diff options
Diffstat (limited to 'mm/swapfile.c')
| -rw-r--r-- | mm/swapfile.c | 55 |
1 files changed, 50 insertions, 5 deletions
diff --git a/mm/swapfile.c b/mm/swapfile.c index 746af55b845..36af6eeaa67 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -212,7 +212,7 @@ static unsigned long scan_swap_map(struct swap_info_struct *si, si->cluster_nr = SWAPFILE_CLUSTER - 1; goto checks; } - if (si->flags & SWP_DISCARDABLE) { + if (si->flags & SWP_PAGE_DISCARD) { /* * Start range check on racing allocations, in case * they overlap the cluster we eventually decide on @@ -322,7 +322,7 @@ checks: if (si->lowest_alloc) { /* - * Only set when SWP_DISCARDABLE, and there's a scan + * Only set when SWP_PAGE_DISCARD, and there's a scan * for a free cluster in progress or just completed. */ if (found_free_cluster) { @@ -2016,6 +2016,20 @@ static int setup_swap_map_and_extents(struct swap_info_struct *p, return nr_extents; } +/* + * Helper to sys_swapon determining if a given swap + * backing device queue supports DISCARD operations. + */ +static bool swap_discardable(struct swap_info_struct *si) +{ + struct request_queue *q = bdev_get_queue(si->bdev); + + if (!q || !blk_queue_discard(q)) + return false; + + return true; +} + SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags) { struct swap_info_struct *p; @@ -2123,8 +2137,37 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags) p->flags |= SWP_SOLIDSTATE; p->cluster_next = 1 + (prandom_u32() % p->highest_bit); } - if ((swap_flags & SWAP_FLAG_DISCARD) && discard_swap(p) == 0) - p->flags |= SWP_DISCARDABLE; + + if ((swap_flags & SWAP_FLAG_DISCARD) && swap_discardable(p)) { + /* + * When discard is enabled for swap with no particular + * policy flagged, we set all swap discard flags here in + * order to sustain backward compatibility with older + * swapon(8) releases. + */ + p->flags |= (SWP_DISCARDABLE | SWP_AREA_DISCARD | + SWP_PAGE_DISCARD); + + /* + * By flagging sys_swapon, a sysadmin can tell us to + * either do single-time area discards only, or to just + * perform discards for released swap page-clusters. + * Now it's time to adjust the p->flags accordingly. + */ + if (swap_flags & SWAP_FLAG_DISCARD_ONCE) + p->flags &= ~SWP_PAGE_DISCARD; + else if (swap_flags & SWAP_FLAG_DISCARD_PAGES) + p->flags &= ~SWP_AREA_DISCARD; + + /* issue a swapon-time discard if it's still required */ + if (p->flags & SWP_AREA_DISCARD) { + int err = discard_swap(p); + if (unlikely(err)) + printk(KERN_ERR + "swapon: discard_swap(%p): %d\n", + p, err); + } + } } mutex_lock(&swapon_mutex); @@ -2135,11 +2178,13 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags) enable_swap_info(p, prio, swap_map, frontswap_map); printk(KERN_INFO "Adding %uk swap on %s. " - "Priority:%d extents:%d across:%lluk %s%s%s\n", + "Priority:%d extents:%d across:%lluk %s%s%s%s%s\n", p->pages<<(PAGE_SHIFT-10), name->name, p->prio, nr_extents, (unsigned long long)span<<(PAGE_SHIFT-10), (p->flags & SWP_SOLIDSTATE) ? "SS" : "", (p->flags & SWP_DISCARDABLE) ? "D" : "", + (p->flags & SWP_AREA_DISCARD) ? "s" : "", + (p->flags & SWP_PAGE_DISCARD) ? "c" : "", (frontswap_map) ? "FS" : ""); mutex_unlock(&swapon_mutex); |