@@ -538,6 +538,14 @@ struct btrfs_io_ctl {
unsigned check_crcs:1;
};
+/*
+ * Tree to record all locked full stripes of a RAID5/6 block group
+ */
+struct btrfs_full_stripe_locks_tree {
+ struct rb_root root;
+ struct mutex lock;
+};
+
struct btrfs_block_group_cache {
struct btrfs_key key;
struct btrfs_block_group_item item;
@@ -648,6 +656,9 @@ struct btrfs_block_group_cache {
* Protected by free_space_lock.
*/
int needs_free_space;
+
+ /* Record locked full stripes for RAID5/6 block group */
+ struct btrfs_full_stripe_locks_tree full_stripe_locks_root;
};
/* delayed seq elem */
@@ -3647,6 +3658,12 @@ int btrfs_scrub_cancel_dev(struct btrfs_fs_info *info,
struct btrfs_device *dev);
int btrfs_scrub_progress(struct btrfs_fs_info *fs_info, u64 devid,
struct btrfs_scrub_progress *progress);
+static inline void btrfs_init_full_stripe_locks_tree(
+ struct btrfs_full_stripe_locks_tree *locks_root)
+{
+ locks_root->root = RB_ROOT;
+ mutex_init(&locks_root->lock);
+}
/* dev-replace.c */
void btrfs_bio_counter_inc_blocked(struct btrfs_fs_info *fs_info);
@@ -131,6 +131,16 @@ void btrfs_put_block_group(struct btrfs_block_group_cache *cache)
if (atomic_dec_and_test(&cache->count)) {
WARN_ON(cache->pinned > 0);
WARN_ON(cache->reserved > 0);
+
+ /*
+ * If not empty, someone is still holding mutex of
+ * full_stripe_lock, which can only be released by caller.
+ * And it will definitely cause use-after-free when caller
+ * tries to release full stripe lock.
+ *
+ * No better way to resolve, but only to warn.
+ */
+ WARN_ON(!RB_EMPTY_ROOT(&cache->full_stripe_locks_root.root));
kfree(cache->free_space_ctl);
kfree(cache);
}
@@ -9917,6 +9927,7 @@ btrfs_create_block_group_cache(struct btrfs_fs_info *fs_info,
btrfs_init_free_space_ctl(cache);
atomic_set(&cache->trimming, 0);
mutex_init(&cache->free_space_lock);
+ btrfs_init_full_stripe_locks_tree(&cache->full_stripe_locks_root);
return cache;
}
@@ -240,6 +240,13 @@ struct scrub_warning {
struct btrfs_device *dev;
};
+struct full_stripe_lock {
+ struct rb_node node;
+ u64 logical;
+ u64 refs;
+ struct mutex mutex;
+};
+
static void scrub_pending_bio_inc(struct scrub_ctx *sctx);
static void scrub_pending_bio_dec(struct scrub_ctx *sctx);
static void scrub_pending_trans_workers_inc(struct scrub_ctx *sctx);
@@ -349,6 +356,222 @@ static void scrub_blocked_if_needed(struct btrfs_fs_info *fs_info)
}
/*
+ * Insert new full stripe lock into full stripe locks tree
+ *
+ * Return pointer to existing or newly inserted full_stripe_lock structure if
+ * everything works well.
+ * Return ERR_PTR(-ENOMEM) if we failed to allocate memory
+ *
+ * NOTE: caller must hold full_stripe_locks_root->lock before calling this
+ * function
+ */
+static struct full_stripe_lock *insert_full_stripe_lock(
+ struct btrfs_full_stripe_locks_tree *locks_root,
+ u64 fstripe_logical)
+{
+ struct rb_node **p;
+ struct rb_node *parent = NULL;
+ struct full_stripe_lock *entry;
+ struct full_stripe_lock *ret;
+
+ WARN_ON(!mutex_is_locked(&locks_root->lock));
+
+ p = &locks_root->root.rb_node;
+ while (*p) {
+ parent = *p;
+ entry = rb_entry(parent, struct full_stripe_lock, node);
+ if (fstripe_logical < entry->logical) {
+ p = &(*p)->rb_left;
+ } else if (fstripe_logical > entry->logical) {
+ p = &(*p)->rb_right;
+ } else {
+ entry->refs++;
+ return entry;
+ }
+ }
+
+ /* Insert new lock */
+ ret = kmalloc(sizeof(*ret), GFP_KERNEL);
+ if (!ret)
+ return ERR_PTR(-ENOMEM);
+ ret->logical = fstripe_logical;
+ ret->refs = 1;
+ mutex_init(&ret->mutex);
+
+ rb_link_node(&ret->node, parent, p);
+ rb_insert_color(&ret->node, &locks_root->root);
+ return ret;
+}
+
+/*
+ * Search for a full stripe lock of a block group
+ *
+ * Return pointer to existing full stripe lock if found
+ * Return NULL if not found
+ */
+static struct full_stripe_lock *search_full_stripe_lock(
+ struct btrfs_full_stripe_locks_tree *locks_root,
+ u64 fstripe_logical)
+{
+ struct rb_node *node;
+ struct full_stripe_lock *entry;
+
+ WARN_ON(!mutex_is_locked(&locks_root->lock));
+
+ node = locks_root->root.rb_node;
+ while (node) {
+ entry = rb_entry(node, struct full_stripe_lock, node);
+ if (fstripe_logical < entry->logical)
+ node = node->rb_left;
+ else if (fstripe_logical > entry->logical)
+ node = node->rb_right;
+ else
+ return entry;
+ }
+ return NULL;
+}
+
+/*
+ * Helper to get full stripe logical from a normal bytenr.
