[PATCH 3.16 79/99] ext4: make sure enough credits are reserved for dioread_nolock writes

From: Ben Hutchings
Date: Tue Apr 02 2019 - 09:44:33 EST


3.16.65-rc1 review patch. If anyone has any objections, please let me know.

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

From: Theodore Ts'o <tytso@xxxxxxx>

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@xxxxxxx>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
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);
}

/*