From: Theodore Ts'o <tytso@mit.edu>
Date: Tue, 18 Sep 2012 17:33:44 +0000 (-0400)
Subject: ext4: re-enable -o discard functionality in no-journal mode
X-Git-Tag: firefly_0821_release~3680^2~1747^2~44
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=b5e2368baeddf401bf3da9e364fc1c96676279cd;p=firefly-linux-kernel-4.4.55.git

ext4: re-enable -o discard functionality in no-journal mode

This is a revert of commit b56ff9d397ce, which removed the call to
ext4_issue_discard() to fix a BUG reported because
ext4_issue_discard() was being called from inside a block group
spinlock.  As it turns out this bug had already been fixed by Lukas
Czerner in commit 53fdcf992d61 by the simple expedient of moving when
we call ext4_issue_discard() outside the spinlock.

So it should be safe to re-enable this functionality, which I tested
by putting an BUG_ON(in_atomic) just after the restored callsite to
ext4_issue_discard().

Addresses-Google-Bug: #6750518

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: Anatol Pomozov <anatol.pomozov@gmail.com>
---

diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 2102c20f7e98..2c7c082b8169 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -4656,6 +4656,8 @@ do_more:
 		 * with group lock held. generate_buddy look at
 		 * them with group lock_held
 		 */
+		if (test_opt(sb, DISCARD))
+			ext4_issue_discard(sb, block_group, bit, count);
 		ext4_lock_group(sb, block_group);
 		mb_clear_bits(bitmap_bh->b_data, bit, count_clusters);
 		mb_free_blocks(inode, &e4b, bit, count_clusters);