linux/fs/bcachefs/btree_write_buffer.c

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// SPDX-License-Identifier: GPL-2.0
#include "bcachefs.h"
#include "bkey_buf.h"
#include "btree_locking.h"
#include "btree_update.h"
#include "btree_update_interior.h"
#include "btree_write_buffer.h"
#include "disk_accounting.h"
#include "error.h"
#include "extents.h"
#include "journal.h"
#include "journal_io.h"
#include "journal_reclaim.h"
#include <linux/prefetch.h>
#include <linux/sort.h>
static int bch2_btree_write_buffer_journal_flush(struct journal *,
struct journal_entry_pin *, u64);
static int bch2_journal_keys_to_write_buffer(struct bch_fs *, struct journal_buf *);
static inline bool __wb_key_ref_cmp(const struct wb_key_ref *l, const struct wb_key_ref *r)
{
return (cmp_int(l->hi, r->hi) ?:
cmp_int(l->mi, r->mi) ?:
cmp_int(l->lo, r->lo)) >= 0;
}
static inline bool wb_key_ref_cmp(const struct wb_key_ref *l, const struct wb_key_ref *r)
{
#ifdef CONFIG_X86_64
int cmp;
asm("mov (%[l]), %%rax;"
"sub (%[r]), %%rax;"
"mov 8(%[l]), %%rax;"
"sbb 8(%[r]), %%rax;"
"mov 16(%[l]), %%rax;"
"sbb 16(%[r]), %%rax;"
: "=@ccae" (cmp)
: [l] "r" (l), [r] "r" (r)
: "rax", "cc");
EBUG_ON(cmp != __wb_key_ref_cmp(l, r));
return cmp;
#else
return __wb_key_ref_cmp(l, r);
#endif
}
static int wb_key_seq_cmp(const void *_l, const void *_r)
{
const struct btree_write_buffered_key *l = _l;
const struct btree_write_buffered_key *r = _r;
return cmp_int(l->journal_seq, r->journal_seq);
}
/* Compare excluding idx, the low 24 bits: */
static inline bool wb_key_eq(const void *_l, const void *_r)
{
const struct wb_key_ref *l = _l;
const struct wb_key_ref *r = _r;
return !((l->hi ^ r->hi)|
(l->mi ^ r->mi)|
((l->lo >> 24) ^ (r->lo >> 24)));
}
static noinline void wb_sort(struct wb_key_ref *base, size_t num)
{
size_t n = num, a = num / 2;
if (!a) /* num < 2 || size == 0 */
return;
for (;;) {
size_t b, c, d;
if (a) /* Building heap: sift down --a */
--a;
else if (--n) /* Sorting: Extract root to --n */
swap(base[0], base[n]);
else /* Sort complete */
break;
/*
* Sift element at "a" down into heap. This is the
* "bottom-up" variant, which significantly reduces
* calls to cmp_func(): we find the sift-down path all
* the way to the leaves (one compare per level), then
* backtrack to find where to insert the target element.
*
* Because elements tend to sift down close to the leaves,
* this uses fewer compares than doing two per level
* on the way down. (A bit more than half as many on
* average, 3/4 worst-case.)
*/
for (b = a; c = 2*b + 1, (d = c + 1) < n;)
b = wb_key_ref_cmp(base + c, base + d) ? c : d;
if (d == n) /* Special case last leaf with no sibling */
b = c;
/* Now backtrack from "b" to the correct location for "a" */
while (b != a && wb_key_ref_cmp(base + a, base + b))
b = (b - 1) / 2;
c = b; /* Where "a" belongs */
while (b != a) { /* Shift it into place */
b = (b - 1) / 2;
swap(base[b], base[c]);
}
}
}
static noinline int wb_flush_one_slowpath(struct btree_trans *trans,
struct btree_iter *iter,
struct btree_write_buffered_key *wb)
{
struct btree_path *path = btree_iter_path(trans, iter);
bch2_btree_node_unlock_write(trans, path, path->l[0].b);
trans->journal_res.seq = wb->journal_seq;
return bch2_trans_update(trans, iter, &wb->k,
BTREE_UPDATE_internal_snapshot_node) ?:
bch2_trans_commit(trans, NULL, NULL,
BCH_TRANS_COMMIT_no_enospc|
BCH_TRANS_COMMIT_no_check_rw|
BCH_TRANS_COMMIT_no_journal_res|
BCH_TRANS_COMMIT_journal_reclaim);
}
static inline int wb_flush_one(struct btree_trans *trans, struct btree_iter *iter,
struct btree_write_buffered_key *wb,
bool *write_locked,
bool *accounting_accumulated,
size_t *fast)
{
struct btree_path *path;
int ret;
EBUG_ON(!wb->journal_seq);
EBUG_ON(!trans->c->btree_write_buffer.flushing.pin.seq);
EBUG_ON(trans->c->btree_write_buffer.flushing.pin.seq > wb->journal_seq);
ret = bch2_btree_iter_traverse(iter);
if (ret)
return ret;
if (!*accounting_accumulated && wb->k.k.type == KEY_TYPE_accounting) {
struct bkey u;
struct bkey_s_c k = bch2_btree_path_peek_slot_exact(btree_iter_path(trans, iter), &u);
if (k.k->type == KEY_TYPE_accounting)
bch2_accounting_accumulate(bkey_i_to_accounting(&wb->k),
bkey_s_c_to_accounting(k));
}
*accounting_accumulated = true;
/*
* We can't clone a path that has write locks: unshare it now, before
* set_pos and traverse():
*/
if (btree_iter_path(trans, iter)->ref > 1)
iter->path = __bch2_btree_path_make_mut(trans, iter->path, true, _THIS_IP_);
path = btree_iter_path(trans, iter);
if (!*write_locked) {
ret = bch2_btree_node_lock_write(trans, path, &path->l[0].b->c);
if (ret)
return ret;
bch2_btree_node_prep_for_write(trans, path, path->l[0].b);
*write_locked = true;
}
if (unlikely(!bch2_btree_node_insert_fits(path->l[0].b, wb->k.k.u64s))) {
*write_locked = false;
return wb_flush_one_slowpath(trans, iter, wb);
}
bch2_btree_insert_key_leaf(trans, path, &wb->k, wb->journal_seq);
