log()
lock root->log_mutex
sets log root's
log_transid to 2
unlock root->log_mutex
update_log_root()
sees log root's log_transid
with a value of 2
calls btrfs_update_root(),
which fails with -EUCLEAN
and causes transaction abort
Until recently the race lead to a BUG_ON at btrfs_update_root(), but after
the recent commit 7ac1e464c4d47 ("btrfs: Don't panic when we can't find a
root key") we just abort the current transaction.
A sample trace of the BUG_ON() on a SLE12 kernel:
------------[ cut here ]------------
kernel BUG at ../fs/btrfs/root-tree.c:157!
Oops: Exception in kernel mode, sig: 5 [#1]
SMP NR_CPUS=2048 NUMA pSeries
(...)
Supported: Yes, External
CPU: 78 PID: 76303 Comm: rtas_errd Tainted: G X 4.4.156-94.57-default #1
task: c00000ffa906d010 ti: c00000ff42b08000 task.ti: c00000ff42b08000
NIP: d000000036ae5cdc LR: d000000036ae5cd8 CTR: 0000000000000000
REGS: c00000ff42b0b860 TRAP: 0700 Tainted: G X (4.4.156-94.57-default)
MSR: 8000000002029033 <SF,VEC,EE,ME,IR,DR,RI,LE> CR: 22444484 XER: 20000000
CFAR: d000000036aba66c SOFTE: 1
GPR00: d000000036ae5cd8 c00000ff42b0bae0 d000000036bda220 0000000000000054
GPR04: 0000000000000001 0000000000000000 c00007ffff8d37c8 0000000000000000
GPR08: c000000000e19c00 0000000000000000 0000000000000000 3736343438312079
GPR12: 3930373337303434 c000000007a3a800 00000000007fffff 0000000000000023
GPR16: c00000ffa9d26028 c00000ffa9d261f8 0000000000000010 c00000ffa9d2ab28
GPR20: c00000ff42b0bc48 0000000000000001 c00000ff9f0d9888 0000000000000001
GPR24: c00000ffa9d26000 c00000ffa9d261e8 c00000ffa9d2a800 c00000ff9f0d9888
GPR28: c00000ffa9d26028 c00000ffa9d2aa98 0000000000000001 c00000ffa98f5b20
NIP [d000000036ae5cdc] btrfs_update_root+0x25c/0x4e0 [btrfs]
LR [d000000036ae5cd8] btrfs_update_root+0x258/0x4e0 [btrfs]
Call Trace:
[c00000ff42b0bae0] [d000000036ae5cd8] btrfs_update_root+0x258/0x4e0 [btrfs] (unreliable)
[c00000ff42b0bba0] [d000000036b53610] btrfs_sync_log+0x2d0/0xc60 [btrfs]
[c00000ff42b0bce0] [d000000036b1785c] btrfs_sync_file+0x44c/0x4e0 [btrfs]
[c00000ff42b0bd80] [c00000000032e300] vfs_fsync_range+0x70/0x120
[c00000ff42b0bdd0] [c00000000032e44c] do_fsync+0x5c/0xb0
[c00000ff42b0be10] [c00000000032e8dc] SyS_fdatasync+0x2c/0x40
[c00000ff42b0be30] [c000000000009488] system_call+0x3c/0x100
Instruction dump:
7f43d378 4bffebb9 60000000 88d90008 3d220000 e8b90000 3b390009 e87a01f0
e8898e08 e8f90000 4bfd48e5 60000000 <0fe00000> e95b0060 39200004 394a0ea0
---[ end trace 8f2dc8f919cabab8 ]---
So fix this by doing the check of log_transid and updating or creating the
log root's item while holding the root's log_mutex.
Fixes: 7237f1833601d ("Btrfs: fix tree logs parallel sync")
CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 2cc8334270e281815c3850c3adea363c51f21e0d upstream.
When Filipe added the recursive directory logging stuff in
2f2ff0ee5e430 ("Btrfs: fix metadata inconsistencies after directory
fsync") he specifically didn't take the directory i_mutex for the
children directories that we need to log because of lockdep. This is
generally fine, but can lead to this WARN_ON() tripping if we happen to
run delayed deletion's in between our first search and our second search
of dir_item/dir_indexes for this directory. We expect this to happen,
so the WARN_ON() isn't necessary. Drop the WARN_ON() and add a comment
so we know why this case can happen.
CC: stable@vger.kernel.org # 4.4+
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 0f375eed92b5a407657532637ed9652611a682f5 upstream.
In a scenario like the following:
mkdir /mnt/A # inode 258
mkdir /mnt/B # inode 259
touch /mnt/B/bar # inode 260
sync
mv /mnt/B/bar /mnt/A/bar
mv -T /mnt/A /mnt/B
fsync /mnt/B/bar
<power fail>
After replaying the log we end up with file bar having 2 hard links, both
with the name 'bar' and one in the directory with inode number 258 and the
other in the directory with inode number 259. Also, we end up with the
directory inode 259 still existing and with the directory inode 258 still
named as 'A', instead of 'B'. In this scenario, file 'bar' should only
have one hard link, located at directory inode 258, the directory inode
259 should not exist anymore and the name for directory inode 258 should
be 'B'.
This incorrect behaviour happens because when attempting to log the old
parents of an inode, we skip any parents that no longer exist. Fix this
by forcing a full commit if an old parent no longer exists.
A test case for fstests follows soon.
CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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[ Upstream commit 3d3a2e610ea5e7c6d4f9481ecce5d8e2d8317843 ]
Currently the code assumes that there's an implied barrier by the
sequence of code preceding the wakeup, namely the mutex unlock.
As Nikolay pointed out:
I think this is wrong (not your code) but the original assumption that
the RELEASE semantics provided by mutex_unlock is sufficient.
According to memory-barriers.txt:
Section 'LOCK ACQUISITION FUNCTIONS' states:
(2) RELEASE operation implication:
Memory operations issued before the RELEASE will be completed before the
RELEASE operation has completed.
Memory operations issued after the RELEASE *may* be completed before the
RELEASE operation has completed.
(I've bolded the may portion)
The example given there:
As an example, consider the following:
*A = a;
*B = b;
ACQUIRE
*C = c;
*D = d;
RELEASE
*E = e;
*F = f;
The following sequence of events is acceptable:
ACQUIRE, {*F,*A}, *E, {*C,*D}, *B, RELEASE
So if we assume that *C is modifying the flag which the waitqueue is checking,
and *E is the actual wakeup, then those accesses can be re-ordered...
IMHO this code should be considered broken...
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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[ Upstream commit 8434ec46c6e3232cebc25a910363b29f5c617820 ]
When logging an inode, at tree-log.c:copy_items(), if we call
btrfs_next_leaf() at the loop which checks for the need to log holes, we
need to make sure copy_items() returns the value 1 to its caller and
not 0 (on success). This is because the path the caller passed was
released and is now different from what is was before, and the caller
expects a return value of 0 to mean both success and that the path
has not changed, while a return value of 1 means both success and
signals the caller that it can not reuse the path, it has to perform
another tree search.
Even though this is a case that should not be triggered on normal
circumstances or very rare at least, its consequences can be very
unpredictable (especially when replaying a log tree).
Fixes: 16e7549f045d ("Btrfs: incompatible format change to remove hole extents")
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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[ Upstream commit 80c0b4210a963e31529e15bf90519708ec947596 ]
0, 1 and <0 can be returned by btrfs_next_leaf(), and when <0 is
returned, path->nodes[0] could be NULL, log_dir_items lacks such a
check for <0 and we may run into a null pointer dereference panic.
Fixes: e02119d5a7b4 ("Btrfs: Add a write ahead tree log to optimize synchronous operations")
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Liu Bo <bo.liu@linux.alibaba.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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[ Upstream commit b98def7ca6e152ee55e36863dddf6f41f12d1dc6 ]
If errors were returned by btrfs_next_leaf(), replay_dir_deletes needs
to bail out, otherwise @ret would be forced to be 0 after 'break;' and
the caller won't be aware of it.
Fixes: e02119d5a7b4 ("Btrfs: Add a write ahead tree log to optimize synchronous operations")
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Liu Bo <bo.liu@linux.alibaba.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 9a8fca62aacc1599fea8e813d01e1955513e4fad upstream.
If a file has xattrs, we fsync it, to ensure we clear the flags
BTRFS_INODE_NEEDS_FULL_SYNC and BTRFS_INODE_COPY_EVERYTHING from its
inode, the current transaction commits and then we fsync it (without
either of those bits being set in its inode), we end up not logging
all its xattrs. This results in deleting all xattrs when replying the
log after a power failure.
Trivial reproducer
$ mkfs.btrfs -f /dev/sdb
$ mount /dev/sdb /mnt
$ touch /mnt/foobar
$ setfattr -n user.xa -v qwerty /mnt/foobar
$ xfs_io -c "fsync" /mnt/foobar
$ sync
$ xfs_io -c "pwrite -S 0xab 0 64K" /mnt/foobar
$ xfs_io -c "fsync" /mnt/foobar
<power failure>
$ mount /dev/sdb /mnt
$ getfattr --absolute-names --dump /mnt/foobar
<empty output>
$
So fix this by making sure all xattrs are logged if we log a file's inode
item and neither the flags BTRFS_INODE_NEEDS_FULL_SYNC nor
BTRFS_INODE_COPY_EVERYTHING were set in the inode.
Fixes: 36283bf777d9 ("Btrfs: fix fsync xattr loss in the fast fsync path")
Cc: <stable@vger.kernel.org> # 4.2+
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 900c9981680067573671ecc5cbfa7c5770be3a40 upstream.
The highest objectid, which is assigned to new inode, is decided at
the time of initializing fs roots. However, in cases where log replay
gets processed, the btree which fs root owns might be changed, so we
have to search it again for the highest objectid, otherwise creating
new inode would end up with -EEXIST.
cc: <stable@vger.kernel.org> v4.4-rc6+
Fixes: f32e48e92596 ("Btrfs: Initialize btrfs_root->highest_objectid when loading tree root and subvolume roots")
Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Reviewed-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 1846430c24d66e85cc58286b3319c82cd54debb2 upstream.
In cases that the whole fs flips into readonly status due to failures in
critical sections, then log tree's blocks are still dirty, and this leads
to a crash during umount time, the crash is about use-after-free,
umount
-> close_ctree
-> stop workers
-> iput(btree_inode)
-> iput_final
-> write_inode_now
-> ...
-> queue job on stop'd workers
cc: <stable@vger.kernel.org> v3.12+
Fixes: 681ae50917df ("Btrfs: cleanup reserved space when freeing tree log on error")
Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Reviewed-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 2a7bf53f577e49c43de4ffa7776056de26db65d9 upstream.
If a log tree has a layout like the following:
leaf N:
...
item 240 key (282 DIR_LOG_ITEM 0) itemoff 8189 itemsize 8
dir log end 1275809046
leaf N + 1:
item 0 key (282 DIR_LOG_ITEM 3936149215) itemoff 16275 itemsize 8
dir log end 18446744073709551615
...
When we pass the value 1275809046 + 1 as the parameter start_ret to the
function tree-log.c:find_dir_range() (done by replay_dir_deletes()), we
end up with path->slots[0] having the value 239 (points to the last item
of leaf N, item 240). Because the dir log item in that position has an
offset value smaller than *start_ret (1275809046 + 1) we need to move on
to the next leaf, however the logic for that is wrong since it compares
the current slot to the number of items in the leaf, which is smaller
and therefore we don't lookup for the next leaf but instead we set the
slot to point to an item that does not exist, at slot 240, and we later
operate on that slot which has unexpected content or in the worst case
can result in an invalid memory access (accessing beyond the last page
of leaf N's extent buffer).
So fix the logic that checks when we need to lookup at the next leaf
by first incrementing the slot and only after to check if that slot
is beyond the last item of the current leaf.
