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From:   Ben Hutchings <ben@decadent.org.uk>
To:     linux-kernel@vger.kernel.org, stable@vger.kernel.org
CC:     akpm@linux-foundation.org, Denis Kirjanov <kda@linux-powerpc.org>,
        "Theodore Ts'o" <tytso@mit.edu>
Date:   Tue, 02 Apr 2019 14:38:28 +0100
Message-ID: <lsq.1554212308.670738173@decadent.org.uk>
Subject: [PATCH 3.16 79/99] ext4: make sure enough credits are reserved
 for dioread_nolock writes
In-Reply-To: <lsq.1554212307.17110877@decadent.org.uk>
Sender: linux-kernel-owner@vger.kernel.org
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3.16.65-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Theodore Ts'o <tytso@mit.edu>

commit 812c0cab2c0dfad977605dbadf9148490ca5d93f upstream.

There are enough credits reserved for most dioread_nolock writes;
however, if the extent tree is sufficiently deep, and/or quota is
enabled, the code was not allowing for all eventualities when
reserving journal credits for the unwritten extent conversion.

This problem can be seen using xfstests ext4/034:

   WARNING: CPU: 1 PID: 257 at fs/ext4/ext4_jbd2.c:271 __ext4_handle_dirty_metadata+0x10c/0x180
   Workqueue: ext4-rsv-conversion ext4_end_io_rsv_work
   RIP: 0010:__ext4_handle_dirty_metadata+0x10c/0x180
   	...
   EXT4-fs: ext4_free_blocks:4938: aborting transaction: error 28 in __ext4_handle_dirty_metadata
   EXT4: jbd2_journal_dirty_metadata failed: handle type 11 started at line 4921, credits 4/0, errcode -28
   EXT4-fs error (device dm-1) in ext4_free_blocks:4950: error 28

Signed-off-by: Theodore Ts'o <tytso@mit.edu>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
 fs/ext4/inode.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -2579,7 +2579,8 @@ static int ext4_writepages(struct addres
 		 * We may need to convert up to one extent per block in
 		 * the page and we may dirty the inode.
 		 */
-		rsv_blocks = 1 + (PAGE_CACHE_SIZE >> inode->i_blkbits);
+		rsv_blocks = 1 + ext4_chunk_trans_blocks(inode,
+					PAGE_CACHE_SIZE >> inode->i_blkbits);
 	}
 
 	/*