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-rw-r--r--fs/erofs/zutil.c453
1 files changed, 453 insertions, 0 deletions
diff --git a/fs/erofs/zutil.c b/fs/erofs/zutil.c
new file mode 100644
index 000000000000..036024bce9f7
--- /dev/null
+++ b/fs/erofs/zutil.c
@@ -0,0 +1,453 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2018 HUAWEI, Inc.
+ * https://www.huawei.com/
+ */
+#include "internal.h"
+
+struct z_erofs_gbuf {
+ spinlock_t lock;
+ void *ptr;
+ struct page **pages;
+ unsigned int nrpages;
+};
+
+static struct z_erofs_gbuf *z_erofs_gbufpool, *z_erofs_rsvbuf;
+static unsigned int z_erofs_gbuf_count, z_erofs_gbuf_nrpages,
+ z_erofs_rsv_nrpages;
+
+module_param_named(global_buffers, z_erofs_gbuf_count, uint, 0444);
+module_param_named(reserved_pages, z_erofs_rsv_nrpages, uint, 0444);
+
+static atomic_long_t erofs_global_shrink_cnt; /* for all mounted instances */
+/* protected by 'erofs_sb_list_lock' */
+static unsigned int shrinker_run_no;
+
+/* protects the mounted 'erofs_sb_list' */
+static DEFINE_SPINLOCK(erofs_sb_list_lock);
+static LIST_HEAD(erofs_sb_list);
+static struct shrinker *erofs_shrinker_info;
+
+static unsigned int z_erofs_gbuf_id(void)
+{
+ return raw_smp_processor_id() % z_erofs_gbuf_count;
+}
+
+void *z_erofs_get_gbuf(unsigned int requiredpages)
+ __acquires(gbuf->lock)
+{
+ struct z_erofs_gbuf *gbuf;
+
+ gbuf = &z_erofs_gbufpool[z_erofs_gbuf_id()];
+ spin_lock(&gbuf->lock);
+ /* check if the buffer is too small */
+ if (requiredpages > gbuf->nrpages) {
+ spin_unlock(&gbuf->lock);
+ /* (for sparse checker) pretend gbuf->lock is still taken */
+ __acquire(gbuf->lock);
+ return NULL;
+ }
+ return gbuf->ptr;
+}
+
+void z_erofs_put_gbuf(void *ptr) __releases(gbuf->lock)
+{
+ struct z_erofs_gbuf *gbuf;
+
+ gbuf = &z_erofs_gbufpool[z_erofs_gbuf_id()];
+ DBG_BUGON(gbuf->ptr != ptr);
+ spin_unlock(&gbuf->lock);
+}
+
+int z_erofs_gbuf_growsize(unsigned int nrpages)
+{
+ static DEFINE_MUTEX(gbuf_resize_mutex);
+ struct page **tmp_pages = NULL;
+ struct z_erofs_gbuf *gbuf;
+ void *ptr, *old_ptr;
+ int last, i, j;
+
+ mutex_lock(&gbuf_resize_mutex);
+ /* avoid shrinking gbufs, since no idea how many fses rely on */
+ if (nrpages <= z_erofs_gbuf_nrpages) {
+ mutex_unlock(&gbuf_resize_mutex);
+ return 0;
+ }
+
+ for (i = 0; i < z_erofs_gbuf_count; ++i) {
+ gbuf = &z_erofs_gbufpool[i];
+ tmp_pages = kcalloc(nrpages, sizeof(*tmp_pages), GFP_KERNEL);
+ if (!tmp_pages)
+ goto out;
+
+ for (j = 0; j < gbuf->nrpages; ++j)
+ tmp_pages[j] = gbuf->pages[j];
+ do {
+ last = j;
+ j = alloc_pages_bulk_array(GFP_KERNEL, nrpages,
+ tmp_pages);
+ if (last == j)
+ goto out;
+ } while (j != nrpages);
+
+ ptr = vmap(tmp_pages, nrpages, VM_MAP, PAGE_KERNEL);