+ *
+ * Caller must ensure @cache is a RAID56 block group.
+ */
+static u64 get_full_stripe_logical(struct btrfs_block_group_cache *cache,
+ u64 bytenr)
+{
+ u64 ret;
+
+ /*
+ * Due to chunk item size limit, full stripe length should not be
+ * larger than U32_MAX. Just sanity check here.
+ */
+ WARN_ON_ONCE(cache->full_stripe_len >= U32_MAX);
+
+ /*
+ * round_down() can only handle power of 2, while RAID56 full
+ * stripe len can be 64KiB * n, so need manual round down.
+ */
+ ret = div64_u64(bytenr - cache->key.objectid, cache->full_stripe_len) *
+ cache->full_stripe_len + cache->key.objectid;
+ return ret;
+}
+
+/*
+ * To lock a full stripe to avoid concurrency of recovery and read
+ * It's only used for profiles with parities(RAID5/6), for other profiles it
+ * does nothing
+ *
+ * Return 0 if we locked full stripe covering @bytenr, with a mutex hold.
+ * So caller must call unlock_full_stripe() at the same context.
+ *
+ * Return <0 if encounters error.
+ */
+static int lock_full_stripe(struct btrfs_fs_info *fs_info, u64 bytenr,
+ bool *locked_ret)
+{
+ struct btrfs_block_group_cache *bg_cache;
+ struct btrfs_full_stripe_locks_tree *locks_root;
+ struct full_stripe_lock *existing;
+ u64 fstripe_start;
+ int ret = 0;
+
+ *locked_ret = false;
+ bg_cache = btrfs_lookup_block_group(fs_info, bytenr);
+ if (!bg_cache) {
+ ASSERT(0);
+ return -ENOENT;
+ }
+
+ /* Profiles not based on parity don't need full stripe lock */
+ if (!(bg_cache->flags & BTRFS_BLOCK_GROUP_RAID56_MASK))
+ goto out;
+ locks_root = &bg_cache->full_stripe_locks_root;
+
+ fstripe_start = get_full_stripe_logical(bg_cache, bytenr);
+
+ /* Now insert the full stripe lock */
+ mutex_lock(&locks_root->lock);
+ existing = insert_full_stripe_lock(locks_root, fstripe_start);
+ mutex_unlock(&locks_root->lock);
+ if (IS_ERR(existing)) {
+ ret = PTR_ERR(existing);
+ goto out;
+ }
+ mutex_lock(&existing->mutex);
+ *locked_ret = true;
+out:
+ btrfs_put_block_group(bg_cache);
+ return ret;
+}
+
+/*
+ * Unlock a full stripe.
+ * NOTE: Caller must ensure it's the same context calling corresponding
+ * lock_full_stripe().
+ *
+ * Return 0 if we unlock full stripe without problem.
+ * Return <0 for error
+ */
+static int unlock_full_stripe(struct btrfs_fs_info *fs_info, u64 bytenr,
+ bool locked)
+{
+ struct btrfs_block_group_cache *bg_cache;
+ struct btrfs_full_stripe_locks_tree *locks_root;
+ struct full_stripe_lock *fstripe_lock;
+ u64 fstripe_start;
+ bool freeit = false;
+ int ret = 0;
+
+ /* If we didn't acquire full stripe lock, no need to continue */
+ if (!locked)
+ return 0;
+
+ bg_cache = btrfs_lookup_block_group(fs_info, bytenr);
+ if (!bg_cache) {
+ ASSERT(0);
+ return -ENOENT;
+ }
+ if (!(bg_cache->flags & BTRFS_BLOCK_GROUP_RAID56_MASK))
+ goto out;
+
+ locks_root = &bg_cache->full_stripe_locks_root;
+ fstripe_start = get_full_stripe_logical(bg_cache, bytenr);
+ if (ret < 0)
+ goto out;
+
+ mutex_lock(&locks_root->lock);
+ fstripe_lock = search_full_stripe_lock(locks_root, fstripe_start);
+ /* Unpaired unlock_full_stripe() detected */
+ if (!fstripe_lock) {
+ WARN_ON(1);
+ ret = -ENOENT;
+ mutex_unlock(&locks_root->lock);
+ goto out;
+ }
+
+ if (fstripe_lock->refs == 0) {
+ WARN_ON(1);
+ btrfs_warn(fs_info, "full stripe lock at %llu refcount underflow",
+ fstripe_lock->logical);
+ } else {
+ fstripe_lock->refs--;
+ }
+
+ if (fstripe_lock->refs == 0) {
+ rb_erase(&fstripe_lock->node, &locks_root->root);
+ freeit = true;
+ }
+ mutex_unlock(&locks_root->lock);
+
+ mutex_unlock(&fstripe_lock->mutex);
+ if (freeit)
+ kfree(fstripe_lock);
+out:
+ btrfs_put_block_group(bg_cache);
+ return ret;
+}
+
+/*
* used for workers that require transaction commits (i.e., for the
* NOCOW case)
*/