Signed-off-by: Robbie Ko <robbieko@synology.com>
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Fixes: e02119d5a7b4 (Btrfs: Add a write ahead tree log to optimize synchronous operations)
Signed-off-by: Filipe Manana <fdmanana@suse.com>
[Modified changelog for clarity and correctness]
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 570dd45042a7c8a7aba1ee029c5dd0f5ccf41b9b upstream.
btrfs_remove_all_log_ctxs takes a shortcut where it avoids walking the
list because it knows all of the waiters are patiently waiting for the
commit to finish.
But, there's a small race where btrfs_sync_log can remove itself from
the list if it finds a log commit is already done. Also, it uses
list_del_init() to remove itself from the list, but there's no way to
know if btrfs_remove_all_log_ctxs has already run, so we don't know for
sure if it is safe to call list_del_init().
This gets rid of all the shortcuts for btrfs_remove_all_log_ctxs(), and
just calls it with the proper locking.
This is part two of the corruption fixed by cbd60aa7cd1. I should have
done this in the first place, but convinced myself the optimizations were
safe. A 12 hour run of dbench 2048 will eventually trigger a list debug
WARN_ON for the list_del_init() in btrfs_sync_log().
Fixes: d1433debe7f4346cf9fc0dafc71c3137d2a97bc4
Reported-by: Dave Jones <davej@codemonkey.org.uk>
Signed-off-by: Chris Mason <clm@fb.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit cbd60aa7cd17d81a434234268c55192862147439 upstream.
We use a btrfs_log_ctx structure to pass information into the
tree log commit, and get error values out. It gets added to a per
log-transaction list which we walk when things go bad.
Commit d1433debe added an optimization to skip waiting for the log
commit, but didn't take root_log_ctx out of the list. This
patch makes sure we remove things before exiting.
Signed-off-by: Chris Mason <clm@fb.com>
Fixes: d1433debe7f4346cf9fc0dafc71c3137d2a97bc4
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 56f23fdbb600e6087db7b009775b95ce07cc3195 upstream.
If we rename an inode A (be it a file or a directory), create a new
inode B with the old name of inode A and under the same parent directory,
fsync inode B and then power fail, at log tree replay time we end up
removing inode A completely. If inode A is a directory then all its files
are gone too.
Example scenarios where this happens:
This is reproducible with the following steps, taken from a couple of
test cases written for fstests which are going to be submitted upstream
soon:
# Scenario 1
mkfs.btrfs -f /dev/sdc
mount /dev/sdc /mnt
mkdir -p /mnt/a/x
echo "hello" > /mnt/a/x/foo
echo "world" > /mnt/a/x/bar
sync
mv /mnt/a/x /mnt/a/y
mkdir /mnt/a/x
xfs_io -c fsync /mnt/a/x
<power failure happens>
The next time the fs is mounted, log tree replay happens and
the directory "y" does not exist nor do the files "foo" and
"bar" exist anywhere (neither in "y" nor in "x", nor the root
nor anywhere).
# Scenario 2
mkfs.btrfs -f /dev/sdc
mount /dev/sdc /mnt
mkdir /mnt/a
echo "hello" > /mnt/a/foo
sync
mv /mnt/a/foo /mnt/a/bar
echo "world" > /mnt/a/foo
xfs_io -c fsync /mnt/a/foo
<power failure happens>
The next time the fs is mounted, log tree replay happens and the
file "bar" does not exists anymore. A file with the name "foo"
exists and it matches the second file we created.
Another related problem that does not involve file/data loss is when a
new inode is created with the name of a deleted snapshot and we fsync it:
mkfs.btrfs -f /dev/sdc
mount /dev/sdc /mnt
mkdir /mnt/testdir
btrfs subvolume snapshot /mnt /mnt/testdir/snap
btrfs subvolume delete /mnt/testdir/snap
rmdir /mnt/testdir
mkdir /mnt/testdir
xfs_io -c fsync /mnt/testdir # or fsync some file inside /mnt/testdir
<power failure>
The next time the fs is mounted the log replay procedure fails because
it attempts to delete the snapshot entry (which has dir item key type
of BTRFS_ROOT_ITEM_KEY) as if it were a regular (non-root) entry,
resulting in the following error that causes mount to fail:
[52174.510532] BTRFS info (device dm-0): failed to delete reference to snap, inode 257 parent 257
[52174.512570] ------------[ cut here ]------------
[52174.513278] WARNING: CPU: 12 PID: 28024 at fs/btrfs/inode.c:3986 __btrfs_unlink_inode+0x178/0x351 [btrfs]()
[52174.514681] BTRFS: Transaction aborted (error -2)
[52174.515630] Modules linked in: btrfs dm_flakey dm_mod overlay crc32c_generic ppdev xor raid6_pq acpi_cpufreq parport_pc tpm_tis sg parport tpm evdev i2c_piix4 proc
[52174.521568] CPU: 12 PID: 28024 Comm: mount Tainted: G W 4.5.0-rc6-btrfs-next-27+ #1
[52174.522805] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS by qemu-project.org 04/01/2014
[52174.524053] 0000000000000000 ffff8801df2a7710 ffffffff81264e93 ffff8801df2a7758
[52174.524053] 0000000000000009 ffff8801df2a7748 ffffffff81051618 ffffffffa03591cd
[52174.524053] 00000000fffffffe ffff88015e6e5000 ffff88016dbc3c88 ffff88016dbc3c88
[52174.524053] Call Trace:
[52174.524053] [<ffffffff81264e93>] dump_stack+0x67/0x90
[52174.524053] [<ffffffff81051618>] warn_slowpath_common+0x99/0xb2
[52174.524053] [<ffffffffa03591cd>] ? __btrfs_unlink_inode+0x178/0x351 [btrfs]
[52174.524053] [<ffffffff81051679>] warn_slowpath_fmt+0x48/0x50
[52174.524053] [<ffffffffa03591cd>] __btrfs_unlink_inode+0x178/0x351 [btrfs]
[52174.524053] [<ffffffff8118f5e9>] ? iput+0xb0/0x284
[52174.524053] [<ffffffffa0359fe8>] btrfs_unlink_inode+0x1c/0x3d [btrfs]
[52174.524053] [<ffffffffa038631e>] check_item_in_log+0x1fe/0x29b [btrfs]
[52174.524053] [<ffffffffa0386522>] replay_dir_deletes+0x167/0x1cf [btrfs]
[52174.524053] [<ffffffffa038739e>] fixup_inode_link_count+0x289/0x2aa [btrfs]
[52174.524053] [<ffffffffa038748a>] fixup_inode_link_counts+0xcb/0x105 [btrfs]
[52174.524053] [<ffffffffa038a5ec>] btrfs_recover_log_trees+0x258/0x32c [btrfs]
[52174.524053] [<ffffffffa03885b2>] ? replay_one_extent+0x511/0x511 [btrfs]
[52174.524053] [<ffffffffa034f288>] open_ctree+0x1dd4/0x21b9 [btrfs]
[52174.524053] [<ffffffffa032b753>] btrfs_mount+0x97e/0xaed [btrfs]
[52174.524053] [<ffffffff8108e1b7>] ? trace_hardirqs_on+0xd/0xf
[52174.524053] [<ffffffff8117bafa>] mount_fs+0x67/0x131
[52174.524053] [<ffffffff81193003>] vfs_kern_mount+0x6c/0xde
[52174.524053] [<ffffffffa032af81>] btrfs_mount+0x1ac/0xaed [btrfs]
[52174.524053] [<ffffffff8108e1b7>] ? trace_hardirqs_on+0xd/0xf
[52174.524053] [<ffffffff8108c262>] ? lockdep_init_map+0xb9/0x1b3
[52174.524053] [<ffffffff8117bafa>] mount_fs+0x67/0x131
[52174.524053] [<ffffffff81193003>] vfs_kern_mount+0x6c/0xde
[52174.524053] [<ffffffff8119590f>] do_mount+0x8a6/0x9e8
[52174.524053] [<ffffffff811358dd>] ? strndup_user+0x3f/0x59
[52174.524053] [<ffffffff81195c65>] SyS_mount+0x77/0x9f
[52174.524053] [<ffffffff814935d7>] entry_SYSCALL_64_fastpath+0x12/0x6b
[52174.561288] ---[ end trace 6b53049efb1a3ea6 ]---
Fix this by forcing a transaction commit when such cases happen.
This means we check in the commit root of the subvolume tree if there
was any other inode with the same reference when the inode we are
fsync'ing is a new inode (created in the current transaction).
Test cases for fstests, covering all the scenarios given above, were
submitted upstream for fstests:
* fstests: generic test for fsync after renaming directory
https://patchwork.kernel.org/patch/8694281/
* fstests: generic test for fsync after renaming file
https://patchwork.kernel.org/patch/8694301/
* fstests: add btrfs test for fsync after snapshot deletion
https://patchwork.kernel.org/patch/8670671/
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Chris Mason <clm@fb.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
In the kernel 4.2 merge window we had a big changes to the implementation
of delayed references and qgroups which made the no_quota field of delayed
references not used anymore. More specifically the no_quota field is not
used anymore as of:
commit 0ed4792af0e8 ("btrfs: qgroup: Switch to new extent-oriented qgroup mechanism.")
Leaving the no_quota field actually prevents delayed references from
getting merged, which in turn cause the following BUG_ON(), at
fs/btrfs/extent-tree.c, to be hit when qgroups are enabled:
static int run_delayed_tree_ref(...)
{
(...)
BUG_ON(node->ref_mod != 1);
(...)
}
This happens on a scenario like the following:
1) Ref1 bytenr X, action = BTRFS_ADD_DELAYED_REF, no_quota = 1, added.
2) Ref2 bytenr X, action = BTRFS_DROP_DELAYED_REF, no_quota = 0, added.
It's not merged with Ref1 because Ref1->no_quota != Ref2->no_quota.
3) Ref3 bytenr X, action = BTRFS_ADD_DELAYED_REF, no_quota = 1, added.
It's not merged with the reference at the tail of the list of refs
for bytenr X because the reference at the tail, Ref2 is incompatible
due to Ref2->no_quota != Ref3->no_quota.
4) Ref4 bytenr X, action = BTRFS_DROP_DELAYED_REF, no_quota = 0, added.
It's not merged with the reference at the tail of the list of refs
for bytenr X because the reference at the tail, Ref3 is incompatible
due to Ref3->no_quota != Ref4->no_quota.
5) We run delayed references, trigger merging of delayed references,
through __btrfs_run_delayed_refs() -> btrfs_merge_delayed_refs().
6) Ref1 and Ref3 are merged as Ref1->no_quota = Ref3->no_quota and
all other conditions are satisfied too. So Ref1 gets a ref_mod
value of 2.
7) Ref2 and Ref4 are merged as Ref2->no_quota = Ref4->no_quota and
all other conditions are satisfied too. So Ref2 gets a ref_mod
value of 2.
8) Ref1 and Ref2 aren't merged, because they have different values
for their no_quota field.
9) Delayed reference Ref1 is picked for running (select_delayed_ref()
always prefers references with an action == BTRFS_ADD_DELAYED_REF).
So run_delayed_tree_ref() is called for Ref1 which triggers the
BUG_ON because Ref1->red_mod != 1 (equals 2).
So fix this by removing the no_quota field, as it's not used anymore as
of commit 0ed4792af0e8 ("btrfs: qgroup: Switch to new extent-oriented
qgroup mechanism.").
The use of no_quota was also buggy in at least two places:
1) At delayed-refs.c:btrfs_add_delayed_tree_ref() - we were setting
no_quota to 0 instead of 1 when the following condition was true:
is_fstree(ref_root) || !fs_info->quota_enabled
2) At extent-tree.c:__btrfs_inc_extent_ref() - we were attempting to
reset a node's no_quota when the condition "!is_fstree(root_objectid)
|| !root->fs_info->quota_enabled" was true but we did it only in
an unused local stack variable, that is, we never reset the no_quota
value in the node itself.