(*fast)++;
return 0;
}
bcachefs: use prejournaled key updates for write buffer flushes The write buffer mechanism journals keys twice in certain situations. A key is always journaled on write buffer insertion, and is potentially journaled again if a write buffer flush falls into either of the slow btree insert paths. This has shown to cause journal recovery ordering problems in the event of an untimely crash. For example, consider if a key is inserted into index 0 of a write buffer, the active write buffer switches to index 1, the key is deleted in index 1, and then index 0 is flushed. If the original key is rejournaled in the btree update from the index 0 flush, the (now deleted) key is journaled in a seq buffer ahead of the latest version of key (which was journaled when the key was deleted in index 1). If the fs crashes while this is still observable in the log, recovery sees the key from the btree update after the delete key from the write buffer insert, which is the incorrect order. This problem is occasionally reproduced by generic/388 and generally manifests as one or more backpointer entry inconsistencies. To avoid this problem, never rejournal write buffered key updates to the associated btree. Instead, use prejournaled key updates to pass the journal seq of the write buffer insert down to the btree insert, which updates the btree leaf pin to reflect the seq of the key. Note that tracking the seq is required instead of just using NOJOURNAL here because otherwise we lose protection of the write buffer pin when the buffer is flushed, which means the key can fall off the tail of the on-disk journal before the btree leaf is flushed and lead to similar recovery inconsistencies. Signed-off-by: Brian Foster <bfoster@redhat.com> Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-07-19 12:53:06 +00:00
/*
* Update a btree with a write buffered key using the journal seq of the
* original write buffer insert.
*
* It is not safe to rejournal the key once it has been inserted into the write
* buffer because that may break recovery ordering. For example, the key may
* have already been modified in the active write buffer in a seq that comes
* before the current transaction. If we were to journal this key again and
* crash, recovery would process updates in the wrong order.
*/
static int
btree_write_buffered_insert(struct btree_trans *trans,
struct btree_write_buffered_key *wb)
{
struct btree_iter iter;
int ret;
bch2_trans_iter_init(trans, &iter, wb->btree, bkey_start_pos(&wb->k.k),
BTREE_ITER_cached|BTREE_ITER_intent);
bcachefs: use prejournaled key updates for write buffer flushes The write buffer mechanism journals keys twice in certain situations. A key is always journaled on write buffer insertion, and is potentially journaled again if a write buffer flush falls into either of the slow btree insert paths. This has shown to cause journal recovery ordering problems in the event of an untimely crash. For example, consider if a key is inserted into index 0 of a write buffer, the active write buffer switches to index 1, the key is deleted in index 1, and then index 0 is flushed. If the original key is rejournaled in the btree update from the index 0 flush, the (now deleted) key is journaled in a seq buffer ahead of the latest version of key (which was journaled when the key was deleted in index 1). If the fs crashes while this is still observable in the log, recovery sees the key from the btree update after the delete key from the write buffer insert, which is the incorrect order. This problem is occasionally reproduced by generic/388 and generally manifests as one or more backpointer entry inconsistencies. To avoid this problem, never rejournal write buffered key updates to the associated btree. Instead, use prejournaled key updates to pass the journal seq of the write buffer insert down to the btree insert, which updates the btree leaf pin to reflect the seq of the key. Note that tracking the seq is required instead of just using NOJOURNAL here because otherwise we lose protection of the write buffer pin when the buffer is flushed, which means the key can fall off the tail of the on-disk journal before the btree leaf is flushed and lead to similar recovery inconsistencies. Signed-off-by: Brian Foster <bfoster@redhat.com> Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-07-19 12:53:06 +00:00
trans->journal_res.seq = wb->journal_seq;