+ if (!ptr)
+ goto out;
+
+ spin_lock(&gbuf->lock);
+ kfree(gbuf->pages);
+ gbuf->pages = tmp_pages;
+ old_ptr = gbuf->ptr;
+ gbuf->ptr = ptr;
+ gbuf->nrpages = nrpages;
+ spin_unlock(&gbuf->lock);
+ if (old_ptr)
+ vunmap(old_ptr);
+ }
+ z_erofs_gbuf_nrpages = nrpages;
+out:
+ if (i < z_erofs_gbuf_count && tmp_pages) {
+ for (j = 0; j < nrpages; ++j)
+ if (tmp_pages[j] && tmp_pages[j] != gbuf->pages[j])
+ __free_page(tmp_pages[j]);
+ kfree(tmp_pages);
+ }
+ mutex_unlock(&gbuf_resize_mutex);
+ return i < z_erofs_gbuf_count ? -ENOMEM : 0;
+}
+
+int __init z_erofs_gbuf_init(void)
+{
+ unsigned int i, total = num_possible_cpus();
+
+ if (z_erofs_gbuf_count)
+ total = min(z_erofs_gbuf_count, total);
+ z_erofs_gbuf_count = total;
+
+ /* The last (special) global buffer is the reserved buffer */
+ total += !!z_erofs_rsv_nrpages;
+
+ z_erofs_gbufpool = kcalloc(total, sizeof(*z_erofs_gbufpool),
+ GFP_KERNEL);
+ if (!z_erofs_gbufpool)
+ return -ENOMEM;
+
+ if (z_erofs_rsv_nrpages) {
+ z_erofs_rsvbuf = &z_erofs_gbufpool[total - 1];
+ z_erofs_rsvbuf->pages = kcalloc(z_erofs_rsv_nrpages,
+ sizeof(*z_erofs_rsvbuf->pages), GFP_KERNEL);
+ if (!z_erofs_rsvbuf->pages) {
+ z_erofs_rsvbuf = NULL;
+ z_erofs_rsv_nrpages = 0;
+ }
+ }
+ for (i = 0; i < total; ++i)
+ spin_lock_init(&z_erofs_gbufpool[i].lock);
+ return 0;
+}
+
+void z_erofs_gbuf_exit(void)
+{
+ int i;
+
+ for (i = 0; i < z_erofs_gbuf_count + (!!z_erofs_rsvbuf); ++i) {
+ struct z_erofs_gbuf *gbuf = &z_erofs_gbufpool[i];
+
+ if (gbuf->ptr) {
+ vunmap(gbuf->ptr);
+ gbuf->ptr = NULL;
+ }
+
+ if (!gbuf->pages)
+ continue;
+
+ for (i = 0; i < gbuf->nrpages; ++i)
+ if (gbuf->pages[i])
+ put_page(gbuf->pages[i]);
+ kfree(gbuf->pages);
+ gbuf->pages = NULL;
+ }
+ kfree(z_erofs_gbufpool);
+}
+
+struct page *__erofs_allocpage(struct page **pagepool, gfp_t gfp, bool tryrsv)
+{
+ struct page *page = *pagepool;
+
+ if (page) {
+ *pagepool = (struct page *)page_private(page);
+ } else if (tryrsv && z_erofs_rsvbuf && z_erofs_rsvbuf->nrpages) {
+ spin_lock(&z_erofs_rsvbuf->lock);
+ if (z_erofs_rsvbuf->nrpages)
+ page = z_erofs_rsvbuf->pages[--z_erofs_rsvbuf->nrpages];
+ spin_unlock(&z_erofs_rsvbuf->lock);
+ }
+ if (!page)
+ page = alloc_page(gfp);
+ DBG_BUGON(page && page_ref_count(page) != 1);
+ return page;
+}
+
+void erofs_release_pages(struct page **pagepool)
+{
+ while (*pagepool) {
+ struct page *page = *pagepool;
+
+ *pagepool = (struct page *)page_private(page);
+ /* try to fill reserved global pool first */
+ if (z_erofs_rsvbuf && z_erofs_rsvbuf->nrpages <
+ z_erofs_rsv_nrpages) {
+ spin_lock(&z_erofs_rsvbuf->lock);
+ if (z_erofs_rsvbuf->nrpages < z_erofs_rsv_nrpages) {
+ z_erofs_rsvbuf->pages[z_erofs_rsvbuf->nrpages++]
+ = page;
