[PATCH -tip] remove the BKL: remove "BKL auto-drop" assumption from ext3_remount()

[PATCH -tip] remove the BKL: remove "BKL auto-drop" assumption from ext3_remount()

[Alessio Igor Bogani]

Fix ext3_remount()'s "schedule() drops the BKL automatically" assumption,
when ext3_mark_recovery_complete(), which can sleep, does not do that it can
lock up.

Signed-off-by: Alessio Igor Bogani <abogani@texware.it>
---
 fs/ext3/super.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/fs/ext3/super.c b/fs/ext3/super.c
index dc905f9..3fa457a 100644
--- a/fs/ext3/super.c
+++ b/fs/ext3/super.c
@@ -2561,9 +2561,11 @@ static int ext3_remount (struct super_block * sb, int * flags, char * data)
 			 * We have to unlock super so that we can wait for
 			 * transactions.
 			 */
+			unlock_kernel();
 			unlock_super(sb);
 			ext3_mark_recovery_complete(sb, es);
 			lock_super(sb);
+			lock_kernel();
 		} else {
 			__le32 ret;
 			if ((ret = EXT3_HAS_RO_COMPAT_FEATURE(sb,
-- 
1.6.0.4

Re: [PATCH -tip] remove the BKL: remove "BKL auto-drop" assumption from ext3_remount()

[Ingo Molnar]

* Alessio Igor Bogani <abogani@texware.it> wrote:

> Fix ext3_remount()'s "schedule() drops the BKL automatically" assumption,
> when ext3_mark_recovery_complete(), which can sleep, does not do that it can
> lock up.
> 
> Signed-off-by: Alessio Igor Bogani <abogani@texware.it>
> ---
>  fs/ext3/super.c |    2 ++
>  1 files changed, 2 insertions(+), 0 deletions(-)
> 
> diff --git a/fs/ext3/super.c b/fs/ext3/super.c
> index dc905f9..3fa457a 100644
> --- a/fs/ext3/super.c
> +++ b/fs/ext3/super.c
> @@ -2561,9 +2561,11 @@ static int ext3_remount (struct super_block * sb, int * flags, char * data)
>  			 * We have to unlock super so that we can wait for
>  			 * transactions.
>  			 */
> +			unlock_kernel();
>  			unlock_super(sb);
>  			ext3_mark_recovery_complete(sb, es);
>  			lock_super(sb);
> +			lock_kernel();

Shouldnt this be a conditional-unlock, so that if the remount moves 
away from under the BKL we dont break in this place?

	Ingo

Re: [PATCH -tip] remove the BKL: remove "BKL auto-drop" assumption from ext3_remount()

[Alessio Igor Bogani]

Dear Sir Molnar,

2009/4/26 Ingo Molnar <mingo@elte.hu>:
[...]
>> +                     unlock_kernel();
>>                       unlock_super(sb);
>>                       ext3_mark_recovery_complete(sb, es);
>>                       lock_super(sb);
>> +                     lock_kernel();
>
> Shouldnt this be a conditional-unlock, so that if the remount moves
> away from under the BKL we dont break in this place?
[...]

Please excuse me I'm only a stupid howler monkey. :-)

Patch with conditional-unlock/lock follow in a second.

Thank you!

Ciao,
Alessio

[PATCH -tip:kill-the-BKL] remove the BKL: remove "BKL auto-drop" assumption from ext3_remount()

[Alessio Igor Bogani]

Fix ext3_remount()'s "schedule() drops the BKL automatically" assumption,
when ext3_mark_recovery_complete(), which can sleep, does not do that it can
lock up.

Signed-off-by: Alessio Igor Bogani <abogani@texware.it>
---
 fs/ext3/super.c |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)

diff --git a/fs/ext3/super.c b/fs/ext3/super.c
index dc905f9..5d61a7f 100644
--- a/fs/ext3/super.c
+++ b/fs/ext3/super.c
@@ -2503,6 +2503,7 @@ static int ext3_remount (struct super_block * sb, int * flags, char * data)
 #ifdef CONFIG_QUOTA
 	int i;
 #endif
+	int bkl = kernel_locked();
 
 	/* Store the original options */
 	old_sb_flags = sb->s_flags;
@@ -2561,9 +2562,13 @@ static int ext3_remount (struct super_block * sb, int * flags, char * data)
 			 * We have to unlock super so that we can wait for
 			 * transactions.
 			 */
+			if (bkl)
+				unlock_kernel();
 			unlock_super(sb);
 			ext3_mark_recovery_complete(sb, es);
 			lock_super(sb);
+			if (bkl)
+				lock_kernel();
 		} else {
 			__le32 ret;
 			if ((ret = EXT3_HAS_RO_COMPAT_FEATURE(sb,
-- 
1.6.0.4