ext4: make trim/discard optional (and off by default)
It is anticipated that when sb_issue_discard starts doing
real work on trim-capable devices, we may see issues. Make
this mount-time optional, and default it to off until we know
that things are working out OK.
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index bba1282..6e5a23a 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -2529,7 +2529,6 @@
struct ext4_group_info *db;
int err, count = 0, count2 = 0;
struct ext4_free_data *entry;
- ext4_fsblk_t discard_block;
struct list_head *l, *ltmp;
list_for_each_safe(l, ltmp, &txn->t_private_list) {
@@ -2559,13 +2558,19 @@
page_cache_release(e4b.bd_bitmap_page);
}
ext4_unlock_group(sb, entry->group);
- discard_block = (ext4_fsblk_t) entry->group * EXT4_BLOCKS_PER_GROUP(sb)
- + entry->start_blk
- + le32_to_cpu(EXT4_SB(sb)->s_es->s_first_data_block);
- trace_ext4_discard_blocks(sb, (unsigned long long)discard_block,
- entry->count);
- sb_issue_discard(sb, discard_block, entry->count);
+ if (test_opt(sb, DISCARD)) {
+ ext4_fsblk_t discard_block;
+ struct ext4_super_block *es = EXT4_SB(sb)->s_es;
+ discard_block = (ext4_fsblk_t)entry->group *
+ EXT4_BLOCKS_PER_GROUP(sb)
+ + entry->start_blk
+ + le32_to_cpu(es->s_first_data_block);
+ trace_ext4_discard_blocks(sb,
+ (unsigned long long)discard_block,
+ entry->count);
+ sb_issue_discard(sb, discard_block, entry->count);
+ }
kmem_cache_free(ext4_free_ext_cachep, entry);
ext4_mb_release_desc(&e4b);
}