+ spin_unlock(&z_erofs_rsvbuf->lock);
+ continue;
+ }
+ spin_unlock(&z_erofs_rsvbuf->lock);
+ }
+ put_page(page);
+ }
+}
+
+static bool erofs_workgroup_get(struct erofs_workgroup *grp)
+{
+ if (lockref_get_not_zero(&grp->lockref))
+ return true;
+
+ spin_lock(&grp->lockref.lock);
+ if (__lockref_is_dead(&grp->lockref)) {
+ spin_unlock(&grp->lockref.lock);
+ return false;
+ }
+
+ if (!grp->lockref.count++)
+ atomic_long_dec(&erofs_global_shrink_cnt);
+ spin_unlock(&grp->lockref.lock);
+ return true;
+}
+
+struct erofs_workgroup *erofs_find_workgroup(struct super_block *sb,
+ pgoff_t index)
+{
+ struct erofs_sb_info *sbi = EROFS_SB(sb);
+ struct erofs_workgroup *grp;
+
+repeat:
+ rcu_read_lock();
+ grp = xa_load(&sbi->managed_pslots, index);
+ if (grp) {
+ if (!erofs_workgroup_get(grp)) {
+ /* prefer to relax rcu read side */
+ rcu_read_unlock();
+ goto repeat;
+ }
+
+ DBG_BUGON(index != grp->index);
+ }
+ rcu_read_unlock();
+ return grp;
+}
+
+struct erofs_workgroup *erofs_insert_workgroup(struct super_block *sb,
+ struct erofs_workgroup *grp)
+{
+ struct erofs_sb_info *const sbi = EROFS_SB(sb);
+ struct erofs_workgroup *pre;
+
+ DBG_BUGON(grp->lockref.count < 1);
+repeat:
+ xa_lock(&sbi->managed_pslots);
+ pre = __xa_cmpxchg(&sbi->managed_pslots, grp->index,
+ NULL, grp, GFP_KERNEL);
+ if (pre) {
+ if (xa_is_err(pre)) {
+ pre = ERR_PTR(xa_err(pre));
+ } else if (!erofs_workgroup_get(pre)) {
+ /* try to legitimize the current in-tree one */
+ xa_unlock(&sbi->managed_pslots);
+ cond_resched();
+ goto repeat;
+ }
+ grp = pre;
+ }
+ xa_unlock(&sbi->managed_pslots);
+ return grp;
+}
+
+static void __erofs_workgroup_free(struct erofs_workgroup *grp)
+{
+ atomic_long_dec(&erofs_global_shrink_cnt);
+ erofs_workgroup_free_rcu(grp);
+}
+
+void erofs_workgroup_put(struct erofs_workgroup *grp)
+{
+ if (lockref_put_or_lock(&grp->lockref))
+ return;
+
+ DBG_BUGON(__lockref_is_dead(&grp->lockref));
+ if (grp->lockref.count == 1)
+ atomic_long_inc(&erofs_global_shrink_cnt);
+ --grp->lockref.count;
+ spin_unlock(&grp->lockref.lock);
+}
+
+static bool erofs_try_to_release_workgroup(struct erofs_sb_info *sbi,
+ struct erofs_workgroup *grp)
+{
+ int free = false;
+
+ spin_lock(&grp->lockref.lock);
+ if (grp->lockref.count)
+ goto out;
+
+ /*
+ * Note that all cached pages should be detached before deleted from
+ * the XArray. Otherwise some cached pages could be still attached to
+ * the orphan old workgroup when the new one is available in the tree.
+ */
+ if (erofs_try_to_free_all_cached_folios(sbi, grp))
+ goto out;
+
+ /*
+ * It's impossible to fail after the workgroup is freezed,
+ * however in order to avoid some race conditions, add a
+ * DBG_BUGON to observe this in advance.
