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From: Michal Hocko <mhocko@kernel.org>
To: Andrew Morton <akpm@linux-foundation.org>,
	<linux-fsdevel@vger.kernel.org>
Cc: <linux-mm@kvack.org>, Dave Chinner <david@fromorbit.com>,
	djwong@kernel.org, "Theodore Ts'o" <tytso@mit.edu>,
	Chris Mason <clm@fb.com>, David Sterba <dsterba@suse.cz>,
	Jan Kara <jack@suse.cz>,
	ceph-devel@vger.kernel.org, cluster-devel@redhat.com,
	linux-nfs@vger.kernel.org, logfs@logfs.org,
	linux-xfs@vger.kernel.org, linux-ext4@vger.kernel.org,
	linux-btrfs@vger.kernel.org, linux-mtd@lists.infradead.org,
	reiserfs-devel@vger.kernel.org,
	linux-ntfs-dev@lists.sourceforge.net,
	linux-f2fs-devel@lists.sourceforge.net,
	linux-afs@lists.infradead.org,
	LKML <linux-kernel@vger.kernel.org>,
	Michal Hocko <mhocko@suse.com>
Subject: [PATCH 6/7] jbd2: mark the transaction context with the scope GFP_NOFS context
Date: Mon,  6 Mar 2017 14:14:07 +0100
Message-ID: <20170306131408.9828-7-mhocko@kernel.org> (raw)
In-Reply-To: <20170306131408.9828-1-mhocko@kernel.org>

From: Michal Hocko <mhocko@suse.com>

now that we have memalloc_nofs_{save,restore} api we can mark the whole
transaction context as implicitly GFP_NOFS. All allocations will
automatically inherit GFP_NOFS this way. This means that we do not have
to mark any of those requests with GFP_NOFS and moreover all the
ext4_kv[mz]alloc(GFP_NOFS) are also safe now because even the hardcoded
GFP_KERNEL allocations deep inside the vmalloc will be NOFS now.

Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Michal Hocko <mhocko@suse.com>
---
 fs/jbd2/transaction.c | 12 ++++++++++++
 include/linux/jbd2.h  |  2 ++
 2 files changed, 14 insertions(+)

diff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c
index 5e659ee08d6a..d8f09f34285f 100644
--- a/fs/jbd2/transaction.c
+++ b/fs/jbd2/transaction.c
@@ -29,6 +29,7 @@
 #include <linux/backing-dev.h>
 #include <linux/bug.h>
 #include <linux/module.h>
+#include <linux/sched/mm.h>
 
 #include <trace/events/jbd2.h>
 
@@ -388,6 +389,11 @@ static int start_this_handle(journal_t *journal, handle_t *handle,
 
 	rwsem_acquire_read(&journal->j_trans_commit_map, 0, 0, _THIS_IP_);
 	jbd2_journal_free_transaction(new_transaction);
+	/*
+	 * Make sure that no allocations done while the transaction is
+	 * open is going to recurse back to the fs layer.
+	 */
+	handle->saved_alloc_context = memalloc_nofs_save();
 	return 0;
 }
 
@@ -466,6 +472,7 @@ handle_t *jbd2__journal_start(journal_t *journal, int nblocks, int rsv_blocks,
 	trace_jbd2_handle_start(journal->j_fs_dev->bd_dev,
 				handle->h_transaction->t_tid, type,
 				line_no, nblocks);
+
 	return handle;
 }
 EXPORT_SYMBOL(jbd2__journal_start);
@@ -1760,6 +1767,11 @@ int jbd2_journal_stop(handle_t *handle)
 	if (handle->h_rsv_handle)
 		jbd2_journal_free_reserved(handle->h_rsv_handle);
 free_and_exit:
+	/*
+	 * scope of th GFP_NOFS context is over here and so we can
+	 * restore the original alloc context.
+	 */
+	memalloc_nofs_restore(handle->saved_alloc_context);
 	jbd2_free_handle(handle);
 	return err;
 }
diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h
index dfaa1f4dcb0c..606b6bce3a5b 100644
--- a/include/linux/jbd2.h
+++ b/include/linux/jbd2.h
@@ -491,6 +491,8 @@ struct jbd2_journal_handle
 
 	unsigned long		h_start_jiffies;
 	unsigned int		h_requested_credits;
+
+	unsigned int		saved_alloc_context;
 };
 
 
-- 
2.11.0


  parent reply index

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-03-06 13:14 [PATCH 0/7 v5] scope GFP_NOFS api Michal Hocko
2017-03-06 13:14 ` [PATCH 1/7] lockdep: teach lockdep about memalloc_noio_save Michal Hocko
2017-03-06 13:14 ` [PATCH 2/7] lockdep: allow to disable reclaim lockup detection Michal Hocko
2017-03-06 13:14 ` [PATCH 3/7] xfs: abstract PF_FSTRANS to PF_MEMALLOC_NOFS Michal Hocko
2017-03-06 13:14 ` [PATCH 4/7] mm: introduce memalloc_nofs_{save,restore} API Michal Hocko
2017-03-06 21:22   ` Andrew Morton
2017-03-07 15:09     ` Michal Hocko
2017-03-09 11:42       ` David Sterba
2017-03-06 13:14 ` [PATCH 5/7] xfs: use memalloc_nofs_{save,restore} instead of memalloc_noio* Michal Hocko
2017-03-06 13:14 ` Michal Hocko [this message]
2017-03-06 13:14 ` [PATCH 7/7] jbd2: make the whole kjournald2 kthread NOFS safe Michal Hocko

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