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bcachefs: Add option for completely disabling nocow

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This adds an option for completely disabling nocow mode, including the
locking in the data move path.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This commit is contained in:
Kent Overstreet 2023-02-24 19:07:21 -05:00
parent 1a14e25510
commit 33669e0cc9
3 changed files with 27 additions and 17 deletions
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36
fs/bcachefs/data_update.c
View File

@ -327,8 +327,9 @@ void bch2_data_update_exit(struct data_update *update)
const struct bch_extent_ptr *ptr;
bkey_for_each_ptr(ptrs, ptr) {
bch2_bucket_nocow_unlock(&c->nocow_locks,
PTR_BUCKET_POS(c, ptr), 0);
if (c->opts.nocow_enabled)
bch2_bucket_nocow_unlock(&c->nocow_locks,
PTR_BUCKET_POS(c, ptr), 0);
percpu_ref_put(&bch_dev_bkey_exists(c, ptr->dev)->ref);
}
@ -488,23 +489,26 @@ int bch2_data_update_init(struct btree_trans *trans,
if (p.crc.compression_type == BCH_COMPRESSION_TYPE_incompressible)
m->op.incompressible = true;
if (ctxt) {
move_ctxt_wait_event(ctxt, trans,
(locked = bch2_bucket_nocow_trylock(&c->nocow_locks,
PTR_BUCKET_POS(c, &p.ptr), 0)) ||
!atomic_read(&ctxt->read_sectors));
if (c->opts.nocow_enabled) {
if (ctxt) {
move_ctxt_wait_event(ctxt, trans,
(locked = bch2_bucket_nocow_trylock(&c->nocow_locks,
PTR_BUCKET_POS(c, &p.ptr), 0)) ||
!atomic_read(&ctxt->read_sectors));
if (!locked)
bch2_bucket_nocow_lock(&c->nocow_locks,
PTR_BUCKET_POS(c, &p.ptr), 0);
} else {
if (!bch2_bucket_nocow_trylock(&c->nocow_locks,
PTR_BUCKET_POS(c, &p.ptr), 0)) {
ret = -BCH_ERR_nocow_lock_blocked;
goto err;
if (!locked)
bch2_bucket_nocow_lock(&c->nocow_locks,
PTR_BUCKET_POS(c, &p.ptr), 0);
} else {
if (!bch2_bucket_nocow_trylock(&c->nocow_locks,
PTR_BUCKET_POS(c, &p.ptr), 0)) {
ret = -BCH_ERR_nocow_lock_blocked;
goto err;
}
}
ptrs_locked |= (1U << i);
}
ptrs_locked |= (1U << i);
i++;
}

2
fs/bcachefs/io.c
View File

@ -1649,7 +1649,7 @@ static void __bch2_write(struct bch_write_op *op)
nofs_flags = memalloc_nofs_save();
if (unlikely(op->opts.nocow)) {
if (unlikely(op->opts.nocow && c->opts.nocow_enabled)) {
bch2_nocow_write(op);
if (op->flags & BCH_WRITE_DONE)
goto out_nofs_restore;

6
fs/bcachefs/opts.h
View File

@ -404,6 +404,12 @@ enum opt_type {
NULL, "Nocow mode: Writes will be done in place when possible.\n"\
"Snapshots and reflink will still caused writes to be COW\n"\
"Implicitly disables data checksumming, compression and encryption")\
x(nocow_enabled, u8, \
OPT_FS|OPT_MOUNT, \
OPT_BOOL(), \
BCH2_NO_SB_OPT, true, \
NULL, "Enable nocow mode: enables runtime locking in\n"\
"data move path needed if nocow will ever be in use\n")\
x(no_data_io, u8, \
OPT_MOUNT, \
OPT_BOOL(), \