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| author | Javier González <javier@javigon.com> | 2018-10-09 13:12:15 +0200 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2018-10-09 16:25:08 +0200 |
| commit | 766c8ceb16fce904d6b8985ca2c0a547e053d1d5 (patch) | |
| tree | 36e7d365c27ed8c6173375b4ba59d5b6980dbdfa /drivers/lightnvm/pblk-rb.c | |
| parent | lightnvm: pblk: consider max hw sectors supported for max_write_pgs (diff) | |
| download | linux-766c8ceb16fce904d6b8985ca2c0a547e053d1d5.tar.xz linux-766c8ceb16fce904d6b8985ca2c0a547e053d1d5.zip | |
lightnvm: pblk: guarantee that backpointer is respected on writer stall
pblk's write buffer must guarantee that it respects the device's
constrains for reads (i.e., mw_cunits). This is done by maintaining a
backpointer that updates the L2P table as entries wrap up, making them
point to the media instead of pointing to the write buffer.
This mechanism can race in case that the write thread stalls, as the
write pointer will protect the last written entry, thus disregarding the
read constrains.
This patch adds an extra check on wrap up, making sure that the
threshold is respected at all times, preventing new entries to overwrite
committed data, also in case of write thread stall.
Reported-by: Heiner Litz <hlitz@ucsc.edu>
Signed-off-by: Javier González <javier@cnexlabs.com>
Reviewed-by: Heiner Litz <hlitz@ucsc.edu>
Signed-off-by: Matias Bjørling <mb@lightnvm.io>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'drivers/lightnvm/pblk-rb.c')
| -rw-r--r-- | drivers/lightnvm/pblk-rb.c | 9 |
1 files changed, 7 insertions, 2 deletions
diff --git a/drivers/lightnvm/pblk-rb.c b/drivers/lightnvm/pblk-rb.c index f653faa6a9ed..b1f4b51783f4 100644 --- a/drivers/lightnvm/pblk-rb.c +++ b/drivers/lightnvm/pblk-rb.c @@ -56,7 +56,8 @@ static unsigned int pblk_rb_calculate_size(unsigned int nr_entries) * allocated and their size must be a power of two * (Documentation/core-api/circular-buffers.rst) */ -int pblk_rb_init(struct pblk_rb *rb, unsigned int size, unsigned int seg_size) +int pblk_rb_init(struct pblk_rb *rb, unsigned int size, unsigned int threshold, + unsigned int seg_size) { struct pblk *pblk = container_of(rb, struct pblk, rwb); struct pblk_rb_entry *entries; @@ -79,6 +80,7 @@ int pblk_rb_init(struct pblk_rb *rb, unsigned int size, unsigned int seg_size) rb->seg_size = (1 << power_seg_sz); rb->nr_entries = (1 << power_size); rb->mem = rb->subm = rb->sync = rb->l2p_update = 0; + rb->back_thres = threshold; rb->flush_point = EMPTY_ENTRY; spin_lock_init(&rb->w_lock); @@ -404,11 +406,14 @@ static int __pblk_rb_may_write(struct pblk_rb *rb, unsigned int nr_entries, { unsigned int mem; unsigned int sync; + unsigned int threshold; sync = READ_ONCE(rb->sync); mem = READ_ONCE(rb->mem); - if (pblk_rb_ring_space(rb, mem, sync, rb->nr_entries) < nr_entries) + threshold = nr_entries + rb->back_thres; + + if (pblk_rb_ring_space(rb, mem, sync, rb->nr_entries) < threshold) return 0; if (pblk_rb_update_l2p(rb, nr_entries, mem, sync)) |