This fixes the remainder of problems several people have been having when
running delayed references, mostly while a balance is running in parallel,
on a 4.2+ kernel.
Very special thanks to Stéphane Lesimple for helping debugging this issue
and testing this fix on his multi terabyte filesystem (which took more
than one day to balance alone, plus fsck, etc).
Also, this fixes deadlock issue when using the clone ioctl with qgroups
enabled, as reported by Elias Probst in the mailing list. The deadlock
happens because after calling btrfs_insert_empty_item we have our path
holding a write lock on a leaf of the fs/subvol tree and then before
releasing the path we called check_ref() which did backref walking, when
qgroups are enabled, and tried to read lock the same leaf. The trace for
this case is the following:
INFO: task systemd-nspawn:6095 blocked for more than 120 seconds.
(...)
Call Trace:
[<ffffffff86999201>] schedule+0x74/0x83
[<ffffffff863ef64c>] btrfs_tree_read_lock+0xc0/0xea
[<ffffffff86137ed7>] ? wait_woken+0x74/0x74
[<ffffffff8639f0a7>] btrfs_search_old_slot+0x51a/0x810
[<ffffffff863a129b>] btrfs_next_old_leaf+0xdf/0x3ce
[<ffffffff86413a00>] ? ulist_add_merge+0x1b/0x127
[<ffffffff86411688>] __resolve_indirect_refs+0x62a/0x667
[<ffffffff863ef546>] ? btrfs_clear_lock_blocking_rw+0x78/0xbe
[<ffffffff864122d3>] find_parent_nodes+0xaf3/0xfc6
[<ffffffff86412838>] __btrfs_find_all_roots+0x92/0xf0
[<ffffffff864128f2>] btrfs_find_all_roots+0x45/0x65
[<ffffffff8639a75b>] ? btrfs_get_tree_mod_seq+0x2b/0x88
[<ffffffff863e852e>] check_ref+0x64/0xc4
[<ffffffff863e9e01>] btrfs_clone+0x66e/0xb5d
[<ffffffff863ea77f>] btrfs_ioctl_clone+0x48f/0x5bb
[<ffffffff86048a68>] ? native_sched_clock+0x28/0x77
[<ffffffff863ed9b0>] btrfs_ioctl+0xabc/0x25cb
(...)
The problem goes away by eleminating check_ref(), which no longer is
needed as its purpose was to get a value for the no_quota field of
a delayed reference (this patch removes the no_quota field as mentioned
earlier).
Reported-by: Stéphane Lesimple <stephane_btrfs@lesimple.fr>
Tested-by: Stéphane Lesimple <stephane_btrfs@lesimple.fr>
Reported-by: Elias Probst <mail@eliasprobst.eu>
Reported-by: Peter Becker <floyd.net@gmail.com>
Reported-by: Malte Schröder <malte@tnxip.de>
Reported-by: Derek Dongray <derek@valedon.co.uk>
Reported-by: Erkki Seppala <flux-btrfs@inside.org>
Cc: stable@vger.kernel.org # 4.2+
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
|
|
git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux into for-linus-4.4
|
|
Removing barriers is scary, but a call to atomic_dec_and_test implies
a barrier, so we don't need to issue another one.
Signed-off-by: David Sterba <dsterba@suse.com>
|
|
Suggested-by: Chris Mason <clm@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>
|
|
btrfs_error() and btrfs_std_error() does the same thing
and calls _btrfs_std_error(), so consolidate them together.
And the main motivation is that btrfs_error() is closely
named with btrfs_err(), one handles error action the other
is to log the error, so don't closely name them.
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Suggested-by: David Sterba <dsterba@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
|
|
If we partially clone one extent of a file into a lower offset of the
file, fsync the file, power fail and then mount the fs to trigger log
replay, we can get multiple checksum items in the csum tree that overlap
each other and result in checksum lookup failures later. Those failures
can make file data read requests assume a checksum value of 0, but they
will not return an error (-EIO for example) to userspace exactly because
the expected checksum value 0 is a special value that makes the read bio
endio callback return success and set all the bytes of the corresponding
page with the value 0x01 (at fs/btrfs/inode.c:__readpage_endio_check()).
From a userspace perspective this is equivalent to file corruption
because we are not returning what was written to the file.
Details about how this can happen, and why, are included inline in the
following reproducer test case for fstests and the comment added to
tree-log.c.
seq=`basename $0`
seqres=$RESULT_DIR/$seq
echo "QA output created by $seq"
tmp=/tmp/$$
status=1 # failure is the default!
trap "_cleanup; exit \$status" 0 1 2 3 15
_cleanup()
{
_cleanup_flakey
rm -f $tmp.*
}
# get standard environment, filters and checks
. ./common/rc
. ./common/filter
. ./common/dmflakey
# real QA test starts here
_need_to_be_root
_supported_fs btrfs
_supported_os Linux
_require_scratch
_require_dm_flakey
_require_cloner
_require_metadata_journaling $SCRATCH_DEV
rm -f $seqres.full
_scratch_mkfs >>$seqres.full 2>&1
_init_flakey
_mount_flakey
# Create our test file with a single 100K extent starting at file
# offset 800K. We fsync the file here to make the fsync log tree gets
# a single csum item that covers the whole 100K extent, which causes
# the second fsync, done after the cloning operation below, to not
# leave in the log tree two csum items covering two sub-ranges
# ([0, 20K[ and [20K, 100K[)) of our extent.
$XFS_IO_PROG -f -c "pwrite -S 0xaa 800K 100K" \
-c "fsync" \
$SCRATCH_MNT/foo | _filter_xfs_io
# Now clone part of our extent into file offset 400K. This adds a file
# extent item to our inode's metadata that points to the 100K extent
# we created before, using a data offset of 20K and a data length of
# 20K, so that it refers to the sub-range [20K, 40K[ of our original
# extent.
$CLONER_PROG -s $((800 * 1024 + 20 * 1024)) -d $((400 * 1024)) \
-l $((20 * 1024)) $SCRATCH_MNT/foo $SCRATCH_MNT/foo
# Now fsync our file to make sure the extent cloning is durably
# persisted. This fsync will not add a second csum item to the log
# tree containing the checksums for the blocks in the sub-range
# [20K, 40K[ of our extent, because there was already a csum item in
# the log tree covering the whole extent, added by the first fsync
# we did before.
$XFS_IO_PROG -c "fsync" $SCRATCH_MNT/foo
echo "File digest before power failure:"
md5sum $SCRATCH_MNT/foo | _filter_scratch
# Silently drop all writes and ummount to simulate a crash/power
# failure.
_load_flakey_table $FLAKEY_DROP_WRITES
_unmount_flakey
# Allow writes again, mount to trigger log replay and validate file
# contents.
# The fsync log replay first processes the file extent item
# corresponding to the file offset 400K (the one which refers to the
# [20K, 40K[ sub-range of our 100K extent) and then processes the file
# extent item for file offset 800K. It used to happen that when
# processing the later, it erroneously left in the csum tree 2 csum
# items that overlapped each other, 1 for the sub-range [20K, 40K[ and
# 1 for the whole range of our extent. This introduced a problem where
# subsequent lookups for the checksums of blocks within the range
# [40K, 100K[ of our extent would not find anything because lookups in
# the csum tree ended up looking only at the smaller csum item, the
# one covering the subrange [20K, 40K[. This made read requests assume
# an expected checksum with a value of 0 for those blocks, which caused
# checksum verification failure when the read operations finished.
# However those checksum failure did not result in read requests
# returning an error to user space (like -EIO for e.g.) because the
# expected checksum value had the special value 0, and in that case
# btrfs set all bytes of the corresponding pages with the value 0x01
# and produce the following warning in dmesg/syslog:
#
# "BTRFS warning (device dm-0): csum failed ino 257 off 917504 csum\
# 1322675045 expected csum 0"
#
_load_flakey_table $FLAKEY_ALLOW_WRITES
_mount_flakey
echo "File digest after log replay:"
# Must match the same digest he had after cloning the extent and
# before the power failure happened.
md5sum $SCRATCH_MNT/foo | _filter_scratch
_unmount_flakey
status=0
exit
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: Chris Mason <clm@fb.com>
|
|
Following arguments are not used in tree-log.c:
insert_one_name(): path, type
wait_log_commit(): trans
wait_for_writer(): trans
This patch remove them.
Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com>
Signed-off-by: Chris Mason <clm@fb.com>
|
|
Dan Carpenter <dan.carpenter@oracle.com> reported a smatch warning
for start_log_trans():
fs/btrfs/tree-log.c:178 start_log_trans()
warn: we tested 'root->log_root' before and it was 'false'
fs/btrfs/tree-log.c
147 if (root->log_root) {
We test "root->log_root" here.
...
Reason:
Condition of:
fs/btrfs/tree-log.c:178: if (!root->log_root) {
is not necessary after commit: 7237f1833
It caused a smatch warning, and no functionally error.
Fix:
Deleting above condition will make smatch shut up,
but a better way is to do cleanup for start_log_trans()
to remove duplicated code and make code more readable.
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com>
Signed-off-by: Chris Mason <clm@fb.com>
|
|
We have one more case where after a log tree is replayed we get
inconsistent metadata leading to stale directory entries, due to
some directories having entries pointing to some inode while the
inode does not have a matching BTRFS_INODE_[REF|EXTREF]_KEY item.
To trigger the problem we need to have a file with multiple hard links
belonging to different parent directories. Then if one of those hard
links is removed and we fsync the file using one of its other links
that belongs to a different parent directory, we end up not logging
the fact that the removed hard link doesn't exists anymore in the
parent directory.
Simple reproducer:
seq=`basename $0`
seqres=$RESULT_DIR/$seq
echo "QA output created by $seq"
tmp=/tmp/$$
status=1 # failure is the default!
trap "_cleanup; exit \$status" 0 1 2 3 15
_cleanup()
{
_cleanup_flakey
rm -f $tmp.*
}
# get standard environment, filters and checks
. ./common/rc
. ./common/filter
. ./common/dmflakey
# real QA test starts here
_need_to_be_root
_supported_fs generic
_supported_os Linux
_require_scratch
_require_dm_flakey
_require_metadata_journaling $SCRATCH_DEV
rm -f $seqres.full
_scratch_mkfs >>$seqres.full 2>&1
_init_flakey
_mount_flakey
# Create our test directory and file.
mkdir $SCRATCH_MNT/testdir
touch $SCRATCH_MNT/foo
ln $SCRATCH_MNT/foo $SCRATCH_MNT/testdir/foo2
ln $SCRATCH_MNT/foo $SCRATCH_MNT/testdir/foo3
# Make sure everything done so far is durably persisted.
sync
# Now we remove one of our file's hardlinks in the directory testdir.
unlink $SCRATCH_MNT/testdir/foo3
# We now fsync our file using the "foo" link, which has a parent that
# is not the directory "testdir".
$XFS_IO_PROG -c "fsync" $SCRATCH_MNT/foo
# Silently drop all writes and unmount to simulate a crash/power
# failure.
_load_flakey_table $FLAKEY_DROP_WRITES
_unmount_flakey
# Allow writes again, mount to trigger journal/log replay.
_load_flakey_table $FLAKEY_ALLOW_WRITES
_mount_flakey
# After the journal/log is replayed we expect to not see the "foo3"
# link anymore and we should be able to remove all names in the
# directory "testdir" and then remove it (no stale directory entries
# left after the journal/log replay).
echo "Entries in testdir:"
ls -1 $SCRATCH_MNT/testdir
rm -f $SCRATCH_MNT/testdir/*
rmdir $SCRATCH_MNT/testdir
_unmount_flakey
status=0
exit
The test fails with:
$ ./check generic/107
FSTYP -- btrfs
PLATFORM -- Linux/x86_64 debian3 4.1.0-rc6-btrfs-next-11+
MKFS_OPTIONS -- /dev/sdc
MOUNT_OPTIONS -- /dev/sdc /home/fdmanana/btrfs-tests/scratch_1
generic/107 3s ... - output mismatch (see .../results/generic/107.out.bad)
--- tests/generic/107.out 2015-08-01 01:39:45.807462161 +0100
+++ /home/fdmanana/git/hub/xfstests/results//generic/107.out.bad
@@ -1,3 +1,5 @@
QA output created by 107
Entries in testdir:
foo2
+foo3
+rmdir: failed to remove '/home/fdmanana/btrfs-tests/scratch_1/testdir': Directory not empty
...
