From: Michal Hocko <mhocko@xxxxxxx>
Subject: jbd2: revert must-not-fail allocation loops back to GFP_NOFAIL
This basically reverts 47def82672b3 ("jbd2: Remove __GFP_NOFAIL from jbd2
layer"). The deprecation of __GFP_NOFAIL was a bad choice because it led
to open coding the endless loop around the allocator rather than removing
the dependency on the non failing allocation. So the deprecation was a
clear failure and the reality tells us that __GFP_NOFAIL is not even close
to go away.
It is still true that __GFP_NOFAIL allocations are generally discouraged
and new uses should be evaluated and an alternative (pre-allocations or
reservations) should be considered but it doesn't make any sense to lie
the allocator about the requirements. Allocator can take steps to help
making a progress if it knows the requirements.
Signed-off-by: Michal Hocko <mhocko@xxxxxxx>
Acked-by: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Dave Chinner <david@xxxxxxxxxxxxx>
Cc: "Theodore Ts'o" <tytso@xxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxx>
Cc: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
Cc: Vipul Pandya <vipul@xxxxxxxxxxx>
Cc: Jan Kara <jack@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/jbd2/journal.c | 11 +----------
fs/jbd2/transaction.c | 20 +++++++-------------
2 files changed, 8 insertions(+), 23 deletions(-)
diff -puN fs/jbd2/journal.c~jbd2-revert-must-not-fail-allocation-loops-back-to-gfp_nofail fs/jbd2/journal.c
--- a/fs/jbd2/journal.c~jbd2-revert-must-not-fail-allocation-loops-back-to-gfp_nofail
+++ a/fs/jbd2/journal.c
@@ -371,16 +371,7 @@ int jbd2_journal_write_metadata_buffer(t
*/
J_ASSERT_BH(bh_in, buffer_jbddirty(bh_in));
-retry_alloc:
- new_bh = alloc_buffer_head(GFP_NOFS);
- if (!new_bh) {
- /*
- * Failure is not an option, but __GFP_NOFAIL is going
- * away; so we retry ourselves here.
- */
- congestion_wait(BLK_RW_ASYNC, HZ/50);
- goto retry_alloc;
- }
+ new_bh = alloc_buffer_head(GFP_NOFS|__GFP_NOFAIL);
/* keep subsequent assertions sane */
atomic_set(&new_bh->b_count, 1);
diff -puN fs/jbd2/transaction.c~jbd2-revert-must-not-fail-allocation-loops-back-to-gfp_nofail fs/jbd2/transaction.c
--- a/fs/jbd2/transaction.c~jbd2-revert-must-not-fail-allocation-loops-back-to-gfp_nofail
+++ a/fs/jbd2/transaction.c
@@ -278,22 +278,16 @@ static int start_this_handle(journal_t *
alloc_transaction:
if (!journal->j_running_transaction) {
+ /*
+ * If __GFP_FS is not present, then we may be being called from
+ * inside the fs writeback layer, so we MUST NOT fail.
+ */
+ if ((gfp_mask & __GFP_FS) == 0)
+ gfp_mask |= __GFP_NOFAIL;
new_transaction = kmem_cache_zalloc(transaction_cache,
gfp_mask);
- if (!new_transaction) {
- /*
- * If __GFP_FS is not present, then we may be
- * being called from inside the fs writeback
- * layer, so we MUST NOT fail. Since
- * __GFP_NOFAIL is going away, we will arrange
- * to retry the allocation ourselves.
- */
- if ((gfp_mask & __GFP_FS) == 0) {
- congestion_wait(BLK_RW_ASYNC, HZ/50);
- goto alloc_transaction;
- }
+ if (!new_transaction)
return -ENOMEM;
- }
}
jbd_debug(3, "New handle %p going live.\n", handle);
_
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