Patchwork jbd2: Move bdget out of critical section

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Submitter Zhu Yanhai
Date April 2, 2011, 9:01 a.m.
Message ID <1301734876-22207-1-git-send-email-gaoyang.zyh@taobao.com>
Download mbox | patch
Permalink /patch/89440/
State Accepted
Headers show

Comments

Zhu Yanhai - April 2, 2011, 9:01 a.m.
bdget() should not be called when we hold spinlocks since
it might sleep.

Signed-off-by: Zhu Yanhai <gaoyang.zyh@taobao.com>
---
 fs/jbd2/journal.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)
Jan Kara - April 3, 2011, 9:40 a.m.
On Sat 02-04-11 17:01:16, Zhu Yanhai wrote:
> bdget() should not be called when we hold spinlocks since
> it might sleep.
> 
> Signed-off-by: Zhu Yanhai <gaoyang.zyh@taobao.com>
  Looks good.
Acked-by: Jan Kara <jack@suse.cz>

PS: Added Ted to CC since he merges JBD2 patches.


								Honza
> ---
>  fs/jbd2/journal.c |    3 ++-
>  1 files changed, 2 insertions(+), 1 deletions(-)
> 
> diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
> index 90407b8..33dd3ef 100644
> --- a/fs/jbd2/journal.c
> +++ b/fs/jbd2/journal.c
> @@ -2413,10 +2413,12 @@ const char *jbd2_dev_to_name(dev_t device)
>  	new_dev = kmalloc(sizeof(struct devname_cache), GFP_KERNEL);
>  	if (!new_dev)
>  		return "NODEV-ALLOCFAILURE"; /* Something non-NULL */
> +	bd = bdget(device);
>  	spin_lock(&devname_cache_lock);
>  	if (devcache[i]) {
>  		if (devcache[i]->device == device) {
>  			kfree(new_dev);
> +			bdput(bd);
>  			ret = devcache[i]->devname;
>  			spin_unlock(&devname_cache_lock);
>  			return ret;
> @@ -2425,7 +2427,6 @@ const char *jbd2_dev_to_name(dev_t device)
>  	}
>  	devcache[i] = new_dev;
>  	devcache[i]->device = device;
> -	bd = bdget(device);
>  	if (bd) {
>  		bdevname(bd, devcache[i]->devname);
>  		bdput(bd);
> -- 
> 1.7.4
>
Theodore Ts'o - April 4, 2011, 4:36 p.m.
On Sat, Apr 02, 2011 at 05:01:16PM +0800, Zhu Yanhai wrote:
> bdget() should not be called when we hold spinlocks since
> it might sleep.
> 
> Signed-off-by: Zhu Yanhai <gaoyang.zyh@taobao.com>

I've added the patch to the patch queue.  Technically we should never
have a problem, though, since we only use this for the journal inode,
which is not going to be a fresly created inode.  So I don't think we
should ever hit the paths that will result in the kernel sleeping.
But I agree it's better to move it out, if for no other reason to make
life easier for static checkers.

          	       	     	       	    - Ted
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Patch

diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
index 90407b8..33dd3ef 100644
--- a/fs/jbd2/journal.c
+++ b/fs/jbd2/journal.c
@@ -2413,10 +2413,12 @@  const char *jbd2_dev_to_name(dev_t device)
 	new_dev = kmalloc(sizeof(struct devname_cache), GFP_KERNEL);
 	if (!new_dev)
 		return "NODEV-ALLOCFAILURE"; /* Something non-NULL */
+	bd = bdget(device);
 	spin_lock(&devname_cache_lock);
 	if (devcache[i]) {
 		if (devcache[i]->device == device) {
 			kfree(new_dev);
+			bdput(bd);
 			ret = devcache[i]->devname;
 			spin_unlock(&devname_cache_lock);
 			return ret;
@@ -2425,7 +2427,6 @@  const char *jbd2_dev_to_name(dev_t device)
 	}
 	devcache[i] = new_dev;
 	devcache[i]->device = device;
-	bd = bdget(device);
 	if (bd) {
 		bdevname(bd, devcache[i]->devname);
 		bdput(bd);