bcachefs: use prejournaled key updates for write buffer flushes The write buffer mechanism journals keys twice in certain situations. A key is always journaled on write buffer insertion, and is potentially journaled again if a write buffer flush falls into either of the slow btree insert paths. This has shown to cause journal recovery ordering problems in the event of an untimely crash. For example, consider if a key is inserted into index 0 of a write buffer, the active write buffer switches to index 1, the key is deleted in index 1, and then index 0 is flushed. If the original key is rejournaled in the btree update from the index 0 flush, the (now deleted) key is journaled in a seq buffer ahead of the latest version of key (which was journaled when the key was deleted in index 1). If the fs crashes while this is still observable in the log, recovery sees the key from the btree update after the delete key from the write buffer insert, which is the incorrect order. This problem is occasionally reproduced by generic/388 and generally manifests as one or more backpointer entry inconsistencies. To avoid this problem, never rejournal write buffered key updates to the associated btree. Instead, use prejournaled key updates to pass the journal seq of the write buffer insert down to the btree insert, which updates the btree leaf pin to reflect the seq of the key. Note that tracking the seq is required instead of just using NOJOURNAL here because otherwise we lose protection of the write buffer pin when the buffer is flushed, which means the key can fall off the tail of the on-disk journal before the btree leaf is flushed and lead to similar recovery inconsistencies. Signed-off-by: Brian Foster <bfoster@redhat.com> Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-07-19 12:53:06 +00:00
ret = bch2_btree_iter_traverse(&iter) ?:
bch2_trans_update(trans, &iter, &wb->k,
BTREE_UPDATE_internal_snapshot_node);
bcachefs: use prejournaled key updates for write buffer flushes The write buffer mechanism journals keys twice in certain situations. A key is always journaled on write buffer insertion, and is potentially journaled again if a write buffer flush falls into either of the slow btree insert paths. This has shown to cause journal recovery ordering problems in the event of an untimely crash. For example, consider if a key is inserted into index 0 of a write buffer, the active write buffer switches to index 1, the key is deleted in index 1, and then index 0 is flushed. If the original key is rejournaled in the btree update from the index 0 flush, the (now deleted) key is journaled in a seq buffer ahead of the latest version of key (which was journaled when the key was deleted in index 1). If the fs crashes while this is still observable in the log, recovery sees the key from the btree update after the delete key from the write buffer insert, which is the incorrect order. This problem is occasionally reproduced by generic/388 and generally manifests as one or more backpointer entry inconsistencies. To avoid this problem, never rejournal write buffered key updates to the associated btree. Instead, use prejournaled key updates to pass the journal seq of the write buffer insert down to the btree insert, which updates the btree leaf pin to reflect the seq of the key. Note that tracking the seq is required instead of just using NOJOURNAL here because otherwise we lose protection of the write buffer pin when the buffer is flushed, which means the key can fall off the tail of the on-disk journal before the btree leaf is flushed and lead to similar recovery inconsistencies. Signed-off-by: Brian Foster <bfoster@redhat.com> Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-07-19 12:53:06 +00:00
bch2_trans_iter_exit(trans, &iter);
return ret;
}
static void move_keys_from_inc_to_flushing(struct btree_write_buffer *wb)
{
struct bch_fs *c = container_of(wb, struct bch_fs, btree_write_buffer);
struct journal *j = &c->journal;
if (!wb->inc.keys.nr)
return;
bch2_journal_pin_add(j, wb->inc.keys.data[0].journal_seq, &wb->flushing.pin,
bch2_btree_write_buffer_journal_flush);
darray_resize(&wb->flushing.keys, min_t(size_t, 1U << 20, wb->flushing.keys.nr + wb->inc.keys.nr));
darray_resize(&wb->sorted, wb->flushing.keys.size);
if (!wb->flushing.keys.nr && wb->sorted.size >= wb->inc.keys.nr) {
swap(wb->flushing.keys, wb->inc.keys);
goto out;
}
size_t nr = min(darray_room(wb->flushing.keys),
wb->sorted.size - wb->flushing.keys.nr);
nr = min(nr, wb->inc.keys.nr);
memcpy(&darray_top(wb->flushing.keys),
wb->inc.keys.data,
sizeof(wb->inc.keys.data[0]) * nr);
memmove(wb->inc.keys.data,
wb->inc.keys.data + nr,
sizeof(wb->inc.keys.data[0]) * (wb->inc.keys.nr - nr));
wb->flushing.keys.nr += nr;
wb->inc.keys.nr -= nr;
out:
if (!wb->inc.keys.nr)
bch2_journal_pin_drop(j, &wb->inc.pin);
else
bch2_journal_pin_update(j, wb->inc.keys.data[0].journal_seq, &wb->inc.pin,
bch2_btree_write_buffer_journal_flush);
if (j->watermark) {
spin_lock(&j->lock);
bch2_journal_set_watermark(j);
spin_unlock(&j->lock);
}
BUG_ON(wb->sorted.size < wb->flushing.keys.nr);
}
static int bch2_btree_write_buffer_flush_locked(struct btree_trans *trans)
{
struct bch_fs *c = trans->c;
struct journal *j = &c->journal;
struct btree_write_buffer *wb = &c->btree_write_buffer;
struct btree_iter iter = { NULL };
