ext4: make sure enough credits are reserved for dioread_nolock writes

tytso · tytso · commit 812c0cab2c0d · 2018-12-24T20:27:08.000-05:00
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 &lt;tytso@mit.edu&gt;
Cc: stable@kernel.org
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
@@ -2778,7 +2778,8 @@ 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_SIZE >> inode->i_blkbits);
+		rsv_blocks = 1 + ext4_chunk_trans_blocks(inode,
+						PAGE_SIZE >> inode->i_blkbits);
 	}
 
 	/*

Original file line number	Diff line number	Diff line change
`@@ -2778,7 +2778,8 @@ static int ext4_writepages(struct address_space *mapping,`
`2778`	`2778`	`* We may need to convert up to one extent per block in`
`2779`	`2779`	`* the page and we may dirty the inode.`
`2780`	`2780`	`*/`
`2781`		`- rsv_blocks = 1 + (PAGE_SIZE >> inode->i_blkbits);`
	`2781`	`+ rsv_blocks = 1 + ext4_chunk_trans_blocks(inode,`
	`2782`	`+ PAGE_SIZE >> inode->i_blkbits);`
`2782`	`2783`	`}`
`2783`	`2784`
`2784`	`2785`	`/*`