Syzbot reports a problem that a warning is triggered due to suspicious
use of rcu_dereference_check(). That is triggered by a call of
bch2_snapshot_tree_oldest_subvol().

The cause of the warning is that inside
bch2_snapshot_tree_oldest_subvol(), snapshot_t() is called which calls
rcu_dereference() that requires a read lock to be held. Also, the call
of bch2_snapshot_tree_next() eventually calls snapshot_t().

To fix this, call rcu_read_lock() before calling snapshot_t(). Then,
release the lock after the termination of the while loop.

Reported-by: <syzbot+f7c41a878676b72c16a6@syzkaller.appspotmail.com>
Signed-off-by: Ahmed Ehab <bottaawesome633@gmail.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

syzbot reported a null-ptr-deref in bch2_fs_start. [0]

When a sb is marked clear but doesn't have a clean section
bch2_read_superblock_clean returns NULL which PTR_ERR_OR_ZERO
lets through, eventually leading to a null ptr dereference down
the line. Adjust read sb clean to return an ERR_PTR indicating the
invalid clean section.

[0] https://syzkaller.appspot.com/bug?extid=1cecc37d87c4286e5543

Reported-by: syzbot+1cecc37d87c4286e5543@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=1cecc37d87c4286e5543Signed-off-by: Diogo Jahchan Koike <djahchankoike@gmail.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

The header files bbpos.h is included twice in backpointers.c,
so one inclusion of each can be removed.
Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Closes: https://bugzilla.openanolis.cn/show_bug.cgi?id=10783Signed-off-by: Yang Li <yang.lee@linux.alibaba.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

This factors out ec_strie_head_devs_update(), which initializes the
bitmap of devices we're allocating from, and runs it every time
c->rw_devs_change_count changes.

We also cancel pending, not allocated stripes, since they may refer to
devices that are no longer available.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

Add a counter that's incremented whenever rw devices change; this will
be used for erasure coding so that it can keep ec_stripe_head in sync
and not deadlock on a new stripe when a device it wants goes away.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

We can now correctly force-remove a device that has stripes on it; this
uses the new BCH_SB_MEMBER_INVALID sentinal value.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

This is necessary for erasure coded pointers to devices that have been
removed.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

also print out the new stripe key
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

additional debug stat
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

When reshaping existing stripes, we should keep them on the same target
that they were allocated on; to do this, we need to add a field to the
btree stripe type.

This is a tad awkward, because we only have 8 bits left, and targets are
16 bits - but we only need to store a label, not a full target.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

factor out a common helper
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

We want to be using private errcodes whenever possible, for better error
messages.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

In backpointers fsck, we do a seqential scan of one btree, and check
references to another: extents <-> backpointers

Checking references generates random lookups, so we want to pin that
btree in memory (or only a range, if it doesn't fit in ram).

Previously, this was done with a simple check in the shrinker - "if
btree node is in range being pinned, don't free it" - but this generated
OOMs, as our shrinker wasn't well behaved if there was less memory
available than expected.

Instead, we now have two different shrinkers and lru lists; the second
shrinker being for pinned nodes, with seeks set much higher than normal
- so they can still be freed if necessary, but we'll prefer not to.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

this is prep for introducing a second live list and shrinker for pinned
nodes
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

32 bits won't overflow any time soon, but size_t is the correct type for
counting objects in memory.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

bch2_dev_rcu() now properly errors if the device is invalid
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

Factor out bch2_show_options() into a generic helper, for debugging
option passing issues.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

Fix the following compilation error:

```
fs/bcachefs/sb-members.c: In function ‘bch2_sb_member_alloc’:
fs/bcachefs/sb-members.c:508:2: error: a label can only be part of a statement and a declaration is not a statement
  508 |  unsigned nr_devices = max_t(unsigned, dev_idx + 1, c->sb.nr_devices);
```

Fixes: a7d364a133c7 ("bcachefs: bch2_sb_member_alloc()")
Signed-off-by: Hongbo Li <lihongbo22@huawei.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

refactoring
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

No reason for it not to be where it's needed.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

This adds mount options for specifying recovery passes to run, or
exclude; the immediate need for this is that backpointers fsck is having
trouble completing, so we need a way to skip it.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

When freeing in a shrinker callback, we need to notify memory reclaim,
so it knows forward progress has been made.

Normally this is done in e.g. slab code, but we're not freeing through
slab - or rather we are, but these allocations are big, and use the
kmalloc_large() path.

This is really a bug in the slub code, but we're working around it here
for now.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

This is needed for overlayfs, which is used by container managers.
Signed-off-by: Sasha Finkelstein <fnkl.kernel@gmail.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

this was an oversight: rebalance is moving data to a specific device, so
we don't want it falling back to the full filesystem
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

rebalance writes must be BCH_WRITE_ALLOC_NOWAIT because they don't
allocate from the full filesystem - but we don't want spurious
allocation failures due to open buckets.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

like the previous patch, kill use of bare arrays; the encryption code
likes to work in big batches, so this is a small performance
improvement.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

convert to darray, and add a fallback when allocation fails
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

Add the __counted_by compiler attribute to the flexible array members
devs to improve access bounds-checking via CONFIG_UBSAN_BOUNDS and
CONFIG_FORTIFY_SOURCE.

Increment nr_devs before adding a new device to the devs array and
adjust the array indexes accordingly. Add a helper macro for adding a
new device.

In bch2_journal_read(), explicitly set nr_devs to 0.
Signed-off-by: Thorsten Blum <thorsten.blum@toblux.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>