size_t overwritten = 0, fast = 0, slowpath = 0, could_not_insert = 0;
bool write_locked = false;
bool accounting_replay_done = test_bit(BCH_FS_accounting_replay_done, &c->flags);
int ret = 0;
bch2_trans_unlock(trans);
bch2_trans_begin(trans);
mutex_lock(&wb->inc.lock);
move_keys_from_inc_to_flushing(wb);
mutex_unlock(&wb->inc.lock);
for (size_t i = 0; i < wb->flushing.keys.nr; i++) {
wb->sorted.data[i].idx = i;
wb->sorted.data[i].btree = wb->flushing.keys.data[i].btree;
memcpy(&wb->sorted.data[i].pos, &wb->flushing.keys.data[i].k.k.p, sizeof(struct bpos));
}
wb->sorted.nr = wb->flushing.keys.nr;
/*
* We first sort so that we can detect and skip redundant updates, and
* then we attempt to flush in sorted btree order, as this is most
* efficient.
*
* However, since we're not flushing in the order they appear in the
* journal we won't be able to drop our journal pin until everything is
bcachefs: more aggressive fast path write buffer key flushing The btree write buffer flush code is prone to causing journal deadlock due to inefficient use and release of reservation space. Reservation is not pre-reserved for write buffered keys (as is done for key cache keys, for example), because the write buffer flush side uses a fast path that attempts insertion without need for any reservation at all. The write buffer flush attempts to deal with this by inserting keys using the BTREE_INSERT_JOURNAL_RECLAIM flag to return an error on journal reservations that require blocking. Upon first error, it falls back to a slow path that inserts in journal order and supports moving the associated journal pin forward. The problem is that under pathological conditions (i.e. smaller log, larger write buffer and journal reservation pressure), we've seen instances where the fast path fails fairly quickly without having completed many insertions, and then the slow path is unable to push the journal pin forward enough to free up the space it needs to completely flush the buffer. This problem is occasionally reproduced by fstest generic/333. To avoid this problem, update the fast path algorithm to skip key inserts that fail due to inability to acquire needed journal reservation without immediately breaking out of the loop. Instead, insert as many keys as possible, zap the sequence numbers to mark them as processed, and then fall back to the slow path to process the remaining set in journal order. This reduces the amount of journal reservation that might be required to flush the entire buffer and increases the odds that the slow path is able to move the journal pin forward and free up space as keys are processed. Signed-off-by: Brian Foster <bfoster@redhat.com> Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-03-17 12:54:01 +00:00
* flushed - which means this could deadlock the journal if we weren't
* passing BCH_TRANS_COMMIT_journal_reclaim. This causes the update to fail
* if it would block taking a journal reservation.
*
bcachefs: more aggressive fast path write buffer key flushing The btree write buffer flush code is prone to causing journal deadlock due to inefficient use and release of reservation space. Reservation is not pre-reserved for write buffered keys (as is done for key cache keys, for example), because the write buffer flush side uses a fast path that attempts insertion without need for any reservation at all. The write buffer flush attempts to deal with this by inserting keys using the BTREE_INSERT_JOURNAL_RECLAIM flag to return an error on journal reservations that require blocking. Upon first error, it falls back to a slow path that inserts in journal order and supports moving the associated journal pin forward. The problem is that under pathological conditions (i.e. smaller log, larger write buffer and journal reservation pressure), we've seen instances where the fast path fails fairly quickly without having completed many insertions, and then the slow path is unable to push the journal pin forward enough to free up the space it needs to completely flush the buffer. This problem is occasionally reproduced by fstest generic/333. To avoid this problem, update the fast path algorithm to skip key inserts that fail due to inability to acquire needed journal reservation without immediately breaking out of the loop. Instead, insert as many keys as possible, zap the sequence numbers to mark them as processed, and then fall back to the slow path to process the remaining set in journal order. This reduces the amount of journal reservation that might be required to flush the entire buffer and increases the odds that the slow path is able to move the journal pin forward and free up space as keys are processed. Signed-off-by: Brian Foster <bfoster@redhat.com> Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-03-17 12:54:01 +00:00
* If that happens, simply skip the key so we can optimistically insert
* as many keys as possible in the fast path.
