bcachefs: Add a fallback when journal_keys doesn't fit in ram

We may end up in a situation where allocating the buffer for the sorted
journal_keys fails - but it would likely succeed, post compaction where
we drop duplicates.

We've had reports of this allocation failing, so this adds a slowpath to
do the compaction incrementally.

This is only a band-aid fix; we need to look at limiting the number of
keys in the journal based on the amount of system RAM.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

diff --git a/fs/bcachefs/recovery.c b/fs/bcachefs/recovery.c
index 73f7663cbd3f4bad5d6bfe8c9de303e65913ca34..6aa99f57a00135a9bdc51ac509613087139fa8d7 100644 (file)
--- a/fs/bcachefs/recovery.c
+++ b/fs/bcachefs/recovery.c
@@ -476,6 +476,26 @@ void bch2_journal_keys_free(struct journal_keys *keys)
        keys->nr = keys->gap = keys->size = 0;
 }
 
+static void __journal_keys_sort(struct journal_keys *keys)
+{
+       struct journal_key *src, *dst;
+
+       sort(keys->d, keys->nr, sizeof(keys->d[0]), journal_sort_key_cmp, NULL);
+
+       src = dst = keys->d;
+       while (src < keys->d + keys->nr) {
+               while (src + 1 < keys->d + keys->nr &&
+                      src[0].btree_id  == src[1].btree_id &&
+                      src[0].level     == src[1].level &&
+                      bpos_eq(src[0].k->k.p, src[1].k->k.p))
+                       src++;
+
+               *dst++ = *src++;
+       }
+
+       keys->nr = dst - keys->d;
+}
+
 static int journal_keys_sort(struct bch_fs *c)
 {
        struct genradix_iter iter;
@@ -483,8 +503,7 @@ static int journal_keys_sort(struct bch_fs *c)
        struct jset_entry *entry;
        struct bkey_i *k;
        struct journal_keys *keys = &c->journal_keys;
-       struct journal_key *src, *dst;
-       size_t nr_keys = 0;
+       size_t nr_keys = 0, nr_read = 0;
 
        genradix_for_each(&c->journal_entries, iter, _i) {
                i = *_i;
@@ -503,9 +522,19 @@ static int journal_keys_sort(struct bch_fs *c)
 
        keys->d = kvmalloc_array(keys->size, sizeof(keys->d[0]), GFP_KERNEL);
        if (!keys->d) {
-               bch_err(c, "Failed to allocate buffer for sorted journal keys (%zu keys)",
+               bch_err(c, "Failed to allocate buffer for sorted journal keys (%zu keys); trying slowpath",
                        nr_keys);
-               return -BCH_ERR_ENOMEM_journal_keys_sort;
+
+               do {
+                       keys->size >>= 1;
+                       keys->d = kvmalloc_array(keys->size, sizeof(keys->d[0]), GFP_KERNEL);
+               } while (!keys->d && keys->size > nr_keys / 8);
+
+               if (!keys->d) {
+                       bch_err(c, "Failed to allocate %zu size buffer for sorted journal keys; exiting",
+                               keys->size);
+                       return -BCH_ERR_ENOMEM_journal_keys_sort;
+               }
        }
 
        genradix_for_each(&c->journal_entries, iter, _i) {
@@ -514,7 +543,17 @@ static int journal_keys_sort(struct bch_fs *c)
                if (!i || i->ignore)
                        continue;
 
-               for_each_jset_key(k, entry, &i->j)
+               for_each_jset_key(k, entry, &i->j) {
+                       if (keys->nr == keys->size) {
+                               __journal_keys_sort(keys);
+
+                               if (keys->nr > keys->size * 7 / 8) {
+                                       bch_err(c, "Too many journal keys for slowpath; have %zu compacted, buf size %zu, processed %zu/%zu",
+                                               keys->nr, keys->size, nr_read, nr_keys);
+                                       return -BCH_ERR_ENOMEM_journal_keys_sort;
+                               }
+                       }
+
                        keys->d[keys->nr++] = (struct journal_key) {
                                .btree_id       = entry->btree_id,
                                .level          = entry->level,
@@ -522,23 +561,15 @@ static int journal_keys_sort(struct bch_fs *c)
                                .journal_seq    = le64_to_cpu(i->j.seq),
                                .journal_offset = k->_data - i->j._data,
                        };
-       }
-
-       sort(keys->d, keys->nr, sizeof(keys->d[0]), journal_sort_key_cmp, NULL);
 
-       src = dst = keys->d;
-       while (src < keys->d + keys->nr) {
-               while (src + 1 < keys->d + keys->nr &&
-                      src[0].btree_id  == src[1].btree_id &&
-                      src[0].level     == src[1].level &&
-                      bpos_eq(src[0].k->k.p, src[1].k->k.p))
-                       src++;
-
-               *dst++ = *src++;
+                       nr_read++;
+               }
        }
 
-       keys->nr = dst - keys->d;
+       __journal_keys_sort(keys);
        keys->gap = keys->nr;
+
+       bch_verbose(c, "Journal keys: %zu read, %zu after sorting and compacting", nr_keys, keys->nr);
        return 0;
 }