+ */
+ DBG_BUGON(__xa_erase(&sbi->managed_pslots, grp->index) != grp);
+
+ lockref_mark_dead(&grp->lockref);
+ free = true;
+out:
+ spin_unlock(&grp->lockref.lock);
+ if (free)
+ __erofs_workgroup_free(grp);
+ return free;
+}
+
+static unsigned long erofs_shrink_workstation(struct erofs_sb_info *sbi,
+ unsigned long nr_shrink)
+{
+ struct erofs_workgroup *grp;
+ unsigned int freed = 0;
+ unsigned long index;
+
+ xa_lock(&sbi->managed_pslots);
+ xa_for_each(&sbi->managed_pslots, index, grp) {
+ /* try to shrink each valid workgroup */
+ if (!erofs_try_to_release_workgroup(sbi, grp))
+ continue;
+ xa_unlock(&sbi->managed_pslots);
+
+ ++freed;
+ if (!--nr_shrink)
+ return freed;
+ xa_lock(&sbi->managed_pslots);
+ }
+ xa_unlock(&sbi->managed_pslots);
+ return freed;
+}
+
+void erofs_shrinker_register(struct super_block *sb)
+{
+ struct erofs_sb_info *sbi = EROFS_SB(sb);
+
+ mutex_init(&sbi->umount_mutex);
+
+ spin_lock(&erofs_sb_list_lock);
+ list_add(&sbi->list, &erofs_sb_list);
+ spin_unlock(&erofs_sb_list_lock);
+}
+
+void erofs_shrinker_unregister(struct super_block *sb)
+{
+ struct erofs_sb_info *const sbi = EROFS_SB(sb);
+
+ mutex_lock(&sbi->umount_mutex);
+ /* clean up all remaining workgroups in memory */
+ erofs_shrink_workstation(sbi, ~0UL);
+
+ spin_lock(&erofs_sb_list_lock);
+ list_del(&sbi->list);
+ spin_unlock(&erofs_sb_list_lock);
+ mutex_unlock(&sbi->umount_mutex);
+}
+
+static unsigned long erofs_shrink_count(struct shrinker *shrink,
+ struct shrink_control *sc)
+{
+ return atomic_long_read(&erofs_global_shrink_cnt);
+}
+
+static unsigned long erofs_shrink_scan(struct shrinker *shrink,
+ struct shrink_control *sc)
+{
+ struct erofs_sb_info *sbi;
+ struct list_head *p;
+
+ unsigned long nr = sc->nr_to_scan;
+ unsigned int run_no;
+ unsigned long freed = 0;
+
+ spin_lock(&erofs_sb_list_lock);
+ do {
+ run_no = ++shrinker_run_no;
+ } while (run_no == 0);
+
+ /* Iterate over all mounted superblocks and try to shrink them */
+ p = erofs_sb_list.next;
+ while (p != &erofs_sb_list) {
+ sbi = list_entry(p, struct erofs_sb_info, list);
+
+ /*
+ * We move the ones we do to the end of the list, so we stop
+ * when we see one we have already done.
+ */
+ if (sbi->shrinker_run_no == run_no)
+ break;
+
+ if (!mutex_trylock(&sbi->umount_mutex)) {
+ p = p->next;
+ continue;
+ }
+
+ spin_unlock(&erofs_sb_list_lock);
+ sbi->shrinker_run_no = run_no;
+
+ freed += erofs_shrink_workstation(sbi, nr - freed);
+
+ spin_lock(&erofs_sb_list_lock);
+ /* Get the next list element before we move this one */
+ p = p->next;
+
+ /*
+ * Move this one to the end of the list to provide some
+ * fairness.
+ */
+ list_move_tail(&sbi->list, &erofs_sb_list);
+ mutex_unlock(&sbi->umount_mutex);
+
+ if (freed >= nr)
+ break;
+ }
+ spin_unlock(&erofs_sb_list_lock);
+ return freed;
+}
+
+int __init erofs_init_shrinker(void)
+{
+ erofs_shrinker_info = shrinker_alloc(0, "erofs-shrinker");
+ if (!erofs_shrinker_info)
+ return -ENOMEM;
+
+ erofs_shrinker_info->count_objects = erofs_shrink_count;
+ erofs_shrinker_info->scan_objects = erofs_shrink_scan;
+ shrinker_register(erofs_shrinker_info);
+ return 0;
+}
+
+void erofs_exit_shrinker(void)
+{
+ shrinker_free(erofs_shrinker_info);
+}
generated by cgit v1.2.3 (git 2.25.1) at 2024-06-20 09:54:50 +0000