_check_btrfs_filesystem: filesystem on /dev/sdc is inconsistent \
(see /home/fdmanana/git/hub/xfstests/results//generic/107.full)
_check_dmesg: something found in dmesg (see .../results/generic/107.dmesg)
Ran: generic/107
Failures: generic/107
Failed 1 of 1 tests
$ cat /home/fdmanana/git/hub/xfstests/results//generic/107.full
(...)
checking fs roots
root 5 inode 257 errors 200, dir isize wrong
unresolved ref dir 257 index 3 namelen 4 name foo3 filetype 1 errors 5, no dir item, no inode ref
(...)
And produces the following warning in dmesg:
[127298.759064] BTRFS info (device dm-0): failed to delete reference to foo3, inode 258 parent 257
[127298.762081] ------------[ cut here ]------------
[127298.763311] WARNING: CPU: 10 PID: 7891 at fs/btrfs/inode.c:3956 __btrfs_unlink_inode+0x182/0x35a [btrfs]()
[127298.767327] BTRFS: Transaction aborted (error -2)
(...)
[127298.788611] Call Trace:
[127298.789137] [<ffffffff8145f077>] dump_stack+0x4f/0x7b
[127298.790090] [<ffffffff81095de5>] ? console_unlock+0x356/0x3a2
[127298.791157] [<ffffffff8104b3b0>] warn_slowpath_common+0xa1/0xbb
[127298.792323] [<ffffffffa065ad09>] ? __btrfs_unlink_inode+0x182/0x35a [btrfs]
[127298.793633] [<ffffffff8104b410>] warn_slowpath_fmt+0x46/0x48
[127298.794699] [<ffffffffa065ad09>] __btrfs_unlink_inode+0x182/0x35a [btrfs]
[127298.797640] [<ffffffffa065be8f>] btrfs_unlink_inode+0x1e/0x40 [btrfs]
[127298.798876] [<ffffffffa065bf11>] btrfs_unlink+0x60/0x9b [btrfs]
[127298.800154] [<ffffffff8116fb48>] vfs_unlink+0x9c/0xed
[127298.801303] [<ffffffff81173481>] do_unlinkat+0x12b/0x1fb
[127298.802450] [<ffffffff81253855>] ? lockdep_sys_exit_thunk+0x12/0x14
[127298.803797] [<ffffffff81174056>] SyS_unlinkat+0x29/0x2b
[127298.805017] [<ffffffff81465197>] system_call_fastpath+0x12/0x6f
[127298.806310] ---[ end trace bbfddacb7aaada7b ]---
[127298.807325] BTRFS warning (device dm-0): __btrfs_unlink_inode:3956: Aborting unused transaction(No such entry).
So fix this by logging all parent inodes, current and old ones, to make
sure we do not get stale entries after log replay. This is not a simple
solution such as triggering a full transaction commit because it would
imply full transaction commit when an inode is fsynced in the same
transaction that modified it and reloaded it after eviction (because its
last_unlink_trans is set to the same value as its last_trans as of the
commit with the title "Btrfs: fix stale dir entries after unlink, inode
eviction and fsync"), and it would also make fstest generic/066 fail
since one of the fsyncs triggers a full commit and the next fsync will
not find the inode in the log anymore (therefore not removing the xattr).
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Chris Mason <clm@fb.com>
|
|
We have another case where after an fsync log replay we get an inode with
a wrong link count (smaller than it should be) and a number of directory
entries greater than its link count. This happens when we add a new link
hard link to our inode A and then we fsync some other inode B that has
the side effect of logging the parent directory inode too. In this case
at log replay time we add the new hard link to our inode (the item with
key BTRFS_INODE_REF_KEY) when processing the parent directory but we
never adjust the link count of our inode A. As a result we get stale dir
entries for our inode A that can never be deleted and therefore it makes
it impossible to remove the parent directory (as its i_size can never
decrease back to 0).
A simple reproducer for fstests that triggers this issue:
seq=`basename $0`
seqres=$RESULT_DIR/$seq
echo "QA output created by $seq"
tmp=/tmp/$$
status=1 # failure is the default!
trap "_cleanup; exit \$status" 0 1 2 3 15
_cleanup()
{
_cleanup_flakey
rm -f $tmp.*
}
# get standard environment, filters and checks
. ./common/rc
. ./common/filter
. ./common/dmflakey
# real QA test starts here
_need_to_be_root
_supported_fs generic
_supported_os Linux
_require_scratch
_require_dm_flakey
_require_metadata_journaling $SCRATCH_DEV
rm -f $seqres.full
_scratch_mkfs >>$seqres.full 2>&1
_init_flakey
_mount_flakey
# Create our test directory and files.
mkdir $SCRATCH_MNT/testdir
touch $SCRATCH_MNT/testdir/foo
touch $SCRATCH_MNT/testdir/bar
# Make sure everything done so far is durably persisted.
sync
# Create one hard link for file foo and another one for file bar. After
# that fsync only the file bar.
ln $SCRATCH_MNT/testdir/bar $SCRATCH_MNT/testdir/bar_link
ln $SCRATCH_MNT/testdir/foo $SCRATCH_MNT/testdir/foo_link
$XFS_IO_PROG -c "fsync" $SCRATCH_MNT/testdir/bar
# Silently drop all writes on scratch device to simulate power failure.
_load_flakey_table $FLAKEY_DROP_WRITES
_unmount_flakey
# Allow writes again and mount the fs to trigger log/journal replay.
_load_flakey_table $FLAKEY_ALLOW_WRITES
_mount_flakey
# Now verify both our files have a link count of 2.
echo "Link count for file foo: $(stat --format=%h $SCRATCH_MNT/testdir/foo)"
echo "Link count for file bar: $(stat --format=%h $SCRATCH_MNT/testdir/bar)"
# We should be able to remove all the links of our files in testdir, and
# after that the parent directory should become empty and therefore
# possible to remove it.
rm -f $SCRATCH_MNT/testdir/*
rmdir $SCRATCH_MNT/testdir
_unmount_flakey
# The fstests framework will call fsck against our filesystem which will verify
# that all metadata is in a consistent state.
status=0
exit
The test fails with:
-Link count for file foo: 2
+Link count for file foo: 1
Link count for file bar: 2
+rm: cannot remove '/home/fdmanana/btrfs-tests/scratch_1/testdir/foo_link': Stale file handle
+rmdir: failed to remove '/home/fdmanana/btrfs-tests/scratch_1/testdir': Directory not empty
(...)
_check_btrfs_filesystem: filesystem on /dev/sdc is inconsistent
And fsck's output:
(...)
checking fs roots
root 5 inode 258 errors 2001, no inode item, link count wrong
unresolved ref dir 257 index 5 namelen 8 name foo_link filetype 1 errors 4, no inode ref
Checking filesystem on /dev/sdc
(...)
So fix this by marking inodes for link count fixup at log replay time
whenever a directory entry is replayed if the entry was created in the
transaction where the fsync was made and if it points to a non-directory
inode.
This isn't a new problem/regression, the issue exists for a long time,
possibly since the log tree feature was added (2008).
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Chris Mason <clm@fb.com>
|
|
When we have the no_holes feature enabled, if a we truncate a file to a
smaller size, truncate it again but to a size greater than or equals to
its original size and fsync it, the log tree will not have any information
about the hole covering the range [truncate_1_offset, new_file_size[.
Which means if the fsync log is replayed, the file will remain with the
state it had before both truncate operations.
Without the no_holes feature this does not happen, since when the inode
is logged (full sync flag is set) it will find in the fs/subvol tree a
leaf with a generation matching the current transaction id that has an
explicit extent item representing the hole.
Fix this by adding an explicit extent item representing a hole between
the last extent and the inode's i_size if we are doing a full sync.
The issue is easy to reproduce with the following test case for fstests:
. ./common/rc
. ./common/filter
. ./common/dmflakey
_need_to_be_root
_supported_fs generic
_supported_os Linux
_require_scratch
_require_dm_flakey
# This test was motivated by an issue found in btrfs when the btrfs
# no-holes feature is enabled (introduced in kernel 3.14). So enable
# the feature if the fs being tested is btrfs.
if [ $FSTYP == "btrfs" ]; then
_require_btrfs_fs_feature "no_holes"
_require_btrfs_mkfs_feature "no-holes"
MKFS_OPTIONS="$MKFS_OPTIONS -O no-holes"
fi
rm -f $seqres.full
_scratch_mkfs >>$seqres.full 2>&1
_init_flakey
_mount_flakey
# Create our test files and make sure everything is durably persisted.
$XFS_IO_PROG -f -c "pwrite -S 0xaa 0 64K" \
-c "pwrite -S 0xbb 64K 61K" \
$SCRATCH_MNT/foo | _filter_xfs_io
$XFS_IO_PROG -f -c "pwrite -S 0xee 0 64K" \
-c "pwrite -S 0xff 64K 61K" \
$SCRATCH_MNT/bar | _filter_xfs_io
sync
# Now truncate our file foo to a smaller size (64Kb) and then truncate
# it to the size it had before the shrinking truncate (125Kb). Then
# fsync our file. If a power failure happens after the fsync, we expect
# our file to have a size of 125Kb, with the first 64Kb of data having
# the value 0xaa and the second 61Kb of data having the value 0x00.
$XFS_IO_PROG -c "truncate 64K" \
-c "truncate 125K" \
-c "fsync" \
$SCRATCH_MNT/foo
# Do something similar to our file bar, but the first truncation sets
# the file size to 0 and the second truncation expands the size to the
# double of what it was initially.
$XFS_IO_PROG -c "truncate 0" \
-c "truncate 253K" \
-c "fsync" \
$SCRATCH_MNT/bar
_load_flakey_table $FLAKEY_DROP_WRITES
_unmount_flakey
# Allow writes again, mount to trigger log replay and validate file
# contents.
_load_flakey_table $FLAKEY_ALLOW_WRITES
_mount_flakey
# We expect foo to have a size of 125Kb, the first 64Kb of data all
# having the value 0xaa and the remaining 61Kb to be a hole (all bytes
# with value 0x00).
echo "File foo content after log replay:"
od -t x1 $SCRATCH_MNT/foo
# We expect bar to have a size of 253Kb and no extents (any byte read
# from bar has the value 0x00).
echo "File bar content after log replay:"
od -t x1 $SCRATCH_MNT/bar
status=0
exit
The expected file contents in the golden output are:
File foo content after log replay:
0000000 aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa
*
0200000 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
*
0372000
File bar content after log replay:
0000000 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
*
0772000
Without this fix, their contents are:
File foo content after log replay:
0000000 aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa
*
0200000 bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb
*
0372000
File bar content after log replay:
0000000 ee ee ee ee ee ee ee ee ee ee ee ee ee ee ee ee
*
0200000 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
*
0372000 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
*
0772000
A test case submission for fstests follows soon.
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: Chris Mason <clm@fb.com>
|
|
After commit 4f764e515361 ("Btrfs: remove deleted xattrs on fsync log
replay"), we can end up in a situation where during log replay we end up
deleting xattrs that were never deleted when their file was last fsynced.
