[PATCH] Revert "Btrfs: device_list_add() should not update list when

[PATCH] Revert "Btrfs: device_list_add() should not update list when

[Chris Mason]

Johannes and Sam, could you please confirm this patch fixes your mount
regression for now?  Anand, please make sure I kept the generation check
properly.

This reverts commit b96de000bc8bc9688b3a2abea4332bd57648a49f.

This commit is triggering failures to mount by subvolume id in some
configurations.  The main problem is how many different ways this
scanning function is used, both for scanning while mounted and
unmounted.  A proper cleanup is too big for late rcs.

For now, just revert the commit and we'll put a better fix into a later
merge window.

Signed-off-by: Chris Mason <clm@fb.com>
---
 fs/btrfs/volumes.c | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 340a92d..2c2d6d1 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -529,12 +529,12 @@ static noinline int device_list_add(const char *path,
 		 */
 
 		/*
-		 * As of now don't allow update to btrfs_fs_device through
-		 * the btrfs dev scan cli, after FS has been mounted.
+		 * For now, we do allow update to btrfs_fs_device through the
+		 * btrfs dev scan cli after FS has been mounted.  We're still
+		 * tracking a problem where systems fail mount by subvolume id
+		 * when we reject replacement on a mounted FS.
 		 */
-		if (fs_devices->opened) {
-			return -EBUSY;
-		} else {
+		if (!fs_devices->opened && found_transid < device->generation) {
 			/*
 			 * That is if the FS is _not_ mounted and if you
 			 * are here, that means there is more than one
@@ -542,8 +542,7 @@ static noinline int device_list_add(const char *path,
 			 * with larger generation number or the last-in if
 			 * generation are equal.
 			 */
-			if (found_transid < device->generation)
-				return -EEXIST;
+			return -EEXIST;
 		}
 
 		name = rcu_string_strdup(path, GFP_NOFS);
-- 
1.8.1

Re: [PATCH] Revert "Btrfs: device_list_add() should not update list when

[Anand Jain]

   Looks good to me Chris. Thank you.


Reviewed-by: Anand Jain <anand.jain@oracle.com>


On 09/18/2014 11:00 PM, Chris Mason wrote:
>
> Johannes and Sam, could you please confirm this patch fixes your mount
> regression for now?  Anand, please make sure I kept the generation check
> properly.
>
> This reverts commit b96de000bc8bc9688b3a2abea4332bd57648a49f.
>
> This commit is triggering failures to mount by subvolume id in some
> configurations.  The main problem is how many different ways this
> scanning function is used, both for scanning while mounted and
> unmounted.  A proper cleanup is too big for late rcs.
>
> For now, just revert the commit and we'll put a better fix into a later
> merge window.
>
> Signed-off-by: Chris Mason <clm@fb.com>
> ---
>   fs/btrfs/volumes.c | 13 ++++++-------
>   1 file changed, 6 insertions(+), 7 deletions(-)
>
> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
> index 340a92d..2c2d6d1 100644
> --- a/fs/btrfs/volumes.c
> +++ b/fs/btrfs/volumes.c
> @@ -529,12 +529,12 @@ static noinline int device_list_add(const char *path,
>   		 */
>
>   		/*
> -		 * As of now don't allow update to btrfs_fs_device through
> -		 * the btrfs dev scan cli, after FS has been mounted.
> +		 * For now, we do allow update to btrfs_fs_device through the
> +		 * btrfs dev scan cli after FS has been mounted.  We're still
> +		 * tracking a problem where systems fail mount by subvolume id
> +		 * when we reject replacement on a mounted FS.
>   		 */
> -		if (fs_devices->opened) {
> -			return -EBUSY;
> -		} else {
> +		if (!fs_devices->opened && found_transid < device->generation) {
>   			/*
>   			 * That is if the FS is _not_ mounted and if you
>   			 * are here, that means there is more than one
> @@ -542,8 +542,7 @@ static noinline int device_list_add(const char *path,
>   			 * with larger generation number or the last-in if
>   			 * generation are equal.
>   			 */
> -			if (found_transid < device->generation)
> -				return -EEXIST;
> +			return -EEXIST;
>   		}
>
>   		name = rcu_string_strdup(path, GFP_NOFS);
>

Re: [PATCH] Revert "Btrfs: device_list_add() should not update list when

[Sam Thursfield]

On 18/09/14 16:00, Chris Mason wrote:
>
> Johannes and Sam, could you please confirm this patch fixes your mount
> regression for now?  Anand, please make sure I kept the generation check
> properly.

I've just tested this patch on top of 3.17-rc5 and it fixes the issue 
for me.

Thanks!
Sam


-- 
Sam Thursfield, Codethink Ltd.
Office telephone: +44 161 236 5575

Re: [PATCH] Revert "Btrfs: device_list_add() should not update list when

[Chris Mason]

On 09/19/2014 09:47 AM, Sam Thursfield wrote:
> On 18/09/14 16:00, Chris Mason wrote:
>>
>> Johannes and Sam, could you please confirm this patch fixes your mount
>> regression for now?  Anand, please make sure I kept the generation check
>> properly.
> 
> I've just tested this patch on top of 3.17-rc5 and it fixes the issue
> for me.
> 

Perfect, thanks.

-chris