*/
wb_sort(wb->sorted.data, wb->sorted.nr);
darray_for_each(wb->sorted, i) {
struct btree_write_buffered_key *k = &wb->flushing.keys.data[i->idx];
for (struct wb_key_ref *n = i + 1; n < min(i + 4, &darray_top(wb->sorted)); n++)
prefetch(&wb->flushing.keys.data[n->idx]);
BUG_ON(!k->journal_seq);
if (!accounting_replay_done &&
k->k.k.type == KEY_TYPE_accounting) {
slowpath++;
continue;
}
if (i + 1 < &darray_top(wb->sorted) &&
wb_key_eq(i, i + 1)) {
struct btree_write_buffered_key *n = &wb->flushing.keys.data[i[1].idx];
if (k->k.k.type == KEY_TYPE_accounting &&
n->k.k.type == KEY_TYPE_accounting)
bch2_accounting_accumulate(bkey_i_to_accounting(&n->k),
bkey_i_to_s_c_accounting(&k->k));
overwritten++;
n->journal_seq = min_t(u64, n->journal_seq, k->journal_seq);
k->journal_seq = 0;
continue;
}
if (write_locked) {
struct btree_path *path = btree_iter_path(trans, &iter);
if (path->btree_id != i->btree ||
bpos_gt(k->k.k.p, path->l[0].b->key.k.p)) {
bch2_btree_node_unlock_write(trans, path, path->l[0].b);
write_locked = false;
ret = lockrestart_do(trans,
bch2_btree_iter_traverse(&iter) ?:
bch2_foreground_maybe_merge(trans, iter.path, 0,
BCH_WATERMARK_reclaim|
BCH_TRANS_COMMIT_journal_reclaim|
BCH_TRANS_COMMIT_no_check_rw|
BCH_TRANS_COMMIT_no_enospc));
if (ret)
goto err;
}
}
if (!iter.path || iter.btree_id != k->btree) {
bch2_trans_iter_exit(trans, &iter);
bch2_trans_iter_init(trans, &iter, k->btree, k->k.k.p,
BTREE_ITER_intent|BTREE_ITER_all_snapshots);
}
bch2_btree_iter_set_pos(&iter, k->k.k.p);
btree_iter_path(trans, &iter)->preserve = false;
bool accounting_accumulated = false;
do {
if (race_fault()) {
ret = -BCH_ERR_journal_reclaim_would_deadlock;
break;
}
ret = wb_flush_one(trans, &iter, k, &write_locked,
&accounting_accumulated, &fast);
if (!write_locked)
bch2_trans_begin(trans);
} while (bch2_err_matches(ret, BCH_ERR_transaction_restart));
if (!ret) {
k->journal_seq = 0;
} else if (ret == -BCH_ERR_journal_reclaim_would_deadlock) {
bcachefs: more aggressive fast path write buffer key flushing The btree write buffer flush code is prone to causing journal deadlock due to inefficient use and release of reservation space. Reservation is not pre-reserved for write buffered keys (as is done for key cache keys, for example), because the write buffer flush side uses a fast path that attempts insertion without need for any reservation at all. The write buffer flush attempts to deal with this by inserting keys using the BTREE_INSERT_JOURNAL_RECLAIM flag to return an error on journal reservations that require blocking. Upon first error, it falls back to a slow path that inserts in journal order and supports moving the associated journal pin forward. The problem is that under pathological conditions (i.e. smaller log, larger write buffer and journal reservation pressure), we've seen instances where the fast path fails fairly quickly without having completed many insertions, and then the slow path is unable to push the journal pin forward enough to free up the space it needs to completely flush the buffer. This problem is occasionally reproduced by fstest generic/333. To avoid this problem, update the fast path algorithm to skip key inserts that fail due to inability to acquire needed journal reservation without immediately breaking out of the loop. Instead, insert as many keys as possible, zap the sequence numbers to mark them as processed, and then fall back to the slow path to process the remaining set in journal order. This reduces the amount of journal reservation that might be required to flush the entire buffer and increases the odds that the slow path is able to move the journal pin forward and free up space as keys are processed. Signed-off-by: Brian Foster <bfoster@redhat.com> Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-03-17 12:54:01 +00:00
slowpath++;
ret = 0;
} else
break;
}
if (write_locked) {
struct btree_path *path = btree_iter_path(trans, &iter);
bch2_btree_node_unlock_write(trans, path, path->l[0].b);
}
bch2_trans_iter_exit(trans, &iter);
if (ret)
goto err;
if (slowpath) {
/*
* Flush in the order they were present in the journal, so that
* we can release journal pins:
* The fastpath zapped the seq of keys that were successfully flushed so
* we can skip those here.
