Re: [PATCH 09/10] FIX: Honor !reshape state on wait_reshape() entry

[Neil Brown <neilb@suse.de>]

On Thu, 02 Dec 2010 09:19:51 +0100 Adam Kwolek <adam.kwolek@intel.com> wrote:

> When wait_reshape() function starts it can occurs that reshape is finished already,
> before wait_reshape() start. This can lead to wait for change state inside this function for a long time.
> To avoid this before wait we should test if finish conditions are not reached already.
> 
> Signed-off-by: Adam Kwolek <adam.kwolek@intel.com>
> ---
> 
>  Grow.c |   19 ++++++++++++-------
>  1 files changed, 12 insertions(+), 7 deletions(-)
> 
> diff --git a/Grow.c b/Grow.c
> index 96c9526..24c5c39 100644
> --- a/Grow.c
> +++ b/Grow.c
> @@ -548,17 +548,22 @@ static void wait_reshape(struct mdinfo *sra)
>  	int fd = sysfs_get_fd(sra, NULL, "sync_action");
>  	char action[20];
>  
> -	do {
> +	if (fd < 0)
> +		return;
> +
> +	if (sysfs_fd_get_str(fd, action, 20) < 0) {
> +		close(fd);
> +		return;
> +	}
> +	while  (strncmp(action, "reshape", 7) == 0) {
>  		fd_set rfds;
>  		FD_ZERO(&rfds);
>  		FD_SET(fd, &rfds);
>  		select(fd+1, NULL, NULL, &rfds, NULL);
> -		
> -		if (sysfs_fd_get_str(fd, action, 20) < 0) {
> -			close(fd);
> -			return;
> -		}
> -	} while  (strncmp(action, "reshape", 7) == 0);
> +		if (sysfs_fd_get_str(fd, action, 20) < 0)
> +			break;
> +	}
> +	close(fd);
>  }
>  
>  static int reshape_super(struct supertype *st, long long size, int level,


Thanks for this fix.  There is room to tidy the code up even more. This is
what I have applied.

Thanks,
NeilBrown

commit 92a19f1a78e040202e3d067960e3b1ecc8162881
Author: Adam Kwolek <adam.kwolek@intel.com>
Date:   Fri Dec 3 15:10:20 2010 +1100

    FIX: Honor !reshape state on wait_reshape() entry
    
    When wait_reshape() function starts it can occurs that reshape is
    finished already, before wait_reshape() start. This can lead to wait
    for change state inside this function for a long time.  To avoid this
    before wait we should test if finish conditions are not reached
    already.
    
    Signed-off-by: Adam Kwolek <adam.kwolek@intel.com>
    Signed-off-by: NeilBrown <neilb@suse.de>

diff --git a/Grow.c b/Grow.c
index c408a92..3322cf7 100644
--- a/Grow.c
+++ b/Grow.c
@@ -548,17 +548,17 @@ static void wait_reshape(struct mdinfo *sra)
 	int fd = sysfs_get_fd(sra, NULL, "sync_action");
 	char action[20];
 
-	do {
+	if (fd < 0)
+		return;
+
+	while  (sysfs_fd_get_str(fd, action, 20) > 0 &&
+		strncmp(action, "reshape", 7) == 0) {
 		fd_set rfds;
 		FD_ZERO(&rfds);
 		FD_SET(fd, &rfds);
 		select(fd+1, NULL, NULL, &rfds, NULL);
-		
-		if (sysfs_fd_get_str(fd, action, 20) < 0) {
-			close(fd);
-			return;
-		}
-	} while  (strncmp(action, "reshape", 7) == 0);
+	}
+	close(fd);
 }
 
 static int reshape_super(struct supertype *st, long long size, int level,