This happens in the fast fsync path (flag BTRFS_INODE_NEEDS_FULL_SYNC is
not set in the inode) if the inode has the flag BTRFS_INODE_COPY_EVERYTHING
set, the xattr was added in a past transaction and the leaf where the
xattr is located was not updated (COWed or created) in the current
transaction. In this scenario the xattr item never ends up in the log
tree and therefore at log replay time, which makes the replay code delete
the xattr from the fs/subvol tree as it thinks that xattr was deleted
prior to the last fsync.
Fix this by always logging all xattrs, which is the simplest and most
reliable way to detect deleted xattrs and replay the deletes at log replay
time.
This issue is reproducible with the following test case for fstests:
seq=`basename $0`
seqres=$RESULT_DIR/$seq
echo "QA output created by $seq"
here=`pwd`
tmp=/tmp/$$
status=1 # failure is the default!
_cleanup()
{
_cleanup_flakey
rm -f $tmp.*
}
trap "_cleanup; exit \$status" 0 1 2 3 15
# get standard environment, filters and checks
. ./common/rc
. ./common/filter
. ./common/dmflakey
. ./common/attr
# real QA test starts here
# We create a lot of xattrs for a single file. Only btrfs and xfs are currently
# able to store such a large mount of xattrs per file, other filesystems such
# as ext3/4 and f2fs for example, fail with ENOSPC even if we attempt to add
# less than 1000 xattrs with very small values.
_supported_fs btrfs xfs
_supported_os Linux
_need_to_be_root
_require_scratch
_require_dm_flakey
_require_attrs
_require_metadata_journaling $SCRATCH_DEV
rm -f $seqres.full
_scratch_mkfs >> $seqres.full 2>&1
_init_flakey
_mount_flakey
# Create the test file with some initial data and make sure everything is
# durably persisted.
$XFS_IO_PROG -f -c "pwrite -S 0xaa 0 32k" $SCRATCH_MNT/foo | _filter_xfs_io
sync
# Add many small xattrs to our file.
# We create such a large amount because it's needed to trigger the issue found
# in btrfs - we need to have an amount that causes the fs to have at least 3
# btree leafs with xattrs stored in them, and it must work on any leaf size
# (maximum leaf/node size is 64Kb).
num_xattrs=2000
for ((i = 1; i <= $num_xattrs; i++)); do
name="user.attr_$(printf "%04d" $i)"
$SETFATTR_PROG -n $name -v "val_$(printf "%04d" $i)" $SCRATCH_MNT/foo
done
# Sync the filesystem to force a commit of the current btrfs transaction, this
# is a necessary condition to trigger the bug on btrfs.
sync
# Now update our file's data and fsync the file.
# After a successful fsync, if the fsync log/journal is replayed we expect to
# see all the xattrs we added before with the same values (and the updated file
# data of course). Btrfs used to delete some of these xattrs when it replayed
# its fsync log/journal.
$XFS_IO_PROG -c "pwrite -S 0xbb 8K 16K" \
-c "fsync" \
$SCRATCH_MNT/foo | _filter_xfs_io
# Simulate a crash/power loss.
_load_flakey_table $FLAKEY_DROP_WRITES
_unmount_flakey
# Allow writes again and mount. This makes the fs replay its fsync log.
_load_flakey_table $FLAKEY_ALLOW_WRITES
_mount_flakey
echo "File content after crash and log replay:"
od -t x1 $SCRATCH_MNT/foo
echo "File xattrs after crash and log replay:"
for ((i = 1; i <= $num_xattrs; i++)); do
name="user.attr_$(printf "%04d" $i)"
echo -n "$name="
$GETFATTR_PROG --absolute-names -n $name --only-values $SCRATCH_MNT/foo
echo
done
status=0
exit
The golden output expects all xattrs to be available, and with the correct
values, after the fsync log is replayed.
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Chris Mason <clm@fb.com>
|
|
If we do an append write to a file (which increases its inode's i_size)
that does not have the flag BTRFS_INODE_NEEDS_FULL_SYNC set in its inode,
and the previous transaction added a new hard link to the file, which sets
the flag BTRFS_INODE_COPY_EVERYTHING in the file's inode, and then fsync
the file, the inode's new i_size isn't logged. This has the consequence
that after the fsync log is replayed, the file size remains what it was
before the append write operation, which means users/applications will
not be able to read the data that was successsfully fsync'ed before.
This happens because neither the inode item nor the delayed inode get
their i_size updated when the append write is made - doing so would
require starting a transaction in the buffered write path, something that
we do not do intentionally for performance reasons.
Fix this by making sure that when the flag BTRFS_INODE_COPY_EVERYTHING is
set the inode is logged with its current i_size (log the in-memory inode
into the log tree).
This issue is not a recent regression and is easy to reproduce with the
following test case for fstests:
seq=`basename $0`
seqres=$RESULT_DIR/$seq
echo "QA output created by $seq"
here=`pwd`
tmp=/tmp/$$
status=1 # failure is the default!
_cleanup()
{
_cleanup_flakey
rm -f $tmp.*
}
trap "_cleanup; exit \$status" 0 1 2 3 15
# get standard environment, filters and checks
. ./common/rc
. ./common/filter
. ./common/dmflakey
# real QA test starts here
_supported_fs generic
_supported_os Linux
_need_to_be_root
_require_scratch
_require_dm_flakey
_require_metadata_journaling $SCRATCH_DEV
_crash_and_mount()
{
# Simulate a crash/power loss.
_load_flakey_table $FLAKEY_DROP_WRITES
_unmount_flakey
# Allow writes again and mount. This makes the fs replay its fsync log.
_load_flakey_table $FLAKEY_ALLOW_WRITES
_mount_flakey
}
rm -f $seqres.full
_scratch_mkfs >> $seqres.full 2>&1
_init_flakey
_mount_flakey
# Create the test file with some initial data and then fsync it.
# The fsync here is only needed to trigger the issue in btrfs, as it causes the
# the flag BTRFS_INODE_NEEDS_FULL_SYNC to be removed from the btrfs inode.
$XFS_IO_PROG -f -c "pwrite -S 0xaa 0 32k" \
-c "fsync" \
$SCRATCH_MNT/foo | _filter_xfs_io
sync
# Add a hard link to our file.
# On btrfs this sets the flag BTRFS_INODE_COPY_EVERYTHING on the btrfs inode,
# which is a necessary condition to trigger the issue.
ln $SCRATCH_MNT/foo $SCRATCH_MNT/bar
# Sync the filesystem to force a commit of the current btrfs transaction, this
# is a necessary condition to trigger the bug on btrfs.
sync
# Now append more data to our file, increasing its size, and fsync the file.
# In btrfs because the inode flag BTRFS_INODE_COPY_EVERYTHING was set and the
# write path did not update the inode item in the btree nor the delayed inode
# item (in memory struture) in the current transaction (created by the fsync
# handler), the fsync did not record the inode's new i_size in the fsync
# log/journal. This made the data unavailable after the fsync log/journal is
# replayed.
$XFS_IO_PROG -c "pwrite -S 0xbb 32K 32K" \
-c "fsync" \
$SCRATCH_MNT/foo | _filter_xfs_io
echo "File content after fsync and before crash:"
od -t x1 $SCRATCH_MNT/foo
_crash_and_mount
echo "File content after crash and log replay:"
od -t x1 $SCRATCH_MNT/foo
status=0
exit
The expected file output before and after the crash/power failure expects the
appended data to be available, which is:
0000000 aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa
*
0100000 bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb
*
0200000
Cc: stable@vger.kernel.org
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: Chris Mason <clm@fb.com>
|
|
After commit 8407f553268a
("Btrfs: fix data corruption after fast fsync and writeback error"),
during wait_ordered_extents(), we wait for ordered extent setting
BTRFS_ORDERED_IO_DONE or BTRFS_ORDERED_IOERR, at which point we've
already got checksum information, so we don't need to check
(csum_bytes_left == 0) in the whole logging path.
Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: Chris Mason <clm@fb.com>
|
|
git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull fourth vfs update from Al Viro:
"d_inode() annotations from David Howells (sat in for-next since before
the beginning of merge window) + four assorted fixes"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
RCU pathwalk breakage when running into a symlink overmounting something
fix I_DIO_WAKEUP definition
direct-io: only inc/dec inode->i_dio_count for file systems
fs/9p: fix readdir()
VFS: assorted d_backing_inode() annotations
VFS: fs/inode.c helpers: d_inode() annotations
VFS: fs/cachefiles: d_backing_inode() annotations
VFS: fs library helpers: d_inode() annotations
VFS: assorted weird filesystems: d_inode() annotations
VFS: normal filesystems (and lustre): d_inode() annotations
VFS: security/: d_inode() annotations
VFS: security/: d_backing_inode() annotations
VFS: net/: d_inode() annotations
VFS: net/unix: d_backing_inode() annotations
VFS: kernel/: d_inode() annotations
VFS: audit: d_backing_inode() annotations
VFS: Fix up some ->d_inode accesses in the chelsio driver
VFS: Cachefiles should perform fs modifications on the top layer only
VFS: AF_UNIX sockets should call mknod on the top layer only
|
|
that's the bulk of filesystem drivers dealing with inodes of their own
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
|
|
When we are deleting large files with large extents, we are building up
a huge set of delayed refs for processing. Truncate isn't checking
often enough to see if we need to back off and process those, or let
a commit proceed.
The end result is long stalls after the rm, and very long commit times.
During the commits, other processes back up waiting to start new
transactions and we get into trouble.
Signed-off-by: Chris Mason <clm@fb.com>
|
|
We can get into inconsistency between inodes and directory entries
after fsyncing a directory. The issue is that while a directory gets
the new dentries persisted in the fsync log and replayed at mount time,
the link count of the inode that directory entries point to doesn't
get updated, staying with an incorrect link count (smaller then the
correct value). This later leads to stale file handle errors when
accessing (including attempt to delete) some of the links if all the
other ones are removed, which also implies impossibility to delete the
parent directories, since the dentries can not be removed.
Another issue is that (unlike ext3/4, xfs, f2fs, reiserfs, nilfs2),
when fsyncing a directory, new files aren't logged (their metadata and
dentries) nor any child directories. So this patch fixes this issue too,
since it has the same resolution as the incorrect inode link count issue
mentioned before.