*/
trace_and_count(c, write_buffer_flush_slowpath, trans, slowpath, wb->flushing.keys.nr);
sort(wb->flushing.keys.data,
wb->flushing.keys.nr,
sizeof(wb->flushing.keys.data[0]),
wb_key_seq_cmp, NULL);
darray_for_each(wb->flushing.keys, i) {
if (!i->journal_seq)
continue;
if (!accounting_replay_done &&
i->k.k.type == KEY_TYPE_accounting) {
could_not_insert++;
continue;
}
if (!could_not_insert)
bch2_journal_pin_update(j, i->journal_seq, &wb->flushing.pin,
bch2_btree_write_buffer_journal_flush);
bch2_trans_begin(trans);
ret = commit_do(trans, NULL, NULL,
BCH_WATERMARK_reclaim|
BCH_TRANS_COMMIT_journal_reclaim|
BCH_TRANS_COMMIT_no_check_rw|
BCH_TRANS_COMMIT_no_enospc|
BCH_TRANS_COMMIT_no_journal_res ,
btree_write_buffered_insert(trans, i));
if (ret)
goto err;
i->journal_seq = 0;
}
/*
* If journal replay hasn't finished with accounting keys we
* can't flush accounting keys at all - condense them and leave
* them for next time.
*
* Q: Can the write buffer overflow?
* A Shouldn't be any actual risk. It's just new accounting
* updates that the write buffer can't flush, and those are only
* going to be generated by interior btree node updates as
* journal replay has to split/rewrite nodes to make room for
* its updates.
*
* And for those new acounting updates, updates to the same
* counters get accumulated as they're flushed from the journal
* to the write buffer - see the patch for eytzingcer tree
* accumulated. So we could only overflow if the number of
* distinct counters touched somehow was very large.
*/
if (could_not_insert) {
struct btree_write_buffered_key *dst = wb->flushing.keys.data;
darray_for_each(wb->flushing.keys, i)
if (i->journal_seq)
*dst++ = *i;
wb->flushing.keys.nr = dst - wb->flushing.keys.data;
}
}
err:
if (ret || !could_not_insert) {
bch2_journal_pin_drop(j, &wb->flushing.pin);
wb->flushing.keys.nr = 0;
}
bch2_fs_fatal_err_on(ret, c, "%s", bch2_err_str(ret));
trace_write_buffer_flush(trans, wb->flushing.keys.nr, overwritten, fast, 0);
return ret;
}
static int fetch_wb_keys_from_journal(struct bch_fs *c, u64 seq)
{
struct journal *j = &c->journal;
struct journal_buf *buf;
int ret = 0;
while (!ret && (buf = bch2_next_write_buffer_flush_journal_buf(j, seq))) {
ret = bch2_journal_keys_to_write_buffer(c, buf);
mutex_unlock(&j->buf_lock);
}
return ret;
}
static int btree_write_buffer_flush_seq(struct btree_trans *trans, u64 seq)
{
struct bch_fs *c = trans->c;
struct btree_write_buffer *wb = &c->btree_write_buffer;
int ret = 0, fetch_from_journal_err;
do {
bch2_trans_unlock(trans);
fetch_from_journal_err = fetch_wb_keys_from_journal(c, seq);
/*
* On memory allocation failure, bch2_btree_write_buffer_flush_locked()
* is not guaranteed to empty wb->inc:
*/
mutex_lock(&wb->flushing.lock);
ret = bch2_btree_write_buffer_flush_locked(trans);
mutex_unlock(&wb->flushing.lock);
} while (!ret &&
(fetch_from_journal_err ||
(wb->inc.pin.seq && wb->inc.pin.seq <= seq) ||
(wb->flushing.pin.seq && wb->flushing.pin.seq <= seq)));
return ret;
}
static int bch2_btree_write_buffer_journal_flush(struct journal *j,
struct journal_entry_pin *_pin, u64 seq)
{
struct bch_fs *c = container_of(j, struct bch_fs, journal);
return bch2_trans_run(c, btree_write_buffer_flush_seq(trans, seq));
}
int bch2_btree_write_buffer_flush_sync(struct btree_trans *trans)
{
struct bch_fs *c = trans->c;
trace_and_count(c, write_buffer_flush_sync, trans, _RET_IP_);
return btree_write_buffer_flush_seq(trans, journal_cur_seq(&c->journal));
}
int bch2_btree_write_buffer_flush_nocheck_rw(struct btree_trans *trans)
{
struct bch_fs *c = trans->c;
struct btree_write_buffer *wb = &c->btree_write_buffer;
int ret = 0;
if (mutex_trylock(&wb->flushing.lock)) {
ret = bch2_btree_write_buffer_flush_locked(trans);
mutex_unlock(&wb->flushing.lock);
}
return ret;
}
int bch2_btree_write_buffer_tryflush(struct btree_trans *trans)
{
struct bch_fs *c = trans->c;
if (!bch2_write_ref_tryget(c, BCH_WRITE_REF_btree_write_buffer))
return -BCH_ERR_erofs_no_writes;
int ret = bch2_btree_write_buffer_flush_nocheck_rw(trans);
bch2_write_ref_put(c, BCH_WRITE_REF_btree_write_buffer);
return ret;
}
/*
* In check and repair code, when checking references to write buffer btrees we
* need to issue a flush before we have a definitive error: this issues a flush
* if this is a key we haven't yet checked.
