From bcd5321039c3de29c14eac1068d392c15ad7fe2c Mon Sep 17 00:00:00 2001 From: George Amanakis Date: Tue, 6 Jun 2023 21:32:37 +0200 Subject: [PATCH] Fix the L2ARC write size calculating logic l2arc_write_size() should return the write size after adjusting for trim and overhead of the L2ARC log blocks. Also take into account the allocated size of log blocks when deciding when to stop writing buffers to L2ARC. Reviewed-by: Brian Behlendorf Signed-off-by: George Amanakis Closes #14939 --- module/zfs/arc.c | 45 +++++++++++++++++++++++++++++---------------- 1 file changed, 29 insertions(+), 16 deletions(-) diff --git a/module/zfs/arc.c b/module/zfs/arc.c index a78f664c4f..6f68c29fc7 100644 --- a/module/zfs/arc.c +++ b/module/zfs/arc.c @@ -965,7 +965,7 @@ static void l2arc_hdr_restore(const l2arc_log_ent_phys_t *le, l2arc_dev_t *dev); /* L2ARC persistence write I/O routines. */ -static void l2arc_log_blk_commit(l2arc_dev_t *dev, zio_t *pio, +static uint64_t l2arc_log_blk_commit(l2arc_dev_t *dev, zio_t *pio, l2arc_write_callback_t *cb); /* L2ARC persistence auxiliary routines. */ @@ -8175,7 +8175,7 @@ l2arc_write_eligible(uint64_t spa_guid, arc_buf_hdr_t *hdr) static uint64_t l2arc_write_size(l2arc_dev_t *dev) { - uint64_t size, dev_size, tsize; + uint64_t size; /* * Make sure our globals have meaningful values in case the user @@ -8192,35 +8192,40 @@ l2arc_write_size(l2arc_dev_t *dev) if (arc_warm == B_FALSE) size += l2arc_write_boost; - /* - * Make sure the write size does not exceed the size of the cache - * device. This is important in l2arc_evict(), otherwise infinite - * iteration can occur. - */ - dev_size = dev->l2ad_end - dev->l2ad_start; - /* We need to add in the worst case scenario of log block overhead. */ - tsize = size + l2arc_log_blk_overhead(size, dev); + size += l2arc_log_blk_overhead(size, dev); if (dev->l2ad_vdev->vdev_has_trim && l2arc_trim_ahead > 0) { /* * Trim ahead of the write size 64MB or (l2arc_trim_ahead/100) * times the writesize, whichever is greater. */ - tsize += MAX(64 * 1024 * 1024, - (tsize * l2arc_trim_ahead) / 100); + size += MAX(64 * 1024 * 1024, + (size * l2arc_trim_ahead) / 100); } - if (tsize >= dev_size) { + /* + * Make sure the write size does not exceed the size of the cache + * device. This is important in l2arc_evict(), otherwise infinite + * iteration can occur. + */ + if (size >= dev->l2ad_end - dev->l2ad_start) { cmn_err(CE_NOTE, "l2arc_write_max or l2arc_write_boost " "plus the overhead of log blocks (persistent L2ARC, " "%llu bytes) exceeds the size of the cache device " "(guid %llu), resetting them to the default (%d)", (u_longlong_t)l2arc_log_blk_overhead(size, dev), (u_longlong_t)dev->l2ad_vdev->vdev_guid, L2ARC_WRITE_SIZE); + size = l2arc_write_max = l2arc_write_boost = L2ARC_WRITE_SIZE; if (arc_warm == B_FALSE) size += l2arc_write_boost; + + size += l2arc_log_blk_overhead(size, dev); + if (dev->l2ad_vdev->vdev_has_trim && l2arc_trim_ahead > 0) { + size += MAX(64 * 1024 * 1024, + (size * l2arc_trim_ahead) / 100); + } } return (size); @@ -9413,8 +9418,14 @@ l2arc_write_buffers(spa_t *spa, l2arc_dev_t *dev, uint64_t target_sz) * arcstat_l2_{size,asize} kstats are updated * internally. */ - if (l2arc_log_blk_insert(dev, hdr)) - l2arc_log_blk_commit(dev, pio, cb); + if (l2arc_log_blk_insert(dev, hdr)) { + /* + * l2ad_hand has been accounted for in + * l2arc_log_blk_commit(). + */ + write_asize += + l2arc_log_blk_commit(dev, pio, cb); + } zio_nowait(wzio); } @@ -10564,7 +10575,7 @@ l2arc_dev_hdr_update(l2arc_dev_t *dev) * This function allocates some memory to temporarily hold the serialized * buffer to be written. This is then released in l2arc_write_done. */ -static void +static uint64_t l2arc_log_blk_commit(l2arc_dev_t *dev, zio_t *pio, l2arc_write_callback_t *cb) { l2arc_log_blk_phys_t *lb = &dev->l2ad_log_blk; @@ -10675,6 +10686,8 @@ l2arc_log_blk_commit(l2arc_dev_t *dev, zio_t *pio, l2arc_write_callback_t *cb) dev->l2ad_log_ent_idx = 0; dev->l2ad_log_blk_payload_asize = 0; dev->l2ad_log_blk_payload_start = 0; + + return (asize); } /*