This is very easy to reproduce, and the following excerpt from my test
case for xfstests shows how:
_scratch_mkfs >> $seqres.full 2>&1
_init_flakey
_mount_flakey
# Create our main test file and directory.
$XFS_IO_PROG -f -c "pwrite -S 0xaa 0 8K" $SCRATCH_MNT/foo | _filter_xfs_io
mkdir $SCRATCH_MNT/mydir
# Make sure all metadata and data are durably persisted.
sync
# Add a hard link to 'foo' inside our test directory and fsync only the
# directory. The btrfs fsync implementation had a bug that caused the new
# directory entry to be visible after the fsync log replay but, the inode
# of our file remained with a link count of 1.
ln $SCRATCH_MNT/foo $SCRATCH_MNT/mydir/foo_2
# Add a few more links and new files.
# This is just to verify nothing breaks or gives incorrect results after the
# fsync log is replayed.
ln $SCRATCH_MNT/foo $SCRATCH_MNT/mydir/foo_3
$XFS_IO_PROG -f -c "pwrite -S 0xff 0 64K" $SCRATCH_MNT/hello | _filter_xfs_io
ln $SCRATCH_MNT/hello $SCRATCH_MNT/mydir/hello_2
# Add some subdirectories and new files and links to them. This is to verify
# that after fsyncing our top level directory 'mydir', all the subdirectories
# and their files/links are registered in the fsync log and exist after the
# fsync log is replayed.
mkdir -p $SCRATCH_MNT/mydir/x/y/z
ln $SCRATCH_MNT/foo $SCRATCH_MNT/mydir/x/y/foo_y_link
ln $SCRATCH_MNT/foo $SCRATCH_MNT/mydir/x/y/z/foo_z_link
touch $SCRATCH_MNT/mydir/x/y/z/qwerty
# Now fsync only our top directory.
$XFS_IO_PROG -c "fsync" $SCRATCH_MNT/mydir
# And fsync now our new file named 'hello', just to verify later that it has
# the expected content and that the previous fsync on the directory 'mydir' had
# no bad influence on this fsync.
$XFS_IO_PROG -c "fsync" $SCRATCH_MNT/hello
# Simulate a crash/power loss.
_load_flakey_table $FLAKEY_DROP_WRITES
_unmount_flakey
_load_flakey_table $FLAKEY_ALLOW_WRITES
_mount_flakey
# Verify the content of our file 'foo' remains the same as before, 8192 bytes,
# all with the value 0xaa.
echo "File 'foo' content after log replay:"
od -t x1 $SCRATCH_MNT/foo
# Remove the first name of our inode. Because of the directory fsync bug, the
# inode's link count was 1 instead of 5, so removing the 'foo' name ended up
# deleting the inode and the other names became stale directory entries (still
# visible to applications). Attempting to remove or access the remaining
# dentries pointing to that inode resulted in stale file handle errors and
# made it impossible to remove the parent directories since it was impossible
# for them to become empty.
echo "file 'foo' link count after log replay: $(stat -c %h $SCRATCH_MNT/foo)"
rm -f $SCRATCH_MNT/foo
# Now verify that all files, links and directories created before fsyncing our
# directory exist after the fsync log was replayed.
[ -f $SCRATCH_MNT/mydir/foo_2 ] || echo "Link mydir/foo_2 is missing"
[ -f $SCRATCH_MNT/mydir/foo_3 ] || echo "Link mydir/foo_3 is missing"
[ -f $SCRATCH_MNT/hello ] || echo "File hello is missing"
[ -f $SCRATCH_MNT/mydir/hello_2 ] || echo "Link mydir/hello_2 is missing"
[ -f $SCRATCH_MNT/mydir/x/y/foo_y_link ] || \
echo "Link mydir/x/y/foo_y_link is missing"
[ -f $SCRATCH_MNT/mydir/x/y/z/foo_z_link ] || \
echo "Link mydir/x/y/z/foo_z_link is missing"
[ -f $SCRATCH_MNT/mydir/x/y/z/qwerty ] || \
echo "File mydir/x/y/z/qwerty is missing"
# We expect our file here to have a size of 64Kb and all the bytes having the
# value 0xff.
echo "file 'hello' content after log replay:"
od -t x1 $SCRATCH_MNT/hello
# Now remove all files/links, under our test directory 'mydir', and verify we
# can remove all the directories.
rm -f $SCRATCH_MNT/mydir/x/y/z/*
rmdir $SCRATCH_MNT/mydir/x/y/z
rm -f $SCRATCH_MNT/mydir/x/y/*
rmdir $SCRATCH_MNT/mydir/x/y
rmdir $SCRATCH_MNT/mydir/x
rm -f $SCRATCH_MNT/mydir/*
rmdir $SCRATCH_MNT/mydir
# An fsck, run by the fstests framework everytime a test finishes, also detected
# the inconsistency and printed the following error message:
#
# root 5 inode 257 errors 2001, no inode item, link count wrong
# unresolved ref dir 258 index 2 namelen 5 name foo_2 filetype 1 errors 4, no inode ref
# unresolved ref dir 258 index 3 namelen 5 name foo_3 filetype 1 errors 4, no inode ref
status=0
exit
The expected golden output for the test is:
wrote 8192/8192 bytes at offset 0
XXX Bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
wrote 65536/65536 bytes at offset 0
XXX Bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
File 'foo' content after log replay:
0000000 aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa
*
0020000
file 'foo' link count after log replay: 5
file 'hello' content after log replay:
0000000 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
*
0200000
Which is the output after this patch and when running the test against
ext3/4, xfs, f2fs, reiserfs or nilfs2. Without this patch, the test's
output is:
wrote 8192/8192 bytes at offset 0
XXX Bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
wrote 65536/65536 bytes at offset 0
XXX Bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
File 'foo' content after log replay:
0000000 aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa
*
0020000
file 'foo' link count after log replay: 1
Link mydir/foo_2 is missing
Link mydir/foo_3 is missing
Link mydir/x/y/foo_y_link is missing
Link mydir/x/y/z/foo_z_link is missing
File mydir/x/y/z/qwerty is missing
file 'hello' content after log replay:
0000000 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
*
0200000
rmdir: failed to remove '/home/fdmanana/btrfs-tests/scratch_1/mydir/x/y/z': No such file or directory
rmdir: failed to remove '/home/fdmanana/btrfs-tests/scratch_1/mydir/x/y': No such file or directory
rmdir: failed to remove '/home/fdmanana/btrfs-tests/scratch_1/mydir/x': No such file or directory
rm: cannot remove '/home/fdmanana/btrfs-tests/scratch_1/mydir/foo_2': Stale file handle
rm: cannot remove '/home/fdmanana/btrfs-tests/scratch_1/mydir/foo_3': Stale file handle
rmdir: failed to remove '/home/fdmanana/btrfs-tests/scratch_1/mydir': Directory not empty
Fsck, without this fix, also complains about the wrong link count:
root 5 inode 257 errors 2001, no inode item, link count wrong
unresolved ref dir 258 index 2 namelen 5 name foo_2 filetype 1 errors 4, no inode ref
unresolved ref dir 258 index 3 namelen 5 name foo_3 filetype 1 errors 4, no inode ref
So fix this by logging the inodes that the dentries point to when
fsyncing a directory.
A test case for xfstests follows.
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Chris Mason <clm@fb.com>
|
|
If we deleted xattrs from a file and fsynced the file, after a log replay
the xattrs would remain associated to the file. This was an unexpected
behaviour and differs from what other filesystems do, such as for example
xfs and ext3/4.
Fix this by, on fsync log replay, check if every xattr in the fs/subvol
tree (that belongs to a logged inode) has a matching xattr in the log,
and if it does not, delete it from the fs/subvol tree. This is a similar
approach to what we do for dentries when we replay a directory from the
fsync log.
This issue is trivial to reproduce, and the following excerpt from my
test for xfstests triggers the issue:
_crash_and_mount()
{
# Simulate a crash/power loss.
_load_flakey_table $FLAKEY_DROP_WRITES
_unmount_flakey
_load_flakey_table $FLAKEY_ALLOW_WRITES
_mount_flakey
}
rm -f $seqres.full
_scratch_mkfs >> $seqres.full 2>&1
_init_flakey
_mount_flakey
# Create out test file and add 3 xattrs to it.
touch $SCRATCH_MNT/foobar
$SETFATTR_PROG -n user.attr1 -v val1 $SCRATCH_MNT/foobar
$SETFATTR_PROG -n user.attr2 -v val2 $SCRATCH_MNT/foobar
$SETFATTR_PROG -n user.attr3 -v val3 $SCRATCH_MNT/foobar
# Make sure everything is durably persisted.
sync
# Now delete the second xattr and fsync the inode.
$SETFATTR_PROG -x user.attr2 $SCRATCH_MNT/foobar
$XFS_IO_PROG -c "fsync" $SCRATCH_MNT/foobar
_crash_and_mount
# After the fsync log is replayed, the file should have only 2 xattrs, the ones
# named user.attr1 and user.attr3. The btrfs fsync log replay bug left the file
# with the 3 xattrs that we had before deleting the second one and fsyncing the
# file.
echo "xattr names and values after first fsync log replay:"
$GETFATTR_PROG --absolute-names --dump $SCRATCH_MNT/foobar | _filter_scratch
# Now write some data to our file, fsync it, remove the first xattr, add a new
# hard link to our file and commit the fsync log by fsyncing some other new
# file. This is to verify that after log replay our first xattr does not exist
# anymore.
echo "hello world!" >> $SCRATCH_MNT/foobar
$XFS_IO_PROG -c "fsync" $SCRATCH_MNT/foobar
$SETFATTR_PROG -x user.attr1 $SCRATCH_MNT/foobar
ln $SCRATCH_MNT/foobar $SCRATCH_MNT/foobar_link
touch $SCRATCH_MNT/qwerty
$XFS_IO_PROG -c "fsync" $SCRATCH_MNT/qwerty
_crash_and_mount
# Now only the xattr with name user.attr3 should be set in our file.
echo "xattr names and values after second fsync log replay:"
$GETFATTR_PROG --absolute-names --dump $SCRATCH_MNT/foobar | _filter_scratch
status=0
exit
The expected golden output, which is produced with this patch applied or
when testing against xfs or ext3/4, is:
xattr names and values after first fsync log replay:
# file: SCRATCH_MNT/foobar
user.attr1="val1"
user.attr3="val3"
xattr names and values after second fsync log replay:
# file: SCRATCH_MNT/foobar
user.attr3="val3"
Without this patch applied, the output is:
xattr names and values after first fsync log replay:
# file: SCRATCH_MNT/foobar
user.attr1="val1"
user.attr2="val2"
user.attr3="val3"
xattr names and values after second fsync log replay:
# file: SCRATCH_MNT/foobar
user.attr1="val1"
user.attr2="val2"
user.attr3="val3"
A patch with a test case for xfstests follows soon.
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Chris Mason <clm@fb.com>
|
|
git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux into for-linus-4.1
Signed-off-by: Chris Mason <clm@fb.com>
Conflicts:
fs/btrfs/disk-io.c
|
|
git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs
Pull btrfs fixes from Chris Mason:
"Outside of misc fixes, Filipe has a few fsync corners and we're
pulling in one more of Josef's fixes from production use here"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs:
Btrfs:__add_inode_ref: out of bounds memory read when looking for extended ref.
Btrfs: fix data loss in the fast fsync path
Btrfs: remove extra run_delayed_refs in update_cowonly_root
Btrfs: incremental send, don't rename a directory too soon
btrfs: fix lost return value due to variable shadowing
Btrfs: do not ignore errors from btrfs_lookup_xattr in do_setxattr
Btrfs: fix off-by-one logic error in btrfs_realloc_node
Btrfs: add missing inode update when punching hole
Btrfs: abort the transaction if we fail to update the free space cache inode
Btrfs: fix fsync race leading to ordered extent memory leaks
|
|
Improper arithmetics when calculting the address of the extended ref could
lead to an out of bounds memory read and kernel panic.
Signed-off-by: Quentin Casasnovas <quentin.casasnovas@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.cz>
cc: stable@vger.kernel.org # v3.7+
Signed-off-by: Chris Mason <clm@fb.com>
|
|
git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs
Pull btrfs updates from Chris Mason:
"This pull is mostly cleanups and fixes:
- The raid5/6 cleanups from Zhao Lei fixup some long standing warts
in the code and add improvements on top of the scrubbing support
from 3.19.
- Josef has round one of our ENOSPC fixes coming from large btrfs
clusters here at FB.
- Dave Sterba continues a long series of cleanups (thanks Dave), and
Filipe continues hammering on corner cases in fsync and others
This all was held up a little trying to track down a use-after-free in
btrfs raid5/6. It's not clear yet if this is just made easier to
trigger with this pull or if its a new bug from the raid5/6 cleanups.
Dave Sterba is the only one to trigger it so far, but he has a
consistent way to reproduce, so we'll get it nailed shortly"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs: (68 commits)
Btrfs: don't remove extents and xattrs when logging new names
Btrfs: fix fsync data loss after adding hard link to inode
Btrfs: fix BUG_ON in btrfs_orphan_add() when delete unused block group
Btrfs: account for large extents with enospc
Btrfs: don't set and clear delalloc for O_DIRECT writes
Btrfs: only adjust outstanding_extents when we do a short write
btrfs: Fix out-of-space bug
Btrfs: scrub, fix sleep in atomic context
Btrfs: fix scheduler warning when syncing log
Btrfs: Remove unnecessary placeholder in btrfs_err_code
btrfs: cleanup init for list in free-space-cache
btrfs: delete chunk allocation attemp when setting block group ro
btrfs: clear bio reference after submit_one_bio()
Btrfs: fix scrub race leading to use-after-free
Btrfs: add missing cleanup on sysfs init failure
Btrfs: fix race between transaction commit and empty block group removal
btrfs: add more checks to btrfs_read_sys_array
btrfs: cleanup, rename a few variables in btrfs_read_sys_array
btrfs: add checks for sys_chunk_array sizes
btrfs: more superblock checks, lower bounds on devices and sectorsize/nodesize
...
|
|
This is the 3rd independent patch of a larger project to cleanup btrfs's
internal usage of btrfs_root. Many functions take btrfs_root only to
grab the fs_info struct.
