Re: [PATCH 4/5] xfs: free inodes on log recovery error

[Mark Tinguely <tinguely@sgi.com>]

On 07/07/14 09:30, Brian Foster wrote:
> On Wed, Jul 02, 2014 at 09:32:10AM -0500, Mark Tinguely wrote:
>> Recovery may free inodes that end up on the inode
>> reclaim RCU. If recovery fails, we leak these inodes.
>> The filesystem should be in forced shutdown at this
>> point, so a call to xfs_reclaim_inode is a fast path
>> to freeing the inodes and RCU entries.
>>
>> Signed-off-by: Mark Tinguely<tinguely@sgi.com>
>> ---
>>   fs/xfs/xfs_log.c   |    2 ++
>>   fs/xfs/xfs_mount.c |    1 +
>>   2 files changed, 3 insertions(+)
>>
>> Index: b/fs/xfs/xfs_log.c
>> ===================================================================
>> --- a/fs/xfs/xfs_log.c
>> +++ b/fs/xfs/xfs_log.c
>> @@ -31,6 +31,7 @@
>>   #include "xfs_log_priv.h"
>>   #include "xfs_log_recover.h"
>>   #include "xfs_inode.h"
>> +#include "xfs_icache.h"
>>   #include "xfs_trace.h"
>>   #include "xfs_fsops.h"
>>   #include "xfs_cksum.h"
>> @@ -720,6 +721,7 @@ xfs_log_mount(
>>   	return 0;
>>
>>   out_destroy_ail:
>> +	xfs_reclaim_inodes(mp, SYNC_WAIT);
>
> So an inode in the perag cache means an xfs_iget(). I see that in
> xlog_recover_process_one_iunlink(), which is via
> xfs_log_mount_finish(). Assuming I'm following that correctly, why the
> reclaim here (and in response to failure here by the caller) as opposed
> to closer to a failure of xfs_log_mount_finish()?
>
> Brian
>
>>   	xfs_trans_ail_destroy(mp);
>>   out_free_log:
>>   	xlog_dealloc_log(mp->m_log);
>> Index: b/fs/xfs/xfs_mount.c
>> ===================================================================
>> --- a/fs/xfs/xfs_mount.c
>> +++ b/fs/xfs/xfs_mount.c
>> @@ -980,6 +980,7 @@ xfs_mountfs(
>>    out_log_dealloc:
>>   	xfs_log_unmount(mp);
>>    out_fail_wait:
>> +	xfs_reclaim_inodes(mp, SYNC_WAIT);
>>   	if (mp->m_logdev_targp&&  mp->m_logdev_targp != mp->m_ddev_targp)
>>   		xfs_wait_buftarg(mp->m_logdev_targp);
>>   	xfs_wait_buftarg(mp->m_ddev_targp);
>>
>>
>> _______________________________________________

You are right, the reclaim in xfs_log_mount() is now redundant.

The xfs_reclaim_inodes call location in xfs_mount error path had changed 
when I learned that the xfs_log_unmount() left inodes in the RCU. I did 
not notice that with the new location that they were the same.

--Mark.

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