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authorJavier González <jg@lightnvm.io>2017-06-30 17:56:42 +0200
committerJens Axboe <axboe@kernel.dk>2017-06-30 11:08:18 -0600
commit076984669db8476c3c9a9f6d0c59a8e2c7e0092f (patch)
tree390b5fc24a3911f43b7dffec622786c27c5ee292 /drivers/lightnvm/pblk-rb.c
parentb5e063a2861a3af00fe3770e5fb85f936facbf42 (diff)
lightnvm: pblk: verify that cache read is still valid
When a read is directed to the cache, we risk that the lba has been updated during the time we made the L2P table lookup and the time we are actually reading form the cache. We intentionally not hold the L2P lock not to block other threads. While strict ordering is not a guarantee at this level (unless REQ_FLUSH has been previously issued), we have experience that some databases that have recently implemented direct I/O support, issue metadata reads very close to the writes, without issuing a fsync in the middle. An easy way to support them while they is to make an extra effort and check the L2P map right before reading the cache. Signed-off-by: Javier González <javier@cnexlabs.com> Signed-off-by: Matias Bjørling <matias@cnexlabs.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'drivers/lightnvm/pblk-rb.c')
-rw-r--r--drivers/lightnvm/pblk-rb.c15
1 files changed, 12 insertions, 3 deletions
diff --git a/drivers/lightnvm/pblk-rb.c b/drivers/lightnvm/pblk-rb.c
index 7300be98e831..5ecc154f6831 100644
--- a/drivers/lightnvm/pblk-rb.c
+++ b/drivers/lightnvm/pblk-rb.c
@@ -150,6 +150,7 @@ try:
/* Release flags on context. Protect from writes and reads */
smp_store_release(&w_ctx->flags, PBLK_WRITABLE_ENTRY);
pblk_ppa_set_empty(&w_ctx->ppa);
+ w_ctx->lba = ADDR_EMPTY;
}
#define pblk_rb_ring_count(head, tail, size) CIRC_CNT(head, tail, size)
@@ -656,15 +657,17 @@ try:
* be directed to disk.
*/
int pblk_rb_copy_to_bio(struct pblk_rb *rb, struct bio *bio, sector_t lba,
- u64 pos, int bio_iter)
+ struct ppa_addr ppa, int bio_iter)
{
+ struct pblk *pblk = container_of(rb, struct pblk, rwb);
struct pblk_rb_entry *entry;
struct pblk_w_ctx *w_ctx;
+ struct ppa_addr l2p_ppa;
+ u64 pos = pblk_addr_to_cacheline(ppa);
void *data;
int flags;
int ret = 1;
- spin_lock(&rb->w_lock);
#ifdef CONFIG_NVM_DEBUG
/* Caller must ensure that the access will not cause an overflow */
@@ -674,8 +677,14 @@ int pblk_rb_copy_to_bio(struct pblk_rb *rb, struct bio *bio, sector_t lba,
w_ctx = &entry->w_ctx;
flags = READ_ONCE(w_ctx->flags);
+ spin_lock(&rb->w_lock);
+ spin_lock(&pblk->trans_lock);
+ l2p_ppa = pblk_trans_map_get(pblk, lba);
+ spin_unlock(&pblk->trans_lock);
+
/* Check if the entry has been overwritten or is scheduled to be */
- if (w_ctx->lba != lba || flags & PBLK_WRITABLE_ENTRY) {
+ if (!pblk_ppa_comp(l2p_ppa, ppa) || w_ctx->lba != lba ||
+ flags & PBLK_WRITABLE_ENTRY) {
ret = 0;
goto out;
}