By requiring a root these functions cause programmer overhead. That
these functions can accept any valid root is not obvious until
inspection.
This patch reduces the specificity of such functions to accept the
fs_info directly.
These patches can be applied independently and thus are not being
submitted as a patch series. There should be about 26 patches by the
project's completion. Each patch will cleanup between 1 and 34 functions
apiece. Each patch covers a single file's functions.
This patch affects the following function(s):
1) csum_tree_block
2) csum_dirty_buffer
3) check_tree_block_fsid
4) btrfs_find_tree_block
5) clean_tree_block
Signed-off-by: Daniel Dressler <danieru.dressler@gmail.com>
Signed-off-by: David Sterba <dsterba@suse.cz>
|
|
If we are recording in the tree log that an inode has new names (new hard
links were added), we would drop items, belonging to the inode, that we
shouldn't:
1) When the flag BTRFS_INODE_COPY_EVERYTHING is set in the inode's runtime
flags, we ended up dropping all the extent and xattr items that were
previously logged. This was done only in memory, since logging a new
name doesn't imply syncing the log;
2) When the flag BTRFS_INODE_COPY_EVERYTHING is set in the inode's runtime
flags, we ended up dropping all the xattr items that were previously
logged. Like the case before, this was done only in memory because
logging a new name doesn't imply syncing the log.
This led to some surprises in scenarios such as the following:
1) write some extents to an inode;
2) fsync the inode;
3) truncate the inode or delete/modify some of its xattrs
4) add a new hard link for that inode
5) fsync some other file, to force the log tree to be durably persisted
6) power failure happens
The next time the fs is mounted, the fsync log replay code is executed,
and the resulting file doesn't have the content it had when the last fsync
against it was performed, instead if has a content matching what it had
when the last transaction commit happened.
So change the behaviour such that when a new name is logged, only the inode
item and reference items are processed.
This is easy to reproduce with the test I just made for xfstests, whose
main body is:
_scratch_mkfs >> $seqres.full 2>&1
_init_flakey
_mount_flakey
# Create our test file with some data.
$XFS_IO_PROG -f -c "pwrite -S 0xaa -b 8K 0 8K" \
$SCRATCH_MNT/foo | _filter_xfs_io
# Make sure the file is durably persisted.
sync
# Append some data to our file, to increase its size.
$XFS_IO_PROG -f -c "pwrite -S 0xcc -b 4K 8K 4K" \
$SCRATCH_MNT/foo | _filter_xfs_io
# Fsync the file, so from this point on if a crash/power failure happens, our
# new data is guaranteed to be there next time the fs is mounted.
$XFS_IO_PROG -c "fsync" $SCRATCH_MNT/foo
# Now shrink our file to 5000 bytes.
$XFS_IO_PROG -c "truncate 5000" $SCRATCH_MNT/foo
# Now do an expanding truncate to a size larger than what we had when we last
# fsync'ed our file. This is just to verify that after power failure and
# replaying the fsync log, our file matches what it was when we last fsync'ed
# it - 12Kb size, first 8Kb of data had a value of 0xaa and the last 4Kb of
# data had a value of 0xcc.
$XFS_IO_PROG -c "truncate 32K" $SCRATCH_MNT/foo
# Add one hard link to our file. This made btrfs drop all of our file's
# metadata from the fsync log, including the metadata relative to the
# extent we just wrote and fsync'ed. This change was made only to the fsync
# log in memory, so adding the hard link alone doesn't change the persisted
# fsync log. This happened because the previous truncates set the runtime
# flag BTRFS_INODE_NEEDS_FULL_SYNC in the btrfs inode structure.
ln $SCRATCH_MNT/foo $SCRATCH_MNT/foo_link
# Now make sure the in memory fsync log is durably persisted.
# Creating and fsync'ing another file will do it.
# After this our persisted fsync log will no longer have metadata for our file
# foo that points to the extent we wrote and fsync'ed before.
touch $SCRATCH_MNT/bar
$XFS_IO_PROG -c "fsync" $SCRATCH_MNT/bar
# As expected, before the crash/power failure, we should be able to see a file
# with a size of 32Kb, with its first 5000 bytes having the value 0xaa and all
# the remaining bytes with value 0x00.
echo "File content before:"
od -t x1 $SCRATCH_MNT/foo
# Simulate a crash/power loss.
_load_flakey_table $FLAKEY_DROP_WRITES
_unmount_flakey
_load_flakey_table $FLAKEY_ALLOW_WRITES
_mount_flakey
# After mounting the fs again, the fsync log was replayed.
# The expected result is to see a file with a size of 12Kb, with its first 8Kb
# of data having the value 0xaa and its last 4Kb of data having a value of 0xcc.
# The btrfs bug used to leave the file as it used te be as of the last
# transaction commit - that is, with a size of 8Kb with all bytes having a
# value of 0xaa.
echo "File content after:"
od -t x1 $SCRATCH_MNT/foo
The test case for xfstests follows soon.
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Chris Mason <clm@fb.com>
|
|
We have a scenario where after the fsync log replay we can lose file data
that had been previously fsync'ed if we added an hard link for our inode
and after that we sync'ed the fsync log (for example by fsync'ing some
other file or directory).
This is because when adding an hard link we updated the inode item in the
log tree with an i_size value of 0. At that point the new inode item was
in memory only and a subsequent fsync log replay would not make us lose
the file data. However if after adding the hard link we sync the log tree
to disk, by fsync'ing some other file or directory for example, we ended
up losing the file data after log replay, because the inode item in the
persisted log tree had an an i_size of zero.
This is easy to reproduce, and the following excerpt from my test for
xfstests shows this:
_scratch_mkfs >> $seqres.full 2>&1
_init_flakey
_mount_flakey
# Create one file with data and fsync it.
# This made the btrfs fsync log persist the data and the inode metadata with
# a correct inode->i_size (4096 bytes).
$XFS_IO_PROG -f -c "pwrite -S 0xaa -b 4K 0 4K" -c "fsync" \
$SCRATCH_MNT/foo | _filter_xfs_io
# Now add one hard link to our file. This made the btrfs code update the fsync
# log, in memory only, with an inode metadata having a size of 0.
ln $SCRATCH_MNT/foo $SCRATCH_MNT/foo_link
# Now force persistence of the fsync log to disk, for example, by fsyncing some
# other file.
touch $SCRATCH_MNT/bar
$XFS_IO_PROG -c "fsync" $SCRATCH_MNT/bar
# Before a power loss or crash, we could read the 4Kb of data from our file as
# expected.
echo "File content before:"
od -t x1 $SCRATCH_MNT/foo
# Simulate a crash/power loss.
_load_flakey_table $FLAKEY_DROP_WRITES
_unmount_flakey
_load_flakey_table $FLAKEY_ALLOW_WRITES
_mount_flakey
# After the fsync log replay, because the fsync log had a value of 0 for our
# inode's i_size, we couldn't read anymore the 4Kb of data that we previously
# wrote and fsync'ed. The size of the file became 0 after the fsync log replay.
echo "File content after:"
od -t x1 $SCRATCH_MNT/foo
Another alternative test, that doesn't need to fsync an inode in the same
transaction it was created, is:
_scratch_mkfs >> $seqres.full 2>&1
_init_flakey
_mount_flakey
# Create our test file with some data.
$XFS_IO_PROG -f -c "pwrite -S 0xaa -b 8K 0 8K" \
$SCRATCH_MNT/foo | _filter_xfs_io
# Make sure the file is durably persisted.
sync
# Append some data to our file, to increase its size.
$XFS_IO_PROG -f -c "pwrite -S 0xcc -b 4K 8K 4K" \
$SCRATCH_MNT/foo | _filter_xfs_io
# Fsync the file, so from this point on if a crash/power failure happens, our
# new data is guaranteed to be there next time the fs is mounted.
$XFS_IO_PROG -c "fsync" $SCRATCH_MNT/foo
# Add one hard link to our file. This made btrfs write into the in memory fsync
# log a special inode with generation 0 and an i_size of 0 too. Note that this
# didn't update the inode in the fsync log on disk.
ln $SCRATCH_MNT/foo $SCRATCH_MNT/foo_link
# Now make sure the in memory fsync log is durably persisted.
# Creating and fsync'ing another file will do it.
touch $SCRATCH_MNT/bar
$XFS_IO_PROG -c "fsync" $SCRATCH_MNT/bar
# As expected, before the crash/power failure, we should be able to read the
# 12Kb of file data.
echo "File content before:"
od -t x1 $SCRATCH_MNT/foo
# Simulate a crash/power loss.
_load_flakey_table $FLAKEY_DROP_WRITES
_unmount_flakey
_load_flakey_table $FLAKEY_ALLOW_WRITES
_mount_flakey
# After mounting the fs again, the fsync log was replayed.
# The btrfs fsync log replay code didn't update the i_size of the persisted
# inode because the inode item in the log had a special generation with a
# value of 0 (and it couldn't know the correct i_size, since that inode item
# had a 0 i_size too). This made the last 4Kb of file data inaccessible and
# effectively lost.
echo "File content after:"
od -t x1 $SCRATCH_MNT/foo
This isn't a new issue/regression. This problem has been around since the
log tree code was added in 2008:
Btrfs: Add a write ahead tree log to optimize synchronous operations
(commit e02119d5a7b4396c5a872582fddc8bd6d305a70a)
Test cases for xfstests follow soon.