*/
int bch2_btree_write_buffer_maybe_flush(struct btree_trans *trans,
struct bkey_s_c referring_k,
struct bkey_buf *last_flushed)
{
struct bch_fs *c = trans->c;
struct bkey_buf tmp;
int ret = 0;
bch2_bkey_buf_init(&tmp);
if (!bkey_and_val_eq(referring_k, bkey_i_to_s_c(last_flushed->k))) {
bch2_bkey_buf_reassemble(&tmp, c, referring_k);
if (bkey_is_btree_ptr(referring_k.k)) {
bch2_trans_unlock(trans);
bch2_btree_interior_updates_flush(c);
}
ret = bch2_btree_write_buffer_flush_sync(trans);
if (ret)
goto err;
bch2_bkey_buf_copy(last_flushed, c, tmp.k);
ret = -BCH_ERR_transaction_restart_write_buffer_flush;
}
err:
bch2_bkey_buf_exit(&tmp, c);
return ret;
}
static void bch2_btree_write_buffer_flush_work(struct work_struct *work)
{
struct bch_fs *c = container_of(work, struct bch_fs, btree_write_buffer.flush_work);
struct btree_write_buffer *wb = &c->btree_write_buffer;
int ret;
mutex_lock(&wb->flushing.lock);
do {
ret = bch2_trans_run(c, bch2_btree_write_buffer_flush_locked(trans));
} while (!ret && bch2_btree_write_buffer_should_flush(c));
mutex_unlock(&wb->flushing.lock);
bch2_write_ref_put(c, BCH_WRITE_REF_btree_write_buffer);
}
static void wb_accounting_sort(struct btree_write_buffer *wb)
{
eytzinger0_sort(wb->accounting.data, wb->accounting.nr,
sizeof(wb->accounting.data[0]),
wb_key_cmp, NULL);
}
int bch2_accounting_key_to_wb_slowpath(struct bch_fs *c, enum btree_id btree,
struct bkey_i_accounting *k)
{
struct btree_write_buffer *wb = &c->btree_write_buffer;
struct btree_write_buffered_key new = { .btree = btree };
bkey_copy(&new.k, &k->k_i);
int ret = darray_push(&wb->accounting, new);
if (ret)
return ret;
wb_accounting_sort(wb);
return 0;
}
int bch2_journal_key_to_wb_slowpath(struct bch_fs *c,
struct journal_keys_to_wb *dst,
enum btree_id btree, struct bkey_i *k)
{
struct btree_write_buffer *wb = &c->btree_write_buffer;
int ret;
retry:
ret = darray_make_room_gfp(&dst->wb->keys, 1, GFP_KERNEL);
if (!ret && dst->wb == &wb->flushing)
ret = darray_resize(&wb->sorted, wb->flushing.keys.size);
if (unlikely(ret)) {
if (dst->wb == &c->btree_write_buffer.flushing) {
mutex_unlock(&dst->wb->lock);
dst->wb = &c->btree_write_buffer.inc;
bch2_journal_pin_add(&c->journal, dst->seq, &dst->wb->pin,
bch2_btree_write_buffer_journal_flush);
goto retry;
}
return ret;
}
dst->room = darray_room(dst->wb->keys);
if (dst->wb == &wb->flushing)
dst->room = min(dst->room, wb->sorted.size - wb->flushing.keys.nr);
BUG_ON(!dst->room);
BUG_ON(!dst->seq);
struct btree_write_buffered_key *wb_k = &darray_top(dst->wb->keys);
wb_k->journal_seq = dst->seq;
wb_k->btree = btree;
bkey_copy(&wb_k->k, k);
dst->wb->keys.nr++;
dst->room--;
return 0;
}
void bch2_journal_keys_to_write_buffer_start(struct bch_fs *c, struct journal_keys_to_wb *dst, u64 seq)
{
struct btree_write_buffer *wb = &c->btree_write_buffer;
if (mutex_trylock(&wb->flushing.lock)) {
mutex_lock(&wb->inc.lock);
move_keys_from_inc_to_flushing(wb);
/*
* Attempt to skip wb->inc, and add keys directly to
* wb->flushing, saving us a copy later:
*/
if (!wb->inc.keys.nr) {
dst->wb = &wb->flushing;
} else {
mutex_unlock(&wb->flushing.lock);
dst->wb = &wb->inc;
}
} else {
mutex_lock(&wb->inc.lock);
dst->wb = &wb->inc;
}
dst->room = darray_room(dst->wb->keys);
if (dst->wb == &wb->flushing)
