bch2_trigger_alloc() kicks off certain tasks on bucket state changes;
e.g. triggering the bucket discard worker and the invalidate worker.

We've observed the discard worker running too often - most runs it
doesn't do any work, according to the tracepoint - so clearly, we're
kicking it off too often.

This adds an explicit statechange() macro to make these checks more
precise.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

Make sure early error messages get redirected, for
kernel-fsck-from-userland.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

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

THis silences a mm/page_alloc.c warning about allocating more than a
page with GFP_NOFAIL - and there's no reason for this to not have a
vmalloc fallback anyways.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

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

When bch2_btree_iter_peek_slot() clones the iterator to search for the
next key, and then discovers that the key from the cloned iterator is
the key we want to return - we also want to save the
iter->key_cache_path as well, for the update path.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

Various phases of fsck involve checking references from one btree to
another: this means doing a sequential scan of one btree, and then
mostly random access into the second.

This is particularly painful for checking extents <-> backpointers; we
can prefetch btree node access on the sequential scan, but not on the
random access portion, and this is particularly painful on spinning
rust, where we'd like to keep the pipeline fairly full of btree node
reads so that the elevator can reduce seeking.

This patch implements prefetching and pinning of the portion of the
btree that we'll be doing random access to. We already calculate how
much of the random access btree will fit in memory so it's a fairly
straightforward change.

This will put more pressure on system memory usage, so we introduce a
new option, fsck_memory_usage_percent, which is the percentage of total
system ram that fsck is allowed to pin.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

Recursively destroying subvolumes isn't allowed yet.

Fixes: https://github.com/koverstreet/bcachefs/issues/634Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

Add a btree to record a parent -> child subvolume relationships,
according to the filesystem heirarchy.

The subvolume_children btree is a bitset btree: if a bit is set at pos
p, that means p.offset is a child of subvolume p.inode.

This will be used for efficiently listing subvolumes, as well as
recursive deletion.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

Record the filesystem path heirarchy for subvolumes in bch_subvolume
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

Provide a non-write buffer version of bch2_btree_bit_mod_buffered(), for
the subvolume children btree.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

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

Subvolumes need special handling to reattach - we always reattach them
in the root subvolume's lost+found, and they need a slightly different
kind of dirent.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

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

prep work for improving logging/error messages
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

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

bit of renaming, prep for adding a fs path parent
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

when repair switches d_type to or from DT_SUBVOL, we need to update the
target accordingly
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

Check that d_parent_subvol makes sense - the dirent's snapshot must be
visible in d_parent_subvol (i.e. an ancestor of d_parent_subvol's
snapshot) in order to be visible.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

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

these were already checked in check_subvol()
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

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

check for inodes with a nonzero bi_parent_subvol field that aren't
actually subvolume roots
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

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

check that if an inode has a backpointer, the dirent it points to points
back to it.

We do this in check_dirent_inode_dirent(), but only for inodes that have
dirents that point to them - we also have to do the check starting from
the inode to catch inodes that don't have dirents that point to them.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

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

Subvolumes and subvolume root inodes point to each other: this verifies
the subvolume -> inode -> subvolme path.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

This converts -EIOs related to btree node errors to private error codes,
which will help with some ongoing debugging by giving us better error
messages.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

Add a flush op, to return the exit code via close().

Also update bcachefs usage to use this to return fsck exit codes.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

Fixes: https://lore.kernel.org/linux-bcachefs/202402131603.E953E2CF@keescook/T/#u
Reported-by: coverity scan
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

Make it so that a thread_with_stdio user can handle ioctls against the
file descriptor.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

Create an ops structure so we can add more file-based functionality in
the next few patches.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

Experimentally fix some problems with stdio_redirect_vprintf by creating
a MOO variant with which we can experiment.  We can't do a GFP_KERNEL
allocation while holding the spinlock, and I don't like how the printf
function can silently truncate the output if memory allocation fails.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

Create a new run_thread_with_stdout function that opens a file in
O_RDONLY mode so that the kernel can write things to userspace but
userspace cannot write to the kernel.  This will be used to convey xfs
health event information to userspace.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

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

needed for thread_with_file; also rare but not unheard of to need this
in module code, when blocking on user input.

one workaround used by some code is wait_event_interruptible() - but
that can be buggy if the outer context isn't expecting unwinding.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: fuyuanli <fuyuanli@didiglobal.com>

This fixes stdio_redirect_read() getting stuck, not noticing that the
pipe has been closed.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

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

This fixes a bug where we'd return data without waiting for a newline,
if data was present but a newline was not.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

Move the cleanup code to a wrapper function, where we can call it after
the thread_with_stdio fn exits.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>