[Devel] [PATCH RH7] ext4: make sure enough credits are reserved for dioread_nolock writes

[Kirill Tkhai]

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

ms commit 812c0cab2c0dfad977605dbadf9148490ca5d93f.

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 at mit.edu>
Cc: stable at kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
Signed-off-by: Kirill Tkhai <ktkhai at virtuozzo.com>
---
 fs/ext4/inode.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index bc253a0f177c..7c74fe309437 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -2451,7 +2451,8 @@ static int ext4_writepages(struct address_space *mapping,
 		 * 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_SIZE >> inode->i_blkbits);
 	}
 
 	/*