dst->room = min(dst->room, wb->sorted.size - wb->flushing.keys.nr);
dst->seq = seq;
bch2_journal_pin_add(&c->journal, seq, &dst->wb->pin,
bch2_btree_write_buffer_journal_flush);
darray_for_each(wb->accounting, i)
memset(&i->k.v, 0, bkey_val_bytes(&i->k.k));
}
int bch2_journal_keys_to_write_buffer_end(struct bch_fs *c, struct journal_keys_to_wb *dst)
{
struct btree_write_buffer *wb = &c->btree_write_buffer;
unsigned live_accounting_keys = 0;
int ret = 0;
darray_for_each(wb->accounting, i)
if (!bch2_accounting_key_is_zero(bkey_i_to_s_c_accounting(&i->k))) {
i->journal_seq = dst->seq;
live_accounting_keys++;
ret = __bch2_journal_key_to_wb(c, dst, i->btree, &i->k);
if (ret)
break;
}
if (live_accounting_keys * 2 < wb->accounting.nr) {
struct btree_write_buffered_key *dst = wb->accounting.data;
darray_for_each(wb->accounting, src)
if (!bch2_accounting_key_is_zero(bkey_i_to_s_c_accounting(&src->k)))
*dst++ = *src;
wb->accounting.nr = dst - wb->accounting.data;
wb_accounting_sort(wb);
}
if (!dst->wb->keys.nr)
bch2_journal_pin_drop(&c->journal, &dst->wb->pin);
if (bch2_btree_write_buffer_should_flush(c) &&
__bch2_write_ref_tryget(c, BCH_WRITE_REF_btree_write_buffer) &&
!queue_work(system_unbound_wq, &c->btree_write_buffer.flush_work))
bch2_write_ref_put(c, BCH_WRITE_REF_btree_write_buffer);
if (dst->wb == &wb->flushing)
mutex_unlock(&wb->flushing.lock);
mutex_unlock(&wb->inc.lock);
return ret;
}
static int bch2_journal_keys_to_write_buffer(struct bch_fs *c, struct journal_buf *buf)
{
struct journal_keys_to_wb dst;
int ret = 0;
bch2_journal_keys_to_write_buffer_start(c, &dst, le64_to_cpu(buf->data->seq));
for_each_jset_entry_type(entry, buf->data, BCH_JSET_ENTRY_write_buffer_keys) {
jset_entry_for_each_key(entry, k) {
ret = bch2_journal_key_to_wb(c, &dst, entry->btree_id, k);
if (ret)
goto out;
}
entry->type = BCH_JSET_ENTRY_btree_keys;
}
spin_lock(&c->journal.lock);
buf->need_flush_to_write_buffer = false;
spin_unlock(&c->journal.lock);
out:
ret = bch2_journal_keys_to_write_buffer_end(c, &dst) ?: ret;
return ret;
}
static int wb_keys_resize(struct btree_write_buffer_keys *wb, size_t new_size)
{
if (wb->keys.size >= new_size)
return 0;
if (!mutex_trylock(&wb->lock))
return -EINTR;
int ret = darray_resize(&wb->keys, new_size);
mutex_unlock(&wb->lock);
return ret;
}
int bch2_btree_write_buffer_resize(struct bch_fs *c, size_t new_size)
{
struct btree_write_buffer *wb = &c->btree_write_buffer;
return wb_keys_resize(&wb->flushing, new_size) ?:
wb_keys_resize(&wb->inc, new_size);
}
void bch2_fs_btree_write_buffer_exit(struct bch_fs *c)
{
struct btree_write_buffer *wb = &c->btree_write_buffer;
BUG_ON((wb->inc.keys.nr || wb->flushing.keys.nr) &&
!bch2_journal_error(&c->journal));
darray_exit(&wb->accounting);
darray_exit(&wb->sorted);
darray_exit(&wb->flushing.keys);
darray_exit(&wb->inc.keys);
}
int bch2_fs_btree_write_buffer_init(struct bch_fs *c)
{
struct btree_write_buffer *wb = &c->btree_write_buffer;
mutex_init(&wb->inc.lock);
mutex_init(&wb->flushing.lock);
INIT_WORK(&wb->flush_work, bch2_btree_write_buffer_flush_work);
/* Will be resized by journal as needed: */
unsigned initial_size = 1 << 16;
return darray_make_room(&wb->inc.keys, initial_size) ?:
darray_make_room(&wb->flushing.keys, initial_size) ?:
darray_make_room(&wb->sorted, initial_size);
}