CC: <stable@vger.kernel.org>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Chris Mason <clm@fb.com>
|
|
We try to lock a mutex while the current task state is not TASK_RUNNING,
which results in the following warning when CONFIG_DEBUG_LOCK_ALLOC=y:
[30736.772501] ------------[ cut here ]------------
[30736.774545] WARNING: CPU: 9 PID: 19972 at kernel/sched/core.c:7300 __might_sleep+0x8b/0xa8()
[30736.783453] do not call blocking ops when !TASK_RUNNING; state=2 set at [<ffffffff8107499b>] prepare_to_wait+0x43/0x89
[30736.786261] Modules linked in: dm_flakey dm_mod crc32c_generic btrfs xor raid6_pq nfsd auth_rpcgss oid_registry nfs_acl nfs lockd grace fscache sunrpc loop parport_pc psmouse parport pcspkr microcode serio_raw evdev processor thermal_sys i2c_piix4 i2c_core button ext4 crc16 jbd2 mbcache sg sr_mod cdrom sd_mod ata_generic virtio_scsi floppy ata_piix libata virtio_pci virtio_ring e1000 virtio scsi_mod
[30736.794323] CPU: 9 PID: 19972 Comm: fsstress Not tainted 3.19.0-rc7-btrfs-next-5+ #1
[30736.795821] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.7.5-0-ge51488c-20140602_164612-nilsson.home.kraxel.org 04/01/2014
[30736.798788] 0000000000000009 ffff88042743fbd8 ffffffff814248ed ffff88043d32f2d8
[30736.800504] ffff88042743fc28 ffff88042743fc18 ffffffff81045338 0000000000000001
[30736.802131] ffffffff81064514 ffffffff817c52d1 000000000000026d 0000000000000000
[30736.803676] Call Trace:
[30736.804256] [<ffffffff814248ed>] dump_stack+0x4c/0x65
[30736.805245] [<ffffffff81045338>] warn_slowpath_common+0xa1/0xbb
[30736.806360] [<ffffffff81064514>] ? __might_sleep+0x8b/0xa8
[30736.807391] [<ffffffff81045398>] warn_slowpath_fmt+0x46/0x48
[30736.808511] [<ffffffff8107499b>] ? prepare_to_wait+0x43/0x89
[30736.809620] [<ffffffff8107499b>] ? prepare_to_wait+0x43/0x89
[30736.810691] [<ffffffff81064514>] __might_sleep+0x8b/0xa8
[30736.811703] [<ffffffff81426eaf>] mutex_lock_nested+0x2f/0x3a0
[30736.812889] [<ffffffff8107bfa1>] ? trace_hardirqs_on_caller+0x18f/0x1ab
[30736.814138] [<ffffffff8107bfca>] ? trace_hardirqs_on+0xd/0xf
[30736.819878] [<ffffffffa038cfff>] wait_for_writer.isra.12+0x91/0xaa [btrfs]
[30736.821260] [<ffffffff810748bd>] ? signal_pending_state+0x31/0x31
[30736.822410] [<ffffffffa0391f0a>] btrfs_sync_log+0x160/0x947 [btrfs]
[30736.823574] [<ffffffff8107bfa1>] ? trace_hardirqs_on_caller+0x18f/0x1ab
[30736.824847] [<ffffffff8107bfca>] ? trace_hardirqs_on+0xd/0xf
[30736.825972] [<ffffffffa036e555>] btrfs_sync_file+0x2b0/0x319 [btrfs]
[30736.827684] [<ffffffff8117901a>] vfs_fsync_range+0x21/0x23
[30736.828932] [<ffffffff81179038>] vfs_fsync+0x1c/0x1e
[30736.829917] [<ffffffff8117928b>] do_fsync+0x34/0x4e
[30736.830862] [<ffffffff811794b3>] SyS_fsync+0x10/0x14
[30736.831819] [<ffffffff8142a512>] system_call_fastpath+0x12/0x17
[30736.832982] ---[ end trace c0b57df60d32ae5c ]---
Fix this my acquiring the mutex after calling finish_wait(), which sets the
task's state to TASK_RUNNING.
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: Chris Mason <clm@fb.com>
|
|
Add missing blk_finish_plug in btrfs_sync_log()
Signed-off-by: Forrest Liu <forrestl@synology.com>
Reviewed-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Chris Mason <clm@fb.com>
|
|
They just opencode taking address of the timespec member.
Signed-off-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Chris Mason <clm@fb.com>
|
|
If we have an inode with a large number of hard links, some of which may
be extrefs, turn a regular ref into an extref, fsync the inode and then
replay the fsync log (after a crash/reboot), we can endup with an fsync
log that makes the replay code always fail with -EOVERFLOW when processing
the inode's references.
This is easy to reproduce with the test case I made for xfstests. Its steps
are the following:
_scratch_mkfs "-O extref" >> $seqres.full 2>&1
_init_flakey
_mount_flakey
# Create a test file with 3001 hard links. This number is large enough to
# make btrfs start using extrefs at some point even if the fs has the maximum
# possible leaf/node size (64Kb).
echo "hello world" > $SCRATCH_MNT/foo
for i in `seq 1 3000`; do
ln $SCRATCH_MNT/foo $SCRATCH_MNT/foo_link_`printf "%04d" $i`
done
# Make sure all metadata and data are durably persisted.
sync
# Now remove one link, add a new one with a new name, add another new one with
# the same name as the one we just removed and fsync the inode.
rm -f $SCRATCH_MNT/foo_link_0001
ln $SCRATCH_MNT/foo $SCRATCH_MNT/foo_link_3001
ln $SCRATCH_MNT/foo $SCRATCH_MNT/foo_link_0001
rm -f $SCRATCH_MNT/foo_link_0002
ln $SCRATCH_MNT/foo $SCRATCH_MNT/foo_link_3002
ln $SCRATCH_MNT/foo $SCRATCH_MNT/foo_link_3003
$XFS_IO_PROG -c "fsync" $SCRATCH_MNT/foo
# Simulate a crash/power loss. This makes sure the next mount
# will see an fsync log and will replay that log.
_load_flakey_table $FLAKEY_DROP_WRITES
_unmount_flakey
_load_flakey_table $FLAKEY_ALLOW_WRITES
_mount_flakey
# Check that the number of hard links is correct, we are able to remove all
# the hard links and read the file's data. This is just to verify we don't
# get stale file handle errors (due to dangling directory index entries that
# point to inodes that no longer exist).
echo "Link count: $(stat --format=%h $SCRATCH_MNT/foo)"
[ -f $SCRATCH_MNT/foo ] || echo "Link foo is missing"
for ((i = 1; i <= 3003; i++)); do
name=foo_link_`printf "%04d" $i`
if [ $i -eq 2 ]; then
[ -f $SCRATCH_MNT/$name ] && echo "Link $name found"
else
[ -f $SCRATCH_MNT/$name ] || echo "Link $name is missing"
fi
done
rm -f $SCRATCH_MNT/foo_link_*
cat $SCRATCH_MNT/foo
rm -f $SCRATCH_MNT/foo
status=0
exit
The fix is simply to correct the overflow condition when overwriting a
reference item because it was wrong, trying to increase the item in the
fs/subvol tree by an impossible amount. Also ensure that we don't insert
one normal ref and one ext ref for the same dentry - this happened because
processing a dir index entry from the parent in the log happened when
the normal ref item was full, which made the logic insert an extref and
later when the normal ref had enough room, it would be inserted again
when processing the ref item from the child inode in the log.
This issue has been present since the introduction of the extrefs feature
(2012).
A test case for xfstests follows soon. This test only passes if the previous
patch titled "Btrfs: fix fsync when extend references are added to an inode"
is applied too.
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Chris Mason <clm@fb.com>
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If we added an extended reference to an inode and fsync'ed it, the log
replay code would make our inode have an incorrect link count, which
was lower then the expected/correct count.
This resulted in stale directory index entries after deleting some of
the hard links, and any access to the dangling directory entries resulted
in -ESTALE errors because the entries pointed to inode items that don't
exist anymore.
This is easy to reproduce with the test case I made for xfstests, and
the bulk of that test is:
_scratch_mkfs "-O extref" >> $seqres.full 2>&1
_init_flakey
_mount_flakey
# Create a test file with 3001 hard links. This number is large enough to
# make btrfs start using extrefs at some point even if the fs has the maximum
# possible leaf/node size (64Kb).
echo "hello world" > $SCRATCH_MNT/foo
for i in `seq 1 3000`; do
ln $SCRATCH_MNT/foo $SCRATCH_MNT/foo_link_`printf "%04d" $i`
done
# Make sure all metadata and data are durably persisted.
sync
# Add one more link to the inode that ends up being a btrfs extref and fsync
# the inode.
ln $SCRATCH_MNT/foo $SCRATCH_MNT/foo_link_3001
$XFS_IO_PROG -c "fsync" $SCRATCH_MNT/foo
# Simulate a crash/power loss. This makes sure the next mount
# will see an fsync log and will replay that log.
_load_flakey_table $FLAKEY_DROP_WRITES
_unmount_flakey
_load_flakey_table $FLAKEY_ALLOW_WRITES
_mount_flakey
# Now after the fsync log replay btrfs left our inode with a wrong link count N,
# which was smaller than the correct link count M (N < M).
# So after removing N hard links, the remaining M - N directory entries were
# still visible to user space but it was impossible to do anything with them
# because they pointed to an inode that didn't exist anymore. This resulted in
# stale file handle errors (-ESTALE) when accessing those dentries for example.
#
# So remove all hard links except the first one and then attempt to read the
# file, to verify we don't get an -ESTALE error when accessing the inodel
#
# The btrfs fsck tool also detected the incorrect inode link count and it
# reported an error message like the following:
#
# root 5 inode 257 errors 2001, no inode item, link count wrong
# unresolved ref dir 256 index 2978 namelen 13 name foo_link_2976 filetype 1 errors 4, no inode ref
#
# The fstests framework automatically calls fsck after a test is run, so we
# don't need to call fsck explicitly here.
rm -f $SCRATCH_MNT/foo_link_*
cat $SCRATCH_MNT/foo
status=0
exit
So make sure an fsync always flushes the delayed inode item, so that the
fsync log contains it (needed in order to trigger the link count fixup
code) and fix the extref counting function, which always return -ENOENT
to its caller (and made it assume there were always 0 extrefs).
This issue has been present since the introduction of the extrefs feature
(2012).
A test case for xfstests follows soon.
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Chris Mason <clm@fb.com>
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If we have an inode (file) with a link count greater than 1, remove
one of its hard links, fsync the inode, power fail/crash and then
replay the fsync log on the next mount, we end up getting the parent
directory's metadata inconsistent - its i_size still reflects the
deleted hard link and has dangling index entries (with no matching
inode reference entries). This prevents the directory from ever being
deletable, as its i_size can never decrease to BTRFS_EMPTY_DIR_SIZE
even if all of its children inodes are deleted, and the dangling index
entries can never be removed (as they point to an inode that does not
exist anymore).
This is easy to reproduce with the following excerpt from the test case
for xfstests that I just made:
_scratch_mkfs >> $seqres.full 2>&1
_init_flakey
_mount_flakey
# Create a test file with 2 hard links in the same directory.
mkdir -p $SCRATCH_MNT/a/b
echo "hello world" > $SCRATCH_MNT/a/b/foo
ln $SCRATCH_MNT/a/b/foo $SCRATCH_MNT/a/b/bar
# Make sure all metadata and data are durably persisted.
sync
# Now remove one of the hard links and fsync the inode.
rm -f $SCRATCH_MNT/a/b/bar
$XFS_IO_PROG -c "fsync" $SCRATCH_MNT/a/b/foo
# Simulate a crash/power loss. This makes sure the next mount
# will see an fsync log and will replay that log.
_load_flakey_table $FLAKEY_DROP_WRITES
_unmount_flakey
_load_flakey_table $FLAKEY_ALLOW_WRITES
_mount_flakey
# Remove the last hard link of the file and attempt to remove its parent
# directory - this failed in btrfs because the fsync log and replay code
# didn't decrement the parent directory's i_size and left dangling directory
# index entries - this made the btrfs rmdir implementation always fail with
# the error -ENOTEMPTY.
#
# The dangling directory index entries were visible to user space, but it was
# impossible to do anything on them (unlink, open, read, write, stat, etc)
# because the inode they pointed to did not exist anymore.
#
# The parent directory's metadata inconsistency (stale index entries) was
# also detected by btrfs' fsck tool, which is run automatically by the fstests
# framework when the test finishes. The error message reported by fsck was:
#
# root 5 inode 259 errors 2001, no inode item, link count wrong
# unresolved ref dir 258 index 3 namelen 3 name bar filetype 1 errors 4, no inode ref
#
rm -f $SCRATCH_MNT/a/b/*
rmdir $SCRATCH_MNT/a/b
rmdir $SCRATCH_MNT/a
To fix this just make sure that after an unlink, if the inode is fsync'ed,
he parent inode is fully logged in the fsync log.
A test case for xfstests follows soon.
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Chris Mason <clm@fb.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux into for-linus
|
|
We can search and add the orphan item in one go,
btrfs_insert_orphan_item will find out if the item already exists.
Signed-off-by: David Sterba <dsterba@suse.cz>
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If btrfs_find_item is called with NULL path it allocates one locally but
does not free it. Affected paths are inserting an orphan item for a file
and for a subvol root.
Move the path allocation to the callers.
CC: <stable@vger.kernel.org> # 3.14+
Fixes: 3f870c289900 ("btrfs: expand btrfs_find_item() to include find_orphan_item functionality")
Signed-off-by: David Sterba <dsterba@suse.cz>
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